pingqiu ff7ea41099 feat: add engine data/recoverability core (Phase 05 Slice 3) ...

New file: history.go — RetainedHistory connects recovery decisions
to actual WAL retention state:
- IsRecoverable: checks gap against tail/head boundaries
- MakeHandshakeResult: generates HandshakeResult from retention state
- RebuildSourceDecision: chooses snapshot+tail vs full base from
  checkpoint state (trusted vs untrusted)
- ProveRecoverability: generates explicit proof explaining why
  recovery is or is not allowed

14 new tests (recoverability_test.go):
- Recoverable/unrecoverable gap (exact boundary, beyond head)
- Trusted/untrusted/no checkpoint → rebuild source selection
- Handshake from retained history → outcome classification
- Recoverability proofs (zero-gap, ahead, within retention, beyond)
- E2E: two replicas driven by retained history (catch-up + rebuild)
- Truncation required for replica ahead of committed

Engine module at 44 tests (12 + 18 + 14).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2026-03-29 23:04:51 -07:00

..

replication

feat: add engine data/recoverability core (Phase 05 Slice 3)

2026-03-29 23:04:51 -07:00