erl_esdb

# Changelog

All notable changes to erl-esdb will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [0.2.0] - 2024-12-19

### Added

- **End-to-end tests**: 24 comprehensive e2e tests for gater integration:
  - Worker registration (4 tests)
  - Stream operations via gater (9 tests)
  - Subscription operations (4 tests)
  - Snapshot operations (4 tests)
  - Load balancing (3 tests)
- **Subscriptions**: Added `ack/4` function for acknowledging event delivery

### Fixed

- **Gateway worker API compatibility**:
  - `get_version` now handles integer return correctly
  - Snapshot operations use correct function names (`save`, `load_at`, `delete_at`)
  - Subscription unsubscribe uses correct 3-arg version
- **Header conflicts**: Added `ifndef` guards for `DEFAULT_TIMEOUT` macro

### Changed

- **erl-esdb-gater integration**: Updated to work with gater's pg-based registry (replacing Ra)
- **Test counts**: Now 72 unit + 53 integration + 24 e2e = 149 total tests

## [0.1.0] - 2024-12-18

### Added

- Initial release of erl-esdb, a BEAM-native Event Store built on Khepri/Ra
- Event stream operations:
  - `append/4,5` - Write events with optimistic concurrency control
  - `read/5` - Read events from streams (forward/backward)
  - `get_version/2` - Get current stream version
  - `exists/2` - Check if stream exists
  - `list_streams/1` - List all streams in store
  - `delete/2` - Soft delete streams
- Subscription system:
  - Stream subscriptions - events from specific streams
  - Event type subscriptions - events by type across streams
  - Pattern subscriptions - wildcard stream matching
  - Payload subscriptions - content-based filtering
- Snapshot management:
  - `save/5` - Save aggregate state snapshots
  - `load/2,3` - Load latest or specific version snapshots
  - `list/2` - List all snapshots for a stream
  - `delete/3` - Delete old snapshots
- Aggregation utilities:
  - `foldl/4` - Fold over events with accumulator
  - `foldl_from_snapshot/4` - Fold starting from latest snapshot
- Cluster support:
  - UDP multicast discovery (LibCluster gossip compatible)
  - Automatic Khepri/Ra cluster formation
  - Node monitoring and failover
  - Leader election and tracking
- Emitter pools for high-throughput event delivery
- Partitioned writers for concurrent stream writes
- BEAM telemetry integration with configurable handlers
- Comprehensive test suite (72 unit + 53 integration tests)
- Educational guides:
  - Event Sourcing fundamentals
  - CQRS patterns
  - Subscriptions usage
  - Snapshots optimization

### Dependencies

- Khepri 0.17.2 - Raft-based distributed storage
- Ra 2.16.12 - Raft consensus implementation
- Telemetry 1.3.0 - BEAM telemetry for observability