Changelog

All notable changes to reckon-db will be documented in this file.

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

[2.1.4] - 2026-05-17

Fixed — Cluster bootstrap robustness

Four bugs in reckon_db_store_coordinator that, between them, could permanently strand a node outside the Raft cluster after a rough restart cycle:

Infinite-timeout join

khepri_cluster:join/2' internally useskhepri_app:get_default_timeout/0', which defaults to infinity'. Combined with the global lock acquired during the join, simultaneous- boot nodes could deadlock on lock contention forever. (Setting khepri'sdefault_timeout' app env globally would also affect every other khepri operation, so that's not a usable workaround.)

The exported 2-arg version is now wrapped in a side process that's killed after ?KHEPRI_JOIN_TIMEOUT' (20s). On timeout the coordinator returnsfailed' and the retry-with-jitter timer picks up the next round.

(khepri_cluster:join/3' is defined in the source but NOT exported in khepri 0.17.2 — onlyjoin/1' and join/2' are. Passing an explicit timeout via the 3-arg form fails with{undef, ...}'.)

Self-clusters treated as active

has_active_cluster/2 treated {ok, [SingleSelf]}' as an active cluster. Every freshly-booted Khepri node is a 1-member standalone cluster, so during a simultaneous boot every node saw every other node as a cluster and they all raced to join each other under the same global lock — the worst possible bootstrap shape. Tightened tolength(Members) > 1'.

Coordinator election didn't drive cluster formation

The original handle_no_existing_clusters just logged the elected coordinator and returned. Coordinator stayed as a 1-node cluster, non-coordinators sat in waiting' forever, nothing grew the cluster. With the self-clusters fix above, this previously-latent stalemate became reachable: 4 standalone clusters forever. Now: the elected coordinator stays as its 1-node cluster, but each non-coordinator actively joins via the coordinator. Once anyone joins, the coordinator's cluster has 2 members and subsequent retries from remaining non-coordinators find an active cluster via the regularhas_active_cluster' path.

No retry on transient failure

After waiting | failed | no_nodes', the coordinator gave up permanently. Added a jittered retry (3-8s) on the coordinator's own gen_server that re-attemptsdo_join_cluster/1' until status becomes `joined'.

Diagnostic for stale local state

Before khepri_cluster:join' is called, verify the local Ra server is registered under the StoreId. If not, log a pointer to thewipe-and-rejoin.sh' script in reckon-cluster-compose instead of hanging on infrastructure that never arrived.

Verified end-to-end

Cold-start torture against the 4-node beam cluster:

• Wipe all 4 data dirs, parallel docker compose up on all 4
• All 4 nodes converge to 4-of-4 Raft membership without manual intervention
• Existing torture trio (leader_kill / partition_heal / subscription_failover) all pass against the freshly-formed cluster
• Killing the new leader during the subscription scenario: new leader elected on the formerly-stuck beam00 node (proves it's a first-class member)

[2.1.3] - 2026-05-17

Fixed — Cross-node subscription delivery + registration race

Two bugs that, together, caused stream-scoped subscriptions to silently miss roughly half their events whenever the subscription was opened against a non-leader gateway.

Cross-node delivery

reckon_db_emitter:send_to_subscriber/4 had a single clause guarded on node(Pid) =:= node() plus a catch-all that returned ok. maybe_forward_events/2 had the same shape. When the Khepri trigger fired on the Raft leader and reckon_db_emitter_group:broadcast/3 picked an emitter that wasn't co-located with the subscriber pid, the emitter silently dropped the event.

Each cluster node spins up its own emitter pool for every subscription (via reckon_db_leader_tracker and setup_event_notification), so the pg group typically holds 2+ emitters on different nodes — all carrying the same subscriber pid (the one captured by the client that called save_subscription). The random pick had a ~50% chance of landing on an emitter whose node didn't host the subscriber, and those events were lost.

Pid ! Msg works fine across Erlang distribution; the local-only guard was the bug. Remote pids now receive via catch (Pid ! Msg). Liveness probing stays local-only because erlang:is_process_alive/1 is undefined for remote pids — the runtime's own dead-process semantics cover remote delivery to a dead pid.

