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>
Entry counting:
- Session.setRange now initializes recoveredTo = startLSN
- RecordCatchUpProgress delta counts only actual catch-up work
(recoveredTo - startLSN), not the replica's pre-existing prefix
Rebuild transfer gate:
- BeginTailReplay requires TransferredTo >= SnapshotLSN
- Prevents tail replay on incomplete base transfer
3 new regression tests:
- BudgetEntries_NonZeroStart_CountsOnlyDelta (30 entries within 50 budget)
- BudgetEntries_NonZeroStart_ExceedsBudget (30 entries exceeds 20 budget)
- Rebuild_PartialTransfer_BlocksTailReplay
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Registry is now keyed by stable ReplicaID, not by address.
DataAddr changes preserve sender identity — the core V2 invariant.
Changes:
- ReplicaAssignment{ReplicaID, Endpoint} replaces map[string]Endpoint
- AssignmentIntent.Replicas uses []ReplicaAssignment
- Registry.Reconcile takes []ReplicaAssignment
- Tests use stable IDs ("replica-1", "r1") independent of addresses
New test: ChangedDataAddr_PreservesSenderIdentity
- Same ReplicaID, different DataAddr (10.0.0.1 → 10.0.0.2)
- Sender pointer preserved, session invalidated, new session attached
- This is the exact V1/V1.5 regression that V2 must fix
doc.go: clarified Slice 1 core vs carried-forward files
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
All mutable state on Sender and Session is now unexported:
- Sender.state, .epoch, .endpoint, .session, .stopped → accessors
- Session.id, .phase, .kind, etc. → read-only accessors
- Session() replaced by SessionSnapshot() (returns disconnected copy)
- SessionID() and HasActiveSession() for common queries
- AttachSession returns (sessionID, error) not (*Session, error)
- SupersedeSession returns sessionID not *Session
Budget configuration via SessionOption:
- WithBudget(CatchUpBudget) passed to AttachSession
- No direct field mutation on session from external code
New test: Encapsulation_SnapshotIsReadOnly proves snapshot
mutation does not leak back to sender state.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
pingqiuandClaude Opus 4.6