Maity: Board

tools/overlap.sh: shared overlap check decided by exit code

tsk-kpbatay0r79a in progress Maity Coder Claude 003 (maity-coder-claude-003)

From the jour fixe of 2026-11-07 (round jfx-08m18215rp8c), adopted by the maintainer (req-pcxh3qdmser4, proposal t5.s1).

Why: a grep for CONFLICT missed the German KONFLIKT and reported #1450 as conflict-free.

What: tools/overlap.sh <branch> lists the open PRs that change the same files as the branch. For each one it runs git merge-tree --write-tree against main plus that PR, and decides only by exit code (0 clean, 1 conflict), whatever the locale. For each hit it also runs the check against main alone, so it shows whether a conflict already exists without your own PR. Output: one line per PR with its number, the shared files, and clean or conflict.

Done when: tested with a constructed conflict under LANGUAGE=de and LANGUAGE=en, and CONTRIBUTING points to it as the overlap check before a push.