flask-debug-cross-worktree-edit-stale

Flask debug edits cross-worktree stale

Problem

You're running a Flask dev server (python app.py with debug=True, or flask run --debug) from one git worktree. You're editing template / static / view files from a sibling worktree of the same repo, because the branch you want to ship is checked out at the running worktree and git checkout <branch> fails in your editing worktree.

You hit curl http://127.0.0.1:PORT/the-page after each edit, and the response bytes don't change. You hypothesize Jinja bytecode cache, Flask @_ttl_cache, browser caching, CDN, or stale __pycache__. You try touch app.py to bust Flask's debug-reload, restart the process, clear browser cache. Nothing fixes it.

Root cause: git worktrees have independent working trees on disk. Each git worktree directory has its own copy of every tracked file. Flask is reading from <worktree-A>/templates/page.html. Your edits live in <worktree-B>/templates/page.html. They're physically different files; the dev server has no way to see B's edits until A's disk state changes.

Trigger conditions (high-confidence diagnosis)

Fire this skill when ALL of these are true:

1. git worktree list shows ≥2 worktrees of the same repo.
2. A dev server is bound to a known port; lsof -i :PORT shows the server process.
3. The server's CWD (lsof -p <PID> | grep cwd, or check the script that launched it) is in worktree A.
4. Your editor is making changes in worktree B (different path, same repo).
5. curl against the page returns byte-identical responses despite confirmed-saved edits in worktree B.
6. The file you're editing is tracked (git knows about it) — not a new untracked file. (Untracked files exist in only one worktree anyway.)

If condition 6 is FALSE (you created a new file), the new file simply doesn't exist in worktree A's tree. Same root cause, different shape: either commit + ff-merge into A's branch, or create the file in A.

Diagnostic recipe