name: Case Collision Check

# Rejects PRs that track two files whose paths differ only by case
# (README.md vs readme.md, src/Foo.py vs SRC/foo.py).
#
# Linux is case-sensitive; Windows and macOS (default) are not. A
# case-colliding pair lives fine in a Linux checkout and silently breaks
# every clone on a case-insensitive host — the filesystem can hold only
# one of them, so checkout fails or whichever wins overwrites the other.
# Git won't prevent the pair from landing (it only warns at checkout time,
# on a case-insensitive FS, for the client doing the checkout), so the only
# enforcement point is CI, on Linux, against the index.
#
# Runs unconditionally (no change-classifier gate): a collision can ship in
# any kind of PR — docs, JS, config, not just Python — so gating on a
# language lane would be the same "passive rule that cannot enforce a
# policy" trap the infographic check exists to close.

on:
  workflow_call:

permissions:
  contents: read

jobs:
  check-case-collisions:
    runs-on: ubuntu-latest
    timeout-minutes: 5
    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2

      - name: Run case-collision checker
        run: python3 scripts/check-case-collisions.py