From d6eaa63992a921db979678b2a83fbc60a9a3e2e4 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 14:10:41 -0400
Subject: [PATCH 01/10] Add a second type parameter to FirestoreDataConverter
 to fix the updateDoc() typing issue

---
 packages/firestore/src/api/aggregate.ts       |  51 ++--
 packages/firestore/src/api/reference_impl.ts  | 215 ++++++++++------
 packages/firestore/src/api/snapshot.ts        |  95 ++++---
 packages/firestore/src/api/transaction.ts     |   8 +-
 .../firestore/src/core/firestore_client.ts    |   2 +
 packages/firestore/src/lite-api/aggregate.ts  |  58 +++--
 .../firestore/src/lite-api/aggregate_types.ts |  16 +-
 packages/firestore/src/lite-api/query.ts      |  71 +++--
 packages/firestore/src/lite-api/reference.ts  | 242 +++++++++++-------
 .../firestore/src/lite-api/reference_impl.ts  |  92 ++++---
 packages/firestore/src/lite-api/snapshot.ts   |  75 ++++--
 .../firestore/src/lite-api/transaction.ts     |  45 ++--
 .../src/lite-api/user_data_reader.ts          |  15 +-
 .../firestore/src/lite-api/write_batch.ts     |  51 ++--
 .../firestore/test/lite/integration.test.ts   |  79 +++---
 15 files changed, 689 insertions(+), 426 deletions(-)

diff --git a/packages/firestore/src/api/aggregate.ts b/packages/firestore/src/api/aggregate.ts
index 0b9dfd353e3..9628beac32c 100644
--- a/packages/firestore/src/api/aggregate.ts
+++ b/packages/firestore/src/api/aggregate.ts
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { AggregateField, AggregateSpec, Query } from '../api';
+import { AggregateField, AggregateSpec, DocumentData, Query } from '../api';
 import { AggregateImpl } from '../core/aggregate';
 import { firestoreClientRunAggregateQuery } from '../core/firestore_client';
 import { count } from '../lite-api/aggregate';
@@ -56,9 +56,18 @@ export {
  * retrieved from `snapshot.data().count`, where `snapshot` is the
  * `AggregateQuerySnapshot` to which the returned Promise resolves.
  */
-export function getCountFromServer(
-  query: Query<unknown>
-): Promise<AggregateQuerySnapshot<{ count: AggregateField<number> }>> {
+export function getCountFromServer<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>
+): Promise<
+  AggregateQuerySnapshot<
+    { count: AggregateField<number> },
+    AppModelType,
+    DbModelType
+  >
+> {
   const countQuerySpec: { count: AggregateField<number> } = {
     count: count()
   };
@@ -100,10 +109,16 @@ export function getCountFromServer(
  * ```
  * @internal TODO (sum/avg) remove when public
  */
-export function getAggregateFromServer<T extends AggregateSpec>(
-  query: Query<unknown>,
-  aggregateSpec: T
-): Promise<AggregateQuerySnapshot<T>> {
+export function getAggregateFromServer<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>,
+  aggregateSpec: AggregateSpecType
+): Promise<
+  AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>
+> {
   const firestore = cast(query.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
 
@@ -132,16 +147,20 @@ export function getAggregateFromServer<T extends AggregateSpec>(
  * @param aggregateResult Core aggregation result
  * @internal
  */
-function convertToAggregateQuerySnapshot<T extends AggregateSpec>(
+function convertToAggregateQuerySnapshot<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType,
+  DbModelType extends DocumentData
+>(
   firestore: Firestore,
-  query: Query<unknown>,
+  query: Query<AppModelType, DbModelType>,
   aggregateResult: ApiClientObjectMap<Value>
-): AggregateQuerySnapshot<T> {
+): AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType> {
   const userDataWriter = new ExpUserDataWriter(firestore);
-  const querySnapshot = new AggregateQuerySnapshot<T>(
-    query,
-    userDataWriter,
-    aggregateResult
-  );
+  const querySnapshot = new AggregateQuerySnapshot<
+    AggregateSpecType,
+    AppModelType,
+    DbModelType
+  >(query, userDataWriter, aggregateResult);
   return querySnapshot;
 }
diff --git a/packages/firestore/src/api/reference_impl.ts b/packages/firestore/src/api/reference_impl.ts
index eabd0fb0021..13cfb09f518 100644
--- a/packages/firestore/src/api/reference_impl.ts
+++ b/packages/firestore/src/api/reference_impl.ts
@@ -41,6 +41,7 @@ import { validateHasExplicitOrderByForLimitToLast } from '../lite-api/query';
 import {
   CollectionReference,
   doc,
+  DocumentData,
   DocumentReference,
   PartialWithFieldValue,
   Query,
@@ -91,10 +92,13 @@ export interface SnapshotListenOptions {
  * @returns A Promise resolved with a `DocumentSnapshot` containing the
  * current document contents.
  */
-export function getDoc<T>(
-  reference: DocumentReference<T>
-): Promise<DocumentSnapshot<T>> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+export function getDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>
+): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const firestore = cast(reference.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
 
@@ -126,17 +130,20 @@ export class ExpUserDataWriter extends AbstractUserDataWriter {
  * @returns A `Promise` resolved with a `DocumentSnapshot` containing the
  * current document contents.
  */
-export function getDocFromCache<T>(
-  reference: DocumentReference<T>
-): Promise<DocumentSnapshot<T>> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+export function getDocFromCache<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>
+): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const firestore = cast(reference.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
   const userDataWriter = new ExpUserDataWriter(firestore);
 
   return firestoreClientGetDocumentFromLocalCache(client, reference._key).then(
     doc =>
-      new DocumentSnapshot(
+      new DocumentSnapshot<AppModelType, DbModelType>(
         firestore,
         userDataWriter,
         reference._key,
@@ -157,10 +164,16 @@ export function getDocFromCache<T>(
  * @returns A `Promise` resolved with a `DocumentSnapshot` containing the
  * current document contents.
  */
-export function getDocFromServer<T>(
-  reference: DocumentReference<T>
-): Promise<DocumentSnapshot<T>> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+export function getDocFromServer<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  reference: DocumentReference<AppModelType, DbModelType>
+): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const firestore = cast(reference.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
 
@@ -179,8 +192,10 @@ export function getDocFromServer<T>(
  *
  * @returns A `Promise` that will be resolved with the results of the query.
  */
-export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
-  query = cast<Query<T>>(query, Query);
+export function getDocs<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>
+): Promise<QuerySnapshot<AppModelType, DbModelType>> {
+  query = cast<Query<AppModelType, DbModelType>>(query, Query);
   const firestore = cast(query.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
   const userDataWriter = new ExpUserDataWriter(firestore);
@@ -190,7 +205,13 @@ export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
     client,
     query._query
   ).then(
-    snapshot => new QuerySnapshot(firestore, userDataWriter, query, snapshot)
+    snapshot =>
+      new QuerySnapshot<AppModelType, DbModelType>(
+        firestore,
+        userDataWriter,
+        query,
+        snapshot
+      )
   );
 }
 
@@ -201,16 +222,25 @@ export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
  *
  * @returns A `Promise` that will be resolved with the results of the query.
  */
-export function getDocsFromCache<T>(
-  query: Query<T>
-): Promise<QuerySnapshot<T>> {
-  query = cast<Query<T>>(query, Query);
+export function getDocsFromCache<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>
+): Promise<QuerySnapshot<AppModelType, DbModelType>> {
+  query = cast<Query<AppModelType, DbModelType>>(query, Query);
   const firestore = cast(query.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
   const userDataWriter = new ExpUserDataWriter(firestore);
 
   return firestoreClientGetDocumentsFromLocalCache(client, query._query).then(
-    snapshot => new QuerySnapshot(firestore, userDataWriter, query, snapshot)
+    snapshot =>
+      new QuerySnapshot<AppModelType, DbModelType>(
+        firestore,
+        userDataWriter,
+        query,
+        snapshot
+      )
   );
 }
 
@@ -220,10 +250,13 @@ export function getDocsFromCache<T>(
  *
  * @returns A `Promise` that will be resolved with the results of the query.
  */
-export function getDocsFromServer<T>(
-  query: Query<T>
-): Promise<QuerySnapshot<T>> {
-  query = cast<Query<T>>(query, Query);
+export function getDocsFromServer<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>
+): Promise<QuerySnapshot<AppModelType, DbModelType>> {
+  query = cast<Query<AppModelType, DbModelType>>(query, Query);
   const firestore = cast(query.firestore, Firestore);
   const client = ensureFirestoreConfigured(firestore);
   const userDataWriter = new ExpUserDataWriter(firestore);
@@ -244,9 +277,9 @@ export function getDocsFromServer<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend (note that it won't resolve while you're offline).
  */
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: WithFieldValue<T>
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: WithFieldValue<AppModelType>
 ): Promise<void>;
 /**
  * Writes to the document referred to by the specified `DocumentReference`. If
@@ -259,22 +292,25 @@ export function setDoc<T>(
  * @returns A Promise resolved once the data has been successfully written
  * to the backend (note that it won't resolve while you're offline).
  */
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: PartialWithFieldValue<T>,
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: PartialWithFieldValue<AppModelType>,
   options: SetOptions
 ): Promise<void>;
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: PartialWithFieldValue<T>,
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: PartialWithFieldValue<AppModelType>,
   options?: SetOptions
 ): Promise<void> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const firestore = cast(reference.firestore, Firestore);
 
   const convertedValue = applyFirestoreDataConverter(
     reference.converter,
-    data as WithFieldValue<T>,
+    data as WithFieldValue<AppModelType>,
     options
   );
   const dataReader = newUserDataReader(firestore);
@@ -303,9 +339,9 @@ export function setDoc<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend (note that it won't resolve while you're offline).
  */
-export function updateDoc<T>(
-  reference: DocumentReference<T>,
-  data: UpdateData<T>
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: UpdateData<DbModelType>
 ): Promise<void>;
 /**
  * Updates fields in the document referred to by the specified
@@ -322,19 +358,22 @@ export function updateDoc<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend (note that it won't resolve while you're offline).
  */
-export function updateDoc(
-  reference: DocumentReference<unknown>,
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   field: string | FieldPath,
   value: unknown,
   ...moreFieldsAndValues: unknown[]
 ): Promise<void>;
-export function updateDoc<T>(
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
   reference: DocumentReference<unknown>,
-  fieldOrUpdateData: string | FieldPath | UpdateData<T>,
+  fieldOrUpdateData: string | FieldPath | UpdateData<DbModelType>,
   value?: unknown,
   ...moreFieldsAndValues: unknown[]
 ): Promise<void> {
-  reference = cast<DocumentReference<unknown>>(reference, DocumentReference);
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const firestore = cast(reference.firestore, Firestore);
 
   const dataReader = newUserDataReader(firestore);
@@ -376,8 +415,8 @@ export function updateDoc<T>(
  * @returns A Promise resolved once the document has been successfully
  * deleted from the backend (note that it won't resolve while you're offline).
  */
-export function deleteDoc(
-  reference: DocumentReference<unknown>
+export function deleteDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>
 ): Promise<void> {
   const firestore = cast(reference.firestore, Firestore);
   const mutations = [new DeleteMutation(reference._key, Precondition.none())];
@@ -394,10 +433,10 @@ export function deleteDoc(
  * newly created document after it has been written to the backend (Note that it
  * won't resolve while you're offline).
  */
-export function addDoc<T>(
-  reference: CollectionReference<T>,
-  data: WithFieldValue<T>
-): Promise<DocumentReference<T>> {
+export function addDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: CollectionReference<AppModelType, DbModelType>,
+  data: WithFieldValue<AppModelType>
+): Promise<DocumentReference<AppModelType, DbModelType>> {
   const firestore = cast(reference.firestore, Firestore);
 
   const docRef = doc(reference);
@@ -441,10 +480,10 @@ export interface Unsubscribe {
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  reference: DocumentReference<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
   }
@@ -463,11 +502,11 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  reference: DocumentReference<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   options: SnapshotListenOptions,
   observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
   }
@@ -490,9 +529,9 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  reference: DocumentReference<T>,
-  onNext: (snapshot: DocumentSnapshot<T>) => void,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void,
   onError?: (error: FirestoreError) => void,
   onCompletion?: () => void
 ): Unsubscribe;
@@ -515,10 +554,10 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  reference: DocumentReference<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   options: SnapshotListenOptions,
-  onNext: (snapshot: DocumentSnapshot<T>) => void,
+  onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void,
   onError?: (error: FirestoreError) => void,
   onCompletion?: () => void
 ): Unsubscribe;
@@ -536,10 +575,10 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  query: Query<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
   }
@@ -559,11 +598,11 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  query: Query<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   options: SnapshotListenOptions,
   observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
   }
@@ -587,9 +626,9 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  query: Query<T>,
-  onNext: (snapshot: QuerySnapshot<T>) => void,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
+  onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void,
   onError?: (error: FirestoreError) => void,
   onCompletion?: () => void
 ): Unsubscribe;
@@ -613,15 +652,17 @@ export function onSnapshot<T>(
  * @returns An unsubscribe function that can be called to cancel
  * the snapshot listener.
  */
-export function onSnapshot<T>(
-  query: Query<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   options: SnapshotListenOptions,
-  onNext: (snapshot: QuerySnapshot<T>) => void,
+  onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void,
   onError?: (error: FirestoreError) => void,
   onCompletion?: () => void
 ): Unsubscribe;
-export function onSnapshot<T>(
-  reference: Query<T> | DocumentReference<T>,
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(
+  reference:
+    | Query<AppModelType, DbModelType>
+    | DocumentReference<AppModelType, DbModelType>,
   ...args: unknown[]
 ): Unsubscribe {
   reference = getModularInstance(reference);
@@ -640,7 +681,9 @@ export function onSnapshot<T>(
   };
 
   if (isPartialObserver(args[currArg])) {
-    const userObserver = args[currArg] as PartialObserver<QuerySnapshot<T>>;
+    const userObserver = args[currArg] as PartialObserver<
+      QuerySnapshot<AppModelType, DbModelType>
+    >;
     args[currArg] = userObserver.next?.bind(userObserver);
     args[currArg + 1] = userObserver.error?.bind(userObserver);
     args[currArg + 2] = userObserver.complete?.bind(userObserver);
@@ -657,10 +700,12 @@ export function onSnapshot<T>(
     observer = {
       next: snapshot => {
         if (args[currArg]) {
-          (args[currArg] as NextFn<DocumentSnapshot<T>>)(
+          (
+            args[currArg] as NextFn<DocumentSnapshot<AppModelType, DbModelType>>
+          )(
             convertToDocSnapshot(
               firestore,
-              reference as DocumentReference<T>,
+              reference as DocumentReference<AppModelType, DbModelType>,
               snapshot
             )
           );
@@ -670,7 +715,7 @@ export function onSnapshot<T>(
       complete: args[currArg + 2] as CompleteFn
     };
   } else {
-    const query = cast<Query<T>>(reference, Query);
+    const query = cast<Query<AppModelType, DbModelType>>(reference, Query);
     firestore = cast(query.firestore, Firestore);
     internalQuery = query._query;
     const userDataWriter = new ExpUserDataWriter(firestore);
@@ -678,7 +723,7 @@ export function onSnapshot<T>(
     observer = {
       next: snapshot => {
         if (args[currArg]) {
-          (args[currArg] as NextFn<QuerySnapshot<T>>)(
+          (args[currArg] as NextFn<QuerySnapshot<AppModelType, DbModelType>>)(
             new QuerySnapshot(firestore, userDataWriter, query, snapshot)
           );
         }
@@ -776,11 +821,11 @@ export function executeWrite(
  * Converts a {@link ViewSnapshot} that contains the single document specified by `ref`
  * to a {@link DocumentSnapshot}.
  */
-function convertToDocSnapshot<T>(
+function convertToDocSnapshot<AppModelType, DbModelType extends DocumentData>(
   firestore: Firestore,
-  ref: DocumentReference<T>,
+  ref: DocumentReference<AppModelType, DbModelType>,
   snapshot: ViewSnapshot
-): DocumentSnapshot<T> {
+): DocumentSnapshot<AppModelType, DbModelType> {
   debugAssert(
     snapshot.docs.size <= 1,
     'Expected zero or a single result on a document-only query'
@@ -788,7 +833,7 @@ function convertToDocSnapshot<T>(
   const doc = snapshot.docs.get(ref._key);
 
   const userDataWriter = new ExpUserDataWriter(firestore);
-  return new DocumentSnapshot(
+  return new DocumentSnapshot<AppModelType, DbModelType>(
     firestore,
     userDataWriter,
     ref._key,
diff --git a/packages/firestore/src/api/snapshot.ts b/packages/firestore/src/api/snapshot.ts
index 658cb728da4..85671408f1d 100644
--- a/packages/firestore/src/api/snapshot.ts
+++ b/packages/firestore/src/api/snapshot.ts
@@ -83,8 +83,10 @@ import { SnapshotListenOptions } from './reference_impl';
  * }
  * ```
  */
-export interface FirestoreDataConverter<T>
-  extends LiteFirestoreDataConverter<T> {
+export interface FirestoreDataConverter<
+  AppModelType,
+  DbModelType extends DocumentData = DocumentData
+> extends LiteFirestoreDataConverter<AppModelType, DbModelType> {
   /**
    * Called by the Firestore SDK to convert a custom model object of type `T`
    * into a plain JavaScript object (suitable for writing directly to the
@@ -94,7 +96,9 @@ export interface FirestoreDataConverter<T>
    * The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as
    * {@link (deleteField:1)} to be used as property values.
    */
-  toFirestore(modelObject: WithFieldValue<T>): DocumentData;
+  toFirestore(
+    modelObject: WithFieldValue<AppModelType>
+  ): WithFieldValue<DbModelType>;
 
   /**
    * Called by the Firestore SDK to convert a custom model object of type `T`
@@ -108,9 +112,9 @@ export interface FirestoreDataConverter<T>
    * omitted.
    */
   toFirestore(
-    modelObject: PartialWithFieldValue<T>,
+    modelObject: PartialWithFieldValue<AppModelType>,
     options: SetOptions
-  ): DocumentData;
+  ): PartialWithFieldValue<DbModelType>;
 
   /**
    * Called by the Firestore SDK to convert Firestore data into an object of
@@ -120,9 +124,9 @@ export interface FirestoreDataConverter<T>
    * @param options - The `SnapshotOptions` from the initial call to `data()`.
    */
   fromFirestore(
-    snapshot: QueryDocumentSnapshot<DocumentData>,
+    snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>,
     options?: SnapshotOptions
-  ): T;
+  ): AppModelType;
 }
 
 /**
@@ -200,12 +204,15 @@ export type DocumentChangeType = 'added' | 'removed' | 'modified';
  * A `DocumentChange` represents a change to the documents matching a query.
  * It contains the document affected and the type of change that occurred.
  */
-export interface DocumentChange<T = DocumentData> {
+export interface DocumentChange<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   /** The type of change ('added', 'modified', or 'removed'). */
   readonly type: DocumentChangeType;
 
   /** The document affected by this change. */
-  readonly doc: QueryDocumentSnapshot<T>;
+  readonly doc: QueryDocumentSnapshot<AppModelType, DbModelType>;
 
   /**
    * The index of the changed document in the result set immediately prior to
@@ -233,8 +240,9 @@ export interface DocumentChange<T = DocumentData> {
  * explicitly verify a document's existence.
  */
 export class DocumentSnapshot<
-  T = DocumentData
-> extends LiteDocumentSnapshot<T> {
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> extends LiteDocumentSnapshot<AppModelType, DbModelType> {
   private readonly _firestoreImpl: Firestore;
 
   /**
@@ -250,7 +258,7 @@ export class DocumentSnapshot<
     key: DocumentKey,
     document: Document | null,
     metadata: SnapshotMetadata,
-    converter: UntypedFirestoreDataConverter<T> | null
+    converter: UntypedFirestoreDataConverter<AppModelType, DbModelType> | null
   ) {
     super(_firestore, userDataWriter, key, document, converter);
     this._firestoreImpl = _firestore;
@@ -260,7 +268,7 @@ export class DocumentSnapshot<
   /**
    * Returns whether or not the data exists. True if the document exists.
    */
-  exists(): this is QueryDocumentSnapshot<T> {
+  exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType> {
     return super.exists();
   }
 
@@ -278,7 +286,7 @@ export class DocumentSnapshot<
    * @returns An `Object` containing all fields in the document or `undefined` if
    * the document doesn't exist.
    */
-  data(options: SnapshotOptions = {}): T | undefined {
+  data(options: SnapshotOptions = {}): AppModelType | undefined {
     if (!this._document) {
       return undefined;
     } else if (this._converter) {
@@ -297,7 +305,7 @@ export class DocumentSnapshot<
       return this._userDataWriter.convertValue(
         this._document.data.value,
         options.serverTimestamps
-      ) as T;
+      ) as AppModelType;
     }
   }
 
@@ -347,8 +355,9 @@ export class DocumentSnapshot<
  * 'undefined'.
  */
 export class QueryDocumentSnapshot<
-  T = DocumentData
-> extends DocumentSnapshot<T> {
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> extends DocumentSnapshot<AppModelType, DbModelType> {
   /**
    * Retrieves all fields in the document as an `Object`.
    *
@@ -362,8 +371,8 @@ export class QueryDocumentSnapshot<
    * have not yet been set to their final value).
    * @returns An `Object` containing all fields in the document.
    */
-  data(options: SnapshotOptions = {}): T {
-    return super.data(options) as T;
+  data(options: SnapshotOptions = {}): AppModelType {
+    return super.data(options) as AppModelType;
   }
 }
 
@@ -374,7 +383,10 @@ export class QueryDocumentSnapshot<
  * number of documents can be determined via the `empty` and `size`
  * properties.
  */
-export class QuerySnapshot<T = DocumentData> {
+export class QuerySnapshot<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   /**
    * Metadata about this snapshot, concerning its source and if it has local
    * modifications.
@@ -385,16 +397,16 @@ export class QuerySnapshot<T = DocumentData> {
    * The query on which you called `get` or `onSnapshot` in order to get this
    * `QuerySnapshot`.
    */
-  readonly query: Query<T>;
+  readonly query: Query<AppModelType, DbModelType>;
 
-  private _cachedChanges?: Array<DocumentChange<T>>;
+  private _cachedChanges?: Array<DocumentChange<AppModelType, DbModelType>>;
   private _cachedChangesIncludeMetadataChanges?: boolean;
 
   /** @hideconstructor */
   constructor(
     readonly _firestore: Firestore,
     readonly _userDataWriter: AbstractUserDataWriter,
-    query: Query<T>,
+    query: Query<AppModelType, DbModelType>,
     readonly _snapshot: ViewSnapshot
   ) {
     this.metadata = new SnapshotMetadata(
@@ -405,8 +417,8 @@ export class QuerySnapshot<T = DocumentData> {
   }
 
   /** An array of all the documents in the `QuerySnapshot`. */
-  get docs(): Array<QueryDocumentSnapshot<T>> {
-    const result: Array<QueryDocumentSnapshot<T>> = [];
+  get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>> {
+    const result: Array<QueryDocumentSnapshot<AppModelType, DbModelType>> = [];
     this.forEach(doc => result.push(doc));
     return result;
   }
@@ -429,13 +441,15 @@ export class QuerySnapshot<T = DocumentData> {
    * @param thisArg - The `this` binding for the callback.
    */
   forEach(
-    callback: (result: QueryDocumentSnapshot<T>) => void,
+    callback: (
+      result: QueryDocumentSnapshot<AppModelType, DbModelType>
+    ) => void,
     thisArg?: unknown
   ): void {
     this._snapshot.docs.forEach(doc => {
       callback.call(
         thisArg,
-        new QueryDocumentSnapshot<T>(
+        new QueryDocumentSnapshot<AppModelType, DbModelType>(
           this._firestore,
           this._userDataWriter,
           doc.key,
@@ -459,7 +473,9 @@ export class QuerySnapshot<T = DocumentData> {
    * changes (i.e. only `DocumentSnapshot.metadata` changed) should trigger
    * snapshot events.
    */
-  docChanges(options: SnapshotListenOptions = {}): Array<DocumentChange<T>> {
+  docChanges(
+    options: SnapshotListenOptions = {}
+  ): Array<DocumentChange<AppModelType, DbModelType>> {
     const includeMetadataChanges = !!options.includeMetadataChanges;
 
     if (includeMetadataChanges && this._snapshot.excludesMetadataChanges) {
@@ -483,10 +499,13 @@ export class QuerySnapshot<T = DocumentData> {
 }
 
 /** Calculates the array of `DocumentChange`s for a given `ViewSnapshot`. */
-export function changesFromSnapshot<T>(
-  querySnapshot: QuerySnapshot<T>,
+export function changesFromSnapshot<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  querySnapshot: QuerySnapshot<AppModelType, DbModelType>,
   includeMetadataChanges: boolean
-): Array<DocumentChange<T>> {
+): Array<DocumentChange<AppModelType, DbModelType>> {
   if (querySnapshot._snapshot.oldDocs.isEmpty()) {
     // Special case the first snapshot because index calculation is easy and
     // fast
@@ -505,7 +524,7 @@ export function changesFromSnapshot<T>(
           ) < 0,
         'Got added events in wrong order'
       );
-      const doc = new QueryDocumentSnapshot<T>(
+      const doc = new QueryDocumentSnapshot<AppModelType, DbModelType>(
         querySnapshot._firestore,
         querySnapshot._userDataWriter,
         change.doc.key,
@@ -533,7 +552,7 @@ export function changesFromSnapshot<T>(
         change => includeMetadataChanges || change.type !== ChangeType.Metadata
       )
       .map(change => {
-        const doc = new QueryDocumentSnapshot<T>(
+        const doc = new QueryDocumentSnapshot<AppModelType, DbModelType>(
           querySnapshot._firestore,
           querySnapshot._userDataWriter,
           change.doc.key,
@@ -588,9 +607,13 @@ export function resultChangeType(type: ChangeType): DocumentChangeType {
  * @param right - A snapshot to compare.
  * @returns true if the snapshots are equal.
  */
-export function snapshotEqual<T>(
-  left: DocumentSnapshot<T> | QuerySnapshot<T>,
-  right: DocumentSnapshot<T> | QuerySnapshot<T>
+export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(
+  left:
+    | DocumentSnapshot<AppModelType, DbModelType>
+    | QuerySnapshot<AppModelType, DbModelType>,
+  right:
+    | DocumentSnapshot<AppModelType, DbModelType>
+    | QuerySnapshot<AppModelType, DbModelType>
 ): boolean {
   if (left instanceof DocumentSnapshot && right instanceof DocumentSnapshot) {
     return (
diff --git a/packages/firestore/src/api/transaction.ts b/packages/firestore/src/api/transaction.ts
index a70cfba231d..a1deab9e295 100644
--- a/packages/firestore/src/api/transaction.ts
+++ b/packages/firestore/src/api/transaction.ts
@@ -22,7 +22,7 @@ import {
   DEFAULT_TRANSACTION_OPTIONS,
   validateTransactionOptions
 } from '../core/transaction_options';
-import { DocumentReference } from '../lite-api/reference';
+import { DocumentData, DocumentReference } from '../lite-api/reference';
 import { Transaction as LiteTransaction } from '../lite-api/transaction';
 import { validateReference } from '../lite-api/write_batch';
 import { cast } from '../util/input_validation';
@@ -57,8 +57,10 @@ export class Transaction extends LiteTransaction {
    * @param documentRef - A reference to the document to be read.
    * @returns A `DocumentSnapshot` with the read data.
    */
-  get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>> {
-    const ref = validateReference<T>(documentRef, this._firestore);
+  get<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>
+  ): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
+    const ref = validateReference(documentRef, this._firestore);
     const userDataWriter = new ExpUserDataWriter(this._firestore);
     return super
       .get(documentRef)
diff --git a/packages/firestore/src/core/firestore_client.ts b/packages/firestore/src/core/firestore_client.ts
index df6127f978e..595cdb0ca01 100644
--- a/packages/firestore/src/core/firestore_client.ts
+++ b/packages/firestore/src/core/firestore_client.ts
@@ -91,6 +91,8 @@ import { TransactionOptions } from './transaction_options';
 import { TransactionRunner } from './transaction_runner';
 import { View } from './view';
 import { ViewSnapshot } from './view_snapshot';
+import { AggregateSpec } from '../lite-api/aggregate_types';
+import { DocumentData } from '../lite-api/reference';
 
 const LOG_TAG = 'FirestoreClient';
 export const MAX_CONCURRENT_LIMBO_RESOLUTIONS = 100;
diff --git a/packages/firestore/src/lite-api/aggregate.ts b/packages/firestore/src/lite-api/aggregate.ts
index 33e8012245e..20cf8805c23 100644
--- a/packages/firestore/src/lite-api/aggregate.ts
+++ b/packages/firestore/src/lite-api/aggregate.ts
@@ -31,7 +31,7 @@ import {
 import { getDatastore } from './components';
 import { Firestore } from './database';
 import { FieldPath } from './field_path';
-import { Query, queryEqual } from './reference';
+import { DocumentData, Query, queryEqual } from './reference';
 import { LiteUserDataWriter } from './reference_impl';
 import { fieldPathFromArgument } from './user_data_reader';
 
