Run on Linux with libfuse2, fusermount3, Python 3, and the repository dependencies installed. Set SLOWFS_PROOF_ROOT to a new scratch directory, place slowfs.py there, and create its Python environment with `python3 -m venv "$SLOWFS_PROOF_ROOT/venv"` followed by `"$SLOWFS_PROOF_ROOT/venv/bin/pip" install fusepy`. Place watcher-lock-responsive.e2e.ts in scripts/scenarios/ of current main, then run the repository scenarios:prove command with the base and head commits listed in the evidence. Use T3CODE_DEV_SEED=0. The scenario makes its own synthetic 50-file project, mounts a passthrough filesystem, waits for the watcher to begin a 40-second read, changes the file mention query, and measures an unrelated HTTP request. Both sides capture the app 29 seconds after the keystroke. The only expectation is that the HTTP request completes within 2 seconds. No real provider turn is started.