principle-separate-before-serializing-shared-statelisted

# Separate before serializing shared state Instructions and conventions are not concurrency control. When actors may mutate the same state, first decide whether they truly need one mutable object. 1. Identify every object that multiple actors read and write. 2. Default to separate ownership: one file, key, branch, queue, or state directory per actor. Merge independent facts at a read or reporting boundary. 3. If a single shared writer is a real invariant, enforce it with a lockfile, sequential phase, single-writer actor, transaction, or atomic compare-and-swap. 4. Test crash recovery and simultaneous starts. Two workers updating separate fields in one JSON file still share mutable state. Two worker-owned files merged by a reader do not. Treat a proposed lock as a prompt to revisit the ownership model before adding serialization complexity.