@@ -49,9 +49,15 @@ import { fieldPathFromArgument } from './user_data_reader';
  * retrieved from `snapshot.data().count`, where `snapshot` is the
  * `AggregateQuerySnapshot` to which the returned Promise resolves.
  */
-export function getCount(
-  query: Query<unknown>
-): Promise<AggregateQuerySnapshot<{ count: AggregateField<number> }>> {
+export function getCount<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>
+): Promise<
+  AggregateQuerySnapshot<
+    { count: AggregateField<number> },
+    AppModelType,
+    DbModelType
+  >
+> {
   const countQuerySpec: { count: AggregateField<number> } = {
     count: count()
   };
@@ -86,10 +92,16 @@ export function getCount(
  * ```
  * @internal TODO (sum/avg) remove when public
  */
-export function getAggregate<T extends AggregateSpec>(
-  query: Query<unknown>,
-  aggregateSpec: T
-): Promise<AggregateQuerySnapshot<T>> {
+export function getAggregate<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>,
+  aggregateSpec: AggregateSpecType
+): Promise<
+  AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>
+> {
   const firestore = cast(query.firestore, Firestore);
   const datastore = getDatastore(firestore);
 
@@ -111,17 +123,21 @@ export function getAggregate<T extends AggregateSpec>(
   );
 }
 
-function convertToAggregateQuerySnapshot<T extends AggregateSpec>(
+function convertToAggregateQuerySnapshot<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType,
+  DbModelType extends DocumentData
+>(
   firestore: Firestore,
-  query: Query<unknown>,
+  query: Query<AppModelType, DbModelType>,
   aggregateResult: ApiClientObjectMap<Value>
-): AggregateQuerySnapshot<T> {
+): AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType> {
   const userDataWriter = new LiteUserDataWriter(firestore);
-  const querySnapshot = new AggregateQuerySnapshot<T>(
-    query,
-    userDataWriter,
-    aggregateResult
-  );
+  const querySnapshot = new AggregateQuerySnapshot<
+    AggregateSpecType,
+    AppModelType,
+    DbModelType
+  >(query, userDataWriter, aggregateResult);
   return querySnapshot;
 }
 
@@ -188,9 +204,13 @@ export function aggregateFieldEqual(
  * @returns `true` if the objects are "equal", as defined above, or `false`
  * otherwise.
  */
-export function aggregateQuerySnapshotEqual<T extends AggregateSpec>(
-  left: AggregateQuerySnapshot<T>,
-  right: AggregateQuerySnapshot<T>
+export function aggregateQuerySnapshotEqual<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>,
+  right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>
 ): boolean {
   return (
     queryEqual(left.query, right.query) && deepEqual(left.data(), right.data())
diff --git a/packages/firestore/src/lite-api/aggregate_types.ts b/packages/firestore/src/lite-api/aggregate_types.ts
index 9223b783138..8546057cc09 100644
--- a/packages/firestore/src/lite-api/aggregate_types.ts
+++ b/packages/firestore/src/lite-api/aggregate_types.ts
@@ -19,7 +19,7 @@ import { AggregateType } from '../core/aggregate';
 import { FieldPath as InternalFieldPath } from '../model/path';
 import { ApiClientObjectMap, Value } from '../protos/firestore_proto_api';
 
-import { Query } from './reference';
+import { DocumentData, Query } from './reference';
 import { AbstractUserDataWriter } from './user_data_writer';
 
 export { AggregateType };
@@ -71,7 +71,11 @@ export type AggregateSpecData<T extends AggregateSpec> = {
 /**
  * The results of executing an aggregation query.
  */
-export class AggregateQuerySnapshot<T extends AggregateSpec> {
+export class AggregateQuerySnapshot<
+  AggregateSpecType extends AggregateSpec,
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   /** A type string to uniquely identify instances of this class. */
   readonly type = 'AggregateQuerySnapshot';
 
@@ -79,11 +83,11 @@ export class AggregateQuerySnapshot<T extends AggregateSpec> {
    * The underlying query over which the aggregations recorded in this
    * `AggregateQuerySnapshot` were performed.
    */
-  readonly query: Query<unknown>;
+  readonly query: Query<AppModelType, DbModelType>;
 
   /** @hideconstructor */
   constructor(
-    query: Query<unknown>,
+    query: Query<AppModelType, DbModelType>,
     private readonly _userDataWriter: AbstractUserDataWriter,
     private readonly _data: ApiClientObjectMap<Value>
   ) {
@@ -101,9 +105,9 @@ export class AggregateQuerySnapshot<T extends AggregateSpec> {
    * @returns The results of the aggregations performed over the underlying
    * query.
    */
-  data(): AggregateSpecData<T> {
+  data(): AggregateSpecData<AggregateSpecType> {
     return this._userDataWriter.convertObjectMap(
       this._data
-    ) as AggregateSpecData<T>;
+    ) as AggregateSpecData<AggregateSpecType>;
   }
 }
diff --git a/packages/firestore/src/lite-api/query.ts b/packages/firestore/src/lite-api/query.ts
index 3afa282048f..cff35769845 100644
--- a/packages/firestore/src/lite-api/query.ts
+++ b/packages/firestore/src/lite-api/query.ts
@@ -53,7 +53,7 @@ import {
 } from '../util/input_validation';
 
 import { FieldPath } from './field_path';
-import { DocumentReference, Query } from './reference';
+import { DocumentData, DocumentReference, Query } from './reference';
 import { DocumentSnapshot, fieldPathFromArgument } from './snapshot';
 import {
   newUserDataReader,
@@ -95,7 +95,9 @@ export abstract class AppliableConstraint {
    * Takes the provided {@link Query} and returns a copy of the {@link Query} with this
    * {@link AppliableConstraint} applied.
    */
-  abstract _apply<T>(query: Query<T>): Query<T>;
+  abstract _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType>;
 }
 
 /**
@@ -114,7 +116,9 @@ export abstract class QueryConstraint extends AppliableConstraint {
    * Takes the provided {@link Query} and returns a copy of the {@link Query} with this
    * {@link AppliableConstraint} applied.
    */
-  abstract _apply<T>(query: Query<T>): Query<T>;
+  abstract _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType>;
 }
 
 /**
@@ -131,11 +135,11 @@ export abstract class QueryConstraint extends AppliableConstraint {
  * @throws if any of the provided query constraints cannot be combined with the
  * existing or new constraints.
  */
-export function query<T>(
-  query: Query<T>,
+export function query<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   compositeFilter: QueryCompositeFilterConstraint,
   ...queryConstraints: QueryNonFilterConstraint[]
-): Query<T>;
+): Query<AppModelType, DbModelType>;
 
 /**
  * Creates a new immutable instance of {@link Query} that is extended to also
@@ -147,18 +151,18 @@ export function query<T>(
  * @throws if any of the provided query constraints cannot be combined with the
  * existing or new constraints.
  */
-export function query<T>(
-  query: Query<T>,
+export function query<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   ...queryConstraints: QueryConstraint[]
-): Query<T>;
+): Query<AppModelType, DbModelType>;
 
-export function query<T>(
-  query: Query<T>,
+export function query<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>,
   queryConstraint: QueryCompositeFilterConstraint | QueryConstraint | undefined,
   ...additionalQueryConstraints: Array<
     QueryConstraint | QueryNonFilterConstraint
   >
-): Query<T> {
+): Query<AppModelType, DbModelType> {
   let queryConstraints: AppliableConstraint[] = [];
 
   if (queryConstraint instanceof AppliableConstraint) {
@@ -205,7 +209,9 @@ export class QueryFieldFilterConstraint extends QueryConstraint {
     return new QueryFieldFilterConstraint(_field, _op, _value);
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     const filter = this._parse(query);
     validateNewFieldFilter(query._query, filter);
     return new Query(
@@ -215,7 +221,9 @@ export class QueryFieldFilterConstraint extends QueryConstraint {
     );
   }
 
-  _parse<T>(query: Query<T>): FieldFilter {
+  _parse<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): FieldFilter {
     const reader = newUserDataReader(query.firestore);
     const filter = newQueryFilter(
       query._query,
@@ -295,7 +303,9 @@ export class QueryCompositeFilterConstraint extends AppliableConstraint {
     return new QueryCompositeFilterConstraint(type, _queryConstraints);
   }
 
-  _parse<T>(query: Query<T>): Filter {
+  _parse<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Filter {
     const parsedFilters = this._queryConstraints
       .map(queryConstraint => {
         return queryConstraint._parse(query);
@@ -309,7 +319,9 @@ export class QueryCompositeFilterConstraint extends AppliableConstraint {
     return CompositeFilter.create(parsedFilters, this._getOperator());
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     const parsedFilter = this._parse(query);
     if (parsedFilter.getFilters().length === 0) {
       // Return the existing query if not adding any more filters (e.g. an empty
@@ -435,7 +447,9 @@ export class QueryOrderByConstraint extends QueryConstraint {
     return new QueryOrderByConstraint(_field, _direction);
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     const orderBy = newQueryOrderBy(query._query, this._field, this._direction);
     return new Query(
       query.firestore,
@@ -500,7 +514,9 @@ export class QueryLimitConstraint extends QueryConstraint {
     return new QueryLimitConstraint(type, _limit, _limitType);
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     return new Query(
       query.firestore,
       query.converter,
@@ -564,14 +580,16 @@ export class QueryStartAtConstraint extends QueryConstraint {
     return new QueryStartAtConstraint(type, _docOrFields, _inclusive);
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     const bound = newQueryBoundFromDocOrFields(
       query,
       this.type,
       this._docOrFields,
       this._inclusive
     );
-    return new Query(
+    return new Query<AppModelType, DbModelType>(
       query.firestore,
       query.converter,
       queryWithStartAt(query._query, bound)
@@ -671,7 +689,9 @@ export class QueryEndAtConstraint extends QueryConstraint {
     return new QueryEndAtConstraint(type, _docOrFields, _inclusive);
   }
 
-  _apply<T>(query: Query<T>): Query<T> {
+  _apply<AppModelType, DbModelType extends DocumentData>(
+    query: Query<AppModelType, DbModelType>
+  ): Query<AppModelType, DbModelType> {
     const bound = newQueryBoundFromDocOrFields(
       query,
       this.type,
@@ -751,10 +771,13 @@ export function endAt(
 }
 
 /** Helper function to create a bound from a document or fields */
-function newQueryBoundFromDocOrFields<T>(
-  query: Query,
+function newQueryBoundFromDocOrFields<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  query: Query<AppModelType, DbModelType>,
   methodName: string,
-  docOrFields: Array<unknown | DocumentSnapshot<T>>,
+  docOrFields: Array<unknown | DocumentSnapshot<AppModelType, DbModelType>>,
   inclusive: boolean
 ): Bound {
   docOrFields[0] = getModularInstance(docOrFields[0]);
diff --git a/packages/firestore/src/lite-api/reference.ts b/packages/firestore/src/lite-api/reference.ts
index 0a9fdcf71cd..466e22caf39 100644
--- a/packages/firestore/src/lite-api/reference.ts
+++ b/packages/firestore/src/lite-api/reference.ts
@@ -108,12 +108,79 @@ export type SetOptions =
       readonly mergeFields?: Array<string | FieldPath>;
     };
 
+/**
+ * A `Query` refers to a query which you can read or listen to. You can also
+ * construct refined `Query` objects by adding filters and ordering.
+ */
+export class Query<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
+  /** The type of this Firestore reference. */
+  readonly type: 'query' | 'collection' = 'query';
+
+  /**
+   * The `Firestore` instance for the Firestore database (useful for performing
+   * transactions, etc.).
+   */
+  readonly firestore: Firestore;
+
+  // This is the lite version of the Query class in the main SDK.
+
+  /** @hideconstructor protected */
+  constructor(
+    firestore: Firestore,
+    /**
+     * If provided, the `FirestoreDataConverter` associated with this instance.
+     */
+    readonly converter: FirestoreDataConverter<
+      AppModelType,
+      DbModelType
+    > | null,
+    readonly _query: InternalQuery
+  ) {
+    this.firestore = firestore;
+  }
+
+  /**
+   * Removes the current converter.
+   *
+   * @param converter - `null` removes the current converter.
+   * @returns A `Query<DocumentData>` that does not use a converter.
+   */
+  withConverter(converter: null): Query<DocumentData, DocumentData>;
+  /**
+   * Applies a custom data converter to this query, allowing you to use your own
+   * custom model objects with Firestore. When you call {@link getDocs} with
+   * the returned query, the provided converter will convert between Firestore
+   * data and your custom type `U`.
+   *
+   * @param converter - Converts objects to and from Firestore.
+   * @returns A `Query<U>` that uses the provided converter.
+   */
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
+  ): Query<NewAppModelType, NewDbModelType>;
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType> | null
+  ): Query<NewAppModelType, NewDbModelType> {
+    return new Query<NewAppModelType, NewDbModelType>(
+      this.firestore,
+      converter,
+      this._query
+    );
+  }
+}
+
 /**
  * A `DocumentReference` refers to a document location in a Firestore database
  * and can be used to write, read, or listen to the location. The document at
  * the referenced location may or may not exist.
  */
-export class DocumentReference<T = DocumentData> {
+export class DocumentReference<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   /** The type of this Firestore reference. */
   readonly type = 'document';
 
@@ -129,7 +196,10 @@ export class DocumentReference<T = DocumentData> {
     /**
      * If provided, the `FirestoreDataConverter` associated with this instance.
      */
-    readonly converter: FirestoreDataConverter<T> | null,
+    readonly converter: FirestoreDataConverter<
+      AppModelType,
+      DbModelType
+    > | null,
     readonly _key: DocumentKey
   ) {
     this.firestore = firestore;
@@ -157,8 +227,8 @@ export class DocumentReference<T = DocumentData> {
   /**
    * The collection this `DocumentReference` belongs to.
    */
-  get parent(): CollectionReference<T> {
-    return new CollectionReference<T>(
+  get parent(): CollectionReference<AppModelType, DbModelType> {
+    return new CollectionReference<AppModelType, DbModelType>(
       this.firestore,
       this.converter,
       this._key.path.popLast()
@@ -175,68 +245,24 @@ export class DocumentReference<T = DocumentData> {
    * @param converter - Converts objects to and from Firestore.
    * @returns A `DocumentReference<U>` that uses the provided converter.
    */
-  withConverter<U>(converter: FirestoreDataConverter<U>): DocumentReference<U>;
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
+  ): DocumentReference<NewAppModelType, NewDbModelType>;
   /**
    * Removes the current converter.
    *
    * @param converter - `null` removes the current converter.
    * @returns A `DocumentReference<DocumentData>` that does not use a converter.
    */
-  withConverter(converter: null): DocumentReference<DocumentData>;
-  withConverter<U>(
-    converter: FirestoreDataConverter<U> | null
-  ): DocumentReference<U> {
-    return new DocumentReference<U>(this.firestore, converter, this._key);
-  }
-}
-
-/**
- * A `Query` refers to a query which you can read or listen to. You can also
- * construct refined `Query` objects by adding filters and ordering.
- */
-export class Query<T = DocumentData> {
-  /** The type of this Firestore reference. */
-  readonly type: 'query' | 'collection' = 'query';
-
-  /**
-   * The `Firestore` instance for the Firestore database (useful for performing
-   * transactions, etc.).
-   */
-  readonly firestore: Firestore;
-
-  // This is the lite version of the Query class in the main SDK.
-
-  /** @hideconstructor protected */
-  constructor(
-    firestore: Firestore,
-    /**
-     * If provided, the `FirestoreDataConverter` associated with this instance.
-     */
-    readonly converter: FirestoreDataConverter<T> | null,
-    readonly _query: InternalQuery
-  ) {
-    this.firestore = firestore;
-  }
-
-  /**
-   * Removes the current converter.
-   *
-   * @param converter - `null` removes the current converter.
-   * @returns A `Query<DocumentData>` that does not use a converter.
-   */
-  withConverter(converter: null): Query<DocumentData>;
-  /**
-   * Applies a custom data converter to this query, allowing you to use your own
-   * custom model objects with Firestore. When you call {@link getDocs} with
-   * the returned query, the provided converter will convert between Firestore
-   * data and your custom type `U`.
-   *
-   * @param converter - Converts objects to and from Firestore.
-   * @returns A `Query<U>` that uses the provided converter.
-   */
-  withConverter<U>(converter: FirestoreDataConverter<U>): Query<U>;
-  withConverter<U>(converter: FirestoreDataConverter<U> | null): Query<U> {
-    return new Query<U>(this.firestore, converter, this._query);
+  withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType> | null
+  ): DocumentReference<NewAppModelType, NewDbModelType> {
+    return new DocumentReference<NewAppModelType, NewDbModelType>(
+      this.firestore,
+      converter,
+      this._key
+    );
   }
 }
 
@@ -244,14 +270,17 @@ export class Query<T = DocumentData> {
  * A `CollectionReference` object can be used for adding documents, getting
  * document references, and querying for documents (using {@link (query:1)}).
  */
-export class CollectionReference<T = DocumentData> extends Query<T> {
+export class CollectionReference<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> extends Query<AppModelType, DbModelType> {
   /** The type of this Firestore reference. */
   readonly type = 'collection';
 
   /** @hideconstructor */
   constructor(
     firestore: Firestore,
-    converter: FirestoreDataConverter<T> | null,
+    converter: FirestoreDataConverter<AppModelType, DbModelType> | null,
     readonly _path: ResourcePath
   ) {
     super(firestore, converter, newQueryForPath(_path));
@@ -274,7 +303,7 @@ export class CollectionReference<T = DocumentData> extends Query<T> {
    * A reference to the containing `DocumentReference` if this is a
    * subcollection. If this isn't a subcollection, the reference is null.
    */
-  get parent(): DocumentReference<DocumentData> | null {
+  get parent(): DocumentReference<DocumentData, DocumentData> | null {
     const parentPath = this._path.popLast();
     if (parentPath.isEmpty()) {
       return null;
@@ -296,9 +325,9 @@ export class CollectionReference<T = DocumentData> extends Query<T> {
    * @param converter - Converts objects to and from Firestore.
    * @returns A `CollectionReference<U>` that uses the provided converter.
    */
-  withConverter<U>(
-    converter: FirestoreDataConverter<U>
-  ): CollectionReference<U>;
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
+  ): CollectionReference<NewAppModelType, NewDbModelType>;
   /**
    * Removes the current converter.
    *
@@ -306,11 +335,17 @@ export class CollectionReference<T = DocumentData> extends Query<T> {
    * @returns A `CollectionReference<DocumentData>` that does not use a
    * converter.
    */
-  withConverter(converter: null): CollectionReference<DocumentData>;
-  withConverter<U>(
-    converter: FirestoreDataConverter<U> | null
-  ): CollectionReference<U> {
-    return new CollectionReference<U>(this.firestore, converter, this._path);
+  withConverter(
+    converter: null
+  ): CollectionReference<DocumentData, DocumentData>;
+  withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
+    converter: FirestoreDataConverter<NewAppModelType, NewDbModelType> | null
+  ): CollectionReference<NewAppModelType, NewDbModelType> {
+    return new CollectionReference<NewAppModelType, NewDbModelType>(
+      this.firestore,
+      converter,
+      this._path
+    );
   }
 }
 
@@ -330,7 +365,7 @@ export function collection(
   firestore: Firestore,
   path: string,
   ...pathSegments: string[]
-): CollectionReference<DocumentData>;
+): CollectionReference<DocumentData, DocumentData>;
 /**
  * Gets a `CollectionReference` instance that refers to a subcollection of
  * `reference` at the the specified relative path.
@@ -343,11 +378,11 @@ export function collection(
  * to a collection.
  * @returns The `CollectionReference` instance.
  */
-export function collection(
-  reference: CollectionReference<unknown>,
+export function collection<AppModelType, DbModelType extends DocumentData>(
+  reference: CollectionReference<AppModelType, DbModelType>,
   path: string,
   ...pathSegments: string[]
-): CollectionReference<DocumentData>;
+): CollectionReference<DocumentData, DocumentData>;
 /**
  * Gets a `CollectionReference` instance that refers to a subcollection of
  * `reference` at the the specified relative path.
@@ -360,16 +395,19 @@ export function collection(
  * to a collection.
  * @returns The `CollectionReference` instance.
  */
-export function collection(
-  reference: DocumentReference,
+export function collection<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   path: string,
   ...pathSegments: string[]
-): CollectionReference<DocumentData>;
-export function collection(
-  parent: Firestore | DocumentReference<unknown> | CollectionReference<unknown>,
+): CollectionReference<DocumentData, DocumentData>;
+export function collection<AppModelType, DbModelType extends DocumentData>(
+  parent:
+    | Firestore
+    | DocumentReference<AppModelType, DbModelType>
+    | CollectionReference<AppModelType, DbModelType>,
   path: string,
   ...pathSegments: string[]
-): CollectionReference<DocumentData> {
+): CollectionReference<DocumentData, DocumentData> {
   parent = getModularInstance(parent);
 
   validateNonEmptyArgument('collection', 'path', path);
@@ -417,7 +455,7 @@ export function collection(
 export function collectionGroup(
   firestore: Firestore,
   collectionId: string
-): Query<DocumentData> {
+): Query<DocumentData, DocumentData> {
   firestore = cast(firestore, Firestore);
 
   validateNonEmptyArgument('collectionGroup', 'collection id', collectionId);
@@ -452,7 +490,7 @@ export function doc(
   firestore: Firestore,
   path: string,
   ...pathSegments: string[]
-): DocumentReference<DocumentData>;
+): DocumentReference<DocumentData, DocumentData>;
 /**
  * Gets a `DocumentReference` instance that refers to a document within
  * `reference` at the specified relative path. If no path is specified, an
@@ -468,11 +506,11 @@ export function doc(
  * a document.
  * @returns The `DocumentReference` instance.
  */
-export function doc<T>(
-  reference: CollectionReference<T>,
+export function doc<AppModelType, DbModelType extends DocumentData>(
+  reference: CollectionReference<AppModelType, DbModelType>,
   path?: string,
   ...pathSegments: string[]
-): DocumentReference<T>;
+): DocumentReference<AppModelType, DbModelType>;
 /**
  * Gets a `DocumentReference` instance that refers to a document within
  * `reference` at the specified relative path.
@@ -485,16 +523,19 @@ export function doc<T>(
  * a document.
  * @returns The `DocumentReference` instance.
  */
-export function doc(
-  reference: DocumentReference<unknown>,
+export function doc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   path: string,
   ...pathSegments: string[]
-): DocumentReference<DocumentData>;
-export function doc<T>(
-  parent: Firestore | CollectionReference<T> | DocumentReference<unknown>,
+): DocumentReference<DocumentData, DocumentData>;
+export function doc<AppModelType, DbModelType extends DocumentData>(
+  parent:
+    | Firestore
+    | CollectionReference<AppModelType, DbModelType>
+    | DocumentReference<AppModelType, DbModelType>,
   path?: string,
   ...pathSegments: string[]
-): DocumentReference {
+): DocumentReference<AppModelType, DbModelType> {
   parent = getModularInstance(parent);
 
   // We allow omission of 'pathString' but explicitly prohibit passing in both
@@ -527,7 +568,7 @@ export function doc<T>(
       ResourcePath.fromString(path, ...pathSegments)
     );
     validateDocumentPath(absolutePath);
-    return new DocumentReference(
+    return new DocumentReference<AppModelType, DbModelType>(
       parent.firestore,
       parent instanceof CollectionReference ? parent.converter : null,
       new DocumentKey(absolutePath)
@@ -543,9 +584,13 @@ export function doc<T>(
  * @returns true if the references point to the same location in the same
  * Firestore database.
  */
-export function refEqual<T>(
-  left: DocumentReference<T> | CollectionReference<T>,
-  right: DocumentReference<T> | CollectionReference<T>
+export function refEqual<AppModelType, DbModelType extends DocumentData>(
+  left:
+    | DocumentReference<AppModelType, DbModelType>
+    | CollectionReference<AppModelType, DbModelType>,
+  right:
+    | DocumentReference<AppModelType, DbModelType>
+    | CollectionReference<AppModelType, DbModelType>
 ): boolean {
   left = getModularInstance(left);
   right = getModularInstance(right);
@@ -573,7 +618,10 @@ export function refEqual<T>(
  * @returns true if the references point to the same location in the same
  * Firestore database.
  */
-export function queryEqual<T>(left: Query<T>, right: Query<T>): boolean {
+export function queryEqual<AppModelType, DbModelType extends DocumentData>(
+  left: Query<AppModelType, DbModelType>,
+  right: Query<AppModelType, DbModelType>
+): boolean {
   left = getModularInstance(left);
   right = getModularInstance(right);
 
diff --git a/packages/firestore/src/lite-api/reference_impl.ts b/packages/firestore/src/lite-api/reference_impl.ts
index e478cc76eb4..cc815edc200 100644
--- a/packages/firestore/src/lite-api/reference_impl.ts
+++ b/packages/firestore/src/lite-api/reference_impl.ts
@@ -40,6 +40,7 @@ import { validateHasExplicitOrderByForLimitToLast } from './query';
 import {
   CollectionReference,
   doc,
+  DocumentData,
   DocumentReference,
   PartialWithFieldValue,
   Query,
@@ -120,10 +121,13 @@ export class LiteUserDataWriter extends AbstractUserDataWriter {
  * @returns A Promise resolved with a `DocumentSnapshot` containing the current
  * document contents.
  */
-export function getDoc<T>(
-  reference: DocumentReference<T>
-): Promise<DocumentSnapshot<T>> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+export function getDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>
+): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const datastore = getDatastore(reference.firestore);
   const userDataWriter = new LiteUserDataWriter(reference.firestore);
 
@@ -131,7 +135,7 @@ export function getDoc<T>(
     result => {
       hardAssert(result.length === 1, 'Expected a single document result');
       const document = result[0];
-      return new DocumentSnapshot<T>(
+      return new DocumentSnapshot<AppModelType, DbModelType>(
         reference.firestore,
         userDataWriter,
         reference._key,
@@ -154,8 +158,10 @@ export function getDoc<T>(
  * @param query - The `Query` to execute.
  * @returns A Promise that will be resolved with the results of the query.
  */
-export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
-  query = cast<Query<T>>(query, Query);
+export function getDocs<AppModelType, DbModelType extends DocumentData>(
+  query: Query<AppModelType, DbModelType>
+): Promise<QuerySnapshot<AppModelType, DbModelType>> {
+  query = cast<Query<AppModelType, DbModelType>>(query, Query);
   validateHasExplicitOrderByForLimitToLast(query._query);
 
   const datastore = getDatastore(query.firestore);
@@ -163,7 +169,7 @@ export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
   return invokeRunQueryRpc(datastore, query._query).then(result => {
     const docs = result.map(
       doc =>
-        new QueryDocumentSnapshot<T>(
+        new QueryDocumentSnapshot<AppModelType, DbModelType>(
           query.firestore,
           userDataWriter,
           doc.key,
@@ -179,7 +185,7 @@ export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
       docs.reverse();
     }
 
-    return new QuerySnapshot<T>(query, docs);
+    return new QuerySnapshot<AppModelType, DbModelType>(query, docs);
   });
 }
 
@@ -198,9 +204,9 @@ export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>> {
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend.
  */
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: WithFieldValue<T>
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: WithFieldValue<AppModelType>
 ): Promise<void>;
 /**
  * Writes to the document referred to by the specified `DocumentReference`. If
@@ -219,17 +225,20 @@ export function setDoc<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend.
  */
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: PartialWithFieldValue<T>,
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: PartialWithFieldValue<AppModelType>,
   options: SetOptions
 ): Promise<void>;
-export function setDoc<T>(
-  reference: DocumentReference<T>,
-  data: PartialWithFieldValue<T>,
+export function setDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: PartialWithFieldValue<AppModelType>,
   options?: SetOptions
 ): Promise<void> {
-  reference = cast<DocumentReference<T>>(reference, DocumentReference);
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const convertedValue = applyFirestoreDataConverter(
     reference.converter,
     data,
@@ -269,9 +278,9 @@ export function setDoc<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend.
  */
-export function updateDoc<T>(
-  reference: DocumentReference<T>,
-  data: UpdateData<T>
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  data: UpdateData<DbModelType>
 ): Promise<void>;
 /**
  * Updates fields in the document referred to by the specified
@@ -294,19 +303,22 @@ export function updateDoc<T>(
  * @returns A `Promise` resolved once the data has been successfully written
  * to the backend.
  */
-export function updateDoc(
-  reference: DocumentReference<unknown>,
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
   field: string | FieldPath,
   value: unknown,
   ...moreFieldsAndValues: unknown[]
 ): Promise<void>;
-export function updateDoc<T>(
-  reference: DocumentReference<unknown>,
-  fieldOrUpdateData: string | FieldPath | UpdateData<T>,
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>,
+  fieldOrUpdateData: string | FieldPath | UpdateData<DbModelType>,
   value?: unknown,
   ...moreFieldsAndValues: unknown[]
 ): Promise<void> {
-  reference = cast<DocumentReference<unknown>>(reference, DocumentReference);
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const dataReader = newUserDataReader(reference.firestore);
 
   // For Compat types, we have to "extract" the underlying types before
@@ -353,10 +365,13 @@ export function updateDoc<T>(
  * @returns A `Promise` resolved once the document has been successfully
  * deleted from the backend.
  */
-export function deleteDoc(
-  reference: DocumentReference<unknown>
+export function deleteDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: DocumentReference<AppModelType, DbModelType>
 ): Promise<void> {
-  reference = cast<DocumentReference<unknown>>(reference, DocumentReference);
+  reference = cast<DocumentReference<AppModelType, DbModelType>>(
+    reference,
+    DocumentReference
+  );
   const datastore = getDatastore(reference.firestore);
   return invokeCommitRpc(datastore, [
     new DeleteMutation(reference._key, Precondition.none())
@@ -378,16 +393,19 @@ export function deleteDoc(
  * @returns A `Promise` resolved with a `DocumentReference` pointing to the
  * newly created document after it has been written to the backend.
  */
-export function addDoc<T>(
-  reference: CollectionReference<T>,
-  data: WithFieldValue<T>
-): Promise<DocumentReference<T>> {
-  reference = cast<CollectionReference<T>>(reference, CollectionReference);
+export function addDoc<AppModelType, DbModelType extends DocumentData>(
+  reference: CollectionReference<AppModelType, DbModelType>,
+  data: WithFieldValue<AppModelType>
+): Promise<DocumentReference<AppModelType, DbModelType>> {
+  reference = cast<CollectionReference<AppModelType, DbModelType>>(
+    reference,
+    CollectionReference
+  );
   const docRef = doc(reference);
 
   const convertedValue = applyFirestoreDataConverter(
     reference.converter,
-    data as PartialWithFieldValue<T>
+    data as PartialWithFieldValue<AppModelType>
   );
 
   const dataReader = newUserDataReader(reference.firestore);
diff --git a/packages/firestore/src/lite-api/snapshot.ts b/packages/firestore/src/lite-api/snapshot.ts
index d726d92a7e4..9c268eeb52c 100644
--- a/packages/firestore/src/lite-api/snapshot.ts
+++ b/packages/firestore/src/lite-api/snapshot.ts
@@ -78,7 +78,10 @@ import { AbstractUserDataWriter } from './user_data_writer';
  * }
  * ```
  */
-export interface FirestoreDataConverter<T> {
+export interface FirestoreDataConverter<
+  AppModelType,
+  DbModelType extends DocumentData = DocumentData
+> {
   /**
    * Called by the Firestore SDK to convert a custom model object of type `T`
    * into a plain Javascript object (suitable for writing directly to the
@@ -88,7 +91,9 @@ export interface FirestoreDataConverter<T> {
    * The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as
    * {@link (deleteField:1)} to be used as property values.
    */
-  toFirestore(modelObject: WithFieldValue<T>): DocumentData;
+  toFirestore(
+    modelObject: WithFieldValue<AppModelType>
+  ): WithFieldValue<DbModelType>;
 
   /**
    * Called by the Firestore SDK to convert a custom model object of type `T`
@@ -102,9 +107,9 @@ export interface FirestoreDataConverter<T> {
    * omitted.
    */
   toFirestore(
-    modelObject: PartialWithFieldValue<T>,
+    modelObject: PartialWithFieldValue<AppModelType>,
     options: SetOptions
-  ): DocumentData;
+  ): PartialWithFieldValue<DbModelType>;
 
