Changelog

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

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.6.6] - 2025-12-26

Fixed

Duplicate module conflict: Renamed esdb_crypto_nif module to esdb_gater_crypto_nif to avoid collision with erl_esdb's module of the same name. This fixes Mix release errors when both packages are used together.

[0.6.5] - 2025-12-26

Fixed

Stale rebar.lock: Removed stale ra dependency from lock file that was causing conflicts with erl_esdb. The gateway doesn't use ra directly.

[0.6.4] - 2025-12-22

Added

Configuration Guide: Comprehensive configuration documentation
- All application environment options documented
- Erlang (sys.config) and Elixir (config.exs) examples
- Capability mode configuration examples
- Retry configuration examples
- Complete development/staging/production examples

[0.6.3] - 2025-12-22

Added

Capability Opt-In Mode: Global configuration for capability enforcement
- esdb_gater_config:capability_mode/0 - Get current mode (disabled|optional|required)
- esdb_gater_config:set_capability_mode/1 - Set mode at runtime
- esdb_gater_config:effective_capability_mode/1 - Get mode with channel override
- Configurable via sys.config: {capability_mode, disabled | optional | required}
- Per-channel override still takes precedence (most restrictive wins)
Interactive REPL: Full-featured shell for event store exploration
- esdb_gater_repl:start/0,1 - Start interactive shell
- Store commands: stores, use STORE
- Stream commands: streams, stream STREAM, read, version
- Causation commands: effects, cause, chain, graph, dot FILE
- Temporal commands: until TS, range T1 T2
- Schema commands: schemas, schema TYPE
- Subscription commands: subscriptions, subscription NAME
- Health commands: health, memory
- DOT export for Graphviz visualization

Changed

Channel Server: Updated verify_capability/4 to use 3-mode security logic
- disabled mode: No capability checks (development/testing)
- optional mode: Verify if token provided, allow if not
- required mode: Always require valid capability token

[0.6.2] - 2025-12-22

Added

Stream Operations API:
- delete_stream/2 - Delete a stream and all its events
- read_by_event_types/3 - Native Khepri filtering for type-based queries
Subscription Operations API:
- get_subscription/2 - Get subscription details including checkpoint

These additions support the erl-evoq-esdb adapter improvements.

[0.6.1] - 2025-12-22

Changed

Documentation Overhaul: Fixed client-side guides to use correct gateway API
- shared_types.md - Replaced server API examples with esdb_gater_api calls
- event_sourcing.md - Updated 5 code samples to use gateway API
- cqrs.md - Updated projection examples to use esdb_gater_api
- snapshots.md - Complete rewrite with client-side perspective
- subscriptions.md - Complete rewrite with gateway API and PubSub channels
- stream_links.md - Updated subscription examples
SVG Diagrams: Replaced ASCII diagrams with professional SVG graphics
- auth_traditional.svg - Centralized authorization flow
- auth_capability.svg - Capability-based authorization flow
- verification_flow.svg - Token verification steps
- delegation_chain.svg - Permission delegation visualization
- causation_chain.svg - Event causation chain visualization

[0.6.0] - 2025-12-22

Changed

NIF Extraction: Moved Rust NIF to separate erl-esdb-nifs package
- NIFs are now loaded from erl_esdb_nifs priv/ when available
- Falls back to erl_esdb_gater priv/ for standalone builds
- Renamed NIF to esdb_gater_crypto_nif to avoid conflict with erl-esdb's NIF
- Pure Erlang fallbacks unchanged for community edition
Simplified Configuration: Cleaned up rebar.config
- Removed commented NIF build hooks
- Added clear documentation for enterprise addon usage
Documentation: Updated README for new enterprise pattern
- Enterprise users now add erl_esdb_nifs dependency
- Simplified instructions for NIF acceleration

