Changes in sub pyproject.toml do not cause a cache bust

[fellhorn]

When modifying a pyproject.toml in a subfolder ruff does correctly handle this as a cache bust. The same modification of the root level pyproject.toml causes a cache bust.

The setup can be recreated with this script:

#!/bin/bash

# Create root pyproject.toml
cat << EOF > pyproject.toml
[tool.ruff.lint]
select = []
EOF

# Create lib directory and its pyproject.toml
mkdir lib
cat << EOF > lib/pyproject.toml
[tool.ruff.lint]
select = []
EOF

# Create a Python file with a hello world function
# It violates ANN rules
cat << EOF > lib/hello.py
def hello_world():
    print("Hello, World!")
EOF

# Run ruff check
echo "Running initial ruff check:"
ruff check

# Modify lib/pyproject.toml
cat << EOF > lib/pyproject.toml
[tool.ruff.lint]
select = ["ANN"]
EOF

# Run ruff check again - it works due to a cache hit
echo "Running ruff check after modification:"
ruff check

# Ruff check without cache will fail
echo "Running ruff check without cache"
ruff check --no-cache

Output:

Running initial ruff check:
All checks passed!
Running ruff check after modification:
All checks passed!
Running ruff check without cache
lib/hello.py:1:5: ANN201 Missing return type annotation for public function `hello_world`
  |
1 | def hello_world():
  |     ^^^^^^^^^^^ ANN201
2 |     print("Hello, World!")
  |
  = help: Add return type annotation: `None`

Found 1 error.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).

Tested with ruff 0.5.6.

Searched for different combinations of these keywords and have not found an existing issue: cache pyproject.toml subfolder --no-cache subproject

[dhruvmanila]

#12264 might be related