   /**
    * Called by the Firestore SDK to convert Firestore data into an object of
@@ -113,7 +118,9 @@ export interface FirestoreDataConverter<T> {
    * @param snapshot - A `QueryDocumentSnapshot` containing your data and
    * metadata.
    */
-  fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData>): T;
+  fromFirestore(
+    snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>
+  ): AppModelType;
 }
 
 /**
@@ -125,7 +132,10 @@ export interface FirestoreDataConverter<T> {
  * access will return 'undefined'. You can use the `exists()` method to
  * explicitly verify a document's existence.
  */
-export class DocumentSnapshot<T = DocumentData> {
+export class DocumentSnapshot<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   // Note: This class is stripped down version of the DocumentSnapshot in
   // the legacy SDK. The changes are:
   // - No support for SnapshotMetadata.
@@ -137,7 +147,10 @@ export class DocumentSnapshot<T = DocumentData> {
     public _userDataWriter: AbstractUserDataWriter,
     public _key: DocumentKey,
     public _document: Document | null,
-    public _converter: UntypedFirestoreDataConverter<T> | null
+    public _converter: UntypedFirestoreDataConverter<
+      AppModelType,
+      DbModelType
+    > | null
   ) {}
 
   /** Property of the `DocumentSnapshot` that provides the document's ID. */
@@ -148,8 +161,8 @@ export class DocumentSnapshot<T = DocumentData> {
   /**
    * The `DocumentReference` for the document included in the `DocumentSnapshot`.
    */
-  get ref(): DocumentReference<T> {
-    return new DocumentReference<T>(
+  get ref(): DocumentReference<AppModelType, DbModelType> {
+    return new DocumentReference<AppModelType, DbModelType>(
       this._firestore,
       this._converter,
       this._key
@@ -161,7 +174,7 @@ export class DocumentSnapshot<T = DocumentData> {
    *
    * @returns true if the document exists.
    */
-  exists(): this is QueryDocumentSnapshot<T> {
+  exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType> {
     return this._document !== null;
   }
 
@@ -172,7 +185,7 @@ export class DocumentSnapshot<T = DocumentData> {
    * @returns An `Object` containing all fields in the document or `undefined`
    * if the document doesn't exist.
    */
-  data(): T | undefined {
+  data(): AppModelType | undefined {
     if (!this._document) {
       return undefined;
     } else if (this._converter) {
@@ -187,7 +200,9 @@ export class DocumentSnapshot<T = DocumentData> {
       );
       return this._converter.fromFirestore(snapshot);
     } else {
-      return this._userDataWriter.convertValue(this._document.data.value) as T;
+      return this._userDataWriter.convertValue(
+        this._document.data.value
+      ) as AppModelType;
     }
   }
 
@@ -227,16 +242,17 @@ export class DocumentSnapshot<T = DocumentData> {
  * 'undefined'.
  */
 export class QueryDocumentSnapshot<
-  T = DocumentData
-> extends DocumentSnapshot<T> {
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> extends DocumentSnapshot<AppModelType, DbModelType> {
   /**
    * Retrieves all fields in the document as an `Object`.
    *
    * @override
    * @returns An `Object` containing all fields in the document.
    */
-  data(): T {
-    return super.data() as T;
+  data(): AppModelType {
+    return super.data() as AppModelType;
   }
 }
 
@@ -247,23 +263,26 @@ export class QueryDocumentSnapshot<
  * number of documents can be determined via the `empty` and `size`
  * properties.
  */
-export class QuerySnapshot<T = DocumentData> {
+export class QuerySnapshot<
+  AppModelType = DocumentData,
+  DbModelType extends DocumentData = DocumentData
+> {
   /**
    * The query on which you called {@link getDocs} in order to get this
    * `QuerySnapshot`.
    */
-  readonly query: Query<T>;
+  readonly query: Query<AppModelType, DbModelType>;
 
   /** @hideconstructor */
   constructor(
-    _query: Query<T>,
-    readonly _docs: Array<QueryDocumentSnapshot<T>>
+    _query: Query<AppModelType, DbModelType>,
+    readonly _docs: Array<QueryDocumentSnapshot<AppModelType, DbModelType>>
   ) {
     this.query = _query;
   }
 
   /** An array of all the documents in the `QuerySnapshot`. */
-  get docs(): Array<QueryDocumentSnapshot<T>> {
+  get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>> {
     return [...this._docs];
   }
 
@@ -285,7 +304,9 @@ export class QuerySnapshot<T = DocumentData> {
    * @param thisArg - The `this` binding for the callback.
    */
   forEach(
-    callback: (result: QueryDocumentSnapshot<T>) => void,
+    callback: (
+      result: QueryDocumentSnapshot<AppModelType, DbModelType>
+    ) => void,
     thisArg?: unknown
   ): void {
     this._docs.forEach(callback, thisArg);
@@ -299,9 +320,13 @@ export class QuerySnapshot<T = DocumentData> {
  * @param right - A snapshot to compare.
  * @returns true if the snapshots are equal.
  */
-export function snapshotEqual<T>(
-  left: DocumentSnapshot<T> | QuerySnapshot<T>,
-  right: DocumentSnapshot<T> | QuerySnapshot<T>
+export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(
+  left:
+    | DocumentSnapshot<AppModelType, DbModelType>
+    | QuerySnapshot<AppModelType, DbModelType>,
+  right:
+    | DocumentSnapshot<AppModelType, DbModelType>
+    | QuerySnapshot<AppModelType, DbModelType>
 ): boolean {
   left = getModularInstance(left);
   right = getModularInstance(right);
diff --git a/packages/firestore/src/lite-api/transaction.ts b/packages/firestore/src/lite-api/transaction.ts
index aab718cf91d..40bb70460e8 100644
--- a/packages/firestore/src/lite-api/transaction.ts
+++ b/packages/firestore/src/lite-api/transaction.ts
@@ -33,6 +33,7 @@ import { getDatastore } from './components';
 import { Firestore } from './database';
 import { FieldPath } from './field_path';
 import {
+  DocumentData,
   DocumentReference,
   PartialWithFieldValue,
   SetOptions,
@@ -86,7 +87,9 @@ export class Transaction {
    * @param documentRef - A reference to the document to be read.
    * @returns A `DocumentSnapshot` with the read data.
    */
-  get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>> {
+  get<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>
+  ): Promise<DocumentSnapshot<AppModelType, DbModelType>> {
     const ref = validateReference(documentRef, this._firestore);
     const userDataWriter = new LiteUserDataWriter(this._firestore);
     return this._transaction.lookup([ref._key]).then(docs => {
@@ -95,7 +98,7 @@ export class Transaction {
       }
       const doc = docs[0];
       if (doc.isFoundDocument()) {
-        return new DocumentSnapshot(
+        return new DocumentSnapshot<AppModelType, DbModelType>(
           this._firestore,
           userDataWriter,
           doc.key,
@@ -103,7 +106,7 @@ export class Transaction {
           ref.converter
         );
       } else if (doc.isNoDocument()) {
-        return new DocumentSnapshot(
+        return new DocumentSnapshot<AppModelType, DbModelType>(
           this._firestore,
           userDataWriter,
           ref._key,
@@ -127,7 +130,10 @@ export class Transaction {
    * @throws Error - If the provided input is not a valid Firestore document.
    * @returns This `Transaction` instance. Used for chaining method calls.
    */
-  set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): this;
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: WithFieldValue<AppModelType>
+  ): this;
   /**
    * Writes to the document referred to by the provided {@link
    * DocumentReference}. If the document does not exist yet, it will be created.
@@ -140,14 +146,14 @@ export class Transaction {
    * @throws Error - If the provided input is not a valid Firestore document.
    * @returns This `Transaction` instance. Used for chaining method calls.
    */
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: PartialWithFieldValue<T>,
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: PartialWithFieldValue<AppModelType>,
     options: SetOptions
   ): this;
-  set<T>(
-    documentRef: DocumentReference<T>,
-    value: PartialWithFieldValue<T>,
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    value: PartialWithFieldValue<AppModelType>,
     options?: SetOptions
   ): this {
     const ref = validateReference(documentRef, this._firestore);
@@ -180,7 +186,10 @@ export class Transaction {
    * @throws Error - If the provided input is not valid Firestore data.
    * @returns This `Transaction` instance. Used for chaining method calls.
    */
-  update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): this;
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: UpdateData<DbModelType>
+  ): this;
   /**
    * Updates fields in the document referred to by the provided {@link
    * DocumentReference}. The update will fail if applied to a document that does
@@ -196,15 +205,15 @@ export class Transaction {
    * @throws Error - If the provided input is not valid Firestore data.
    * @returns This `Transaction` instance. Used for chaining method calls.
    */
-  update(
-    documentRef: DocumentReference<unknown>,
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
     field: string | FieldPath,
     value: unknown,
     ...moreFieldsAndValues: unknown[]
   ): this;
-  update<T>(
-    documentRef: DocumentReference<T>,
-    fieldOrUpdateData: string | FieldPath | UpdateData<T>,
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    fieldOrUpdateData: string | FieldPath | UpdateData<DbModelType>,
     value?: unknown,
     ...moreFieldsAndValues: unknown[]
   ): this {
@@ -246,7 +255,9 @@ export class Transaction {
    * @param documentRef - A reference to the document to be deleted.
    * @returns This `Transaction` instance. Used for chaining method calls.
    */
-  delete(documentRef: DocumentReference<unknown>): this {
+  delete<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>
+  ): this {
     const ref = validateReference(documentRef, this._firestore);
     this._transaction.delete(ref._key);
     return this;
diff --git a/packages/firestore/src/lite-api/user_data_reader.ts b/packages/firestore/src/lite-api/user_data_reader.ts
index 0f869ca87e6..52313b2907a 100644
--- a/packages/firestore/src/lite-api/user_data_reader.ts
+++ b/packages/firestore/src/lite-api/user_data_reader.ts
@@ -76,13 +76,18 @@ const RESERVED_FIELD_REGEX = /^__.*__$/;
  * An untyped Firestore Data Converter interface that is shared between the
  * lite, firestore-exp and classic SDK.
  */
-export interface UntypedFirestoreDataConverter<T> {
-  toFirestore(modelObject: WithFieldValue<T>): DocumentData;
+export interface UntypedFirestoreDataConverter<
+  AppModelType,
+  DbModelType extends DocumentData = DocumentData
+> {
   toFirestore(
-    modelObject: PartialWithFieldValue<T>,
+    modelObject: WithFieldValue<AppModelType>
+  ): WithFieldValue<DbModelType>;
+  toFirestore(
+    modelObject: PartialWithFieldValue<AppModelType>,
     options: SetOptions
-  ): DocumentData;
-  fromFirestore(snapshot: unknown, options?: unknown): T;
+  ): PartialWithFieldValue<DbModelType>;
+  fromFirestore(snapshot: unknown, options?: unknown): AppModelType;
 }
 
 /** The result of parsing document data (e.g. for a setData call). */
diff --git a/packages/firestore/src/lite-api/write_batch.ts b/packages/firestore/src/lite-api/write_batch.ts
index e626646f3f7..4c2252d1b24 100644
--- a/packages/firestore/src/lite-api/write_batch.ts
+++ b/packages/firestore/src/lite-api/write_batch.ts
@@ -26,6 +26,7 @@ import { getDatastore } from './components';
 import { Firestore } from './database';
 import { FieldPath } from './field_path';
 import {
+  DocumentData,
   DocumentReference,
   PartialWithFieldValue,
   SetOptions,
@@ -73,9 +74,9 @@ export class WriteBatch {
    * @param data - An object of the fields and values for the document.
    * @returns This `WriteBatch` instance. Used for chaining method calls.
    */
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: WithFieldValue<T>
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: WithFieldValue<AppModelType>
   ): WriteBatch;
   /**
    * Writes to the document referred to by the provided {@link
@@ -89,14 +90,14 @@ export class WriteBatch {
    * @throws Error - If the provided input is not a valid Firestore document.
    * @returns This `WriteBatch` instance. Used for chaining method calls.
    */
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: PartialWithFieldValue<T>,
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: PartialWithFieldValue<AppModelType>,
     options: SetOptions
   ): WriteBatch;
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: WithFieldValue<T> | PartialWithFieldValue<T>,
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: WithFieldValue<AppModelType> | PartialWithFieldValue<AppModelType>,
     options?: SetOptions
   ): WriteBatch {
     this._verifyNotCommitted();
@@ -131,7 +132,10 @@ export class WriteBatch {
    * @throws Error - If the provided input is not valid Firestore data.
    * @returns This `WriteBatch` instance. Used for chaining method calls.
    */
-  update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): WriteBatch;
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: UpdateData<DbModelType>
+  ): WriteBatch;
   /**
    * Updates fields in the document referred to by this {@link
    * DocumentReference}. The update will fail if applied to a document that does
@@ -147,15 +151,15 @@ export class WriteBatch {
    * @throws Error - If the provided input is not valid Firestore data.
    * @returns This `WriteBatch` instance. Used for chaining method calls.
    */
-  update(
-    documentRef: DocumentReference<unknown>,
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
     field: string | FieldPath,
     value: unknown,
     ...moreFieldsAndValues: unknown[]
   ): WriteBatch;
-  update<T>(
-    documentRef: DocumentReference<T>,
-    fieldOrUpdateData: string | FieldPath | UpdateData<T>,
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    fieldOrUpdateData: string | FieldPath | UpdateData<DbModelType>,
     value?: unknown,
     ...moreFieldsAndValues: unknown[]
   ): WriteBatch {
@@ -200,7 +204,9 @@ export class WriteBatch {
    * @param documentRef - A reference to the document to be deleted.
    * @returns This `WriteBatch` instance. Used for chaining method calls.
    */
-  delete(documentRef: DocumentReference<unknown>): WriteBatch {
+  delete<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>
+  ): WriteBatch {
     this._verifyNotCommitted();
     const ref = validateReference(documentRef, this._firestore);
     this._mutations = this._mutations.concat(
@@ -242,10 +248,15 @@ export class WriteBatch {
   }
 }
 
-export function validateReference<T>(
-  documentRef: DocumentReference<T> | Compat<DocumentReference<T>>,
+export function validateReference<
+  AppModelType,
+  DbModelType extends DocumentData
+>(
+  documentRef:
+    | DocumentReference<AppModelType, DbModelType>
+    | Compat<DocumentReference<AppModelType, DbModelType>>,
   firestore: Firestore
-): DocumentReference<T> {
+): DocumentReference<AppModelType, DbModelType> {
   documentRef = getModularInstance(documentRef);
 
   if (documentRef.firestore !== firestore) {
@@ -254,7 +265,7 @@ export function validateReference<T>(
       'Provided document reference is from a different Firestore instance.'
     );
   } else {
-    return documentRef as DocumentReference<T>;
+    return documentRef as DocumentReference<AppModelType, DbModelType>;
   }
 }
 
diff --git a/packages/firestore/test/lite/integration.test.ts b/packages/firestore/test/lite/integration.test.ts
index 0c8515f038c..8dee373a867 100644
--- a/packages/firestore/test/lite/integration.test.ts
+++ b/packages/firestore/test/lite/integration.test.ts
@@ -78,6 +78,7 @@ import {
   updateDoc
 } from '../../src/lite-api/reference_impl';
 import {
+  FirestoreDataConverter,
   snapshotEqual,
   QuerySnapshot,
   QueryDocumentSnapshot
@@ -428,26 +429,28 @@ describe('getDoc()', () => {
  * DocumentReference-based mutation API.
  */
 interface MutationTester {
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: WithFieldValue<T>
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: WithFieldValue<AppModelType>
   ): Promise<void>;
-  set<T>(
-    documentRef: DocumentReference<T>,
-    data: PartialWithFieldValue<T>,
+  set<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: PartialWithFieldValue<AppModelType>,
     options: SetOptions
   ): Promise<void>;
-  update<T>(
-    documentRef: DocumentReference<T>,
-    data: UpdateData<T>
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
+    data: UpdateData<DbModelType>
   ): Promise<void>;
-  update(
-    documentRef: DocumentReference<unknown>,
+  update<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>,
     field: string | FieldPath,
     value: unknown,
     ...moreFieldsAndValues: unknown[]
   ): Promise<void>;
-  delete(documentRef: DocumentReference<unknown>): Promise<void>;
+  delete<AppModelType, DbModelType extends DocumentData>(
+    documentRef: DocumentReference<AppModelType, DbModelType>
+  ): Promise<void>;
 }
 
 genericMutationTests({
@@ -458,15 +461,17 @@ genericMutationTests({
 
 describe('WriteBatch', () => {
   class WriteBatchTester implements MutationTester {
-    delete(ref: DocumentReference<unknown>): Promise<void> {
+    delete<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>
+    ): Promise<void> {
       const batch = writeBatch(ref.firestore);
       batch.delete(ref);
       return batch.commit();
     }
 
-    set<T>(
-      ref: DocumentReference<T>,
-      data: PartialWithFieldValue<T>,
+    set<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>,
+      data: PartialWithFieldValue<AppModelType>,
       options?: SetOptions
     ): Promise<void> {
       const batch = writeBatch(ref.firestore);
@@ -476,9 +481,9 @@ describe('WriteBatch', () => {
       return batch.commit();
     }
 
-    update<T>(
-      ref: DocumentReference<T>,
-      dataOrField: UpdateData<T> | string | FieldPath,
+    update<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>,
+      dataOrField: UpdateData<DbModelType> | string | FieldPath,
       value?: unknown,
       ...moreFieldsAndValues: unknown[]
     ): Promise<void> {
@@ -521,29 +526,31 @@ describe('WriteBatch', () => {
 
 describe('Transaction', () => {
   class TransactionTester implements MutationTester {
-    delete(ref: DocumentReference<unknown>): Promise<void> {
+    delete<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>
+    ): Promise<void> {
       return runTransaction(ref.firestore, async transaction => {
         transaction.delete(ref);
       });
     }
 
-    set<T>(
-      ref: DocumentReference<T>,
-      data: PartialWithFieldValue<T>,
+    set<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>,
+      data: PartialWithFieldValue<AppModelType>,
       options?: SetOptions
     ): Promise<void> {
       return runTransaction(ref.firestore, async transaction => {
         if (options) {
           transaction.set(ref, data, options);
         } else {
-          transaction.set(ref, data as WithFieldValue<T>);
+          transaction.set(ref, data as WithFieldValue<AppModelType>);
         }
       });
     }
 
-    update<T>(
-      ref: DocumentReference<T>,
-      dataOrField: UpdateData<T> | string | FieldPath,
+    update<AppModelType, DbModelType extends DocumentData>(
+      ref: DocumentReference<AppModelType, DbModelType>,
+      dataOrField: UpdateData<DbModelType> | string | FieldPath,
       value?: unknown,
       ...moreFieldsAndValues: unknown[]
     ): Promise<void> {
@@ -556,7 +563,7 @@ describe('Transaction', () => {
             ...moreFieldsAndValues
           );
         } else {
-          transaction.update(ref, dataOrField as UpdateData<T>);
+          transaction.update(ref, dataOrField as UpdateData<DbModelType>);
         }
       });
     }
@@ -1385,7 +1392,7 @@ describe('withConverter() support', () => {
       ) {}
     }
 
-    const testConverter = {
+    const testConverter: FirestoreDataConverter<TestObject, TestObject> = {
       toFirestore(testObj: WithFieldValue<TestObject>) {
         return { ...testObj };
       },
@@ -1780,8 +1787,7 @@ describe('withConverter() support', () => {
 
       it('supports string-separated fields', () => {
         return withTestDocAndInitialData(initialData, async docRef => {
-          const testDocRef: DocumentReference<TestObject> =
-            docRef.withConverter(testConverter);
+          const testDocRef = docRef.withConverter(testConverter);
           await updateDoc(testDocRef, {
             // @ts-expect-error
             outerString: 3,
@@ -1895,7 +1901,10 @@ describe('withConverter() support', () => {
             | { requiredNumber: number };
         }
 
-        const testConverterUnion = {
+        const testConverterUnion: FirestoreDataConverter<
+          TestObjectUnion,
+          TestObjectUnion
+        > = {
           toFirestore(testObj: WithFieldValue<TestObjectUnion>) {
             return { ...testObj };
           },
@@ -1909,8 +1918,7 @@ describe('withConverter() support', () => {
         };
 
         return withTestDocAndInitialData(initialData, async docRef => {
-          const testDocRef: DocumentReference<TestObjectUnion> =
-            docRef.withConverter(testConverterUnion);
+          const testDocRef = docRef.withConverter(testConverterUnion);
 
           await updateDoc(testDocRef, {
             nested: {
@@ -1943,8 +1951,7 @@ describe('withConverter() support', () => {
 
       it('checks for nonexistent fields', () => {
         return withTestDocAndInitialData(initialData, async docRef => {
-          const testDocRef: DocumentReference<TestObject> =
-            docRef.withConverter(testConverter);
+          const testDocRef = docRef.withConverter(testConverter);
 
           // Top-level fields.
           await updateDoc(testDocRef, {

From 802b1fb3aa61118136c7fce192fdacdeb2fc3fd5 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 14:10:48 -0400
Subject: [PATCH 02/10] Update common/api-review/firestore.api.md and
 common/api-review/firestore-lite.api.md

---
 common/api-review/firestore-lite.api.md | 128 +++++++++---------
 common/api-review/firestore.api.md      | 166 ++++++++++++------------
 2 files changed, 147 insertions(+), 147 deletions(-)

diff --git a/common/api-review/firestore-lite.api.md b/common/api-review/firestore-lite.api.md
index 35802afacb7..a1592cd14f3 100644
--- a/common/api-review/firestore-lite.api.md
+++ b/common/api-review/firestore-lite.api.md
@@ -10,7 +10,7 @@ import { FirebaseError } from '@firebase/util';
 import { LogLevelString as LogLevel } from '@firebase/logger';
 
 // @public
-export function addDoc<T>(reference: CollectionReference<T>, data: WithFieldValue<T>): Promise<DocumentReference<T>>;
+export function addDoc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<DocumentReference<AppModelType, DbModelType>>;
 
 // @public
 export type AddPrefixToKeys<Prefix extends string, T extends Record<string, unknown>> = {
@@ -26,14 +26,14 @@ export class AggregateField<T> {
 export type AggregateFieldType = AggregateField<number | null>;
 
 // @public
-export class AggregateQuerySnapshot<T extends AggregateSpec> {
-    data(): AggregateSpecData<T>;
-    readonly query: Query<unknown>;
+export class AggregateQuerySnapshot<AggregateSpecType extends AggregateSpec, AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    data(): AggregateSpecData<AggregateSpecType>;
+    readonly query: Query<AppModelType, DbModelType>;
     readonly type = "AggregateQuerySnapshot";
 }
 
 // @public
-export function aggregateQuerySnapshotEqual<T extends AggregateSpec>(left: AggregateQuerySnapshot<T>, right: AggregateQuerySnapshot<T>): boolean;
+export function aggregateQuerySnapshotEqual<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>, right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>): boolean;
 
 // @public
 export interface AggregateSpec {
@@ -69,25 +69,25 @@ export class Bytes {
 export type ChildUpdateFields<K extends string, V> = V extends Record<string, unknown> ? AddPrefixToKeys<K, UpdateData<V>> : never;
 
 // @public
-export function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collection(reference: CollectionReference<unknown>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collection(reference: DocumentReference, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData>;
+export function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData, DocumentData>;
 
 // @public
-export class CollectionReference<T = DocumentData> extends Query<T> {
+export class CollectionReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends Query<AppModelType, DbModelType> {
     get id(): string;
-    get parent(): DocumentReference<DocumentData> | null;
+    get parent(): DocumentReference<DocumentData, DocumentData> | null;
     get path(): string;
     readonly type = "collection";
-    withConverter<U>(converter: FirestoreDataConverter<U>): CollectionReference<U>;
-    withConverter(converter: null): CollectionReference<DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): CollectionReference<NewAppModelType, NewDbModelType>;
+    withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 }
 
 // @public
@@ -96,19 +96,19 @@ export function connectFirestoreEmulator(firestore: Firestore, host: string, por
 }): void;
 
 // @public
-export function deleteDoc(reference: DocumentReference<unknown>): Promise<void>;
+export function deleteDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<void>;
 
 // @public
 export function deleteField(): FieldValue;
 
 // @public
-export function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 
 // @public
-export function doc<T>(reference: CollectionReference<T>, path?: string, ...pathSegments: string[]): DocumentReference<T>;
+export function doc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path?: string, ...pathSegments: string[]): DocumentReference<AppModelType, DbModelType>;
 
 // @public
-export function doc(reference: DocumentReference<unknown>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export function doc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 
 // @public
 export interface DocumentData {
@@ -119,25 +119,25 @@ export interface DocumentData {
 export function documentId(): FieldPath;
 
 // @public
-export class DocumentReference<T = DocumentData> {
-    readonly converter: FirestoreDataConverter<T> | null;
+export class DocumentReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
     readonly firestore: Firestore;
     get id(): string;
-    get parent(): CollectionReference<T>;
+    get parent(): CollectionReference<AppModelType, DbModelType>;
     get path(): string;
     readonly type = "document";
-    withConverter<U>(converter: FirestoreDataConverter<U>): DocumentReference<U>;
-    withConverter(converter: null): DocumentReference<DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): DocumentReference<NewAppModelType, NewDbModelType>;
+    withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 }
 
 // @public
-export class DocumentSnapshot<T = DocumentData> {
+export class DocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
     protected constructor();
-    data(): T | undefined;
-    exists(): this is QueryDocumentSnapshot<T>;
+    data(): AppModelType | undefined;
+    exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType>;
     get(fieldPath: string | FieldPath): any;
     get id(): string;
-    get ref(): DocumentReference<T>;
+    get ref(): DocumentReference<AppModelType, DbModelType>;
 }
 
 export { EmulatorMockTokenOptions }
@@ -173,10 +173,10 @@ export class Firestore {
 }
 
 // @public
-export interface FirestoreDataConverter<T> {
-    fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData>): T;
-    toFirestore(modelObject: WithFieldValue<T>): DocumentData;
-    toFirestore(modelObject: PartialWithFieldValue<T>, options: SetOptions): DocumentData;
+export interface FirestoreDataConverter<AppModelType, DbModelType extends DocumentData = DocumentData> {
+    fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>): AppModelType;
+    toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelType>;
+    toFirestore(modelObject: PartialWithFieldValue<AppModelType>, options: SetOptions): PartialWithFieldValue<DbModelType>;
 }
 
 // @public
@@ -202,15 +202,15 @@ export class GeoPoint {
 }
 
 // @public
-export function getCount(query: Query<unknown>): Promise<AggregateQuerySnapshot<{
+export function getCount<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<AggregateQuerySnapshot<{
     count: AggregateField<number>;
-}>>;
+}, AppModelType, DbModelType>>;
 
 // @public
-export function getDoc<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export function getDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export function getDocs<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 
 // @public
 export function getFirestore(): Firestore;
@@ -255,20 +255,20 @@ export type PartialWithFieldValue<T> = Partial<T> | (T extends Primitive ? T : T
 export type Primitive = string | number | boolean | undefined | null;
 
 // @public
-export class Query<T = DocumentData> {
+export class Query<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
     protected constructor();
-    readonly converter: FirestoreDataConverter<T> | null;
+    readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
     readonly firestore: Firestore;
     readonly type: 'query' | 'collection';
-    withConverter(converter: null): Query<DocumentData>;
-    withConverter<U>(converter: FirestoreDataConverter<U>): Query<U>;
+    withConverter(converter: null): Query<DocumentData, DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): Query<NewAppModelType, NewDbModelType>;
 }
 
 // @public
-export function query<T>(query: Query<T>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<T>;
+export function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<AppModelType, DbModelType>;
 
 // @public
-export function query<T>(query: Query<T>, ...queryConstraints: QueryConstraint[]): Query<T>;
+export function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, ...queryConstraints: QueryConstraint[]): Query<AppModelType, DbModelType>;
 
 // @public
 export class QueryCompositeFilterConstraint {
@@ -284,9 +284,9 @@ export abstract class QueryConstraint {
 export type QueryConstraintType = 'where' | 'orderBy' | 'limit' | 'limitToLast' | 'startAt' | 'startAfter' | 'endAt' | 'endBefore';
 
 // @public
-export class QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot<T> {
+export class QueryDocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends DocumentSnapshot<AppModelType, DbModelType> {
     // @override
-    data(): T;
+    data(): AppModelType;
 }
 
 // @public
@@ -295,7 +295,7 @@ export class QueryEndAtConstraint extends QueryConstraint {
 }
 
 // @public
-export function queryEqual<T>(left: Query<T>, right: Query<T>): boolean;
+export function queryEqual<AppModelType, DbModelType extends DocumentData>(left: Query<AppModelType, DbModelType>, right: Query<AppModelType, DbModelType>): boolean;
 
 // @public
 export class QueryFieldFilterConstraint extends QueryConstraint {
@@ -319,11 +319,11 @@ export class QueryOrderByConstraint extends QueryConstraint {
 }
 
 // @public
-export class QuerySnapshot<T = DocumentData> {
-    get docs(): Array<QueryDocumentSnapshot<T>>;
+export class QuerySnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>>;
     get empty(): boolean;
-    forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: unknown): void;
-    readonly query: Query<T>;
+    forEach(callback: (result: QueryDocumentSnapshot<AppModelType, DbModelType>) => void, thisArg?: unknown): void;
+    readonly query: Query<AppModelType, DbModelType>;
     get size(): number;
 }
 
@@ -333,7 +333,7 @@ export class QueryStartAtConstraint extends QueryConstraint {
 }
 
 // @public
-export function refEqual<T>(left: DocumentReference<T> | CollectionReference<T>, right: DocumentReference<T> | CollectionReference<T>): boolean;
+export function refEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>, right: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>): boolean;
 
 // @public
 export function runTransaction<T>(firestore: Firestore, updateFunction: (transaction: Transaction) => Promise<T>, options?: TransactionOptions): Promise<T>;
@@ -342,10 +342,10 @@ export function runTransaction<T>(firestore: Firestore, updateFunction: (transac
 export function serverTimestamp(): FieldValue;
 
 // @public
-export function setDoc<T>(reference: DocumentReference<T>, data: WithFieldValue<T>): Promise<void>;
+export function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<void>;
 
 // @public
-export function setDoc<T>(reference: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): Promise<void>;
+export function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): Promise<void>;
 
 // @public
 export function setLogLevel(logLevel: LogLevel): void;
@@ -365,7 +365,7 @@ export interface Settings {
 }
 
 // @public
-export function snapshotEqual<T>(left: DocumentSnapshot<T> | QuerySnapshot<T>, right: DocumentSnapshot<T> | QuerySnapshot<T>): boolean;
+export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>, right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>): boolean;
 
 // @public
 export function startAfter(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
@@ -405,12 +405,12 @@ export class Timestamp {
 