[0.5.0] - 2025-12-22

Added

Temporal Query Operations (esdb_gater_api):
- read_until/3,4 - Read events up to a timestamp
- read_range/4,5 - Read events in a time range
- version_at/3 - Get stream version at a specific timestamp
- New guide: guides/temporal_queries.md
Scavenge Operations (esdb_gater_api):
- scavenge/3 - Delete old events from a stream
- scavenge_matching/3 - Scavenge streams matching a pattern
- scavenge_dry_run/3 - Preview what would be deleted
- New guide: guides/scavenging.md
Causation Tracking (esdb_gater_api):
- get_effects/2 - Get events caused by an event
- get_cause/2 - Get the event that caused this one
- get_causation_chain/2 - Trace back to root cause
- get_correlated/2 - Get all events with same correlation ID
- build_causation_graph/2 - Build graph for visualization
- New guide: guides/causation.md
- New SVG: assets/causation_graph.svg
Schema Operations (esdb_gater_api):
- register_schema/3 - Register event schema with version
- unregister_schema/2 - Remove a schema
- get_schema/2 - Get schema for an event type
- list_schemas/1 - List all registered schemas
- get_schema_version/2 - Get current schema version
- upcast_events/2 - Transform events to current schema
- New guide: guides/schema_evolution.md
- New SVG: assets/schema_upcasting.svg
Memory Pressure Operations (esdb_gater_api):
- get_memory_level/1 - Get current pressure level (normal/elevated/critical)
- get_memory_stats/1 - Get detailed memory statistics
- New guide: guides/memory_pressure.md
Stream Link Operations (esdb_gater_api):
- create_link/2 - Create a derived stream with filter/transform
- delete_link/2 - Delete a link
- get_link/2 - Get link configuration
- list_links/1 - List all links
- start_link/2, stop_link/2 - Control link processing
- link_info/2 - Get detailed link statistics
- New guide: guides/stream_links.md
- New SVG: assets/stream_links.svg

Changed

README: Added documentation for all new API sections
ex_doc: Added 6 new guides to documentation configuration

[0.4.3] - 2025-12-20

Fixed

Documentation: Corrected all code samples in README.md
- Quick Start now uses actual descriptive API (append_events, stream_forward)
- API Reference documents real exports instead of non-existent call/execute
- "Accessing the Event Store" section uses correct function signatures
- Removed worker registration examples (server concern, not client)

[0.4.2] - 2025-12-20

Changed

Documentation: Replaced ASCII diagrams with SVG in README.md
- supervision_tree.svg - Supervision hierarchy
- worker_registry_flow.svg - Registration and execution flow
- channel_message_flow.svg - Publish message flow
- worker_registration.svg - Automatic worker registration architecture

[0.4.1] - 2025-12-20

Changed

Documentation: Replaced ASCII diagrams with SVG in all guides
- capability_architecture.svg - Security architecture flow
- cqrs_traditional.svg - Traditional single model
- cqrs_separated.svg - CQRS command/query separation
- cqrs_scaling.svg - Independent read/write scaling
- snapshots_comparison.svg - Performance comparison
- subscription_flow.svg - Event write flow with triggers

[0.4.0] - 2025-12-20

Added

Capability-Based Security (esdb_capability.erl, esdb_identity.erl):
- UCAN-inspired capability tokens for decentralized authorization
- Ed25519 keypair generation and DID encoding (did:key method)
- Token creation, signing, and delegation with attenuation
- JWT and Erlang binary encoding formats (auto-detected on decode)
- Base58 encoding for DIDs (Bitcoin alphabet)
- Shared types in include/esdb_capability_types.hrl
- Comprehensive security guide (guides/capability_security.md)
Channel Capability Authorization:
- esdb_channel:publish/4 and esdb_channel:subscribe/4 with capability token
- Channels can require capabilities via requires_capability/0 callback
- Resource URI format: esdb://{realm}/channel/{channel_name}/{topic}
- Actions: channel/publish and channel/subscribe
- Integrates with esdb_capability_verifier in erl-esdb for server-side verification
Optional NIF Acceleration (Enterprise Edition):
- Rust-based NIFs for Base58 encoding/decoding (5-10x faster)
- esdb_crypto_nif.erl wrapper with automatic fallback
- native/ directory with Rust crate (excluded from hex.pm)
- Commented hooks in rebar.config for opt-in compilation
- Pattern: Community (hex.pm) = pure Erlang, Enterprise (git) = NIF-accelerated

This completes the capability-based security integration for PubSub channels.

