Changelog

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All notable changes to this project will be documented in this file.

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

Unreleased

Changed

  • Publish every umbrella package to Hex.pm at the Concord release version.
  • Version replicated Concord command envelopes while retaining replay support and frozen legacy semantics for the exact pre-versioning envelope. Unknown command schemas are rejected before they enter the replicated log.
  • Reject executable and runtime-local terms from replicated commands, including anonymous index extractors, PIDs, ports, and references, even when hidden in a compressed value. Existing legacy index definitions remain readable long enough to drop by exact name. Version-one admission then requires explicit state-representation reconciliation before indexes are recreated with non-empty UTF-8 names of at most 255 bytes, declarative extractors, and a full reindex.
  • Freeze version-one validation and logical size limits independently of local API settings. Compression cannot change value, transaction, or aggregate command admission; local limits may only lower the protocol maxima.
  • Give each default VSR client process incarnation a cryptographically unique identity; use transaction idempotency keys for restart-safe write retries while their bounded replicated-cache entries are retained.
  • Support fixed VSR configurations of one through six replicas with strict majority quorums.
  • Add an explicit VSR benchmark for throughput and latency across every supported cluster size.
  • Document that VSR prefix scans filter the authoritative state in O(N) time.
  • Route VSR queries through quorum-confirmed linearizable read barriers without appending reads to the replicated log.
  • Require viewstamped_replication 0.2.0 in Hex builds so packaged Concord includes the read-barrier and durable-recovery runtime used by Concord 3.

Fixed

  • Decode valid checksummed WAL records containing atoms that have not yet been loaded in a restarted VM, preserving committed application values.
  • Retransmit uncommitted VSR prepares so dropped Prepare or PrepareOk messages cannot indefinitely stall a healthy quorum.
  • Checksum version-two WAL/checkpoint lengths and fail closed on malformed, corrupt, or unsupported records, while retaining torn-tail recovery for incomplete version-two WAL records and read compatibility with complete version-one data. Version-two writes are gated behind CONCORD_VSR_WAL_VERSION=2; the default remains rollback-compatible version one and no automatic downgrade is attempted.
  • Install a transferred state-machine snapshot and its matching VSR durable state crash-atomically; custom storage adapters must provide the same atomic callback instead of exposing either half independently.
  • Reject malformed or unsupported Concord snapshot versions instead of normalizing them as legacy state.
  • Preserve :quorum_unavailable and :not_ready errors instead of collapsing them into generic caller timeouts.
  • Replay file-backed state machines from their snapshot without decreasing the durable applied-operation watermark during restart.
  • Derive the VSR package version in the release workflow instead of repeatedly checking and skipping the already-published 0.1.0 release.

3.0.0-beta.0 - 2026-07-19

Added

  • Add the standalone viewstamped_replication application and use it as Concord's replicated runtime.
  • Publish viewstamped_replication 0.1.0 as Concord's protocol runtime dependency.
  • Publish the migrated Turso.* API as ex_turso 0.5.0 and use it for Concord's Turso engine.
  • Add three-node VSR release tests for KV, MVCC, transactions, leases, engine isolation, primary failover, and strong reads.

Changed

  • Rebuilt the changelog with the full published package release history.
  • Make Viewstamped Replication the only replicated engine in Concord 3.0.
  • Require explicit, ordered membership for multi-node VSR configurations.

Removed

  • Remove the Ra runtime, dependency, configuration switch, test harness, and operational scripts. Concord 3.0 does not read or migrate Ra storage.

Fixed

  • Align source package metadata and installation docs with the released 2.x API package.
  • Document embedded boot fixes for Ra default system startup, Prometheus opt-in metrics, disabled clustering, and restart from existing Ra data directories. Fixes #17.

2.0.1 - 2026-05-30

Fixed

  • Start the Ra default system before Concord cluster initialization so embedded host applications do not need to start :ra manually.
  • Return actionable backup errors when the Ra cluster is not available.
  • Disable the Prometheus exporter by default so embedded hosts do not crash on metrics port conflicts.
  • Add a :clustering switch so single-node embedded deployments can disable libcluster.
  • Restart existing Ra servers from persisted data directories during app startup.