 // @public
 export class Transaction {
-    delete(documentRef: DocumentReference<unknown>): this;
-    get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
-    set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): this;
-    set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): this;
-    update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): this;
-    update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
+    delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): this;
+    get<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): this;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): this;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): this;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
 }
 
 // @public
@@ -427,10 +427,10 @@ export type UpdateData<T> = T extends Primitive ? T : T extends {} ? {
 } & NestedUpdateFields<T> : Partial<T>;
 
 // @public
-export function updateDoc<T>(reference: DocumentReference<T>, data: UpdateData<T>): Promise<void>;
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): Promise<void>;
 
 // @public
-export function updateDoc(reference: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
 
 // @public
 export function where(fieldPath: string | FieldPath, opStr: WhereFilterOp, value: unknown): QueryFieldFilterConstraint;
@@ -446,11 +446,11 @@ export type WithFieldValue<T> = T | (T extends Primitive ? T : T extends {} ? {
 // @public
 export class WriteBatch {
     commit(): Promise<void>;
-    delete(documentRef: DocumentReference<unknown>): WriteBatch;
-    set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): WriteBatch;
-    set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): WriteBatch;
-    update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): WriteBatch;
-    update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
+    delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): WriteBatch;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): WriteBatch;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): WriteBatch;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): WriteBatch;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
 }
 
 // @public
diff --git a/common/api-review/firestore.api.md b/common/api-review/firestore.api.md
index 580320b0aa3..3ab6a88cd74 100644
--- a/common/api-review/firestore.api.md
+++ b/common/api-review/firestore.api.md
@@ -10,7 +10,7 @@ import { FirebaseError } from '@firebase/util';
 import { LogLevelString as LogLevel } from '@firebase/logger';
 
 // @public
-export function addDoc<T>(reference: CollectionReference<T>, data: WithFieldValue<T>): Promise<DocumentReference<T>>;
+export function addDoc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<DocumentReference<AppModelType, DbModelType>>;
 
 // @public
 export type AddPrefixToKeys<Prefix extends string, T extends Record<string, unknown>> = {
@@ -26,14 +26,14 @@ export class AggregateField<T> {
 export type AggregateFieldType = AggregateField<number | null>;
 
 // @public
-export class AggregateQuerySnapshot<T extends AggregateSpec> {
-    data(): AggregateSpecData<T>;
-    readonly query: Query<unknown>;
+export class AggregateQuerySnapshot<AggregateSpecType extends AggregateSpec, AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    data(): AggregateSpecData<AggregateSpecType>;
+    readonly query: Query<AppModelType, DbModelType>;
     readonly type = "AggregateQuerySnapshot";
 }
 
 // @public
-export function aggregateQuerySnapshotEqual<T extends AggregateSpec>(left: AggregateQuerySnapshot<T>, right: AggregateQuerySnapshot<T>): boolean;
+export function aggregateQuerySnapshotEqual<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>, right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>): boolean;
 
 // @public
 export interface AggregateSpec {
@@ -75,25 +75,25 @@ export type ChildUpdateFields<K extends string, V> = V extends Record<string, un
 export function clearIndexedDbPersistence(firestore: Firestore): Promise<void>;
 
 // @public
-export function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collection(reference: CollectionReference<unknown>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collection(reference: DocumentReference, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export function collection<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 
 // @public
-export function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData>;
+export function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData, DocumentData>;
 
 // @public
-export class CollectionReference<T = DocumentData> extends Query<T> {
+export class CollectionReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends Query<AppModelType, DbModelType> {
     get id(): string;
-    get parent(): DocumentReference<DocumentData> | null;
+    get parent(): DocumentReference<DocumentData, DocumentData> | null;
     get path(): string;
     readonly type = "collection";
-    withConverter<U>(converter: FirestoreDataConverter<U>): CollectionReference<U>;
-    withConverter(converter: null): CollectionReference<DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): CollectionReference<NewAppModelType, NewDbModelType>;
+    withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 }
 
 // @public
@@ -102,7 +102,7 @@ export function connectFirestoreEmulator(firestore: Firestore, host: string, por
 }): void;
 
 // @public
-export function deleteDoc(reference: DocumentReference<unknown>): Promise<void>;
+export function deleteDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<void>;
 
 // @public
 export function deleteField(): FieldValue;
@@ -111,17 +111,17 @@ export function deleteField(): FieldValue;
 export function disableNetwork(firestore: Firestore): Promise<void>;
 
 // @public
-export function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 
 // @public
-export function doc<T>(reference: CollectionReference<T>, path?: string, ...pathSegments: string[]): DocumentReference<T>;
+export function doc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path?: string, ...pathSegments: string[]): DocumentReference<AppModelType, DbModelType>;
 
 // @public
-export function doc(reference: DocumentReference<unknown>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export function doc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 
 // @public
-export interface DocumentChange<T = DocumentData> {
-    readonly doc: QueryDocumentSnapshot<T>;
+export interface DocumentChange<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    readonly doc: QueryDocumentSnapshot<AppModelType, DbModelType>;
     readonly newIndex: number;
     readonly oldIndex: number;
     readonly type: DocumentChangeType;
@@ -139,26 +139,26 @@ export interface DocumentData {
 export function documentId(): FieldPath;
 
 // @public
-export class DocumentReference<T = DocumentData> {
-    readonly converter: FirestoreDataConverter<T> | null;
+export class DocumentReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
     readonly firestore: Firestore;
     get id(): string;
-    get parent(): CollectionReference<T>;
+    get parent(): CollectionReference<AppModelType, DbModelType>;
     get path(): string;
     readonly type = "document";
-    withConverter<U>(converter: FirestoreDataConverter<U>): DocumentReference<U>;
-    withConverter(converter: null): DocumentReference<DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): DocumentReference<NewAppModelType, NewDbModelType>;
+    withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 }
 
 // @public
-export class DocumentSnapshot<T = DocumentData> {
+export class DocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
     protected constructor();
-    data(options?: SnapshotOptions): T | undefined;
-    exists(): this is QueryDocumentSnapshot<T>;
+    data(options?: SnapshotOptions): AppModelType | undefined;
+    exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType>;
     get(fieldPath: string | FieldPath, options?: SnapshotOptions): any;
     get id(): string;
     readonly metadata: SnapshotMetadata;
-    get ref(): DocumentReference<T>;
+    get ref(): DocumentReference<AppModelType, DbModelType>;
 }
 
 export { EmulatorMockTokenOptions }
@@ -208,10 +208,10 @@ export class Firestore {
 }
 
 // @public
-export interface FirestoreDataConverter<T> {
-    fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData>, options?: SnapshotOptions): T;
-    toFirestore(modelObject: WithFieldValue<T>): DocumentData;
-    toFirestore(modelObject: PartialWithFieldValue<T>, options: SetOptions): DocumentData;
+export interface FirestoreDataConverter<AppModelType, DbModelType extends DocumentData = DocumentData> {
+    fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>, options?: SnapshotOptions): AppModelType;
+    toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelType>;
+    toFirestore(modelObject: PartialWithFieldValue<AppModelType>, options: SetOptions): PartialWithFieldValue<DbModelType>;
 }
 
 // @public
@@ -252,27 +252,27 @@ export class GeoPoint {
 }
 
 // @public
-export function getCountFromServer(query: Query<unknown>): Promise<AggregateQuerySnapshot<{
+export function getCountFromServer<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<AggregateQuerySnapshot<{
     count: AggregateField<number>;
-}>>;
+}, AppModelType, DbModelType>>;
 
 // @public
-export function getDoc<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export function getDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocFromCache<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export function getDocFromCache<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocFromServer<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export function getDocFromServer<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export function getDocs<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocsFromCache<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export function getDocsFromCache<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 
 // @public
-export function getDocsFromServer<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export function getDocsFromServer<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 
 // @public
 export function getFirestore(app: FirebaseApp): Firestore;
@@ -383,44 +383,44 @@ export type NestedUpdateFields<T extends Record<string, unknown>> = UnionToInter
 }[keyof T & string]>;
 
 // @public
-export function onSnapshot<T>(reference: DocumentReference<T>, observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, observer: {
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(reference: DocumentReference<T>, options: SnapshotListenOptions, observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, options: SnapshotListenOptions, observer: {
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(reference: DocumentReference<T>, onNext: (snapshot: DocumentSnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(reference: DocumentReference<T>, options: SnapshotListenOptions, onNext: (snapshot: DocumentSnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, options: SnapshotListenOptions, onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(query: Query<T>, observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, observer: {
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(query: Query<T>, options: SnapshotListenOptions, observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, options: SnapshotListenOptions, observer: {
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(query: Query<T>, onNext: (snapshot: QuerySnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 
 // @public
-export function onSnapshot<T>(query: Query<T>, options: SnapshotListenOptions, onNext: (snapshot: QuerySnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, options: SnapshotListenOptions, onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 
 // @public
 export function onSnapshotsInSync(firestore: Firestore, observer: {
@@ -496,20 +496,20 @@ export type PersistentTabManager = PersistentSingleTabManager | PersistentMultip
 export type Primitive = string | number | boolean | undefined | null;
 
 // @public
-export class Query<T = DocumentData> {
+export class Query<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
     protected constructor();
-    readonly converter: FirestoreDataConverter<T> | null;
+    readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
     readonly firestore: Firestore;
     readonly type: 'query' | 'collection';
-    withConverter(converter: null): Query<DocumentData>;
-    withConverter<U>(converter: FirestoreDataConverter<U>): Query<U>;
+    withConverter(converter: null): Query<DocumentData, DocumentData>;
+    withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): Query<NewAppModelType, NewDbModelType>;
 }
 
 // @public
-export function query<T>(query: Query<T>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<T>;
+export function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<AppModelType, DbModelType>;
 
 // @public
-export function query<T>(query: Query<T>, ...queryConstraints: QueryConstraint[]): Query<T>;
+export function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, ...queryConstraints: QueryConstraint[]): Query<AppModelType, DbModelType>;
 
 // @public
 export class QueryCompositeFilterConstraint {
@@ -525,9 +525,9 @@ export abstract class QueryConstraint {
 export type QueryConstraintType = 'where' | 'orderBy' | 'limit' | 'limitToLast' | 'startAt' | 'startAfter' | 'endAt' | 'endBefore';
 
 // @public
-export class QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot<T> {
+export class QueryDocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends DocumentSnapshot<AppModelType, DbModelType> {
     // @override
-    data(options?: SnapshotOptions): T;
+    data(options?: SnapshotOptions): AppModelType;
 }
 
 // @public
@@ -536,7 +536,7 @@ export class QueryEndAtConstraint extends QueryConstraint {
 }
 
 // @public
-export function queryEqual<T>(left: Query<T>, right: Query<T>): boolean;
+export function queryEqual<AppModelType, DbModelType extends DocumentData>(left: Query<AppModelType, DbModelType>, right: Query<AppModelType, DbModelType>): boolean;
 
 // @public
 export class QueryFieldFilterConstraint extends QueryConstraint {
@@ -560,13 +560,13 @@ export class QueryOrderByConstraint extends QueryConstraint {
 }
 
 // @public
-export class QuerySnapshot<T = DocumentData> {
-    docChanges(options?: SnapshotListenOptions): Array<DocumentChange<T>>;
-    get docs(): Array<QueryDocumentSnapshot<T>>;
+export class QuerySnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> {
+    docChanges(options?: SnapshotListenOptions): Array<DocumentChange<AppModelType, DbModelType>>;
+    get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>>;
     get empty(): boolean;
-    forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: unknown): void;
+    forEach(callback: (result: QueryDocumentSnapshot<AppModelType, DbModelType>) => void, thisArg?: unknown): void;
     readonly metadata: SnapshotMetadata;
-    readonly query: Query<T>;
+    readonly query: Query<AppModelType, DbModelType>;
     get size(): number;
 }
 
@@ -576,7 +576,7 @@ export class QueryStartAtConstraint extends QueryConstraint {
 }
 
 // @public
-export function refEqual<T>(left: DocumentReference<T> | CollectionReference<T>, right: DocumentReference<T> | CollectionReference<T>): boolean;
+export function refEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>, right: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>): boolean;
 
 // @public
 export function runTransaction<T>(firestore: Firestore, updateFunction: (transaction: Transaction) => Promise<T>, options?: TransactionOptions): Promise<T>;
@@ -585,10 +585,10 @@ export function runTransaction<T>(firestore: Firestore, updateFunction: (transac
 export function serverTimestamp(): FieldValue;
 
 // @public
-export function setDoc<T>(reference: DocumentReference<T>, data: WithFieldValue<T>): Promise<void>;
+export function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<void>;
 
 // @public
-export function setDoc<T>(reference: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): Promise<void>;
+export function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): Promise<void>;
 
 // @beta
 export function setIndexConfiguration(firestore: Firestore, configuration: IndexConfiguration): Promise<void>;
@@ -607,7 +607,7 @@ export type SetOptions = {
 };
 
 // @public
-export function snapshotEqual<T>(left: DocumentSnapshot<T> | QuerySnapshot<T>, right: DocumentSnapshot<T> | QuerySnapshot<T>): boolean;
+export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>, right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>): boolean;
 
 // @public
 export interface SnapshotListenOptions {
@@ -667,12 +667,12 @@ export class Timestamp {
 
 // @public
 export class Transaction {
-    delete(documentRef: DocumentReference<unknown>): this;
-    get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
-    set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): this;
-    set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): this;
-    update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): this;
-    update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
+    delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): this;
+    get<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): this;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): this;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): this;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
 }
 
 // @public
@@ -694,10 +694,10 @@ export type UpdateData<T> = T extends Primitive ? T : T extends {} ? {
 } & NestedUpdateFields<T> : Partial<T>;
 
 // @public
-export function updateDoc<T>(reference: DocumentReference<T>, data: UpdateData<T>): Promise<void>;
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): Promise<void>;
 
 // @public
-export function updateDoc(reference: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
+export function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
 
 // @public
 export function waitForPendingWrites(firestore: Firestore): Promise<void>;
@@ -716,11 +716,11 @@ export type WithFieldValue<T> = T | (T extends Primitive ? T : T extends {} ? {
 // @public
 export class WriteBatch {
     commit(): Promise<void>;
-    delete(documentRef: DocumentReference<unknown>): WriteBatch;
-    set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): WriteBatch;
-    set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): WriteBatch;
-    update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): WriteBatch;
-    update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
+    delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): WriteBatch;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): WriteBatch;
+    set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): WriteBatch;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): WriteBatch;
+    update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
 }
 
 // @public

From e2d238d9d451913acf5f4a87a6a822e833783a1e Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 14:11:23 -0400
Subject: [PATCH 03/10] yarn docgen devsite

---
 .../firestore_.aggregatequerysnapshot.md      |  10 +-
 .../firestore_.collectionreference.md         |  18 +-
 docs-devsite/firestore_.documentchange.md     |   6 +-
 docs-devsite/firestore_.documentreference.md  |  20 +-
 docs-devsite/firestore_.documentsnapshot.md   |  14 +-
 .../firestore_.firestoredataconverter.md      |  20 +-
 docs-devsite/firestore_.md                    | 206 +++++++++---------
 docs-devsite/firestore_.query.md              |  16 +-
 .../firestore_.querydocumentsnapshot.md       |   8 +-
 docs-devsite/firestore_.querysnapshot.md      |  18 +-
 docs-devsite/firestore_.transaction.md        |  32 +--
 docs-devsite/firestore_.writebatch.md         |  26 +--
 .../firestore_lite.aggregatequerysnapshot.md  |  10 +-
 .../firestore_lite.collectionreference.md     |  18 +-
 .../firestore_lite.documentreference.md       |  20 +-
 .../firestore_lite.documentsnapshot.md        |  14 +-
 .../firestore_lite.firestoredataconverter.md  |  20 +-
 docs-devsite/firestore_lite.md                | 126 +++++------
 docs-devsite/firestore_lite.query.md          |  16 +-
 .../firestore_lite.querydocumentsnapshot.md   |   8 +-
 docs-devsite/firestore_lite.querysnapshot.md  |  14 +-
 docs-devsite/firestore_lite.transaction.md    |  32 +--
 docs-devsite/firestore_lite.writebatch.md     |  26 +--
 23 files changed, 349 insertions(+), 349 deletions(-)

diff --git a/docs-devsite/firestore_.aggregatequerysnapshot.md b/docs-devsite/firestore_.aggregatequerysnapshot.md
index 1cf63b5db8b..875ed923174 100644
--- a/docs-devsite/firestore_.aggregatequerysnapshot.md
+++ b/docs-devsite/firestore_.aggregatequerysnapshot.md
@@ -15,14 +15,14 @@ The results of executing an aggregation query.
 <b>Signature:</b>
 
 ```typescript
-export declare class AggregateQuerySnapshot<T extends AggregateSpec> 
+export declare class AggregateQuerySnapshot<AggregateSpecType extends AggregateSpec, AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [query](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshotquery) |  | [Query](./firestore_.query.md#query_class)<!-- -->&lt;unknown&gt; | The underlying query over which the aggregations recorded in this <code>AggregateQuerySnapshot</code> were performed. |
+|  [query](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshotquery) |  | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The underlying query over which the aggregations recorded in this <code>AggregateQuerySnapshot</code> were performed. |
 |  [type](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshottype) |  | (not declared) | A type string to uniquely identify instances of this class. |
 
 ## Methods
@@ -38,7 +38,7 @@ The underlying query over which the aggregations recorded in this `AggregateQuer
 <b>Signature:</b>
 
 ```typescript
-readonly query: Query<unknown>;
+readonly query: Query<AppModelType, DbModelType>;
 ```
 
 ## AggregateQuerySnapshot.type
@@ -60,11 +60,11 @@ The keys of the returned object will be the same as those of the `AggregateSpec`
 <b>Signature:</b>
 
 ```typescript
-data(): AggregateSpecData<T>;
+data(): AggregateSpecData<AggregateSpecType>;
 ```
 <b>Returns:</b>
 
-[AggregateSpecData](./firestore_.md#aggregatespecdata)<!-- -->&lt;T&gt;
+[AggregateSpecData](./firestore_.md#aggregatespecdata)<!-- -->&lt;AggregateSpecType&gt;
 
 The results of the aggregations performed over the underlying query.
 
diff --git a/docs-devsite/firestore_.collectionreference.md b/docs-devsite/firestore_.collectionreference.md
index 56c81c6b245..81fd7e218dc 100644
--- a/docs-devsite/firestore_.collectionreference.md
+++ b/docs-devsite/firestore_.collectionreference.md
@@ -15,16 +15,16 @@ A `CollectionReference` object can be used for adding documents, getting documen
 <b>Signature:</b>
 
 ```typescript
-export declare class CollectionReference<T = DocumentData> extends Query<T> 
+export declare class CollectionReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends Query<AppModelType, DbModelType> 
 ```
-<b>Extends:</b> [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt;
+<b>Extends:</b> [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
 |  [id](./firestore_.collectionreference.md#collectionreferenceid) |  | string | The collection's identifier. |
-|  [parent](./firestore_.collectionreference.md#collectionreferenceparent) |  | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt; \| null | A reference to the containing <code>DocumentReference</code> if this is a subcollection. If this isn't a subcollection, the reference is null. |
+|  [parent](./firestore_.collectionreference.md#collectionreferenceparent) |  | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt; \| null | A reference to the containing <code>DocumentReference</code> if this is a subcollection. If this isn't a subcollection, the reference is null. |
 |  [path](./firestore_.collectionreference.md#collectionreferencepath) |  | string | A string representing the path of the referenced collection (relative to the root of the database). |
 |  [type](./firestore_.collectionreference.md#collectionreferencetype) |  | (not declared) | The type of this Firestore reference. |
 
@@ -52,7 +52,7 @@ A reference to the containing `DocumentReference` if this is a subcollection. If
 <b>Signature:</b>
 
 ```typescript
-get parent(): DocumentReference<DocumentData> | null;
+get parent(): DocumentReference<DocumentData, DocumentData> | null;
 ```
 
 ## CollectionReference.path
@@ -82,18 +82,18 @@ Applies a custom data converter to this `CollectionReference`<!-- -->, allowing
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): CollectionReference<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): CollectionReference<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;U&gt;
+[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `CollectionReference<U>` that uses the provided converter.
 
@@ -104,7 +104,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): CollectionReference<DocumentData>;
+withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -115,7 +115,7 @@ withConverter(converter: null): CollectionReference<DocumentData>;
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `CollectionReference<DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_.documentchange.md b/docs-devsite/firestore_.documentchange.md
index afef795956d..be65980dfc6 100644
--- a/docs-devsite/firestore_.documentchange.md
+++ b/docs-devsite/firestore_.documentchange.md
@@ -15,14 +15,14 @@ A `DocumentChange` represents a change to the documents matching a query. It con
 <b>Signature:</b>
 
 ```typescript
-export declare interface DocumentChange<T = DocumentData> 
+export declare interface DocumentChange<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Type | Description |
 |  --- | --- | --- |
-|  [doc](./firestore_.documentchange.md#documentchangedoc) | [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt; | The document affected by this change. |
+|  [doc](./firestore_.documentchange.md#documentchangedoc) | [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The document affected by this change. |
 |  [newIndex](./firestore_.documentchange.md#documentchangenewindex) | number | The index of the changed document in the result set immediately after this <code>DocumentChange</code> (i.e. supposing that all prior <code>DocumentChange</code> objects and the current <code>DocumentChange</code> object have been applied). Is -1 for 'removed' events. |
 |  [oldIndex](./firestore_.documentchange.md#documentchangeoldindex) | number | The index of the changed document in the result set immediately prior to this <code>DocumentChange</code> (i.e. supposing that all prior <code>DocumentChange</code> objects have been applied). Is <code>-1</code> for 'added' events. |
 |  [type](./firestore_.documentchange.md#documentchangetype) | [DocumentChangeType](./firestore_.md#documentchangetype) | The type of change ('added', 'modified', or 'removed'). |
@@ -34,7 +34,7 @@ The document affected by this change.
 <b>Signature:</b>
 
 ```typescript
-readonly doc: QueryDocumentSnapshot<T>;
+readonly doc: QueryDocumentSnapshot<AppModelType, DbModelType>;
 ```
 
 ## DocumentChange.newIndex
diff --git a/docs-devsite/firestore_.documentreference.md b/docs-devsite/firestore_.documentreference.md
index 16dff93b9c8..cc4d8ecc6b4 100644
--- a/docs-devsite/firestore_.documentreference.md
+++ b/docs-devsite/firestore_.documentreference.md
@@ -15,17 +15,17 @@ A `DocumentReference` refers to a document location in a Firestore database and
 <b>Signature:</b>
 
 ```typescript
-export declare class DocumentReference<T = DocumentData> 
+export declare class DocumentReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [converter](./firestore_.documentreference.md#documentreferenceconverter) |  | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;T&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
+|  [converter](./firestore_.documentreference.md#documentreferenceconverter) |  | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;AppModelType, DbModelType&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
 |  [firestore](./firestore_.documentreference.md#documentreferencefirestore) |  | [Firestore](./firestore_.firestore.md#firestore_class) | The [Firestore](./firestore_.firestore.md#firestore_class) instance the document is in. This is useful for performing transactions, for example. |
 |  [id](./firestore_.documentreference.md#documentreferenceid) |  | string | The document's identifier within its collection. |
-|  [parent](./firestore_.documentreference.md#documentreferenceparent) |  | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | The collection this <code>DocumentReference</code> belongs to. |
+|  [parent](./firestore_.documentreference.md#documentreferenceparent) |  | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The collection this <code>DocumentReference</code> belongs to. |
 |  [path](./firestore_.documentreference.md#documentreferencepath) |  | string | A string representing the path of the referenced document (relative to the root of the database). |
 |  [type](./firestore_.documentreference.md#documentreferencetype) |  | (not declared) | The type of this Firestore reference. |
 
@@ -43,7 +43,7 @@ If provided, the `FirestoreDataConverter` associated with this instance.
 <b>Signature:</b>
 
 ```typescript
-readonly converter: FirestoreDataConverter<T> | null;
+readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
 ```
 
 ## DocumentReference.firestore
@@ -73,7 +73,7 @@ The collection this `DocumentReference` belongs to.
 <b>Signature:</b>
 
 ```typescript
-get parent(): CollectionReference<T>;
+get parent(): CollectionReference<AppModelType, DbModelType>;
 ```
 
 ## DocumentReference.path
@@ -103,18 +103,18 @@ Applies a custom data converter to this `DocumentReference`<!-- -->, allowing yo
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): DocumentReference<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): DocumentReference<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;U&gt;
+[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `DocumentReference<U>` that uses the provided converter.
 
@@ -125,7 +125,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): DocumentReference<DocumentData>;
+withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -136,7 +136,7 @@ withConverter(converter: null): DocumentReference<DocumentData>;
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `DocumentReference<DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_.documentsnapshot.md b/docs-devsite/firestore_.documentsnapshot.md
index 3ac2ec7dcb2..956d834b1ca 100644
--- a/docs-devsite/firestore_.documentsnapshot.md
+++ b/docs-devsite/firestore_.documentsnapshot.md
@@ -17,7 +17,7 @@ For a `DocumentSnapshot` that points to a non-existing document, any data access
 <b>Signature:</b>
 
 ```typescript
-export declare class DocumentSnapshot<T = DocumentData> 
+export declare class DocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Constructors
@@ -32,7 +32,7 @@ export declare class DocumentSnapshot<T = DocumentData>
 |  --- | --- | --- | --- |
 |  [id](./firestore_.documentsnapshot.md#documentsnapshotid) |  | string | Property of the <code>DocumentSnapshot</code> that provides the document's ID. |
 |  [metadata](./firestore_.documentsnapshot.md#documentsnapshotmetadata) |  | [SnapshotMetadata](./firestore_.snapshotmetadata.md#snapshotmetadata_class) | Metadata about the <code>DocumentSnapshot</code>, including information about its source and local modifications. |
-|  [ref](./firestore_.documentsnapshot.md#documentsnapshotref) |  | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | The <code>DocumentReference</code> for the document included in the <code>DocumentSnapshot</code>. |
+|  [ref](./firestore_.documentsnapshot.md#documentsnapshotref) |  | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The <code>DocumentReference</code> for the document included in the <code>DocumentSnapshot</code>. |
 
 ## Methods
 
@@ -79,7 +79,7 @@ The `DocumentReference` for the document included in the `DocumentSnapshot`<!--
 <b>Signature:</b>
 
 ```typescript
-get ref(): DocumentReference<T>;
+get ref(): DocumentReference<AppModelType, DbModelType>;
 ```
 
 ## DocumentSnapshot.data()
@@ -91,7 +91,7 @@ By default, `serverTimestamp()` values that have not yet been set to their final
 <b>Signature:</b>
 
 ```typescript
-data(options?: SnapshotOptions): T | undefined;
+data(options?: SnapshotOptions): AppModelType | undefined;
 ```
 
 ### Parameters
@@ -102,7 +102,7 @@ data(options?: SnapshotOptions): T | undefined;
 
 <b>Returns:</b>
 
-T \| undefined
+AppModelType \| undefined
 
 An `Object` containing all fields in the document or `undefined` if the document doesn't exist.
 
@@ -113,11 +113,11 @@ Returns whether or not the data exists. True if the document exists.
 <b>Signature:</b>
 
 ```typescript
-exists(): this is QueryDocumentSnapshot<T>;
+exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType>;
 ```
 <b>Returns:</b>
 
-this is [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;
+this is [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## DocumentSnapshot.get()
 
diff --git a/docs-devsite/firestore_.firestoredataconverter.md b/docs-devsite/firestore_.firestoredataconverter.md
index f7d80ac4a13..246c510e212 100644
--- a/docs-devsite/firestore_.firestoredataconverter.md
+++ b/docs-devsite/firestore_.firestoredataconverter.md
@@ -17,7 +17,7 @@ Using the converter allows you to specify generic type arguments when storing an
 <b>Signature:</b>
 
 ```typescript
-export declare interface FirestoreDataConverter<T> 
+export declare interface FirestoreDataConverter<AppModelType, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Methods
@@ -35,19 +35,19 @@ Called by the Firestore SDK to convert Firestore data into an object of type T.
 <b>Signature:</b>
 
 ```typescript
-fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData>, options?: SnapshotOptions): T;
+fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>, options?: SnapshotOptions): AppModelType;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt; | A <code>QueryDocumentSnapshot</code> containing your data and metadata. |
+|  snapshot | [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt; | A <code>QueryDocumentSnapshot</code> containing your data and metadata. |
 |  options | [SnapshotOptions](./firestore_.snapshotoptions.md#snapshotoptions_interface) | The <code>SnapshotOptions</code> from the initial call to <code>data()</code>. |
 
 <b>Returns:</b>
 
-T
+AppModelType
 
 ## FirestoreDataConverter.toFirestore()
 
@@ -58,18 +58,18 @@ The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as [dele
 <b>Signature:</b>
 
 ```typescript
-toFirestore(modelObject: WithFieldValue<T>): DocumentData;
+toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  modelObject | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;T&gt; |  |
+|  modelObject | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; |  |
 
 <b>Returns:</b>
 
-[DocumentData](./firestore_.documentdata.md#documentdata_interface)
+[WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;DbModelType&gt;
 
 ## FirestoreDataConverter.toFirestore()
 
@@ -80,19 +80,19 @@ The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow FieldValues su
 <b>Signature:</b>
 
 ```typescript
-toFirestore(modelObject: PartialWithFieldValue<T>, options: SetOptions): DocumentData;
+toFirestore(modelObject: PartialWithFieldValue<AppModelType>, options: SetOptions): PartialWithFieldValue<DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  modelObject | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;T&gt; |  |
+|  modelObject | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; |  |
 |  options | [SetOptions](./firestore_.md#setoptions) |  |
 
 <b>Returns:</b>
 
-[DocumentData](./firestore_.documentdata.md#documentdata_interface)
+[PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;DbModelType&gt;
 
 ### Example
 
diff --git a/docs-devsite/firestore_.md b/docs-devsite/firestore_.md
index c38b6bb8407..9a386348a32 100644
--- a/docs-devsite/firestore_.md
+++ b/docs-devsite/firestore_.md
@@ -283,7 +283,7 @@ Gets a `CollectionReference` instance that refers to the collection at the speci
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -296,7 +296,7 @@ export declare function collection(firestore: Firestore, path: string, ...pathSe
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -311,7 +311,7 @@ Creates and returns a new `Query` instance that includes all documents in the da
 <b>Signature:</b>
 
 ```typescript
-export declare function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData>;
+export declare function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -323,7 +323,7 @@ export declare function collectionGroup(firestore: Firestore, collectionId: stri
 
 <b>Returns:</b>
 
-[Query](./firestore_.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[Query](./firestore_.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The created `Query`<!-- -->.
 
@@ -383,7 +383,7 @@ Gets a `DocumentReference` instance that refers to the document at the specified
 <b>Signature:</b>
 
 ```typescript
-export declare function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export declare function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -396,7 +396,7 @@ export declare function doc(firestore: Firestore, path: string, ...pathSegments:
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `DocumentReference` instance.
 