Registration race

setup_event_notification registered the Khepri trigger BEFORE starting the emitter pool. Between those two steps, any event commit fired the trigger into an empty pg group — broadcast/3 logged "No emitters for ..." and dropped the event. Particularly noticeable on a hot stream during sub registration.

Swapped the order to (persist names → start pool → register trigger), so the local emitter is in pg before the trigger goes live.

Verification

End-to-end on a 4-node cluster: subscriber received 25 events from our stream out of 25 writer-acked, contiguous version range 0..24, both pre- and post-leader-kill events delivered, zero cross-stream events received (the 2.1.2 catch-up filter still holds).

[2.1.2] - 2026-05-17

Fixed — Catch-up filter

Catch-up replay (the path that delivers historical events to a newly-registered subscription) ignored the subscription's selector and pushed the entire global event log to the subscriber, regardless of its declared filter. The Khepri trigger filter (live path) was correct; only the catch-up path was unfiltered.

Net effect on an active store: every subscription opened with start_from = 0 received the full history of every stream, then flipped to correctly filtered live deliveries. Stream-scoped consumers had to discard 99%+ of what they received on attach.

Implementation

• New reckon_db_filters:matches/3 — in-memory predicate that evaluates a (Type, Selector) pair against an #event{} record. Handles by_stream (exact stream id; <<"$all">> matches all), by_event_type, and by_tags (set inclusion). by_event_pattern and by_event_payload pass through; live trigger filters them correctly so the gap is narrower. A real map-pattern evaluator is a follow-up.
• do_catchup/5 now takes the subscription's type + selector and applies the predicate to each batch before sending. Read window through read_all_global still advances by raw batch size so the scan progresses even when nothing in a window matches.
• deliver_catchup_batch separated into filtered/raw counts; logs "events scanned" rather than "delivered" so the metric reflects what catch-up actually saw.

Behaviour change

Subscribers that relied on receiving cross-stream events from a single by_stream subscription will now miss them. The intended contract is "subscribe per stream; use <<"$all">> for the global firehose" — this release makes the implementation match.

[2.1.1] - 2026-05-15

Added — Backward-direction chain verification

Closes the documented gap from 2.1.0. On integrity-enabled stores, reckon_db_streams:read/5,6 now verifies the chain for backward reads in exactly the same way as forward reads. The only behavioural difference between directions is the result-ordering of the returned events; the chain semantics are identical.

Implementation

The verifier walks events in forward order regardless of read direction (the chain runs forward through time and that's the direction it has to be checked in). For a backward read, the implementation reverses the result to forward order, runs the forward verifier, then reverses the verified list before returning so the caller still sees events highest-version-first.

Behaviour change for callers

Backward reads of integrity-enabled stores that previously succeeded against tampered storage now return {error, {integrity_violation, _}}. This is a hardening, not a regression: 2.1.0's behaviour was the documented gap. Callers relying on the old behaviour to access tampered data deliberately should use the existing Opts = #{verify => skip_all} escape hatch.

Tests

backward_read_bypasses_verification (which had asserted the gap) replaced with two tests in reckon_db_integrity_reads_SUITE:

• backward_read_catches_tampering — symmetric assertion that the same tamper detected on forward reads is also detected on backward reads
• backward_read_returns_events_in_descending_order — intact backward read returns [v4, v3, v2] with integrity fields populated

Full regression: 514 eunit + 5/21/12/4 CT (writes/reads/snapshots/ subscriptions) = 556 tests pass.

[2.1.0] - 2026-05-15

Added — Tamper-resistance for events and snapshots

Implements Layers 2–5 of the cross-package design in plans/PLAN_TAMPER_RESISTANCE.md. Reckon-db now writes HMAC-protected, chain-hashed events when integrity is enabled on a store, and verifies them on every read surface.

Requires reckon_gater >= 2.1.0 for the schema and verification primitives.

Configuration

#store_config{} gains an integrity field (default disabled). To enable:

#store_config{
    %% ... existing fields ...
    integrity = #{
        enabled => true,
        key_source => {env_var, <<"RECKON_DB_KEY_MY_STORE">>}
        %% or: {sealed_file, "/path/to/key"}  (mode 0600 required)
    }
}

Keys are 32 random bytes (HMAC-SHA256). Loaded into persistent_term at store startup; cleared on shutdown. Misconfiguration (missing env, bad base64, insecure file mode, wrong size) is fail-fast — the store refuses to start.

