Master hashes each reported file on a worker, polls size and mtime every
world_watch_seconds (a change must hold still for one poll), and replaces
stale instances with the instance migration (Mythran shift, or seamless
with world_reload_seamless=1); empty ones are stopped. Also on WORLD_RELOAD.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>