@@ -1043,15 +1043,15 @@ Two `AggregateQuerySnapshot` instances are considered "equal" if they have under
 <b>Signature:</b>
 
 ```typescript
-export declare function aggregateQuerySnapshotEqual<T extends AggregateSpec>(left: AggregateQuerySnapshot<T>, right: AggregateQuerySnapshot<T>): boolean;
+export declare function aggregateQuerySnapshotEqual<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>, right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;T&gt; | The first <code>AggregateQuerySnapshot</code> to compare. |
-|  right | [AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;T&gt; | The second <code>AggregateQuerySnapshot</code> to compare. |
+|  left | [AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;AggregateSpecType, AppModelType, DbModelType&gt; | The first <code>AggregateQuerySnapshot</code> to compare. |
+|  right | [AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;AggregateSpecType, AppModelType, DbModelType&gt; | The second <code>AggregateQuerySnapshot</code> to compare. |
 
 <b>Returns:</b>
 
@@ -1066,15 +1066,15 @@ Returns true if the provided queries point to the same collection and apply the
 <b>Signature:</b>
 
 ```typescript
-export declare function queryEqual<T>(left: Query<T>, right: Query<T>): boolean;
+export declare function queryEqual<AppModelType, DbModelType extends DocumentData>(left: Query<AppModelType, DbModelType>, right: Query<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | A <code>Query</code> to compare. |
-|  right | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | A <code>Query</code> to compare. |
+|  left | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A <code>Query</code> to compare. |
+|  right | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A <code>Query</code> to compare. |
 
 <b>Returns:</b>
 
@@ -1089,15 +1089,15 @@ Returns true if the provided references are equal.
 <b>Signature:</b>
 
 ```typescript
-export declare function refEqual<T>(left: DocumentReference<T> | CollectionReference<T>, right: DocumentReference<T> | CollectionReference<T>): boolean;
+export declare function refEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>, right: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; \| [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to compare. |
-|  right | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; \| [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to compare. |
+|  left | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to compare. |
+|  right | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to compare. |
 
 <b>Returns:</b>
 
@@ -1112,15 +1112,15 @@ Returns true if the provided snapshots are equal.
 <b>Signature:</b>
 
 ```typescript
-export declare function snapshotEqual<T>(left: DocumentSnapshot<T> | QuerySnapshot<T>, right: DocumentSnapshot<T> | QuerySnapshot<T>): boolean;
+export declare function snapshotEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>, right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt; \| [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt; | A snapshot to compare. |
-|  right | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt; \| [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt; | A snapshot to compare. |
+|  left | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A snapshot to compare. |
+|  right | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A snapshot to compare. |
 
 <b>Returns:</b>
 
@@ -1231,20 +1231,20 @@ The result received from the server is presented, unaltered, without considering
 <b>Signature:</b>
 
 ```typescript
-export declare function getCountFromServer(query: Query<unknown>): Promise<AggregateQuerySnapshot<{
+export declare function getCountFromServer<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<AggregateQuerySnapshot<{
     count: AggregateField<number>;
-}>>;
+}, AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;unknown&gt; | The query whose result set size to calculate. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query whose result set size to calculate. |
 
 <b>Returns:</b>
 
-Promise&lt;[AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;{ count: [AggregateField](./firestore_.aggregatefield.md#aggregatefield_class)<!-- -->&lt;number&gt;; }&gt;&gt;
+Promise&lt;[AggregateQuerySnapshot](./firestore_.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;{ count: [AggregateField](./firestore_.aggregatefield.md#aggregatefield_class)<!-- -->&lt;number&gt;; }, AppModelType, DbModelType&gt;&gt;
 
 A Promise that will be resolved with the count; the count can be retrieved from `snapshot.data().count`<!-- -->, where `snapshot` is the `AggregateQuerySnapshot` to which the returned Promise resolves.
 
@@ -1257,18 +1257,18 @@ Note: `getDocs()` attempts to provide up-to-date data when possible by waiting f
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export declare function getDocs<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; |  |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; |  |
 
 <b>Returns:</b>
 
-Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` that will be resolved with the results of the query.
 
@@ -1279,18 +1279,18 @@ Executes the query and returns the results as a `QuerySnapshot` from cache. Retu
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocsFromCache<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export declare function getDocsFromCache<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; |  |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; |  |
 
 <b>Returns:</b>
 
-Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` that will be resolved with the results of the query.
 
@@ -1301,18 +1301,18 @@ Executes the query and returns the results as a `QuerySnapshot` from the server.
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocsFromServer<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export declare function getDocsFromServer<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; |  |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; |  |
 
 <b>Returns:</b>
 
-Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` that will be resolved with the results of the query.
 
@@ -1325,8 +1325,8 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(query: Query<T>, observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, observer: {
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
@@ -1336,8 +1336,8 @@ export declare function onSnapshot<T>(query: Query<T>, observer: {
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The query to listen to. |
-|  observer | { next?: (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query to listen to. |
+|  observer | { next?: (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
 
 <b>Returns:</b>
 
@@ -1354,8 +1354,8 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(query: Query<T>, options: SnapshotListenOptions, observer: {
-    next?: (snapshot: QuerySnapshot<T>) => void;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, options: SnapshotListenOptions, observer: {
+    next?: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
@@ -1365,9 +1365,9 @@ export declare function onSnapshot<T>(query: Query<T>, options: SnapshotListenOp
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The query to listen to. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query to listen to. |
 |  options | [SnapshotListenOptions](./firestore_.snapshotlistenoptions.md#snapshotlistenoptions_interface) | Options controlling the listen behavior. |
-|  observer | { next?: (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
+|  observer | { next?: (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
 
 <b>Returns:</b>
 
@@ -1384,15 +1384,15 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(query: Query<T>, onNext: (snapshot: QuerySnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The query to listen to. |
-|  onNext | (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called every time a new <code>QuerySnapshot</code> is available. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query to listen to. |
+|  onNext | (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called every time a new <code>QuerySnapshot</code> is available. |
 |  onError | (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void | A callback to be called if the listen fails or is cancelled. No further callbacks will occur. |
 |  onCompletion | () =&gt; void | Can be provided, but will not be called since streams are never ending. |
 
@@ -1411,16 +1411,16 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(query: Query<T>, options: SnapshotListenOptions, onNext: (snapshot: QuerySnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, options: SnapshotListenOptions, onNext: (snapshot: QuerySnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The query to listen to. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query to listen to. |
 |  options | [SnapshotListenOptions](./firestore_.snapshotlistenoptions.md#snapshotlistenoptions_interface) | Options controlling the listen behavior. |
-|  onNext | (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called every time a new <code>QuerySnapshot</code> is available. |
+|  onNext | (snapshot: [QuerySnapshot](./firestore_.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called every time a new <code>QuerySnapshot</code> is available. |
 |  onError | (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void | A callback to be called if the listen fails or is cancelled. No further callbacks will occur. |
 |  onCompletion | () =&gt; void | Can be provided, but will not be called since streams are never ending. |
 
@@ -1437,20 +1437,20 @@ Creates a new immutable instance of [Query](./firestore_.query.md#query_class) t
 <b>Signature:</b>
 
 ```typescript
-export declare function query<T>(query: Query<T>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<T>;
+export declare function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
 |  compositeFilter | [QueryCompositeFilterConstraint](./firestore_.querycompositefilterconstraint.md#querycompositefilterconstraint_class) | The [QueryCompositeFilterConstraint](./firestore_.querycompositefilterconstraint.md#querycompositefilterconstraint_class) to apply. Create [QueryCompositeFilterConstraint](./firestore_.querycompositefilterconstraint.md#querycompositefilterconstraint_class) using [and()](./firestore_.md#and) or [or()](./firestore_.md#or)<!-- -->. |
 |  queryConstraints | [QueryNonFilterConstraint](./firestore_.md#querynonfilterconstraint)<!-- -->\[\] | Additional [QueryNonFilterConstraint](./firestore_.md#querynonfilterconstraint)<!-- -->s to apply (e.g. [orderBy()](./firestore_.md#orderby)<!-- -->, [limit()](./firestore_.md#limit)<!-- -->). |
 
 <b>Returns:</b>
 
-[Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt;
+[Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Exceptions
 
@@ -1463,19 +1463,19 @@ Creates a new immutable instance of [Query](./firestore_.query.md#query_class) t
 <b>Signature:</b>
 
 ```typescript
-export declare function query<T>(query: Query<T>, ...queryConstraints: QueryConstraint[]): Query<T>;
+export declare function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, ...queryConstraints: QueryConstraint[]): Query<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
+|  query | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
 |  queryConstraints | [QueryConstraint](./firestore_.queryconstraint.md#queryconstraint_class)<!-- -->\[\] | The list of [QueryConstraint](./firestore_.queryconstraint.md#queryconstraint_class)<!-- -->s to apply. |
 
 <b>Returns:</b>
 
-[Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt;
+[Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Exceptions
 
@@ -1532,19 +1532,19 @@ Add a new document to specified `CollectionReference` with the given data, assig
 <b>Signature:</b>
 
 ```typescript
-export declare function addDoc<T>(reference: CollectionReference<T>, data: WithFieldValue<T>): Promise<DocumentReference<T>>;
+export declare function addDoc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<DocumentReference<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to the collection to add this document to. |
-|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;T&gt; | An Object containing the data for the new document. |
+|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the collection to add this document to. |
+|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An Object containing the data for the new document. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` resolved with a `DocumentReference` pointing to the newly created document after it has been written to the backend (Note that it won't resolve while you're offline).
 
@@ -1555,20 +1555,20 @@ Gets a `CollectionReference` instance that refers to a subcollection of `referen
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(reference: CollectionReference<unknown>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;unknown&gt; | A reference to a collection. |
+|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a collection. |
 |  path | string | A slash-separated path to a collection. |
 |  pathSegments | string\[\] | Additional path segments to apply relative to the first argument. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -1583,20 +1583,20 @@ Gets a `CollectionReference` instance that refers to a subcollection of `referen
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(reference: DocumentReference, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class) | A reference to a Firestore document. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a Firestore document. |
 |  path | string | A slash-separated path to a collection. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -1611,14 +1611,14 @@ Deletes the document referred to by the specified `DocumentReference`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-export declare function deleteDoc(reference: DocumentReference<unknown>): Promise<void>;
+export declare function deleteDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to delete. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to delete. |
 
 <b>Returns:</b>
 
@@ -1633,20 +1633,20 @@ Gets a `DocumentReference` instance that refers to a document within `reference`
 <b>Signature:</b>
 
 ```typescript
-export declare function doc<T>(reference: CollectionReference<T>, path?: string, ...pathSegments: string[]): DocumentReference<T>;
+export declare function doc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path?: string, ...pathSegments: string[]): DocumentReference<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to a collection. |
+|  reference | [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a collection. |
 |  path | string | A slash-separated path to a document. Has to be omitted to use auto-genrated IDs. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt;
+[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 The `DocumentReference` instance.
 
@@ -1661,20 +1661,20 @@ Gets a `DocumentReference` instance that refers to a document within `reference`
 <b>Signature:</b>
 
 ```typescript
-export declare function doc(reference: DocumentReference<unknown>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export declare function doc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to a Firestore document. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a Firestore document. |
 |  path | string | A slash-separated path to a document. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `DocumentReference` instance.
 
@@ -1691,18 +1691,18 @@ Note: `getDoc()` attempts to provide up-to-date data when possible by waiting fo
 <b>Signature:</b>
 
 ```typescript
-export declare function getDoc<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export declare function getDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | The reference of the document to fetch. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The reference of the document to fetch. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A Promise resolved with a `DocumentSnapshot` containing the current document contents.
 
@@ -1713,18 +1713,18 @@ Reads the document referred to by this `DocumentReference` from cache. Returns a
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocFromCache<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export declare function getDocFromCache<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; |  |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; |  |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` resolved with a `DocumentSnapshot` containing the current document contents.
 
@@ -1735,18 +1735,18 @@ Reads the document referred to by this `DocumentReference` from the server. Retu
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocFromServer<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export declare function getDocFromServer<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; |  |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; |  |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` resolved with a `DocumentSnapshot` containing the current document contents.
 
@@ -1759,8 +1759,8 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(reference: DocumentReference<T>, observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, observer: {
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
@@ -1770,8 +1770,8 @@ export declare function onSnapshot<T>(reference: DocumentReference<T>, observer:
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to listen to. |
-|  observer | { next?: (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to listen to. |
+|  observer | { next?: (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
 
 <b>Returns:</b>
 
@@ -1788,8 +1788,8 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(reference: DocumentReference<T>, options: SnapshotListenOptions, observer: {
-    next?: (snapshot: DocumentSnapshot<T>) => void;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, options: SnapshotListenOptions, observer: {
+    next?: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void;
     error?: (error: FirestoreError) => void;
     complete?: () => void;
 }): Unsubscribe;
@@ -1799,9 +1799,9 @@ export declare function onSnapshot<T>(reference: DocumentReference<T>, options:
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to listen to. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to listen to. |
 |  options | [SnapshotListenOptions](./firestore_.snapshotlistenoptions.md#snapshotlistenoptions_interface) | Options controlling the listen behavior. |
-|  observer | { next?: (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
+|  observer | { next?: (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void; error?: (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void; complete?: () =&gt; void; } | A single object containing <code>next</code> and <code>error</code> callbacks. |
 
 <b>Returns:</b>
 
@@ -1818,15 +1818,15 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(reference: DocumentReference<T>, onNext: (snapshot: DocumentSnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to listen to. |
-|  onNext | (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called every time a new <code>DocumentSnapshot</code> is available. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to listen to. |
+|  onNext | (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called every time a new <code>DocumentSnapshot</code> is available. |
 |  onError | (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void | A callback to be called if the listen fails or is cancelled. No further callbacks will occur. |
 |  onCompletion | () =&gt; void | Can be provided, but will not be called since streams are never ending. |
 
@@ -1845,16 +1845,16 @@ NOTE: Although an `onCompletion` callback can be provided, it will never be call
 <b>Signature:</b>
 
 ```typescript
-export declare function onSnapshot<T>(reference: DocumentReference<T>, options: SnapshotListenOptions, onNext: (snapshot: DocumentSnapshot<T>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
+export declare function onSnapshot<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, options: SnapshotListenOptions, onNext: (snapshot: DocumentSnapshot<AppModelType, DbModelType>) => void, onError?: (error: FirestoreError) => void, onCompletion?: () => void): Unsubscribe;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to listen to. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to listen to. |
 |  options | [SnapshotListenOptions](./firestore_.snapshotlistenoptions.md#snapshotlistenoptions_interface) | Options controlling the listen behavior. |
-|  onNext | (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called every time a new <code>DocumentSnapshot</code> is available. |
+|  onNext | (snapshot: [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called every time a new <code>DocumentSnapshot</code> is available. |
 |  onError | (error: [FirestoreError](./firestore_.firestoreerror.md#firestoreerror_class)<!-- -->) =&gt; void | A callback to be called if the listen fails or is cancelled. No further callbacks will occur. |
 |  onCompletion | () =&gt; void | Can be provided, but will not be called since streams are never ending. |
 
@@ -1871,15 +1871,15 @@ Writes to the document referred to by this `DocumentReference`<!-- -->. If the d
 <b>Signature:</b>
 
 ```typescript
-export declare function setDoc<T>(reference: DocumentReference<T>, data: WithFieldValue<T>): Promise<void>;
+export declare function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to write. |
-|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;T&gt; | A map of the fields and values for the document. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to write. |
+|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | A map of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -1894,15 +1894,15 @@ Writes to the document referred to by the specified `DocumentReference`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-export declare function setDoc<T>(reference: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): Promise<void>;
+export declare function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to write. |
-|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | A map of the fields and values for the document. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to write. |
+|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | A map of the fields and values for the document. |
 |  options | [SetOptions](./firestore_.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -1918,15 +1918,15 @@ Updates fields in the document referred to by the specified `DocumentReference`<
 <b>Signature:</b>
 
 ```typescript
-export declare function updateDoc<T>(reference: DocumentReference<T>, data: UpdateData<T>): Promise<void>;
+export declare function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to update. |
-|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to update. |
+|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -1943,14 +1943,14 @@ Nested fields can be updated by providing dot-separated field path strings or by
 <b>Signature:</b>
 
 ```typescript
-export declare function updateDoc(reference: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
+export declare function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to update. |
+|  reference | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to update. |
 |  field | string \| [FieldPath](./firestore_.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key value pairs. |
diff --git a/docs-devsite/firestore_.query.md b/docs-devsite/firestore_.query.md
index 1961c2cc5f3..7e7cea4fb45 100644
--- a/docs-devsite/firestore_.query.md
+++ b/docs-devsite/firestore_.query.md
@@ -15,7 +15,7 @@ A `Query` refers to a query which you can read or listen to. You can also constr
 <b>Signature:</b>
 
 ```typescript
-export declare class Query<T = DocumentData> 
+export declare class Query<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Constructors
@@ -28,7 +28,7 @@ export declare class Query<T = DocumentData>
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [converter](./firestore_.query.md#queryconverter) |  | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;T&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
+|  [converter](./firestore_.query.md#queryconverter) |  | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;AppModelType, DbModelType&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
 |  [firestore](./firestore_.query.md#queryfirestore) |  | [Firestore](./firestore_.firestore.md#firestore_class) | The <code>Firestore</code> instance for the Firestore database (useful for performing transactions, etc.). |
 |  [type](./firestore_.query.md#querytype) |  | 'query' \| 'collection' | The type of this Firestore reference. |
 
@@ -56,7 +56,7 @@ If provided, the `FirestoreDataConverter` associated with this instance.
 <b>Signature:</b>
 
 ```typescript
-readonly converter: FirestoreDataConverter<T> | null;
+readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
 ```
 
 ## Query.firestore
@@ -86,7 +86,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): Query<DocumentData>;
+withConverter(converter: null): Query<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -97,7 +97,7 @@ withConverter(converter: null): Query<DocumentData>;
 
 <b>Returns:</b>
 
-[Query](./firestore_.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
+[Query](./firestore_.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `Query<DocumentData>` that does not use a converter.
 
@@ -108,18 +108,18 @@ Applies a custom data converter to this query, allowing you to use your own cust
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): Query<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): Query<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[Query](./firestore_.query.md#query_class)<!-- -->&lt;U&gt;
+[Query](./firestore_.query.md#query_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `Query<U>` that uses the provided converter.
 
diff --git a/docs-devsite/firestore_.querydocumentsnapshot.md b/docs-devsite/firestore_.querydocumentsnapshot.md
index 0755a11915f..d4f71f2fb55 100644
--- a/docs-devsite/firestore_.querydocumentsnapshot.md
+++ b/docs-devsite/firestore_.querydocumentsnapshot.md
@@ -17,9 +17,9 @@ A `QueryDocumentSnapshot` offers the same API surface as a `DocumentSnapshot`<!-
 <b>Signature:</b>
 
 ```typescript
-export declare class QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot<T> 
+export declare class QueryDocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends DocumentSnapshot<AppModelType, DbModelType> 
 ```
-<b>Extends:</b> [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;
+<b>Extends:</b> [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Methods
 
@@ -37,7 +37,7 @@ By default, `serverTimestamp()` values that have not yet been set to their final
 
 ```typescript
 /** @override */
-data(options?: SnapshotOptions): T;
+data(options?: SnapshotOptions): AppModelType;
 ```
 
 ### Parameters
@@ -48,7 +48,7 @@ data(options?: SnapshotOptions): T;
 
 <b>Returns:</b>
 
-T
+AppModelType
 
 An `Object` containing all fields in the document.
 
diff --git a/docs-devsite/firestore_.querysnapshot.md b/docs-devsite/firestore_.querysnapshot.md
index 0abb869c003..cc67c6336d6 100644
--- a/docs-devsite/firestore_.querysnapshot.md
+++ b/docs-devsite/firestore_.querysnapshot.md
@@ -15,17 +15,17 @@ A `QuerySnapshot` contains zero or more `DocumentSnapshot` objects representing
 <b>Signature:</b>
 
 ```typescript
-export declare class QuerySnapshot<T = DocumentData> 
+export declare class QuerySnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [docs](./firestore_.querysnapshot.md#querysnapshotdocs) |  | Array&lt;[QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;&gt; | An array of all the documents in the <code>QuerySnapshot</code>. |
+|  [docs](./firestore_.querysnapshot.md#querysnapshotdocs) |  | Array&lt;[QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt; | An array of all the documents in the <code>QuerySnapshot</code>. |
 |  [empty](./firestore_.querysnapshot.md#querysnapshotempty) |  | boolean | True if there are no documents in the <code>QuerySnapshot</code>. |
 |  [metadata](./firestore_.querysnapshot.md#querysnapshotmetadata) |  | [SnapshotMetadata](./firestore_.snapshotmetadata.md#snapshotmetadata_class) | Metadata about this snapshot, concerning its source and if it has local modifications. |
-|  [query](./firestore_.querysnapshot.md#querysnapshotquery) |  | [Query](./firestore_.query.md#query_class)<!-- -->&lt;T&gt; | The query on which you called <code>get</code> or <code>onSnapshot</code> in order to get this <code>QuerySnapshot</code>. |
+|  [query](./firestore_.querysnapshot.md#querysnapshotquery) |  | [Query](./firestore_.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query on which you called <code>get</code> or <code>onSnapshot</code> in order to get this <code>QuerySnapshot</code>. |
 |  [size](./firestore_.querysnapshot.md#querysnapshotsize) |  | number | The number of documents in the <code>QuerySnapshot</code>. |
 
 ## Methods
@@ -42,7 +42,7 @@ An array of all the documents in the `QuerySnapshot`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-get docs(): Array<QueryDocumentSnapshot<T>>;
+get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ## QuerySnapshot.empty
@@ -72,7 +72,7 @@ The query on which you called `get` or `onSnapshot` in order to get this `QueryS
 <b>Signature:</b>
 
 ```typescript
-readonly query: Query<T>;
+readonly query: Query<AppModelType, DbModelType>;
 ```
 
 ## QuerySnapshot.size
@@ -92,7 +92,7 @@ Returns an array of the documents changes since the last snapshot. If this is th
 <b>Signature:</b>
 
 ```typescript
-docChanges(options?: SnapshotListenOptions): Array<DocumentChange<T>>;
+docChanges(options?: SnapshotListenOptions): Array<DocumentChange<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
@@ -103,7 +103,7 @@ docChanges(options?: SnapshotListenOptions): Array<DocumentChange<T>>;
 
 <b>Returns:</b>
 
-Array&lt;[DocumentChange](./firestore_.documentchange.md#documentchange_interface)<!-- -->&lt;T&gt;&gt;
+Array&lt;[DocumentChange](./firestore_.documentchange.md#documentchange_interface)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 ## QuerySnapshot.forEach()
 
@@ -112,14 +112,14 @@ Enumerates all of the documents in the `QuerySnapshot`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: unknown): void;
+forEach(callback: (result: QueryDocumentSnapshot<AppModelType, DbModelType>) => void, thisArg?: unknown): void;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  callback | (result: [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called with a <code>QueryDocumentSnapshot</code> for each document in the snapshot. |
+|  callback | (result: [QueryDocumentSnapshot](./firestore_.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called with a <code>QueryDocumentSnapshot</code> for each document in the snapshot. |
 |  thisArg | unknown | The <code>this</code> binding for the callback. |
 
 <b>Returns:</b>
diff --git a/docs-devsite/firestore_.transaction.md b/docs-devsite/firestore_.transaction.md
index 24f0690bea4..b25fa2acb84 100644
--- a/docs-devsite/firestore_.transaction.md
+++ b/docs-devsite/firestore_.transaction.md
@@ -38,14 +38,14 @@ Deletes the document referred to by the provided [DocumentReference](./firestore
 <b>Signature:</b>
 
 ```typescript
-delete(documentRef: DocumentReference<unknown>): this;
+delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be deleted. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be deleted. |
 
 <b>Returns:</b>
 
@@ -60,18 +60,18 @@ Reads the document referenced by the provided [DocumentReference](./firestore_.d
 <b>Signature:</b>
 
 ```typescript
-get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+get<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be read. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be read. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `DocumentSnapshot` with the read data.
 
@@ -82,15 +82,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): this;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -109,15 +109,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): this;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 |  options | [SetOptions](./firestore_.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -137,15 +137,15 @@ Updates fields in the document referred to by the provided [DocumentReference](.
 <b>Signature:</b>
 
 ```typescript
-update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): this;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be updated. |
-|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
+|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -166,14 +166,14 @@ Nested fields can be updated by providing dot-separated field path strings or by
 <b>Signature:</b>
 
 ```typescript
-update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be updated. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
 |  field | string \| [FieldPath](./firestore_.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key/value pairs. |
diff --git a/docs-devsite/firestore_.writebatch.md b/docs-devsite/firestore_.writebatch.md
index 878cb66810a..7fce73d40ea 100644
--- a/docs-devsite/firestore_.writebatch.md
+++ b/docs-devsite/firestore_.writebatch.md
@@ -55,14 +55,14 @@ Deletes the document referred to by the provided [DocumentReference](./firestore
 <b>Signature:</b>
 
 ```typescript
-delete(documentRef: DocumentReference<unknown>): WriteBatch;
+delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be deleted. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be deleted. |
 
 <b>Returns:</b>
 
@@ -77,15 +77,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): WriteBatch;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [WithFieldValue](./firestore_.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -100,15 +100,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): WriteBatch;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [PartialWithFieldValue](./firestore_.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 |  options | [SetOptions](./firestore_.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -128,15 +128,15 @@ Updates fields in the document referred to by the provided [DocumentReference](.
 <b>Signature:</b>
 
 ```typescript
-update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): WriteBatch;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be updated. |
-|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
+|  data | [UpdateData](./firestore_.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -157,14 +157,14 @@ Nested fields can be update by providing dot-separated field path strings or by
 <b>Signature:</b>
 
 ```typescript
-update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be updated. |
+|  documentRef | [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
 |  field | string \| [FieldPath](./firestore_.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key value pairs. |
diff --git a/docs-devsite/firestore_lite.aggregatequerysnapshot.md b/docs-devsite/firestore_lite.aggregatequerysnapshot.md
index 4b5d3120ba3..3b9c5129be0 100644
--- a/docs-devsite/firestore_lite.aggregatequerysnapshot.md
+++ b/docs-devsite/firestore_lite.aggregatequerysnapshot.md
@@ -15,14 +15,14 @@ The results of executing an aggregation query.
 <b>Signature:</b>
 
 ```typescript
-export declare class AggregateQuerySnapshot<T extends AggregateSpec> 
+export declare class AggregateQuerySnapshot<AggregateSpecType extends AggregateSpec, AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [query](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshotquery) |  | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;unknown&gt; | The underlying query over which the aggregations recorded in this <code>AggregateQuerySnapshot</code> were performed. |
+|  [query](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshotquery) |  | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The underlying query over which the aggregations recorded in this <code>AggregateQuerySnapshot</code> were performed. |
 |  [type](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshottype) |  | (not declared) | A type string to uniquely identify instances of this class. |
 
 ## Methods
@@ -38,7 +38,7 @@ The underlying query over which the aggregations recorded in this `AggregateQuer
 <b>Signature:</b>
 
 ```typescript
-readonly query: Query<unknown>;
+readonly query: Query<AppModelType, DbModelType>;
 ```
 
 ## AggregateQuerySnapshot.type
@@ -60,11 +60,11 @@ The keys of the returned object will be the same as those of the `AggregateSpec`
 <b>Signature:</b>
 
 ```typescript
-data(): AggregateSpecData<T>;
+data(): AggregateSpecData<AggregateSpecType>;
 ```
 <b>Returns:</b>
 
-[AggregateSpecData](./firestore_lite.md#aggregatespecdata)<!-- -->&lt;T&gt;
+[AggregateSpecData](./firestore_lite.md#aggregatespecdata)<!-- -->&lt;AggregateSpecType&gt;
 
 The results of the aggregations performed over the underlying query.
 
diff --git a/docs-devsite/firestore_lite.collectionreference.md b/docs-devsite/firestore_lite.collectionreference.md
index d446560a02f..18e64e719eb 100644
--- a/docs-devsite/firestore_lite.collectionreference.md
+++ b/docs-devsite/firestore_lite.collectionreference.md
@@ -15,16 +15,16 @@ A `CollectionReference` object can be used for adding documents, getting documen
 <b>Signature:</b>
 
 ```typescript
-export declare class CollectionReference<T = DocumentData> extends Query<T> 
+export declare class CollectionReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends Query<AppModelType, DbModelType> 
 ```
-<b>Extends:</b> [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt;
+<b>Extends:</b> [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
 |  [id](./firestore_lite.collectionreference.md#collectionreferenceid) |  | string | The collection's identifier. |
-|  [parent](./firestore_lite.collectionreference.md#collectionreferenceparent) |  | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt; \| null | A reference to the containing <code>DocumentReference</code> if this is a subcollection. If this isn't a subcollection, the reference is null. |
+|  [parent](./firestore_lite.collectionreference.md#collectionreferenceparent) |  | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt; \| null | A reference to the containing <code>DocumentReference</code> if this is a subcollection. If this isn't a subcollection, the reference is null. |
 |  [path](./firestore_lite.collectionreference.md#collectionreferencepath) |  | string | A string representing the path of the referenced collection (relative to the root of the database). |
 |  [type](./firestore_lite.collectionreference.md#collectionreferencetype) |  | (not declared) | The type of this Firestore reference. |
 
@@ -52,7 +52,7 @@ A reference to the containing `DocumentReference` if this is a subcollection. If
 <b>Signature:</b>
 
 ```typescript
-get parent(): DocumentReference<DocumentData> | null;
+get parent(): DocumentReference<DocumentData, DocumentData> | null;
 ```
 
 ## CollectionReference.path
@@ -82,18 +82,18 @@ Applies a custom data converter to this `CollectionReference`<!-- -->, allowing
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): CollectionReference<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): CollectionReference<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;U&gt;
+[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `CollectionReference<U>` that uses the provided converter.
 