Write path (Layer 2)

• reckon_db_streams:append/4,5 populates prev_event_hash + mac on every event when integrity is enabled.
• New per-stream watermark stored under [metadata, integrity, chain_start, StreamId]. Set on the first integrity-bearing append to a stream. Events with version below the watermark stay legacy; events at or above must carry integrity fields.
• Pre-existing legacy streams gain a watermark equal to current_highest_version + 1 on first integrity write — legacy data is preserved untouched.

Read path (Layer 3)

• New reckon_db_streams:read/6 accepts an Opts map with verify => skip_legacy | strict | skip_all. Default skip_legacy for backward compatibility.
• Forward reads on integrity-enabled stores verify each event's MAC and chain link against a running tip. Failure surfaces as {error, {integrity_violation, _}} — non-retriable, distinct from wrong_expected_version.
• Backward reads bypass chain verification in 2.1.0 (documented gap; MAC-only check possible in future).
• New telemetry event [reckon, db, read, legacy_event_returned] fires when legacy events are returned under skip_legacy, for operator remediation tracking.

Snapshot path (Layer 4)

• reckon_db_snapshots:save/4,5 populates anchor_hash (chain hash of the event at the snapshot's version) + mac when integrity is enabled.
• load/2 and load_at/3 recompute the chain hash from the underlying event at load time and verify against the stored anchor. Detects post-snapshot stream tampering even when the snapshot itself is intact — the headline property this layer provides over MAC alone.
• Save refused when no event exists at the target version or when the target event is legacy — a snapshot whose anchor cannot be established is unverifiable and worse than no snapshot.

Subscription catch-up (Layer 5)

• reckon_db_subscriptions:do_catchup/3 MAC-verifies each integrity-bearing event before delivery. Cross-stream chain verification is intentionally NOT performed here (catch-up reads sort by epoch_us across all streams; per-stream chain integrity belongs at the consumer / aggregate-rebuild layer).
• Tampered event during catch-up halts replay and sends {subscription_error, {integrity_violation, _}} to the subscriber. Emits [reckon, db, subscription, integrity, violation] telemetry.
• Live events come from the write path with integrity fields already populated — no emitter-side change needed.

New modules

• reckon_db_integrity_key — per-store HMAC key loader with validation (32-byte size, base64 decode, file mode 0600).
• reckon_db_chain_watermark — per-stream watermark CRUD against the metadata tree.

Tests

41 new Common Test cases plus 12 new eunit tests across four suites:

• reckon_db_integrity_key_tests (12 eunit)
• reckon_db_integrity_writes_SUITE (5 CT)
• reckon_db_integrity_reads_SUITE (20 CT, 5 groups)
• reckon_db_integrity_snapshots_SUITE (12 CT, 2 groups)
• reckon_db_integrity_subscriptions_SUITE (4 CT)

Full regression: 514 eunit + 41 integrity CT pass with zero existing-test regressions.

Fixed

• src/reckon_db_log_backend.erl — converted 11 @doc tags on -callback declarations to plain %% comments. EDoc strict rules disallow @doc before -callback; the previous shape broke rebar3 ex_doc and would have blocked hex publication. Text content preserved verbatim.

Changed

• src/reckon_db.app.src — {links, [{"GitHub", ...}]} updated to {"Codeberg", ...} to match canonical hosting.
• ?RECKON_DB_VERSION macro in include/reckon_db.hrl synchronised with the package version (was 1.7.2, now 2.1.0).
• README.md install snippet bumped from 1.0.0 to 2.1.0.

Out of scope (deferred)

• Backward-direction read chain verification.
• Cross-stream chain reconstruction on catch-up (per-event MAC only at that surface).
• Ed25519 signatures for cross-trust-domain authenticity. The signature field is reserved on the schema but not populated; external authenticity is currently absent over the reckon-gateway wire.
• Key rotation. The key_id slot is reserved ({1, MacBytes} shape); 2.1.0 always writes key_id = 1.

