2026.08.23 - DCP Reliability Troubleshooting - Phase 5: Persistence Lifecycle

[lanhhoang]

• Replace the durable fingerprint with a projection that omits the entire messageIds object, so message-reference growth alone no longer forces a pi-dcp-state write (src/state/persistence.ts).
• Keep snapshot v1 serialization unchanged: serializeDcpSnapshot() still emits messageIds.byRawId and messageIds.nextRefIndex, so persisted snapshots remain byte-compatible with earlier versions.
• Add fingerprint regressions proving that messageIds bookkeeping is excluded while every semantic mutation (manualMode, compressPermission, stats, lastCompaction, prune.tools, nextBlockId, nextRunId, nudges) still changes the fingerprint (tests/persistence.test.ts).
• Add reconstruction regressions covering same-owner resume, sibling-branch tree navigation in both directions, compaction followed by a restarted extension instance, and compression-block boundaries rebuilt after omitted ID-only checkpoints (tests/stable-ids.test.ts, tests/index.test.ts, tests/pipeline.test.ts).
• Replace the obsolete "persists one context mutation and skips an unchanged repeated pass" expectation with two contracts: growing contexts that change only message IDs append zero entries, and a context pass that adds a context-limit nudge anchor appends exactly one entry with the full snapshot payload (tests/index.test.ts).

Verified end-to-end with pnpm vitest run (481/481 tests) and pnpm typecheck on commit 390c2ab.

Historical corpus projection over the ten session JSONLs named in docs/superpowers/specs/2026-08-22-dcp-troubleshooting-design.md Appendix A remains 692 states total, with semanticCheckpoints at 56 — no historical file was rewritten.