@@ -104,7 +104,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): CollectionReference<DocumentData>;
+withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -115,7 +115,7 @@ withConverter(converter: null): CollectionReference<DocumentData>;
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `CollectionReference<DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_lite.documentreference.md b/docs-devsite/firestore_lite.documentreference.md
index 0e307435949..7c02494faf4 100644
--- a/docs-devsite/firestore_lite.documentreference.md
+++ b/docs-devsite/firestore_lite.documentreference.md
@@ -15,17 +15,17 @@ A `DocumentReference` refers to a document location in a Firestore database and
 <b>Signature:</b>
 
 ```typescript
-export declare class DocumentReference<T = DocumentData> 
+export declare class DocumentReference<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [converter](./firestore_lite.documentreference.md#documentreferenceconverter) |  | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;T&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
+|  [converter](./firestore_lite.documentreference.md#documentreferenceconverter) |  | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;AppModelType, DbModelType&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
 |  [firestore](./firestore_lite.documentreference.md#documentreferencefirestore) |  | [Firestore](./firestore_lite.firestore.md#firestore_class) | The [Firestore](./firestore_.firestore.md#firestore_class) instance the document is in. This is useful for performing transactions, for example. |
 |  [id](./firestore_lite.documentreference.md#documentreferenceid) |  | string | The document's identifier within its collection. |
-|  [parent](./firestore_lite.documentreference.md#documentreferenceparent) |  | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | The collection this <code>DocumentReference</code> belongs to. |
+|  [parent](./firestore_lite.documentreference.md#documentreferenceparent) |  | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The collection this <code>DocumentReference</code> belongs to. |
 |  [path](./firestore_lite.documentreference.md#documentreferencepath) |  | string | A string representing the path of the referenced document (relative to the root of the database). |
 |  [type](./firestore_lite.documentreference.md#documentreferencetype) |  | (not declared) | The type of this Firestore reference. |
 
@@ -43,7 +43,7 @@ If provided, the `FirestoreDataConverter` associated with this instance.
 <b>Signature:</b>
 
 ```typescript
-readonly converter: FirestoreDataConverter<T> | null;
+readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
 ```
 
 ## DocumentReference.firestore
@@ -73,7 +73,7 @@ The collection this `DocumentReference` belongs to.
 <b>Signature:</b>
 
 ```typescript
-get parent(): CollectionReference<T>;
+get parent(): CollectionReference<AppModelType, DbModelType>;
 ```
 
 ## DocumentReference.path
@@ -103,18 +103,18 @@ Applies a custom data converter to this `DocumentReference`<!-- -->, allowing yo
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): DocumentReference<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): DocumentReference<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;U&gt;
+[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `DocumentReference<U>` that uses the provided converter.
 
@@ -125,7 +125,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): DocumentReference<DocumentData>;
+withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -136,7 +136,7 @@ withConverter(converter: null): DocumentReference<DocumentData>;
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `DocumentReference<DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_lite.documentsnapshot.md b/docs-devsite/firestore_lite.documentsnapshot.md
index cfea1feb919..00b4b005c70 100644
--- a/docs-devsite/firestore_lite.documentsnapshot.md
+++ b/docs-devsite/firestore_lite.documentsnapshot.md
@@ -17,7 +17,7 @@ For a `DocumentSnapshot` that points to a non-existing document, any data access
 <b>Signature:</b>
 
 ```typescript
-export declare class DocumentSnapshot<T = DocumentData> 
+export declare class DocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Constructors
@@ -31,7 +31,7 @@ export declare class DocumentSnapshot<T = DocumentData>
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
 |  [id](./firestore_lite.documentsnapshot.md#documentsnapshotid) |  | string | Property of the <code>DocumentSnapshot</code> that provides the document's ID. |
-|  [ref](./firestore_lite.documentsnapshot.md#documentsnapshotref) |  | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | The <code>DocumentReference</code> for the document included in the <code>DocumentSnapshot</code>. |
+|  [ref](./firestore_lite.documentsnapshot.md#documentsnapshotref) |  | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The <code>DocumentReference</code> for the document included in the <code>DocumentSnapshot</code>. |
 
 ## Methods
 
@@ -68,7 +68,7 @@ The `DocumentReference` for the document included in the `DocumentSnapshot`<!--
 <b>Signature:</b>
 
 ```typescript
-get ref(): DocumentReference<T>;
+get ref(): DocumentReference<AppModelType, DbModelType>;
 ```
 
 ## DocumentSnapshot.data()
@@ -78,11 +78,11 @@ Retrieves all fields in the document as an `Object`<!-- -->. Returns `undefined`
 <b>Signature:</b>
 
 ```typescript
-data(): T | undefined;
+data(): AppModelType | undefined;
 ```
 <b>Returns:</b>
 
-T \| undefined
+AppModelType \| undefined
 
 An `Object` containing all fields in the document or `undefined` if the document doesn't exist.
 
@@ -93,11 +93,11 @@ Signals whether or not the document at the snapshot's location exists.
 <b>Signature:</b>
 
 ```typescript
-exists(): this is QueryDocumentSnapshot<T>;
+exists(): this is QueryDocumentSnapshot<AppModelType, DbModelType>;
 ```
 <b>Returns:</b>
 
-this is [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;
+this is [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 true if the document exists.
 
diff --git a/docs-devsite/firestore_lite.firestoredataconverter.md b/docs-devsite/firestore_lite.firestoredataconverter.md
index 00510e0c22b..e508471ecfa 100644
--- a/docs-devsite/firestore_lite.firestoredataconverter.md
+++ b/docs-devsite/firestore_lite.firestoredataconverter.md
@@ -17,7 +17,7 @@ Using the converter allows you to specify generic type arguments when storing an
 <b>Signature:</b>
 
 ```typescript
-export declare interface FirestoreDataConverter<T> 
+export declare interface FirestoreDataConverter<AppModelType, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Methods
@@ -35,18 +35,18 @@ Called by the Firestore SDK to convert Firestore data into an object of type T.
 <b>Signature:</b>
 
 ```typescript
-fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData>): T;
+fromFirestore(snapshot: QueryDocumentSnapshot<DocumentData, DocumentData>): AppModelType;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt; | A <code>QueryDocumentSnapshot</code> containing your data and metadata. |
+|  snapshot | [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt; | A <code>QueryDocumentSnapshot</code> containing your data and metadata. |
 
 <b>Returns:</b>
 
-T
+AppModelType
 
 ## FirestoreDataConverter.toFirestore()
 
@@ -57,18 +57,18 @@ The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as [dele
 <b>Signature:</b>
 
 ```typescript
-toFirestore(modelObject: WithFieldValue<T>): DocumentData;
+toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  modelObject | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;T&gt; |  |
+|  modelObject | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; |  |
 
 <b>Returns:</b>
 
-[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)
+[WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;DbModelType&gt;
 
 ## FirestoreDataConverter.toFirestore()
 
@@ -79,19 +79,19 @@ The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow FieldValues su
 <b>Signature:</b>
 
 ```typescript
-toFirestore(modelObject: PartialWithFieldValue<T>, options: SetOptions): DocumentData;
+toFirestore(modelObject: PartialWithFieldValue<AppModelType>, options: SetOptions): PartialWithFieldValue<DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  modelObject | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;T&gt; |  |
+|  modelObject | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; |  |
 |  options | [SetOptions](./firestore_lite.md#setoptions) |  |
 
 <b>Returns:</b>
 
-[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)
+[PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;DbModelType&gt;
 
 ### Example
 
diff --git a/docs-devsite/firestore_lite.md b/docs-devsite/firestore_lite.md
index b0ec302e722..f4748a838cd 100644
--- a/docs-devsite/firestore_lite.md
+++ b/docs-devsite/firestore_lite.md
@@ -193,7 +193,7 @@ Gets a `CollectionReference` instance that refers to the collection at the speci
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection(firestore: Firestore, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -206,7 +206,7 @@ export declare function collection(firestore: Firestore, path: string, ...pathSe
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -221,7 +221,7 @@ Creates and returns a new `Query` instance that includes all documents in the da
 <b>Signature:</b>
 
 ```typescript
-export declare function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData>;
+export declare function collectionGroup(firestore: Firestore, collectionId: string): Query<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -233,7 +233,7 @@ export declare function collectionGroup(firestore: Firestore, collectionId: stri
 
 <b>Returns:</b>
 
-[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The created `Query`<!-- -->.
 
@@ -271,7 +271,7 @@ Gets a `DocumentReference` instance that refers to the document at the specified
 <b>Signature:</b>
 
 ```typescript
-export declare function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export declare function doc(firestore: Firestore, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -284,7 +284,7 @@ export declare function doc(firestore: Firestore, path: string, ...pathSegments:
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `DocumentReference` instance.
 
@@ -614,15 +614,15 @@ Two `AggregateQuerySnapshot` instances are considered "equal" if they have under
 <b>Signature:</b>
 
 ```typescript
-export declare function aggregateQuerySnapshotEqual<T extends AggregateSpec>(left: AggregateQuerySnapshot<T>, right: AggregateQuerySnapshot<T>): boolean;
+export declare function aggregateQuerySnapshotEqual<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>, right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;T&gt; | The first <code>AggregateQuerySnapshot</code> to compare. |
-|  right | [AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;T&gt; | The second <code>AggregateQuerySnapshot</code> to compare. |
+|  left | [AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;AggregateSpecType, AppModelType, DbModelType&gt; | The first <code>AggregateQuerySnapshot</code> to compare. |
+|  right | [AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;AggregateSpecType, AppModelType, DbModelType&gt; | The second <code>AggregateQuerySnapshot</code> to compare. |
 
 <b>Returns:</b>
 
@@ -637,15 +637,15 @@ Returns true if the provided queries point to the same collection and apply the
 <b>Signature:</b>
 
 ```typescript
-export declare function queryEqual<T>(left: Query<T>, right: Query<T>): boolean;
+export declare function queryEqual<AppModelType, DbModelType extends DocumentData>(left: Query<AppModelType, DbModelType>, right: Query<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | A <code>Query</code> to compare. |
-|  right | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | A <code>Query</code> to compare. |
+|  left | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A <code>Query</code> to compare. |
+|  right | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A <code>Query</code> to compare. |
 
 <b>Returns:</b>
 
@@ -660,15 +660,15 @@ Returns true if the provided references are equal.
 <b>Signature:</b>
 
 ```typescript
-export declare function refEqual<T>(left: DocumentReference<T> | CollectionReference<T>, right: DocumentReference<T> | CollectionReference<T>): boolean;
+export declare function refEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>, right: DocumentReference<AppModelType, DbModelType> | CollectionReference<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; \| [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to compare. |
-|  right | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; \| [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to compare. |
+|  left | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to compare. |
+|  right | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to compare. |
 
 <b>Returns:</b>
 
@@ -683,15 +683,15 @@ Returns true if the provided snapshots are equal.
 <b>Signature:</b>
 
 ```typescript
-export declare function snapshotEqual<T>(left: DocumentSnapshot<T> | QuerySnapshot<T>, right: DocumentSnapshot<T> | QuerySnapshot<T>): boolean;
+export declare function snapshotEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>, right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>): boolean;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  left | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt; \| [QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt; | A snapshot to compare. |
-|  right | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt; \| [QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt; | A snapshot to compare. |
+|  left | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A snapshot to compare. |
+|  right | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; \| [QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A snapshot to compare. |
 
 <b>Returns:</b>
 
@@ -800,20 +800,20 @@ Using this function to count the documents is efficient because only the final c
 <b>Signature:</b>
 
 ```typescript
-export declare function getCount(query: Query<unknown>): Promise<AggregateQuerySnapshot<{
+export declare function getCount<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<AggregateQuerySnapshot<{
     count: AggregateField<number>;
-}>>;
+}, AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;unknown&gt; | The query whose result set size to calculate. |
+|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query whose result set size to calculate. |
 
 <b>Returns:</b>
 
-Promise&lt;[AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;{ count: [AggregateField](./firestore_lite.aggregatefield.md#aggregatefield_class)<!-- -->&lt;number&gt;; }&gt;&gt;
+Promise&lt;[AggregateQuerySnapshot](./firestore_lite.aggregatequerysnapshot.md#aggregatequerysnapshot_class)<!-- -->&lt;{ count: [AggregateField](./firestore_lite.aggregatefield.md#aggregatefield_class)<!-- -->&lt;number&gt;; }, AppModelType, DbModelType&gt;&gt;
 
 A Promise that will be resolved with the count; the count can be retrieved from `snapshot.data().count`<!-- -->, where `snapshot` is the `AggregateQuerySnapshot` to which the returned Promise resolves.
 
@@ -826,18 +826,18 @@ All queries are executed directly by the server, even if the the query was previ
 <b>Signature:</b>
 
 ```typescript
-export declare function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
+export declare function getDocs<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<QuerySnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | The <code>Query</code> to execute. |
+|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The <code>Query</code> to execute. |
 
 <b>Returns:</b>
 
-Promise&lt;[QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[QuerySnapshot](./firestore_lite.querysnapshot.md#querysnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A Promise that will be resolved with the results of the query.
 
@@ -848,20 +848,20 @@ Creates a new immutable instance of [Query](./firestore_.query.md#query_class) t
 <b>Signature:</b>
 
 ```typescript
-export declare function query<T>(query: Query<T>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<T>;
+export declare function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, compositeFilter: QueryCompositeFilterConstraint, ...queryConstraints: QueryNonFilterConstraint[]): Query<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
+|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
 |  compositeFilter | [QueryCompositeFilterConstraint](./firestore_lite.querycompositefilterconstraint.md#querycompositefilterconstraint_class) | The [QueryCompositeFilterConstraint](./firestore_.querycompositefilterconstraint.md#querycompositefilterconstraint_class) to apply. Create [QueryCompositeFilterConstraint](./firestore_.querycompositefilterconstraint.md#querycompositefilterconstraint_class) using [and()](./firestore_.md#and) or [or()](./firestore_.md#or)<!-- -->. |
 |  queryConstraints | [QueryNonFilterConstraint](./firestore_lite.md#querynonfilterconstraint)<!-- -->\[\] | Additional [QueryNonFilterConstraint](./firestore_.md#querynonfilterconstraint)<!-- -->s to apply (e.g. [orderBy()](./firestore_.md#orderby)<!-- -->, [limit()](./firestore_.md#limit)<!-- -->). |
 
 <b>Returns:</b>
 
-[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt;
+[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Exceptions
 
@@ -874,19 +874,19 @@ Creates a new immutable instance of [Query](./firestore_.query.md#query_class) t
 <b>Signature:</b>
 
 ```typescript
-export declare function query<T>(query: Query<T>, ...queryConstraints: QueryConstraint[]): Query<T>;
+export declare function query<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, ...queryConstraints: QueryConstraint[]): Query<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
+|  query | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The [Query](./firestore_.query.md#query_class) instance to use as a base for the new constraints. |
 |  queryConstraints | [QueryConstraint](./firestore_lite.queryconstraint.md#queryconstraint_class)<!-- -->\[\] | The list of [QueryConstraint](./firestore_.queryconstraint.md#queryconstraint_class)<!-- -->s to apply. |
 
 <b>Returns:</b>
 
-[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt;
+[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Exceptions
 
@@ -945,19 +945,19 @@ The result of this write will only be reflected in document reads that occur aft
 <b>Signature:</b>
 
 ```typescript
-export declare function addDoc<T>(reference: CollectionReference<T>, data: WithFieldValue<T>): Promise<DocumentReference<T>>;
+export declare function addDoc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<DocumentReference<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to the collection to add this document to. |
-|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;T&gt; | An Object containing the data for the new document. |
+|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the collection to add this document to. |
+|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An Object containing the data for the new document. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `Promise` resolved with a `DocumentReference` pointing to the newly created document after it has been written to the backend.
 
@@ -972,20 +972,20 @@ Gets a `CollectionReference` instance that refers to a subcollection of `referen
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(reference: CollectionReference<unknown>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;unknown&gt; | A reference to a collection. |
+|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a collection. |
 |  path | string | A slash-separated path to a collection. |
 |  pathSegments | string\[\] | Additional path segments to apply relative to the first argument. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -1000,20 +1000,20 @@ Gets a `CollectionReference` instance that refers to a subcollection of `referen
 <b>Signature:</b>
 
 ```typescript
-export declare function collection(reference: DocumentReference, path: string, ...pathSegments: string[]): CollectionReference<DocumentData>;
+export declare function collection<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): CollectionReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class) | A reference to a Firestore document. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a Firestore document. |
 |  path | string | A slash-separated path to a collection. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `CollectionReference` instance.
 
@@ -1030,14 +1030,14 @@ The deletion will only be reflected in document reads that occur after the retur
 <b>Signature:</b>
 
 ```typescript
-export declare function deleteDoc(reference: DocumentReference<unknown>): Promise<void>;
+export declare function deleteDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to delete. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to delete. |
 
 <b>Returns:</b>
 
@@ -1052,20 +1052,20 @@ Gets a `DocumentReference` instance that refers to a document within `reference`
 <b>Signature:</b>
 
 ```typescript
-export declare function doc<T>(reference: CollectionReference<T>, path?: string, ...pathSegments: string[]): DocumentReference<T>;
+export declare function doc<AppModelType, DbModelType extends DocumentData>(reference: CollectionReference<AppModelType, DbModelType>, path?: string, ...pathSegments: string[]): DocumentReference<AppModelType, DbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;T&gt; | A reference to a collection. |
+|  reference | [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a collection. |
 |  path | string | A slash-separated path to a document. Has to be omitted to use auto-genrated IDs. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt;
+[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 The `DocumentReference` instance.
 
@@ -1080,20 +1080,20 @@ Gets a `DocumentReference` instance that refers to a document within `reference`
 <b>Signature:</b>
 
 ```typescript
-export declare function doc(reference: DocumentReference<unknown>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData>;
+export declare function doc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, path: string, ...pathSegments: string[]): DocumentReference<DocumentData, DocumentData>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to a Firestore document. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to a Firestore document. |
 |  path | string | A slash-separated path to a document. |
 |  pathSegments | string\[\] | Additional path segments that will be applied relative to the first argument. |
 
 <b>Returns:</b>
 
-[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 The `DocumentReference` instance.
 
@@ -1110,18 +1110,18 @@ All documents are directly fetched from the server, even if the document was pre
 <b>Signature:</b>
 
 ```typescript
-export declare function getDoc<T>(reference: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+export declare function getDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | The reference of the document to fetch. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The reference of the document to fetch. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A Promise resolved with a `DocumentSnapshot` containing the current document contents.
 
@@ -1134,15 +1134,15 @@ The result of this write will only be reflected in document reads that occur aft
 <b>Signature:</b>
 
 ```typescript
-export declare function setDoc<T>(reference: DocumentReference<T>, data: WithFieldValue<T>): Promise<void>;
+export declare function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to write. |
-|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;T&gt; | A map of the fields and values for the document. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to write. |
+|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | A map of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -1163,15 +1163,15 @@ The result of this write will only be reflected in document reads that occur aft
 <b>Signature:</b>
 
 ```typescript
-export declare function setDoc<T>(reference: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): Promise<void>;
+export declare function setDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to write. |
-|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | A map of the fields and values for the document. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to write. |
+|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | A map of the fields and values for the document. |
 |  options | [SetOptions](./firestore_lite.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -1193,15 +1193,15 @@ The result of this update will only be reflected in document reads that occur af
 <b>Signature:</b>
 
 ```typescript
-export declare function updateDoc<T>(reference: DocumentReference<T>, data: UpdateData<T>): Promise<void>;
+export declare function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to update. |
-|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to update. |
+|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -1224,14 +1224,14 @@ The result of this update will only be reflected in document reads that occur af
 <b>Signature:</b>
 
 ```typescript
-export declare function updateDoc(reference: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
+export declare function updateDoc<AppModelType, DbModelType extends DocumentData>(reference: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): Promise<void>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to update. |
+|  reference | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to update. |
 |  field | string \| [FieldPath](./firestore_lite.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key value pairs. |
diff --git a/docs-devsite/firestore_lite.query.md b/docs-devsite/firestore_lite.query.md
index f2eac7560dc..d3b72d1ed04 100644
--- a/docs-devsite/firestore_lite.query.md
+++ b/docs-devsite/firestore_lite.query.md
@@ -15,7 +15,7 @@ A `Query` refers to a query which you can read or listen to. You can also constr
 <b>Signature:</b>
 
 ```typescript
-export declare class Query<T = DocumentData> 
+export declare class Query<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Constructors
@@ -28,7 +28,7 @@ export declare class Query<T = DocumentData>
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [converter](./firestore_lite.query.md#queryconverter) |  | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;T&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
+|  [converter](./firestore_lite.query.md#queryconverter) |  | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;AppModelType, DbModelType&gt; \| null | If provided, the <code>FirestoreDataConverter</code> associated with this instance. |
 |  [firestore](./firestore_lite.query.md#queryfirestore) |  | [Firestore](./firestore_lite.firestore.md#firestore_class) | The <code>Firestore</code> instance for the Firestore database (useful for performing transactions, etc.). |
 |  [type](./firestore_lite.query.md#querytype) |  | 'query' \| 'collection' | The type of this Firestore reference. |
 
@@ -56,7 +56,7 @@ If provided, the `FirestoreDataConverter` associated with this instance.
 <b>Signature:</b>
 
 ```typescript
-readonly converter: FirestoreDataConverter<T> | null;
+readonly converter: FirestoreDataConverter<AppModelType, DbModelType> | null;
 ```
 
 ## Query.firestore
@@ -86,7 +86,7 @@ Removes the current converter.
 <b>Signature:</b>
 
 ```typescript
-withConverter(converter: null): Query<DocumentData>;
+withConverter(converter: null): Query<DocumentData, DocumentData>;
 ```
 
 ### Parameters
@@ -97,7 +97,7 @@ withConverter(converter: null): Query<DocumentData>;
 
 <b>Returns:</b>
 
-[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
+[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
 A `Query<DocumentData>` that does not use a converter.
 
@@ -108,18 +108,18 @@ Applies a custom data converter to this query, allowing you to use your own cust
 <b>Signature:</b>
 
 ```typescript
-withConverter<U>(converter: FirestoreDataConverter<U>): Query<U>;
+withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>): Query<NewAppModelType, NewDbModelType>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;U&gt; | Converts objects to and from Firestore. |
+|  converter | [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface)<!-- -->&lt;NewAppModelType, NewDbModelType&gt; | Converts objects to and from Firestore. |
 
 <b>Returns:</b>
 
-[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;U&gt;
+[Query](./firestore_lite.query.md#query_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
 A `Query<U>` that uses the provided converter.
 
diff --git a/docs-devsite/firestore_lite.querydocumentsnapshot.md b/docs-devsite/firestore_lite.querydocumentsnapshot.md
index 356d7ecaeed..14824fe3ffc 100644
--- a/docs-devsite/firestore_lite.querydocumentsnapshot.md
+++ b/docs-devsite/firestore_lite.querydocumentsnapshot.md
@@ -17,9 +17,9 @@ A `QueryDocumentSnapshot` offers the same API surface as a `DocumentSnapshot`<!-
 <b>Signature:</b>
 
 ```typescript
-export declare class QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot<T> 
+export declare class QueryDocumentSnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> extends DocumentSnapshot<AppModelType, DbModelType> 
 ```
-<b>Extends:</b> [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;
+<b>Extends:</b> [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;
 
 ## Methods
 
@@ -35,11 +35,11 @@ Retrieves all fields in the document as an `Object`<!-- -->.
 
 ```typescript
 /** @override */
-data(): T;
+data(): AppModelType;
 ```
 <b>Returns:</b>
 
-T
+AppModelType
 
 An `Object` containing all fields in the document.
 
diff --git a/docs-devsite/firestore_lite.querysnapshot.md b/docs-devsite/firestore_lite.querysnapshot.md
index 8e805af948d..61ea8fa3f87 100644
--- a/docs-devsite/firestore_lite.querysnapshot.md
+++ b/docs-devsite/firestore_lite.querysnapshot.md
@@ -15,16 +15,16 @@ A `QuerySnapshot` contains zero or more `DocumentSnapshot` objects representing
 <b>Signature:</b>
 
 ```typescript
-export declare class QuerySnapshot<T = DocumentData> 
+export declare class QuerySnapshot<AppModelType = DocumentData, DbModelType extends DocumentData = DocumentData> 
 ```
 
 ## Properties
 
 |  Property | Modifiers | Type | Description |
 |  --- | --- | --- | --- |
-|  [docs](./firestore_lite.querysnapshot.md#querysnapshotdocs) |  | Array&lt;[QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;&gt; | An array of all the documents in the <code>QuerySnapshot</code>. |
+|  [docs](./firestore_lite.querysnapshot.md#querysnapshotdocs) |  | Array&lt;[QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt; | An array of all the documents in the <code>QuerySnapshot</code>. |
 |  [empty](./firestore_lite.querysnapshot.md#querysnapshotempty) |  | boolean | True if there are no documents in the <code>QuerySnapshot</code>. |
-|  [query](./firestore_lite.querysnapshot.md#querysnapshotquery) |  | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;T&gt; | The query on which you called [getDocs()](./firestore_.md#getdocs) in order to get this <code>QuerySnapshot</code>. |
+|  [query](./firestore_lite.querysnapshot.md#querysnapshotquery) |  | [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The query on which you called [getDocs()](./firestore_.md#getdocs) in order to get this <code>QuerySnapshot</code>. |
 |  [size](./firestore_lite.querysnapshot.md#querysnapshotsize) |  | number | The number of documents in the <code>QuerySnapshot</code>. |
 
 ## Methods
@@ -40,7 +40,7 @@ An array of all the documents in the `QuerySnapshot`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-get docs(): Array<QueryDocumentSnapshot<T>>;
+get docs(): Array<QueryDocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ## QuerySnapshot.empty
@@ -60,7 +60,7 @@ The query on which you called [getDocs()](./firestore_.md#getdocs) in order to g
 <b>Signature:</b>
 
 ```typescript
-readonly query: Query<T>;
+readonly query: Query<AppModelType, DbModelType>;
 ```
 
 ## QuerySnapshot.size
@@ -80,14 +80,14 @@ Enumerates all of the documents in the `QuerySnapshot`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: unknown): void;
+forEach(callback: (result: QueryDocumentSnapshot<AppModelType, DbModelType>) => void, thisArg?: unknown): void;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  callback | (result: [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;T&gt;) =&gt; void | A callback to be called with a <code>QueryDocumentSnapshot</code> for each document in the snapshot. |
+|  callback | (result: [QueryDocumentSnapshot](./firestore_lite.querydocumentsnapshot.md#querydocumentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;) =&gt; void | A callback to be called with a <code>QueryDocumentSnapshot</code> for each document in the snapshot. |
 |  thisArg | unknown | The <code>this</code> binding for the callback. |
 
 <b>Returns:</b>
diff --git a/docs-devsite/firestore_lite.transaction.md b/docs-devsite/firestore_lite.transaction.md
index c643f08d66e..503c762553c 100644
--- a/docs-devsite/firestore_lite.transaction.md
+++ b/docs-devsite/firestore_lite.transaction.md
@@ -38,14 +38,14 @@ Deletes the document referred to by the provided [DocumentReference](./firestore
 <b>Signature:</b>
 
 ```typescript
-delete(documentRef: DocumentReference<unknown>): this;
+delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be deleted. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be deleted. |
 
 <b>Returns:</b>
 
@@ -60,18 +60,18 @@ Reads the document referenced by the provided [DocumentReference](./firestore_.d
 <b>Signature:</b>
 
 ```typescript
-get<T>(documentRef: DocumentReference<T>): Promise<DocumentSnapshot<T>>;
+get<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): Promise<DocumentSnapshot<AppModelType, DbModelType>>;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be read. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be read. |
 
 <b>Returns:</b>
 
-Promise&lt;[DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;T&gt;&gt;
+Promise&lt;[DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt;&gt;
 
 A `DocumentSnapshot` with the read data.
 
