[Pepps233]

Summary

Prevent concurrent evolution runtimes from processing the same skill-candidate job, producing duplicate drafts, and recording a failure after another processor has already completed the work. Also keep evolved-skill detail output focused on the target harness and review material.

Reasoning

Candidate polling was advisory: every Diffex process could select the same completed evolution job, and registry compare-and-swap protected individual appends without claiming the full processing operation. Two processors could therefore share a work ID and attempt, invoke synthesis twice, race lifecycle transitions, and leave contradictory completion/failure history.

A renewable, fenced candidate-work lease makes ownership durable across processes while preserving the existing completion-dominates-retry behavior. Retry paths remain safe by treating identical downstream lifecycle records as idempotent and by binding draft identity to synthesized content.

Changes

• Add renewable candidate-work leases with unique runtime owners and heartbeat-based lease-loss cancellation.
• Fence candidate registry appends with the active work lease and return busy workers to the polling delay.
• Suppress failure records once durable completion exists.
• Make identical draft, validation, and evaluation retries idempotent after downstream transitions.
• Include synthesized content in immutable draft identity.
• Remove redundant operation, state, and rollback lines from evolved-skill details.
• Add deterministic lease, race, acknowledgement-loss, retry, draft-identity, and UI coverage.
• No dependency changes.

Testing

• npm run check
• ./test.sh
• cd packages/evolution && node ../../node_modules/vitest/dist/cli.js --run test/skill-candidate-worker.test.ts test/skill-candidate-registry.test.ts test/skill-synthesizer.test.ts test/filesystem-store.test.ts
• cd packages/coding-agent && node ../../node_modules/vitest/dist/cli.js --run test/evolution-runtime.test.ts