2.0.0 - 2026-05-16

Added

  • Add the v2 KV and transaction API, including Concord.KV, Concord.Txn, prefix/range listing, revision metadata, conditional operations, leases, and sync/watch support.
  • Add v2 design documentation for MVCC records, transactions, sync/watch, leases, validation, and agent coordination.
  • Add a release-mode E2E test suite for distributed node validation.

Changed

  • Move long-form documentation into versioned docs/v1 and docs/v2 directories.
  • Update README and E2E documentation for the release-based architecture.
  • Simplify the library surface around the embedded database use case.

Removed

  • Remove out-of-scope Web, AuditLog, EventStream, Tracing, and Prometheus modules and dependencies from the core library.

Fixed

  • Fix Ra 3.0 query calls and MFA query argument order.
  • Fix CI, Credo, Dialyzer, ETS ownership, and release test data cleanup issues.

1.1.0 - 2026-03-23

Changed

  • Upgrade Ra and related dependency constraints for Ra 3.0 compatibility.

Fixed

  • Fix Ra 3.0 API usage in the state machine query path and test helper.
  • Fix formatting and Credo issues before publishing the package.

1.0.2 - 2026-03-22

Changed

  • Optimize prefix scans from O(N) to O(log N + K).

Removed

  • Remove token authentication, RBAC, and multitenancy from the embedded database surface.

Fixed

  • Fix ETS match specification formatting and remaining formatter violations.

1.0.1 - 2026-03-09

Changed

  • Reorganize the README into focused documentation guides.
  • Add the Concord database skill and supporting API, HTTP, and state-machine references.

Fixed

  • Address review findings around correctness, deterministic replay, snapshot coverage, backup behavior, documentation, and tests.
  • Improve E2E network partition coverage and test workflow behavior.

1.0.0 - 2025-12-09

Added

  • Add multi-node E2E coverage using manually spawned Erlang nodes.
  • Add cluster connection helper scripts for manual distributed testing.
  • Add Spec Kit command templates and project scaffolding.
  • Improve the Hex.pm release workflow.

Changed

  • Make the HTTP API opt-in by default.
  • Replace LocalCluster-based E2E tests with manual node spawning for OTP 28.
  • Update development environment dependencies and project documentation.

Fixed

  • Fix distributed test startup and cleanup issues.
  • Fix cluster restart handling when the Ra system is not started.
  • Disable Prometheus metrics by default.
  • Fix Dialyzer and CI release workflow issues.

0.3.0 - 2026-03-09

Changed

  • Publish a 0.x package line from the post-v1.0 cleanup state.
  • Include the V3 deterministic state-machine work and documentation cleanup from the 1.0.x line.

Removed

  • Remove token authentication, RBAC, and multitenancy features from the 0.x package line.

0.2.0 - 2025-10-30

Added

  • Add TTL support, bulk operations, configurable read consistency, conditional updates, secondary indexes, and query filtering.
  • Add backup/restore, value compression, performance benchmarks, and production configuration documentation.
  • Add the HTTP API, OpenAPI documentation, TLS support, Mix tasks, and certificate generation.
  • Add Prometheus metrics, OpenTelemetry tracing, audit logging, CDC event streaming, RBAC, and multitenancy features.

Fixed

  • Fix test isolation, ETS initialization, API response, TTL, bulk operation, Credo, Dialyzer, and CI issues discovered while hardening the feature set.

0.1.3 - 2025-10-18

Added

  • Initial embedded distributed key-value store built on Raft.
  • Add ETS-backed reads, core CRUD operations, cluster startup, configuration, documentation, tests, CI, and release workflow scaffolding.

Fixed

  • Add required Hex.pm package metadata.
  • Fix early formatting, lint, coverage, and release workflow failures.