@@ -82,15 +82,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): this;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -109,15 +109,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): this;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 |  options | [SetOptions](./firestore_lite.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -137,15 +137,15 @@ Updates fields in the document referred to by the provided [DocumentReference](.
 <b>Signature:</b>
 
 ```typescript
-update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): this;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be updated. |
-|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
+|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -166,14 +166,14 @@ Nested fields can be updated by providing dot-separated field path strings or by
 <b>Signature:</b>
 
 ```typescript
-update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): this;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be updated. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
 |  field | string \| [FieldPath](./firestore_lite.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key/value pairs. |
diff --git a/docs-devsite/firestore_lite.writebatch.md b/docs-devsite/firestore_lite.writebatch.md
index 141a99e8585..f3b80a0250d 100644
--- a/docs-devsite/firestore_lite.writebatch.md
+++ b/docs-devsite/firestore_lite.writebatch.md
@@ -55,14 +55,14 @@ Deletes the document referred to by the provided [DocumentReference](./firestore
 <b>Signature:</b>
 
 ```typescript
-delete(documentRef: DocumentReference<unknown>): WriteBatch;
+delete<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be deleted. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be deleted. |
 
 <b>Returns:</b>
 
@@ -77,15 +77,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: WithFieldValue<T>): WriteBatch;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: WithFieldValue<AppModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [WithFieldValue](./firestore_lite.md#withfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 
 <b>Returns:</b>
 
@@ -100,15 +100,15 @@ Writes to the document referred to by the provided [DocumentReference](./firesto
 <b>Signature:</b>
 
 ```typescript
-set<T>(documentRef: DocumentReference<T>, data: PartialWithFieldValue<T>, options: SetOptions): WriteBatch;
+set<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: PartialWithFieldValue<AppModelType>, options: SetOptions): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be set. |
-|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;T&gt; | An object of the fields and values for the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be set. |
+|  data | [PartialWithFieldValue](./firestore_lite.md#partialwithfieldvalue)<!-- -->&lt;AppModelType&gt; | An object of the fields and values for the document. |
 |  options | [SetOptions](./firestore_lite.md#setoptions) | An object to configure the set behavior. |
 
 <b>Returns:</b>
@@ -128,15 +128,15 @@ Updates fields in the document referred to by the provided [DocumentReference](.
 <b>Signature:</b>
 
 ```typescript
-update<T>(documentRef: DocumentReference<T>, data: UpdateData<T>): WriteBatch;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, data: UpdateData<DbModelType>): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;T&gt; | A reference to the document to be updated. |
-|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;T&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
+|  data | [UpdateData](./firestore_lite.md#updatedata)<!-- -->&lt;DbModelType&gt; | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. |
 
 <b>Returns:</b>
 
@@ -157,14 +157,14 @@ Nested fields can be update by providing dot-separated field path strings or by
 <b>Signature:</b>
 
 ```typescript
-update(documentRef: DocumentReference<unknown>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
+update<AppModelType, DbModelType extends DocumentData>(documentRef: DocumentReference<AppModelType, DbModelType>, field: string | FieldPath, value: unknown, ...moreFieldsAndValues: unknown[]): WriteBatch;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;unknown&gt; | A reference to the document to be updated. |
+|  documentRef | [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;AppModelType, DbModelType&gt; | A reference to the document to be updated. |
 |  field | string \| [FieldPath](./firestore_lite.fieldpath.md#fieldpath_class) | The first field to update. |
 |  value | unknown | The first value. |
 |  moreFieldsAndValues | unknown\[\] | Additional key value pairs. |

From 4b5bbc5577512c9b21193a0e4ed82a870cfd6801 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 14:11:29 -0400
Subject: [PATCH 04/10] yarn changeset

---
 .changeset/rude-terms-remain.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/rude-terms-remain.md

diff --git a/.changeset/rude-terms-remain.md b/.changeset/rude-terms-remain.md
new file mode 100644
index 00000000000..61fbb80f829
--- /dev/null
+++ b/.changeset/rude-terms-remain.md
@@ -0,0 +1,6 @@
+---
+'@firebase/firestore': major
+'firebase': major
+---
+
+Fixed updateDoc() typing issue by adding a 2nd type parameter to FirestoreDataConverter

From 60dd1b4c45168ca7815abd57d486dca4e34f2677 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 14:57:13 -0400
Subject: [PATCH 05/10] Fix startAt, startAfter, endAt, endBefore

---
 common/api-review/firestore-lite.api.md  |  8 +++---
 common/api-review/firestore.api.md       |  8 +++---
 docs-devsite/firestore_.md               | 16 ++++++------
 docs-devsite/firestore_lite.md           | 16 ++++++------
 packages/firestore/src/lite-api/query.ts | 32 ++++++++++++------------
 5 files changed, 40 insertions(+), 40 deletions(-)

diff --git a/common/api-review/firestore-lite.api.md b/common/api-review/firestore-lite.api.md
index a1592cd14f3..dec76c665e4 100644
--- a/common/api-review/firestore-lite.api.md
+++ b/common/api-review/firestore-lite.api.md
@@ -143,13 +143,13 @@ export class DocumentSnapshot<AppModelType = DocumentData, DbModelType extends D
 export { EmulatorMockTokenOptions }
 
 // @public
-export function endAt(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export function endAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 
 // @public
 export function endAt(...fieldValues: unknown[]): QueryEndAtConstraint;
 
 // @public
-export function endBefore(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export function endBefore<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 
 // @public
 export function endBefore(...fieldValues: unknown[]): QueryEndAtConstraint;
@@ -368,13 +368,13 @@ export interface Settings {
 export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>, right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>): boolean;
 
 // @public
-export function startAfter(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export function startAfter<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 
 // @public
 export function startAfter(...fieldValues: unknown[]): QueryStartAtConstraint;
 
 // @public
-export function startAt(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export function startAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 
 // @public
 export function startAt(...fieldValues: unknown[]): QueryStartAtConstraint;
diff --git a/common/api-review/firestore.api.md b/common/api-review/firestore.api.md
index 3ab6a88cd74..12d2c9bb296 100644
--- a/common/api-review/firestore.api.md
+++ b/common/api-review/firestore.api.md
@@ -173,13 +173,13 @@ export function enableMultiTabIndexedDbPersistence(firestore: Firestore): Promis
 export function enableNetwork(firestore: Firestore): Promise<void>;
 
 // @public
-export function endAt(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export function endAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 
 // @public
 export function endAt(...fieldValues: unknown[]): QueryEndAtConstraint;
 
 // @public
-export function endBefore(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export function endBefore<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 
 // @public
 export function endBefore(...fieldValues: unknown[]): QueryEndAtConstraint;
@@ -627,13 +627,13 @@ export interface SnapshotOptions {
 }
 
 // @public
-export function startAfter(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export function startAfter<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 
 // @public
 export function startAfter(...fieldValues: unknown[]): QueryStartAtConstraint;
 
 // @public
-export function startAt(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export function startAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 
 // @public
 export function startAt(...fieldValues: unknown[]): QueryStartAtConstraint;
diff --git a/docs-devsite/firestore_.md b/docs-devsite/firestore_.md
index 9a386348a32..d700f9e7162 100644
--- a/docs-devsite/firestore_.md
+++ b/docs-devsite/firestore_.md
@@ -2052,14 +2052,14 @@ Creates a [QueryEndAtConstraint](./firestore_.queryendatconstraint.md#queryendat
 <b>Signature:</b>
 
 ```typescript
-export declare function endAt(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export declare function endAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to end at. |
+|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to end at. |
 
 <b>Returns:</b>
 
@@ -2074,14 +2074,14 @@ Creates a [QueryEndAtConstraint](./firestore_.queryendatconstraint.md#queryendat
 <b>Signature:</b>
 
 ```typescript
-export declare function endBefore(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export declare function endBefore<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to end before. |
+|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to end before. |
 
 <b>Returns:</b>
 
@@ -2096,14 +2096,14 @@ Creates a [QueryStartAtConstraint](./firestore_.querystartatconstraint.md#querys
 <b>Signature:</b>
 
 ```typescript
-export declare function startAfter(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export declare function startAfter<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to start after. |
+|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to start after. |
 
 <b>Returns:</b>
 
@@ -2118,14 +2118,14 @@ Creates a [QueryStartAtConstraint](./firestore_.querystartatconstraint.md#querys
 <b>Signature:</b>
 
 ```typescript
-export declare function startAt(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export declare function startAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to start at. |
+|  snapshot | [DocumentSnapshot](./firestore_.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to start at. |
 
 <b>Returns:</b>
 
diff --git a/docs-devsite/firestore_lite.md b/docs-devsite/firestore_lite.md
index f4748a838cd..26472b12b6c 100644
--- a/docs-devsite/firestore_lite.md
+++ b/docs-devsite/firestore_lite.md
@@ -1253,14 +1253,14 @@ Creates a [QueryEndAtConstraint](./firestore_.queryendatconstraint.md#queryendat
 <b>Signature:</b>
 
 ```typescript
-export declare function endAt(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export declare function endAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to end at. |
+|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to end at. |
 
 <b>Returns:</b>
 
@@ -1275,14 +1275,14 @@ Creates a [QueryEndAtConstraint](./firestore_.queryendatconstraint.md#queryendat
 <b>Signature:</b>
 
 ```typescript
-export declare function endBefore(snapshot: DocumentSnapshot<unknown>): QueryEndAtConstraint;
+export declare function endBefore<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryEndAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to end before. |
+|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to end before. |
 
 <b>Returns:</b>
 
@@ -1297,14 +1297,14 @@ Creates a [QueryStartAtConstraint](./firestore_.querystartatconstraint.md#querys
 <b>Signature:</b>
 
 ```typescript
-export declare function startAfter(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export declare function startAfter<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to start after. |
+|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to start after. |
 
 <b>Returns:</b>
 
@@ -1319,14 +1319,14 @@ Creates a [QueryStartAtConstraint](./firestore_.querystartatconstraint.md#querys
 <b>Signature:</b>
 