[0.3.0] - 2024-12-20

Added

Shared Types Header (include/esdb_gater_types.hrl):
- #event{} record for event data
- #snapshot{} record for aggregate snapshots
- #subscription{} record for subscription state
- #append_result{} record for append operation results
- subscription_type() type (stream | event_type | event_pattern | event_payload)
- read_direction() type (forward | backward)
- append_error() and read_error() types
- Version constants: ?NO_STREAM, ?ANY_VERSION, ?STREAM_EXISTS
- Content type constants: ?CONTENT_TYPE_JSON, ?CONTENT_TYPE_BINARY

This header enables downstream libraries (erl-evoq, erl-evoq-esdb) to depend on erl-esdb-gater for shared type definitions without requiring a direct dependency on erl-esdb.

[0.2.0] - 2024-12-19

Changed

Worker Registry: Replaced Ra-based registry with pg-based implementation
- Uses OTP's built-in pg (process groups) module
- Simpler architecture with no external consensus dependency
- Cluster-wide discovery via pg:get_members/2 across all nodes
- Eventual consistency model (acceptable for stateless gateway workers)
- Automatic cleanup on worker death via process monitoring
- Automatic cleanup on node failure via pg membership

Removed

Ra dependency: No longer required since registry uses pg
esdb_gater_api worker: Removed from supervision tree (API is now purely functional)

Added

End-to-end tests: 24 comprehensive e2e tests in erl-esdb covering:
- Worker registration (4 tests)
- Stream operations via gater (9 tests)
- Subscription operations (4 tests)
- Snapshot operations (4 tests)
- Load balancing (3 tests)

Fixed

API compatibility with erl-esdb gateway worker:
- get_version now handles integer return directly
- Snapshot operations use correct function names (save, load_at, delete_at)
- Subscription unsubscribe uses 3-arg version

Dependencies

Removed: Ra (no longer needed)
Telemetry 1.3.0 - BEAM telemetry for observability

[0.1.0] - 2024-12-18

Added

Initial release of erl-esdb-gater, gateway for distributed erl-esdb access
Worker Registry:
- Ra-based distributed worker registration
- Automatic process monitoring and cleanup
- Node-aware worker lookup
Gateway API:
- register_worker/1,2 - Register workers for stores
- unregister_worker/1,2 - Unregister workers
- call/2,3 - Synchronous calls with load balancing
- cast/2 - Asynchronous fire-and-forget
- get_workers/1 - List registered workers
- health/0 - Gateway health status
Retry mechanism:
- Exponential backoff with jitter
- Configurable base delay, max delay, max attempts
- Telemetry integration for retry tracking
PubSub Channel System:
- esdb_channel behavior for channel implementations
- 10 dedicated channels with different priorities:
  - Critical: alerts, security (HMAC required, no rate limit)
  - High: events, health
  - Normal: system, metrics, audit, lifecycle
  - Low: logging, diagnostics
- Rate limiting per topic per second
- HMAC-SHA256 message signing for security
- Topic-based pub/sub using pg groups
Security:
- HMAC-SHA256 message signing
- Constant-time signature verification (timing attack resistant)
- Configurable message TTL (default 5 minutes)
- Environment variable or application config for secrets
Telemetry events:
- Worker registration/unregistration
- Request start/stop/error
- Retry attempts and exhaustion
- Cluster node up/down
- Channel broadcast metrics
Comprehensive test suite (44 unit + 8 integration tests)
Educational guides (shared with erl-esdb):
- Event Sourcing fundamentals
- CQRS patterns
- Subscriptions usage
- Snapshots optimization

Dependencies

Ra 2.16.12 - Raft consensus for worker registry (replaced with pg in 0.2.0)
Telemetry 1.3.0 - BEAM telemetry for observability

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