principle-separate-before-serializing-shared-state
About principle-separate-before-serializing-shared-state
A concurrency design skill for systems where multiple actors may modify shared state. It recommends removing unnecessary sharing first, then using structural serialization when shared writes are required.
Key features
- 01Identify shared mutable state
- 02Prefer separate write targets
- 03Serialize necessary shared writes
- 04Reduce race-condition risk
Use cases
- 01Designing concurrent worker state
- 02Preventing races in shared files or branches
Install
Copy the command and run it in a terminal.
npx skills add https:/After installing, type/principle-separate-before-serializing-shared-statein Claude Code to confirm it loaded.
Details
From the project READMESeparate Before Serializing Shared State
When concurrent actors might share mutable state, first ask whether they need the same mutable object. If not, eliminate the sharing. When sharing is real, enforce serialization structurally: lockfiles, sequential phases, exclusive ownership. Instructions and conventions are not concurrency control.
Why: Concurrent writes to shared state create race conditions that are intermittent, hard to reproduce, and expensive to debug.
Pattern:
- Identify shared mutable state (files both read and write, branches both push to, APIs both define and consume).
- Default: eliminate the shared write target. Ask: do these actors need one canonical object, or are they publishing independent facts? Give each actor its own owned file, key, branch, or state directory, and merge only at the read/reporting boundary. Two workers writing their own
lastXfield into onestate.jsonis still shared mutation.indexer-state.json+metrics-state.jsonis not. - Only when one shared write target is a real invariant, serialize access structurally (lockfiles, sequential phases, single-writer actor, or atomic compare-and-swap). Treat "we need a lock" as a design smell to check, not as the default answer.