 ```typescript
-export declare function startAt(snapshot: DocumentSnapshot<unknown>): QueryStartAtConstraint;
+export declare function startAt<AppModelType, DbModelType extends DocumentData>(snapshot: DocumentSnapshot<AppModelType, DbModelType>): QueryStartAtConstraint;
 ```
 
 ### Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;unknown&gt; | The snapshot of the document to start at. |
+|  snapshot | [DocumentSnapshot](./firestore_lite.documentsnapshot.md#documentsnapshot_class)<!-- -->&lt;AppModelType, DbModelType&gt; | The snapshot of the document to start at. |
 
 <b>Returns:</b>
 
diff --git a/packages/firestore/src/lite-api/query.ts b/packages/firestore/src/lite-api/query.ts
index cff35769845..617a60a4462 100644
--- a/packages/firestore/src/lite-api/query.ts
+++ b/packages/firestore/src/lite-api/query.ts
@@ -606,8 +606,8 @@ export class QueryStartAtConstraint extends QueryConstraint {
  * @param snapshot - The snapshot of the document to start at.
  * @returns A {@link QueryStartAtConstraint} to pass to `query()`.
  */
-export function startAt(
-  snapshot: DocumentSnapshot<unknown>
+export function startAt<AppModelType, DbModelType extends DocumentData>(
+  snapshot: DocumentSnapshot<AppModelType, DbModelType>
 ): QueryStartAtConstraint;
 /**
  * Creates a {@link QueryStartAtConstraint} that modifies the result set to
@@ -619,8 +619,8 @@ export function startAt(
  * @returns A {@link QueryStartAtConstraint} to pass to `query()`.
  */
 export function startAt(...fieldValues: unknown[]): QueryStartAtConstraint;
-export function startAt(
-  ...docOrFields: Array<unknown | DocumentSnapshot<unknown>>
+export function startAt<AppModelType, DbModelType extends DocumentData>(
+  ...docOrFields: Array<unknown | DocumentSnapshot<AppModelType, DbModelType>>
 ): QueryStartAtConstraint {
   return QueryStartAtConstraint._create(
     'startAt',
@@ -638,8 +638,8 @@ export function startAt(
  * @param snapshot - The snapshot of the document to start after.
  * @returns A {@link QueryStartAtConstraint} to pass to `query()`
  */
-export function startAfter(
-  snapshot: DocumentSnapshot<unknown>
+export function startAfter<AppModelType, DbModelType extends DocumentData>(
+  snapshot: DocumentSnapshot<AppModelType, DbModelType>
 ): QueryStartAtConstraint;
 /**
  * Creates a {@link QueryStartAtConstraint} that modifies the result set to
@@ -651,8 +651,8 @@ export function startAfter(
  * @returns A {@link QueryStartAtConstraint} to pass to `query()`
  */
 export function startAfter(...fieldValues: unknown[]): QueryStartAtConstraint;
-export function startAfter(
-  ...docOrFields: Array<unknown | DocumentSnapshot<unknown>>
+export function startAfter<AppModelType, DbModelType extends DocumentData>(
+  ...docOrFields: Array<unknown | DocumentSnapshot<AppModelType, DbModelType>>
 ): QueryStartAtConstraint {
   return QueryStartAtConstraint._create(
     'startAfter',
@@ -715,8 +715,8 @@ export class QueryEndAtConstraint extends QueryConstraint {
  * @param snapshot - The snapshot of the document to end before.
  * @returns A {@link QueryEndAtConstraint} to pass to `query()`
  */
-export function endBefore(
-  snapshot: DocumentSnapshot<unknown>
+export function endBefore<AppModelType, DbModelType extends DocumentData>(
+  snapshot: DocumentSnapshot<AppModelType, DbModelType>
 ): QueryEndAtConstraint;
 /**
  * Creates a {@link QueryEndAtConstraint} that modifies the result set to end
@@ -728,8 +728,8 @@ export function endBefore(
  * @returns A {@link QueryEndAtConstraint} to pass to `query()`
  */
 export function endBefore(...fieldValues: unknown[]): QueryEndAtConstraint;
-export function endBefore(
-  ...docOrFields: Array<unknown | DocumentSnapshot<unknown>>
+export function endBefore<AppModelType, DbModelType extends DocumentData>(
+  ...docOrFields: Array<unknown | DocumentSnapshot<AppModelType, DbModelType>>
 ): QueryEndAtConstraint {
   return QueryEndAtConstraint._create(
     'endBefore',
@@ -747,8 +747,8 @@ export function endBefore(
  * @param snapshot - The snapshot of the document to end at.
  * @returns A {@link QueryEndAtConstraint} to pass to `query()`
  */
-export function endAt(
-  snapshot: DocumentSnapshot<unknown>
+export function endAt<AppModelType, DbModelType extends DocumentData>(
+  snapshot: DocumentSnapshot<AppModelType, DbModelType>
 ): QueryEndAtConstraint;
 /**
  * Creates a {@link QueryEndAtConstraint} that modifies the result set to end at
@@ -760,8 +760,8 @@ export function endAt(
  * @returns A {@link QueryEndAtConstraint} to pass to `query()`
  */
 export function endAt(...fieldValues: unknown[]): QueryEndAtConstraint;
-export function endAt(
-  ...docOrFields: Array<unknown | DocumentSnapshot<unknown>>
+export function endAt<AppModelType, DbModelType extends DocumentData>(
+  ...docOrFields: Array<unknown | DocumentSnapshot<AppModelType, DbModelType>>
 ): QueryEndAtConstraint {
   return QueryEndAtConstraint._create(
     'endAt',

From 1ddf0bdc0be506512acfa9c24df2ae47826921eb Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 19 May 2023 15:15:20 -0400
Subject: [PATCH 06/10] firestore_client.ts: removed unused imports

---
 packages/firestore/src/core/firestore_client.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/packages/firestore/src/core/firestore_client.ts b/packages/firestore/src/core/firestore_client.ts
index 595cdb0ca01..df6127f978e 100644
--- a/packages/firestore/src/core/firestore_client.ts
+++ b/packages/firestore/src/core/firestore_client.ts
@@ -91,8 +91,6 @@ import { TransactionOptions } from './transaction_options';
 import { TransactionRunner } from './transaction_runner';
 import { View } from './view';
 import { ViewSnapshot } from './view_snapshot';
-import { AggregateSpec } from '../lite-api/aggregate_types';
-import { DocumentData } from '../lite-api/reference';
 
 const LOG_TAG = 'FirestoreClient';
 export const MAX_CONCURRENT_LIMBO_RESOLUTIONS = 100;

From 41b8a5af4ab62474d923221ecc0db024594cc015 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Thu, 25 May 2023 14:37:30 -0700
Subject: [PATCH 07/10] add unit tests for v9 data converter uses

---
 .../test/unit/lite-api/types.test.ts          | 185 ++++++++++++++++++
 1 file changed, 185 insertions(+)
 create mode 100644 packages/firestore/test/unit/lite-api/types.test.ts

diff --git a/packages/firestore/test/unit/lite-api/types.test.ts b/packages/firestore/test/unit/lite-api/types.test.ts
new file mode 100644
index 00000000000..5facffb89f1
--- /dev/null
+++ b/packages/firestore/test/unit/lite-api/types.test.ts
@@ -0,0 +1,185 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0x00 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0x00
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { expect } from 'chai';
+
+import {
+  DocumentData,
+  DocumentReference,
+  WithFieldValue,
+  PartialWithFieldValue,
+  SetOptions
+} from '../../../src/lite-api/reference';
+import {
+  getDoc,
+  setDoc,
+  updateDoc
+} from '../../../src/lite-api/reference_impl';
+import {
+  FirestoreDataConverter,
+  QueryDocumentSnapshot
+} from '../../../src/lite-api/snapshot';
+
+describe('FirestoreTypeConverter', () => {
+  it('converter has the minimal typing information', () => {
+    interface MyModelType {
+      stringProperty: string;
+      numberProperty: number;
+    }
+    const converter = {
+      toFirestore(obj: MyModelType) {
+        return { a: obj.stringProperty, b: obj.numberProperty };
+      },
+      fromFirestore(snapshot: QueryDocumentSnapshot) {
+        return {
+          stringProperty: snapshot.data().a,
+          numberProperty: snapshot.data().b
+        };
+      }
+    };
+    async function foo(docRef: DocumentReference): Promise<void> {
+      const newDocRef = docRef.withConverter(converter);
+      await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      const snapshot = await getDoc(newDocRef);
+      const data: MyModelType = snapshot.data()!;
+      expect(data.stringProperty).to.equal('foo');
+      expect(data.numberProperty).to.equal(42);
+    }
+  });
+
+  it('converter has the minimal typing information plus return types', () => {
+    interface MyModelType {
+      stringProperty: string;
+      numberProperty: number;
+    }
+    const converter = {
+      toFirestore(obj: WithFieldValue<MyModelType>): DocumentData {
+        return { a: obj.stringProperty, b: obj.numberProperty };
+      },
+      fromFirestore(snapshot: QueryDocumentSnapshot): MyModelType {
+        return {
+          stringProperty: snapshot.data().a,
+          numberProperty: snapshot.data().b
+        };
+      }
+    };
+    async function foo(docRef: DocumentReference): Promise<void> {
+      const newDocRef = docRef.withConverter(converter);
+      await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      const snapshot = await getDoc(newDocRef);
+      const data: MyModelType = snapshot.data()!;
+      expect(data.stringProperty).to.equal('foo');
+      expect(data.numberProperty).to.equal(42);
+    }
+  });
+
+  it("has the additional 'merge' version of toFirestore()", () => {
+    interface MyModelType {
+      stringProperty: string;
+      numberProperty: number;
+    }
+    const converter = {
+      toFirestore(
+        modelObject: PartialWithFieldValue<MyModelType>,
+        options?: SetOptions
+      ): DocumentData {
+        if (options === undefined) {
+          return {
+            a: modelObject.stringProperty,
+            b: modelObject.numberProperty
+          };
+        }
+        const result: DocumentData = {};
+        if ('stringProperty' in modelObject) {
+          result.a = modelObject.stringProperty;
+        }
+        if ('numberProperty' in modelObject) {
+          result.b = modelObject.numberProperty;
+        }
+        return result;
+      },
+      fromFirestore(snapshot: QueryDocumentSnapshot): MyModelType {
+        return {
+          stringProperty: snapshot.data().a,
+          numberProperty: snapshot.data().b
+        };
+      }
+    };
+    async function foo(docRef: DocumentReference): Promise<void> {
+      const newDocRef = docRef.withConverter(converter);
+      await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      const snapshot = await getDoc(newDocRef);
+      const data: MyModelType = snapshot.data()!;
+      expect(data.stringProperty).to.equal('foo');
+      expect(data.numberProperty).to.equal(42);
+    }
+  });
+
+  it('converter is explicitly typed as FirestoreDataConverter<T>', () => {
+    interface MyModelType {
+      stringProperty: string;
+      numberProperty: number;
+    }
+    const converter: FirestoreDataConverter<MyModelType> = {
+      toFirestore(obj: WithFieldValue<MyModelType>) {
+        return { a: obj.stringProperty, b: obj.numberProperty };
+      },
+      fromFirestore(snapshot: QueryDocumentSnapshot) {
+        return {
+          stringProperty: snapshot.data().a,
+          numberProperty: snapshot.data().b
+        };
+      }
+    };
+    async function foo(docRef: DocumentReference): Promise<void> {
+      const newDocRef = docRef.withConverter(converter);
+      await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      const snapshot = await getDoc(newDocRef);
+      const data: MyModelType = snapshot.data()!;
+      expect(data.stringProperty).to.equal('foo');
+      expect(data.numberProperty).to.equal(42);
+    }
+  });
+
+  it('updateDoc() is typed incorrectly', () => {
+    interface MyModelType {
+      stringProperty: string;
+      numberProperty: number;
+    }
+    const converter: FirestoreDataConverter<MyModelType> = {
+      toFirestore(obj: WithFieldValue<MyModelType>) {
+        return { a: obj.stringProperty, b: obj.numberProperty };
+      },
+      fromFirestore(snapshot: QueryDocumentSnapshot) {
+        return {
+          stringProperty: snapshot.data().a,
+          numberProperty: snapshot.data().b
+        };
+      }
+    };
+    async function foo(docRef: DocumentReference): Promise<void> {
+      const newDocRef = docRef.withConverter(converter);
+      // TODO(dconeybe) Update this test in the fix
+      //  https://github.com/firebase/firebase-js-sdk/pull/7310
+      // @ts-expect-error
+      await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
+      const snapshot = await getDoc(newDocRef);
+      const data: MyModelType = snapshot.data()!;
+      expect(data.stringProperty).to.be.a('string');
+      expect(data.numberProperty).to.be.a('number');
+    }
+  });
+});

From fe55b46a71d103aaecc978f3c32372157aee9ba7 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Thu, 25 May 2023 15:04:13 -0700
Subject: [PATCH 08/10] update lite-api/types.test.ts for new type parameter

---
 .../test/unit/lite-api/types.test.ts          | 36 +++++++++++--------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/packages/firestore/test/unit/lite-api/types.test.ts b/packages/firestore/test/unit/lite-api/types.test.ts
index 5facffb89f1..59e5370effe 100644
--- a/packages/firestore/test/unit/lite-api/types.test.ts
+++ b/packages/firestore/test/unit/lite-api/types.test.ts
@@ -53,10 +53,11 @@ describe('FirestoreTypeConverter', () => {
     async function foo(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
       const snapshot = await getDoc(newDocRef);
       const data: MyModelType = snapshot.data()!;
-      expect(data.stringProperty).to.equal('foo');
-      expect(data.numberProperty).to.equal(42);
+      expect(data.stringProperty).to.equal('newFoo');
+      expect(data.numberProperty).to.equal(43);
     }
   });
 
@@ -79,10 +80,11 @@ describe('FirestoreTypeConverter', () => {
     async function foo(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
       const snapshot = await getDoc(newDocRef);
       const data: MyModelType = snapshot.data()!;
-      expect(data.stringProperty).to.equal('foo');
-      expect(data.numberProperty).to.equal(42);
+      expect(data.stringProperty).to.equal('newFoo');
+      expect(data.numberProperty).to.equal(43);
     }
   });
 
@@ -121,10 +123,11 @@ describe('FirestoreTypeConverter', () => {
     async function foo(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
       const snapshot = await getDoc(newDocRef);
       const data: MyModelType = snapshot.data()!;
-      expect(data.stringProperty).to.equal('foo');
-      expect(data.numberProperty).to.equal(42);
+      expect(data.stringProperty).to.equal('newFoo');
+      expect(data.numberProperty).to.equal(43);
     }
   });
 
@@ -147,19 +150,24 @@ describe('FirestoreTypeConverter', () => {
     async function foo(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
+      await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
       const snapshot = await getDoc(newDocRef);
       const data: MyModelType = snapshot.data()!;
-      expect(data.stringProperty).to.equal('foo');
-      expect(data.numberProperty).to.equal(42);
+      expect(data.stringProperty).to.equal('newFoo');
+      expect(data.numberProperty).to.equal(43);
     }
   });
 
-  it('updateDoc() is typed incorrectly', () => {
+  it('converter is explicitly typed as FirestoreDataConverter<T, U>', () => {
     interface MyModelType {
       stringProperty: string;
       numberProperty: number;
     }
-    const converter: FirestoreDataConverter<MyModelType> = {
+    interface MyDbType {
+      a: string;
+      b: number;
+    }
+    const converter: FirestoreDataConverter<MyModelType, MyDbType> = {
       toFirestore(obj: WithFieldValue<MyModelType>) {
         return { a: obj.stringProperty, b: obj.numberProperty };
       },
@@ -172,14 +180,12 @@ describe('FirestoreTypeConverter', () => {
     };
     async function foo(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
-      // TODO(dconeybe) Update this test in the fix
-      //  https://github.com/firebase/firebase-js-sdk/pull/7310
-      // @ts-expect-error
+      await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
       const snapshot = await getDoc(newDocRef);
       const data: MyModelType = snapshot.data()!;
-      expect(data.stringProperty).to.be.a('string');
-      expect(data.numberProperty).to.be.a('number');
+      expect(data.stringProperty).to.equal('newFoo');
+      expect(data.numberProperty).to.equal(43);
     }
   });
 });

From a79cbea55e3c21a8a87fba8b8fc8602b53b01c01 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Thu, 25 May 2023 15:31:02 -0700
Subject: [PATCH 09/10] lite-api/types.test.ts: fix error: 'foo' is defined but
 never used

---
 packages/firestore/test/unit/lite-api/types.test.ts | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/firestore/test/unit/lite-api/types.test.ts b/packages/firestore/test/unit/lite-api/types.test.ts
index 59e5370effe..0c51193e19e 100644
--- a/packages/firestore/test/unit/lite-api/types.test.ts
+++ b/packages/firestore/test/unit/lite-api/types.test.ts
@@ -50,7 +50,7 @@ describe('FirestoreTypeConverter', () => {
         };
       }
     };
-    async function foo(docRef: DocumentReference): Promise<void> {
+    async function _(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
@@ -77,7 +77,7 @@ describe('FirestoreTypeConverter', () => {
         };
       }
     };
-    async function foo(docRef: DocumentReference): Promise<void> {
+    async function _(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
@@ -120,7 +120,7 @@ describe('FirestoreTypeConverter', () => {
         };
       }
     };
-    async function foo(docRef: DocumentReference): Promise<void> {
+    async function _(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
@@ -147,7 +147,7 @@ describe('FirestoreTypeConverter', () => {
         };
       }
     };
-    async function foo(docRef: DocumentReference): Promise<void> {
+    async function _(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });
@@ -178,7 +178,7 @@ describe('FirestoreTypeConverter', () => {
         };
       }
     };
-    async function foo(docRef: DocumentReference): Promise<void> {
+    async function _(docRef: DocumentReference): Promise<void> {
       const newDocRef = docRef.withConverter(converter);
       await setDoc(newDocRef, { stringProperty: 'foo', numberProperty: 42 });
       await updateDoc(newDocRef, { a: 'newFoo', b: 43 });

From 0708d3160259908ca47a45ca5ccb31c5072e9ec2 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Mon, 26 Jun 2023 15:08:35 -0400
Subject: [PATCH 10/10] update class/function docs

---
 .../firestore_.collectionreference.md         |  8 ++--
 docs-devsite/firestore_.documentreference.md  |  8 ++--
 .../firestore_.firestoredataconverter.md      | 25 +++++++----
 docs-devsite/firestore_.md                    |  2 +-
 docs-devsite/firestore_.query.md              |  8 ++--
 .../firestore_lite.collectionreference.md     |  8 ++--
 .../firestore_lite.documentreference.md       |  8 ++--
 .../firestore_lite.firestoredataconverter.md  | 25 +++++++----
 docs-devsite/firestore_lite.md                |  2 +-
 docs-devsite/firestore_lite.query.md          |  8 ++--
 packages/firestore/src/api/snapshot.ts        | 38 +++++++++++------
 packages/firestore/src/lite-api/reference.ts  | 25 ++++++-----
 packages/firestore/src/lite-api/snapshot.ts   | 41 +++++++++++++------
 13 files changed, 125 insertions(+), 81 deletions(-)

diff --git a/docs-devsite/firestore_.collectionreference.md b/docs-devsite/firestore_.collectionreference.md
index 81fd7e218dc..20e54393813 100644
--- a/docs-devsite/firestore_.collectionreference.md
+++ b/docs-devsite/firestore_.collectionreference.md
@@ -32,7 +32,7 @@ export declare class CollectionReference<AppModelType = DocumentData, DbModelTyp
 
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
-|  [withConverter(converter)](./firestore_.collectionreference.md#collectionreferencewithconverter) |  | Applies a custom data converter to this <code>CollectionReference</code>, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned <code>CollectionReference</code> instance, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_.collectionreference.md#collectionreferencewithconverter) |  | Applies a custom data converter to this <code>CollectionReference</code>, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned <code>CollectionReference</code> instance, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 |  [withConverter(converter)](./firestore_.collectionreference.md#collectionreferencewithconverter) |  | Removes the current converter. |
 
 ## CollectionReference.id
@@ -77,7 +77,7 @@ readonly type = "collection";
 
 ## CollectionReference.withConverter()
 
-Applies a custom data converter to this `CollectionReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned `CollectionReference` instance, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this `CollectionReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned `CollectionReference` instance, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -95,7 +95,7 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `CollectionReference<U>` that uses the provided converter.
+A `CollectionReference` that uses the provided converter.
 
 ## CollectionReference.withConverter()
 
@@ -117,5 +117,5 @@ withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 
 [CollectionReference](./firestore_.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `CollectionReference<DocumentData>` that does not use a converter.
+A `CollectionReference<DocumentData, DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_.documentreference.md b/docs-devsite/firestore_.documentreference.md
index cc4d8ecc6b4..c1356ae58f4 100644
--- a/docs-devsite/firestore_.documentreference.md
+++ b/docs-devsite/firestore_.documentreference.md
@@ -33,7 +33,7 @@ export declare class DocumentReference<AppModelType = DocumentData, DbModelType
 
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
-|  [withConverter(converter)](./firestore_.documentreference.md#documentreferencewithconverter) |  | Applies a custom data converter to this <code>DocumentReference</code>, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned <code>DocumentReference</code> instance, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_.documentreference.md#documentreferencewithconverter) |  | Applies a custom data converter to this <code>DocumentReference</code>, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned <code>DocumentReference</code> instance, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 |  [withConverter(converter)](./firestore_.documentreference.md#documentreferencewithconverter) |  | Removes the current converter. |
 
 ## DocumentReference.converter
@@ -98,7 +98,7 @@ readonly type = "document";
 
 ## DocumentReference.withConverter()
 
-Applies a custom data converter to this `DocumentReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned `DocumentReference` instance, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this `DocumentReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned `DocumentReference` instance, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -116,7 +116,7 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `DocumentReference<U>` that uses the provided converter.
+A `DocumentReference` that uses the provided converter.
 
 ## DocumentReference.withConverter()
 
@@ -138,5 +138,5 @@ withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 
 [DocumentReference](./firestore_.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `DocumentReference<DocumentData>` that does not use a converter.
+A `DocumentReference<DocumentData, DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_.firestoredataconverter.md b/docs-devsite/firestore_.firestoredataconverter.md
index 246c510e212..700d0f38aaa 100644
--- a/docs-devsite/firestore_.firestoredataconverter.md
+++ b/docs-devsite/firestore_.firestoredataconverter.md
@@ -10,7 +10,7 @@ https://github.com/firebase/firebase-js-sdk
 {% endcomment %}
 
 # FirestoreDataConverter interface
-Converter used by `withConverter()` to transform user objects of type `T` into Firestore data.
+Converter used by `withConverter()` to transform user objects of type `AppModelType` into Firestore data of type `DbModelType`<!-- -->.
 
 Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore.
 
@@ -24,13 +24,15 @@ export declare interface FirestoreDataConverter<AppModelType, DbModelType extend
 
 |  Method | Description |
 |  --- | --- |
-|  [fromFirestore(snapshot, options)](./firestore_.firestoredataconverter.md#firestoredataconverterfromfirestore) | Called by the Firestore SDK to convert Firestore data into an object of type T. You can access your data by calling: <code>snapshot.data(options)</code>. |
-|  [toFirestore(modelObject)](./firestore_.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>T</code> into a plain JavaScript object (suitable for writing directly to the Firestore database). To use <code>set()</code> with <code>merge</code> and <code>mergeFields</code>, <code>toFirestore()</code> must be defined with <code>PartialWithFieldValue&lt;T&gt;</code>.<!-- -->The <code>WithFieldValue&lt;T&gt;</code> type extends <code>T</code> to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values. |
-|  [toFirestore(modelObject, options)](./firestore_.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>T</code> into a plain JavaScript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_.md#setdoc)<!-- -->,  and  with <code>merge:true</code> or <code>mergeFields</code>.<!-- -->The <code>PartialWithFieldValue&lt;T&gt;</code> type extends <code>Partial&lt;T&gt;</code> to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested <code>Partial</code> by allowing nested fields to be omitted. |
+|  [fromFirestore(snapshot, options)](./firestore_.firestoredataconverter.md#firestoredataconverterfromfirestore) | Called by the Firestore SDK to convert Firestore data into an object of type <code>AppModelType</code>. You can access your data by calling: <code>snapshot.data(options)</code>.<!-- -->Generally, the data returned from <code>snapshot.data()</code> can be cast to <code>DbModelType</code>; however, this is not guaranteed as writes to the database may have occurred without a type converter enforcing this specific layout. |
+|  [toFirestore(modelObject)](./firestore_.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>AppModelType</code> into a plain JavaScript object (suitable for writing directly to the Firestore database) of type <code>DbModelType</code>. To use <code>set()</code> with <code>merge</code> and <code>mergeFields</code>, <code>toFirestore()</code> must be defined with <code>PartialWithFieldValue&lt;AppModelType&gt;</code>.<!-- -->The <code>WithFieldValue&lt;T&gt;</code> type extends <code>T</code> to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values. |
+|  [toFirestore(modelObject, options)](./firestore_.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>AppModelType</code> into a plain JavaScript object (suitable for writing directly to the Firestore database) of type <code>DbModelType</code>. Used with [setDoc()](./firestore_.md#setdoc)<!-- -->,  and  with <code>merge:true</code> or <code>mergeFields</code>.<!-- -->The <code>PartialWithFieldValue&lt;T&gt;</code> type extends <code>Partial&lt;T&gt;</code> to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested <code>Partial</code> by allowing nested fields to be omitted. |
 
 ## FirestoreDataConverter.fromFirestore()
 
-Called by the Firestore SDK to convert Firestore data into an object of type T. You can access your data by calling: `snapshot.data(options)`<!-- -->.
+Called by the Firestore SDK to convert Firestore data into an object of type `AppModelType`<!-- -->. You can access your data by calling: `snapshot.data(options)`<!-- -->.
+
+Generally, the data returned from `snapshot.data()` can be cast to `DbModelType`<!-- -->; however, this is not guaranteed as writes to the database may have occurred without a type converter enforcing this specific layout.
 
 <b>Signature:</b>
 
@@ -51,7 +53,7 @@ AppModelType
 
 ## FirestoreDataConverter.toFirestore()
 
-Called by the Firestore SDK to convert a custom model object of type `T` into a plain JavaScript object (suitable for writing directly to the Firestore database). To use `set()` with `merge` and `mergeFields`<!-- -->, `toFirestore()` must be defined with `PartialWithFieldValue<T>`<!-- -->.
+Called by the Firestore SDK to convert a custom model object of type `AppModelType` into a plain JavaScript object (suitable for writing directly to the Firestore database) of type `DbModelType`<!-- -->. To use `set()` with `merge` and `mergeFields`<!-- -->, `toFirestore()` must be defined with `PartialWithFieldValue<AppModelType>`<!-- -->.
 
 The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values.
 
@@ -73,7 +75,7 @@ toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelTy
 
 ## FirestoreDataConverter.toFirestore()
 
-Called by the Firestore SDK to convert a custom model object of type `T` into a plain JavaScript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_.md#setdoc)<!-- -->,  and  with `merge:true` or `mergeFields`<!-- -->.
+Called by the Firestore SDK to convert a custom model object of type `AppModelType` into a plain JavaScript object (suitable for writing directly to the Firestore database) of type `DbModelType`<!-- -->. Used with [setDoc()](./firestore_.md#setdoc)<!-- -->,  and  with `merge:true` or `mergeFields`<!-- -->.
 
 The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested `Partial` by allowing nested fields to be omitted.
 
@@ -106,15 +108,20 @@ class Post {
   }
 }
 
+interface PostDbModel {
+  title: string;
+  author: string;
+}
+
 const postConverter = {
-  toFirestore(post: WithFieldValue<Post>): DocumentData {
+  toFirestore(post: WithFieldValue<Post>): PostDbModel {
     return {title: post.title, author: post.author};
   },
   fromFirestore(
     snapshot: QueryDocumentSnapshot,
     options: SnapshotOptions
   ): Post {
-    const data = snapshot.data(options)!;
+    const data = snapshot.data(options) as PostDbModel;
     return new Post(data.title, data.author);
   }
 };
diff --git a/docs-devsite/firestore_.md b/docs-devsite/firestore_.md
index 8491c3e7d4b..462635b0f85 100644
--- a/docs-devsite/firestore_.md
+++ b/docs-devsite/firestore_.md
@@ -153,7 +153,7 @@ https://github.com/firebase/firebase-js-sdk
 |  [DocumentChange](./firestore_.documentchange.md#documentchange_interface) | A <code>DocumentChange</code> represents a change to the documents matching a query. It contains the document affected and the type of change that occurred. |
 |  [DocumentData](./firestore_.documentdata.md#documentdata_interface) | Document data (for use with [setDoc()](./firestore_lite.md#setdoc)<!-- -->) consists of fields mapped to values. |
 |  [ExperimentalLongPollingOptions](./firestore_.experimentallongpollingoptions.md#experimentallongpollingoptions_interface) | Options that configure the SDK’s underlying network transport (WebChannel) when long-polling is used.<!-- -->Note: This interface is "experimental" and is subject to change.<!-- -->See <code>FirestoreSettings.experimentalAutoDetectLongPolling</code>, <code>FirestoreSettings.experimentalForceLongPolling</code>, and <code>FirestoreSettings.experimentalLongPollingOptions</code>. |
-|  [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface) | Converter used by <code>withConverter()</code> to transform user objects of type <code>T</code> into Firestore data.<!-- -->Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore. |
+|  [FirestoreDataConverter](./firestore_.firestoredataconverter.md#firestoredataconverter_interface) | Converter used by <code>withConverter()</code> to transform user objects of type <code>AppModelType</code> into Firestore data of type <code>DbModelType</code>.<!-- -->Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore. |
 |  [FirestoreSettings](./firestore_.firestoresettings.md#firestoresettings_interface) | Specifies custom configurations for your Cloud Firestore instance. You must set these before invoking any other methods. |
 |  [Index](./firestore_.index.md#index_interface) | <b><i>(BETA)</i></b> The SDK definition of a Firestore index. |
 |  [IndexConfiguration](./firestore_.indexconfiguration.md#indexconfiguration_interface) | <b><i>(BETA)</i></b> A list of Firestore indexes to speed up local query execution.<!-- -->See [JSON Format](https://firebase.google.com/docs/reference/firestore/indexes/#json_format) for a description of the format of the index definition. |
diff --git a/docs-devsite/firestore_.query.md b/docs-devsite/firestore_.query.md
index 7e7cea4fb45..678ab1faf89 100644
--- a/docs-devsite/firestore_.query.md
+++ b/docs-devsite/firestore_.query.md
@@ -37,7 +37,7 @@ export declare class Query<AppModelType = DocumentData, DbModelType extends Docu
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
 |  [withConverter(converter)](./firestore_.query.md#querywithconverter) |  | Removes the current converter. |
-|  [withConverter(converter)](./firestore_.query.md#querywithconverter) |  | Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_.query.md#querywithconverter) |  | Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 
 ## Query.(constructor)
 
@@ -99,11 +99,11 @@ withConverter(converter: null): Query<DocumentData, DocumentData>;
 
 [Query](./firestore_.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `Query<DocumentData>` that does not use a converter.
+A `Query<DocumentData, DocumentData>` that does not use a converter.
 
 ## Query.withConverter()
 
-Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -121,5 +121,5 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [Query](./firestore_.query.md#query_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `Query<U>` that uses the provided converter.
+A `Query` that uses the provided converter.
 
diff --git a/docs-devsite/firestore_lite.collectionreference.md b/docs-devsite/firestore_lite.collectionreference.md
index 18e64e719eb..0cb088d24f1 100644
--- a/docs-devsite/firestore_lite.collectionreference.md
+++ b/docs-devsite/firestore_lite.collectionreference.md
@@ -32,7 +32,7 @@ export declare class CollectionReference<AppModelType = DocumentData, DbModelTyp
 
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
-|  [withConverter(converter)](./firestore_lite.collectionreference.md#collectionreferencewithconverter) |  | Applies a custom data converter to this <code>CollectionReference</code>, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned <code>CollectionReference</code> instance, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_lite.collectionreference.md#collectionreferencewithconverter) |  | Applies a custom data converter to this <code>CollectionReference</code>, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned <code>CollectionReference</code> instance, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 |  [withConverter(converter)](./firestore_lite.collectionreference.md#collectionreferencewithconverter) |  | Removes the current converter. |
 
 ## CollectionReference.id
@@ -77,7 +77,7 @@ readonly type = "collection";
 
 ## CollectionReference.withConverter()
 
-Applies a custom data converter to this `CollectionReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned `CollectionReference` instance, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this `CollectionReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [addDoc()](./firestore_.md#adddoc) with the returned `CollectionReference` instance, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -95,7 +95,7 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `CollectionReference<U>` that uses the provided converter.
+A `CollectionReference` that uses the provided converter.
 
 ## CollectionReference.withConverter()
 
@@ -117,5 +117,5 @@ withConverter(converter: null): CollectionReference<DocumentData, DocumentData>;
 
 [CollectionReference](./firestore_lite.collectionreference.md#collectionreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `CollectionReference<DocumentData>` that does not use a converter.
+A `CollectionReference<DocumentData, DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_lite.documentreference.md b/docs-devsite/firestore_lite.documentreference.md
index 7c02494faf4..dc053598c1b 100644
--- a/docs-devsite/firestore_lite.documentreference.md
+++ b/docs-devsite/firestore_lite.documentreference.md
@@ -33,7 +33,7 @@ export declare class DocumentReference<AppModelType = DocumentData, DbModelType
 
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
-|  [withConverter(converter)](./firestore_lite.documentreference.md#documentreferencewithconverter) |  | Applies a custom data converter to this <code>DocumentReference</code>, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned <code>DocumentReference</code> instance, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_lite.documentreference.md#documentreferencewithconverter) |  | Applies a custom data converter to this <code>DocumentReference</code>, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned <code>DocumentReference</code> instance, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 |  [withConverter(converter)](./firestore_lite.documentreference.md#documentreferencewithconverter) |  | Removes the current converter. |
 
 ## DocumentReference.converter
@@ -98,7 +98,7 @@ readonly type = "document";
 
 ## DocumentReference.withConverter()
 
-Applies a custom data converter to this `DocumentReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned `DocumentReference` instance, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this `DocumentReference`<!-- -->, allowing you to use your own custom model objects with Firestore. When you call [setDoc()](./firestore_lite.md#setdoc)<!-- -->, [getDoc()](./firestore_lite.md#getdoc)<!-- -->, etc. with the returned `DocumentReference` instance, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -116,7 +116,7 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `DocumentReference<U>` that uses the provided converter.
+A `DocumentReference` that uses the provided converter.
 
 ## DocumentReference.withConverter()
 
@@ -138,5 +138,5 @@ withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
 
 [DocumentReference](./firestore_lite.documentreference.md#documentreference_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `DocumentReference<DocumentData>` that does not use a converter.
+A `DocumentReference<DocumentData, DocumentData>` that does not use a converter.
 
diff --git a/docs-devsite/firestore_lite.firestoredataconverter.md b/docs-devsite/firestore_lite.firestoredataconverter.md
index e508471ecfa..660f04f371f 100644
--- a/docs-devsite/firestore_lite.firestoredataconverter.md
+++ b/docs-devsite/firestore_lite.firestoredataconverter.md
@@ -10,7 +10,7 @@ https://github.com/firebase/firebase-js-sdk
 {% endcomment %}
 
 # FirestoreDataConverter interface
-Converter used by `withConverter()` to transform user objects of type `T` into Firestore data.
+Converter used by `withConverter()` to transform user objects of type `AppModelType` into Firestore data of type `DbModelType`<!-- -->.
 
 Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore.
 
@@ -24,13 +24,15 @@ export declare interface FirestoreDataConverter<AppModelType, DbModelType extend
 
 |  Method | Description |
 |  --- | --- |
-|  [fromFirestore(snapshot)](./firestore_lite.firestoredataconverter.md#firestoredataconverterfromfirestore) | Called by the Firestore SDK to convert Firestore data into an object of type T. You can access your data by calling: <code>snapshot.data()</code>. |
-|  [toFirestore(modelObject)](./firestore_lite.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>T</code> into a plain Javascript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and .<!-- -->The <code>WithFieldValue&lt;T&gt;</code> type extends <code>T</code> to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values. |
-|  [toFirestore(modelObject, options)](./firestore_lite.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>T</code> into a plain Javascript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and  with <code>merge:true</code> or <code>mergeFields</code>.<!-- -->The <code>PartialWithFieldValue&lt;T&gt;</code> type extends <code>Partial&lt;T&gt;</code> to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested <code>Partial</code> by allowing nested fields to be omitted. |
+|  [fromFirestore(snapshot)](./firestore_lite.firestoredataconverter.md#firestoredataconverterfromfirestore) | Called by the Firestore SDK to convert Firestore data into an object of type <code>AppModelType</code>. You can access your data by calling: <code>snapshot.data()</code>.<!-- -->Generally, the data returned from <code>snapshot.data()</code> can be cast to <code>DbModelType</code>; however, this is not guaranteed as writes to the database may have occurred without a type converter enforcing this specific layout. |
+|  [toFirestore(modelObject)](./firestore_lite.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>AppModelType</code> into a plain Javascript object (suitable for writing directly to the Firestore database) of type <code>DbModelType</code>. Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and .<!-- -->The <code>WithFieldValue&lt;T&gt;</code> type extends <code>T</code> to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values. |
+|  [toFirestore(modelObject, options)](./firestore_lite.firestoredataconverter.md#firestoredataconvertertofirestore) | Called by the Firestore SDK to convert a custom model object of type <code>AppModelType</code> into a plain Javascript object (suitable for writing directly to the Firestore database) of type <code>DbModelType</code>. Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and  with <code>merge:true</code> or <code>mergeFields</code>.<!-- -->The <code>PartialWithFieldValue&lt;T&gt;</code> type extends <code>Partial&lt;T&gt;</code> to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested <code>Partial</code> by allowing nested fields to be omitted. |
 
 ## FirestoreDataConverter.fromFirestore()
 
-Called by the Firestore SDK to convert Firestore data into an object of type T. You can access your data by calling: `snapshot.data()`<!-- -->.
+Called by the Firestore SDK to convert Firestore data into an object of type `AppModelType`<!-- -->. You can access your data by calling: `snapshot.data()`<!-- -->.
+
+Generally, the data returned from `snapshot.data()` can be cast to `DbModelType`<!-- -->; however, this is not guaranteed as writes to the database may have occurred without a type converter enforcing this specific layout.
 
 <b>Signature:</b>
 
@@ -50,7 +52,7 @@ AppModelType
 
 ## FirestoreDataConverter.toFirestore()
 
-Called by the Firestore SDK to convert a custom model object of type `T` into a plain Javascript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and .
+Called by the Firestore SDK to convert a custom model object of type `AppModelType` into a plain Javascript object (suitable for writing directly to the Firestore database) of type `DbModelType`<!-- -->. Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and .
 
 The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as [deleteField()](./firestore_.md#deletefield) to be used as property values.
 
@@ -72,7 +74,7 @@ toFirestore(modelObject: WithFieldValue<AppModelType>): WithFieldValue<DbModelTy
 
 ## FirestoreDataConverter.toFirestore()
 
-Called by the Firestore SDK to convert a custom model object of type `T` into a plain Javascript object (suitable for writing directly to the Firestore database). Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and  with `merge:true` or `mergeFields`<!-- -->.
+Called by the Firestore SDK to convert a custom model object of type `AppModelType` into a plain Javascript object (suitable for writing directly to the Firestore database) of type `DbModelType`<!-- -->. Used with [setDoc()](./firestore_lite.md#setdoc)<!-- -->,  and  with `merge:true` or `mergeFields`<!-- -->.
 
 The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow FieldValues such as [arrayUnion()](./firestore_.md#arrayunion) to be used as property values. It also supports nested `Partial` by allowing nested fields to be omitted.
 
@@ -105,12 +107,17 @@ class Post {
   }
 }
 
+interface PostDbModel {
+  title: string;
+  author: string;
+}
+
 const postConverter = {
-  toFirestore(post: WithFieldValue<Post>): DocumentData {
+  toFirestore(post: WithFieldValue<Post>): PostDbModel {
     return {title: post.title, author: post.author};
   },
   fromFirestore(snapshot: QueryDocumentSnapshot): Post {
-    const data = snapshot.data(options)!;
+    const data = snapshot.data(options) as PostDbModel;
     return new Post(data.title, data.author);
   }
 };
diff --git a/docs-devsite/firestore_lite.md b/docs-devsite/firestore_lite.md
index d53476ba417..b87e2417b93 100644
--- a/docs-devsite/firestore_lite.md
+++ b/docs-devsite/firestore_lite.md
@@ -119,7 +119,7 @@ https://github.com/firebase/firebase-js-sdk
 |  --- | --- |
 |  [AggregateSpec](./firestore_lite.aggregatespec.md#aggregatespec_interface) | Specifies a set of aggregations and their aliases. |
 |  [DocumentData](./firestore_lite.documentdata.md#documentdata_interface) | Document data (for use with [setDoc()](./firestore_lite.md#setdoc)<!-- -->) consists of fields mapped to values. |
-|  [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface) | Converter used by <code>withConverter()</code> to transform user objects of type <code>T</code> into Firestore data.<!-- -->Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore. |
+|  [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md#firestoredataconverter_interface) | Converter used by <code>withConverter()</code> to transform user objects of type <code>AppModelType</code> into Firestore data of type <code>DbModelType</code>.<!-- -->Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore. |
 |  [Settings](./firestore_lite.settings.md#settings_interface) | Specifies custom configurations for your Cloud Firestore instance. You must set these before invoking any other methods. |
 |  [TransactionOptions](./firestore_lite.transactionoptions.md#transactionoptions_interface) | Options to customize transaction behavior. |
 
diff --git a/docs-devsite/firestore_lite.query.md b/docs-devsite/firestore_lite.query.md
index d3b72d1ed04..093a8532bb4 100644
--- a/docs-devsite/firestore_lite.query.md
+++ b/docs-devsite/firestore_lite.query.md
@@ -37,7 +37,7 @@ export declare class Query<AppModelType = DocumentData, DbModelType extends Docu
 |  Method | Modifiers | Description |
 |  --- | --- | --- |
 |  [withConverter(converter)](./firestore_lite.query.md#querywithconverter) |  | Removes the current converter. |
-|  [withConverter(converter)](./firestore_lite.query.md#querywithconverter) |  | Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data and your custom type <code>U</code>. |
+|  [withConverter(converter)](./firestore_lite.query.md#querywithconverter) |  | Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data of type <code>NewDbModelType</code> and your custom type <code>NewAppModelType</code>. |
 
 ## Query.(constructor)
 
@@ -99,11 +99,11 @@ withConverter(converter: null): Query<DocumentData, DocumentData>;
 
 [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;[DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->, [DocumentData](./firestore_lite.documentdata.md#documentdata_interface)<!-- -->&gt;
 
-A `Query<DocumentData>` that does not use a converter.
+A `Query<DocumentData, DocumentData>` that does not use a converter.
 
 ## Query.withConverter()
 
-Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data and your custom type `U`<!-- -->.
+Applies a custom data converter to this query, allowing you to use your own custom model objects with Firestore. When you call [getDocs()](./firestore_.md#getdocs) with the returned query, the provided converter will convert between Firestore data of type `NewDbModelType` and your custom type `NewAppModelType`<!-- -->.
 
 <b>Signature:</b>
 
@@ -121,5 +121,5 @@ withConverter<NewAppModelType, NewDbModelType extends DocumentData>(converter: F
 
 [Query](./firestore_lite.query.md#query_class)<!-- -->&lt;NewAppModelType, NewDbModelType&gt;
 
-A `Query<U>` that uses the provided converter.
+A `Query` that uses the provided converter.
 
diff --git a/packages/firestore/src/api/snapshot.ts b/packages/firestore/src/api/snapshot.ts
index 85671408f1d..9c266d91867 100644
--- a/packages/firestore/src/api/snapshot.ts
+++ b/packages/firestore/src/api/snapshot.ts
@@ -42,8 +42,8 @@ import { Firestore } from './database';
 import { SnapshotListenOptions } from './reference_impl';
 
 /**
- * Converter used by `withConverter()` to transform user objects of type `T`
- * into Firestore data.
+ * Converter used by `withConverter()` to transform user objects of type
+ * `AppModelType` into Firestore data of type `DbModelType`.
  *
  * Using the converter allows you to specify generic type arguments when
  * storing and retrieving objects from Firestore.
@@ -58,15 +58,20 @@ import { SnapshotListenOptions } from './reference_impl';
  *   }
  * }
  *
+ * interface PostDbModel {
+ *   title: string;
+ *   author: string;
+ * }
+ *
  * const postConverter = {
- *   toFirestore(post: WithFieldValue<Post>): DocumentData {
+ *   toFirestore(post: WithFieldValue<Post>): PostDbModel {
  *     return {title: post.title, author: post.author};
  *   },
  *   fromFirestore(
  *     snapshot: QueryDocumentSnapshot,
  *     options: SnapshotOptions
  *   ): Post {
- *     const data = snapshot.data(options)!;
+ *     const data = snapshot.data(options) as PostDbModel;
  *     return new Post(data.title, data.author);
  *   }
  * };
@@ -88,10 +93,11 @@ export interface FirestoreDataConverter<
   DbModelType extends DocumentData = DocumentData
 > extends LiteFirestoreDataConverter<AppModelType, DbModelType> {
   /**
-   * Called by the Firestore SDK to convert a custom model object of type `T`
-   * into a plain JavaScript object (suitable for writing directly to the
-   * Firestore database). To use `set()` with `merge` and `mergeFields`,
-   * `toFirestore()` must be defined with `PartialWithFieldValue<T>`.
+   * Called by the Firestore SDK to convert a custom model object of type
+   * `AppModelType` into a plain JavaScript object (suitable for writing
+   * directly to the Firestore database) of type `DbModelType`. To use `set()`
+   * with `merge` and `mergeFields`, `toFirestore()` must be defined with
+   * `PartialWithFieldValue<AppModelType>`.
    *
    * The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as
    * {@link (deleteField:1)} to be used as property values.
@@ -101,10 +107,11 @@ export interface FirestoreDataConverter<
   ): WithFieldValue<DbModelType>;
 
   /**
-   * Called by the Firestore SDK to convert a custom model object of type `T`
-   * into a plain JavaScript object (suitable for writing directly to the
-   * Firestore database). Used with {@link (setDoc:1)}, {@link (WriteBatch.set:1)}
-   * and {@link (Transaction.set:1)} with `merge:true` or `mergeFields`.
+   * Called by the Firestore SDK to convert a custom model object of type
+   * `AppModelType` into a plain JavaScript object (suitable for writing
+   * directly to the Firestore database) of type `DbModelType`. Used with
+   * {@link (setDoc:1)}, {@link (WriteBatch.set:1)} and
+   * {@link (Transaction.set:1)} with `merge:true` or `mergeFields`.
    *
    * The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow
    * FieldValues such as {@link (arrayUnion:1)} to be used as property values.
@@ -118,7 +125,12 @@ export interface FirestoreDataConverter<
 
   /**
    * Called by the Firestore SDK to convert Firestore data into an object of
-   * type T. You can access your data by calling: `snapshot.data(options)`.
+   * type `AppModelType`. You can access your data by calling:
+   * `snapshot.data(options)`.
+   *
+   * Generally, the data returned from `snapshot.data()` can be cast to
+   * `DbModelType`; however, this is not guaranteed as writes to the database
+   * may have occurred without a type converter enforcing this specific layout.
    *
    * @param snapshot - A `QueryDocumentSnapshot` containing your data and metadata.
    * @param options - The `SnapshotOptions` from the initial call to `data()`.
diff --git a/packages/firestore/src/lite-api/reference.ts b/packages/firestore/src/lite-api/reference.ts
index 466e22caf39..6272f3594a9 100644
--- a/packages/firestore/src/lite-api/reference.ts
+++ b/packages/firestore/src/lite-api/reference.ts
@@ -146,17 +146,18 @@ export class Query<
    * Removes the current converter.
    *
    * @param converter - `null` removes the current converter.
-   * @returns A `Query<DocumentData>` that does not use a converter.
+   * @returns A `Query<DocumentData, DocumentData>` that does not use a
+   * converter.
    */
   withConverter(converter: null): Query<DocumentData, DocumentData>;
   /**
    * Applies a custom data converter to this query, allowing you to use your own
    * custom model objects with Firestore. When you call {@link getDocs} with
    * the returned query, the provided converter will convert between Firestore
-   * data and your custom type `U`.
+   * data of type `NewDbModelType` and your custom type `NewAppModelType`.
    *
    * @param converter - Converts objects to and from Firestore.
-   * @returns A `Query<U>` that uses the provided converter.
+   * @returns A `Query` that uses the provided converter.
    */
   withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
     converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
@@ -239,11 +240,11 @@ export class DocumentReference<
    * Applies a custom data converter to this `DocumentReference`, allowing you
    * to use your own custom model objects with Firestore. When you call {@link
    * @firebase/firestore/lite#(setDoc:1)}, {@link @firebase/firestore/lite#getDoc}, etc. with the returned `DocumentReference`
-   * instance, the provided converter will convert between Firestore data and
-   * your custom type `U`.
+   * instance, the provided converter will convert between Firestore data of
+   * type `NewDbModelType` and your custom type `NewAppModelType`.
    *
    * @param converter - Converts objects to and from Firestore.
-   * @returns A `DocumentReference<U>` that uses the provided converter.
+   * @returns A `DocumentReference` that uses the provided converter.
    */
   withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
     converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
@@ -252,7 +253,8 @@ export class DocumentReference<
    * Removes the current converter.
    *
    * @param converter - `null` removes the current converter.
-   * @returns A `DocumentReference<DocumentData>` that does not use a converter.
+   * @returns A `DocumentReference<DocumentData, DocumentData>` that does not
+   * use a converter.
    */
   withConverter(converter: null): DocumentReference<DocumentData, DocumentData>;
   withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
@@ -320,10 +322,11 @@ export class CollectionReference<
    * Applies a custom data converter to this `CollectionReference`, allowing you
    * to use your own custom model objects with Firestore. When you call {@link
    * addDoc} with the returned `CollectionReference` instance, the provided
-   * converter will convert between Firestore data and your custom type `U`.
+   * converter will convert between Firestore data of type `NewDbModelType` and
+   * your custom type `NewAppModelType`.
    *
    * @param converter - Converts objects to and from Firestore.
-   * @returns A `CollectionReference<U>` that uses the provided converter.
+   * @returns A `CollectionReference` that uses the provided converter.
    */
   withConverter<NewAppModelType, NewDbModelType extends DocumentData>(
     converter: FirestoreDataConverter<NewAppModelType, NewDbModelType>
@@ -332,8 +335,8 @@ export class CollectionReference<
    * Removes the current converter.
    *
    * @param converter - `null` removes the current converter.
-   * @returns A `CollectionReference<DocumentData>` that does not use a
-   * converter.
+   * @returns A `CollectionReference<DocumentData, DocumentData>` that does not
+   * use a converter.
    */
   withConverter(
     converter: null
diff --git a/packages/firestore/src/lite-api/snapshot.ts b/packages/firestore/src/lite-api/snapshot.ts
index 9c268eeb52c..5d243cabc25 100644
--- a/packages/firestore/src/lite-api/snapshot.ts
+++ b/packages/firestore/src/lite-api/snapshot.ts
@@ -40,8 +40,8 @@ import {
 import { AbstractUserDataWriter } from './user_data_writer';
 
 /**
- * Converter used by `withConverter()` to transform user objects of type `T`
- * into Firestore data.
+ * Converter used by `withConverter()` to transform user objects of type
+ * `AppModelType` into Firestore data of type `DbModelType`.
  *
  * Using the converter allows you to specify generic type arguments when
  * storing and retrieving objects from Firestore.
@@ -56,12 +56,17 @@ import { AbstractUserDataWriter } from './user_data_writer';
  *   }
  * }
  *
+ * interface PostDbModel {
+ *   title: string;
+ *   author: string;
+ * }
+ *
  * const postConverter = {
- *   toFirestore(post: WithFieldValue<Post>): DocumentData {
+ *   toFirestore(post: WithFieldValue<Post>): PostDbModel {
  *     return {title: post.title, author: post.author};
  *   },
  *   fromFirestore(snapshot: QueryDocumentSnapshot): Post {
- *     const data = snapshot.data(options)!;
+ *     const data = snapshot.data(options) as PostDbModel;
  *     return new Post(data.title, data.author);
  *   }
  * };
@@ -83,10 +88,12 @@ export interface FirestoreDataConverter<
   DbModelType extends DocumentData = DocumentData
 > {
   /**
-   * Called by the Firestore SDK to convert a custom model object of type `T`
-   * into a plain Javascript object (suitable for writing directly to the
-   * Firestore database). Used with {@link @firebase/firestore/lite#(setDoc:1)}, {@link @firebase/firestore/lite#(WriteBatch.set:1)}
-   * and {@link @firebase/firestore/lite#(Transaction.set:1)}.
+   * Called by the Firestore SDK to convert a custom model object of type
+   * `AppModelType` into a plain Javascript object (suitable for writing
+   * directly to the Firestore database) of type `DbModelType`. Used with
+   * {@link @firebase/firestore/lite#(setDoc:1)},
+   * {@link @firebase/firestore/lite#(WriteBatch.set:1)} and
+   * {@link @firebase/firestore/lite#(Transaction.set:1)}.
    *
    * The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as
    * {@link (deleteField:1)} to be used as property values.
@@ -96,10 +103,13 @@ export interface FirestoreDataConverter<
   ): WithFieldValue<DbModelType>;
 
   /**
-   * Called by the Firestore SDK to convert a custom model object of type `T`
-   * into a plain Javascript object (suitable for writing directly to the
-   * Firestore database). Used with {@link @firebase/firestore/lite#(setDoc:1)}, {@link @firebase/firestore/lite#(WriteBatch.set:1)}
-   * and {@link @firebase/firestore/lite#(Transaction.set:1)} with `merge:true` or `mergeFields`.
+   * Called by the Firestore SDK to convert a custom model object of type
+   * `AppModelType` into a plain Javascript object (suitable for writing
+   * directly to the Firestore database) of type `DbModelType`. Used with
+   * {@link @firebase/firestore/lite#(setDoc:1)},
+   * {@link @firebase/firestore/lite#(WriteBatch.set:1)} and
+   * {@link @firebase/firestore/lite#(Transaction.set:1)} with `merge:true`
+   * or `mergeFields`.
    *
    * The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow
    * FieldValues such as {@link (arrayUnion:1)} to be used as property values.
@@ -113,7 +123,12 @@ export interface FirestoreDataConverter<
 
   /**
    * Called by the Firestore SDK to convert Firestore data into an object of
-   * type T. You can access your data by calling: `snapshot.data()`.
+   * type `AppModelType`. You can access your data by calling:
+   * `snapshot.data()`.
+   *
+   * Generally, the data returned from `snapshot.data()` can be cast to
+   * `DbModelType`; however, this is not guaranteed as writes to the database
+   * may have occurred without a type converter enforcing this specific layout.
    *
    * @param snapshot - A `QueryDocumentSnapshot` containing your data and
    * metadata.