This commit addresses issue #60 by documenting and enforcing the immutability
guarantees of the event store:
- Document that EventStore interface is append-only by design (no Update/Delete methods)
- Document the immutable nature of events once persisted as an audit trail
- Add JetStream stream retention policy configuration documentation
- Add comprehensive immutability test (TestEventImmutability_InMemory, TestEventImmutability_Sequential)
- Enhance InMemoryEventStore to deep-copy events, preventing accidental mutations
- Update README with detailed immutability guarantees and audit trail benefits
The EventStore interface intentionally provides no methods to modify or delete
events. Once persisted, events are immutable facts that serve as a tamper-proof
audit trail. This design ensures compliance, debugging, and historical analysis.
Acceptance criteria met:
- EventStore interface documented as append-only (event.go)
- JetStream retention policy configuration documented (store/jetstream.go)
- Test verifying events cannot be modified after persistence (store/immutability_test.go)
- README documents immutability guarantees (README.md)
Closes#60
Co-Authored-By: Claude Code <noreply@anthropic.com>
Add ReplayError and ReplayResult types to capture information about
malformed events encountered during replay. This allows callers to
inspect and handle corrupted data rather than having it silently skipped.
Key changes:
- Add ReplayError type with sequence number, raw data, and underlying error
- Add ReplayResult type containing both successfully parsed events and errors
- Add EventStoreWithErrors interface for stores that can report replay errors
- Implement GetEventsWithErrors on JetStreamEventStore
- Update GetEvents to maintain backward compatibility (still skips malformed)
- Add comprehensive unit tests for the new types
This addresses the issue of silent data loss during event-sourced replay
by giving callers visibility into data quality issues.
Closes#39
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add Metadata field (map[string]string) to Event struct with omitempty
- Add helper methods for common metadata: SetCorrelationID/GetCorrelationID,
SetCausationID/GetCausationID, SetUserID/GetUserID, SetTraceID/GetTraceID,
SetSpanID/GetSpanID
- Add WithMetadataFrom helper for copying metadata between events
- Add metadata key constants for standard fields
- Add comprehensive unit tests for metadata serialization and helpers
- Add store tests verifying metadata persistence
Closes#7
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add ErrVersionConflict error type and VersionConflictError for detailed
conflict information
- Implement version validation in InMemoryEventStore.SaveEvent that rejects
events with version <= current latest version
- Implement version validation in JetStreamEventStore.SaveEvent with version
caching for performance
- Add comprehensive tests for version conflict detection including concurrent
writes to same actor
- Document versioning semantics in EventStore interface and CLAUDE.md
This ensures events have monotonically increasing versions per actor and
provides clear error messages for version conflicts, enabling optimistic
concurrency control patterns.
Closes#6
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