[2.0.0] - 2026-04-19

Changed

BREAKING: Internal modules renamed from esdb_* to reckon_db_* to match the overall reckon-db-org naming scheme. Most consumers go through reckon_gater_api and should not be affected directly, but any code that reaches into reckon-db internal modules must update:

ETS table atoms also renamed:

• esdb_revoked_tokens → reckon_db_revoked_tokens
• esdb_revoked_issuers → reckon_db_revoked_issuers

Dependencies

• Bumped reckon_gater to ~> 2.0 (requires the corresponding renamed API from reckon-gater 2.0.0).
• NIF binaries now loaded as reckon_db_*_nif.so — requires reckon-nifs 2.0.0.

Migration

Applications that go through reckon_gater_api see only the reckon-gater 2.0.0 renames. Direct-internal users:

%% Before
{ok, Verified} = esdb_capability_verifier:verify(Token).

%% After
{ok, Verified} = reckon_db_capability_verifier:verify(Token).

Rebuild from clean: rm -rf _build rebar.lock && rebar3 compile will re-fetch reckon_gater 2.0+ and reckon_nifs 2.0+ and recompile the renamed NIFs via the rustler hooks.

[1.7.5] - 2026-03-22

Fixed

• Gateway worker version check bypass — reckon_db_gateway_worker had a duplicate version check (version_matches/2) that used atoms (any, stream_exists) instead of the integer constants (?ANY_VERSION = -2, ?STREAM_EXISTS = -4) defined in esdb_gater_types.hrl. This caused append_events/4 via the gateway to reject ANY_VERSION and STREAM_EXISTS with {wrong_expected_version, _}. Removed the duplicate check — the gateway worker now delegates directly to reckon_db_streams:append/4 which handles all version constants correctly.

[1.7.4] - 2026-03-22

Fixed

• Non-blocking nodeup handler — handle_nodeup_cluster_join now runs entirely in a spawned process. The should_handle_nodeup coordinator call was blocking the node monitor, causing 5s timeout crashes on every nodeup event (same pattern as the leader activation fix in 1.7.3).

[1.7.3] - 2026-03-22

Fixed

• Non-blocking leader activation — do_activate now uses gen_server:cast instead of a blocking gen_server:call with 10s timeout. When Khepri/Ra is still initializing, save_default_subscriptions blocks on Khepri queries, causing the node monitor to time out and crash-loop every 15 seconds. The leader worker now handles activation asynchronously in its own process.

[1.6.3] - 2026-03-19

Fixed

• Store Inspector: list_streams/1 returns [binary()] not [{binary(), integer()}] — all inspector functions were destructuring as tuples causing function_clause crashes

[1.6.2] - 2026-03-19

Fixed

• Store Inspector: Fixed badarg crash in subscription_summary/1 when subscriber_pid is undefined
• Store Inspector: Made snapshot listing defensive against per-stream errors
• Store Inspector: Made subscription listing skip malformed entries instead of crashing
• Store Inspector: format_pid/1 handles undefined, binary, and non-pid terms gracefully

[1.6.1] - 2026-03-19

Changed

• Updated reckon_gater dependency to ~> 1.3.1 (includes inspector API exports)

[1.6.0] - 2026-03-19

Added

• Store Inspector (reckon_db_store_inspector): New module for aggregate store-level introspection.
  • store_stats/1 — stream count, total events, snapshot count, subscription count
  • list_all_snapshots/1 — all snapshots across all streams (summaries without data payloads)
  • list_subscriptions/1 — all subscriptions with checkpoint positions
  • subscription_lag/2 — events behind for a specific subscription
  • event_type_summary/1 — census of event types with counts
  • stream_info/2 — detailed info for a single stream (timestamps, snapshot coverage)
• Gateway worker clauses for all inspector operations
• Guide: guides/store_inspector.md with usage examples and performance notes
• Architecture diagram: assets/store_inspector.svg

[1.5.1] - 2026-03-08

Added

• reckon_db_streams:has_events/1: Check if a store contains at least one event. Reads 1 event via read_all_global — correctly handles empty streams (truncation, GDPR erasure) unlike path-existence checks. Exposed via gateway worker.

[1.5.0] - 2026-03-06

Added

• reckon_db_streams:read_all_global/3: Read all events across all streams in global epoch_us order with offset/batch pagination. Used for catch-up subscriptions.

[1.4.5] - 2026-03-06

Fixed

• Stale Khepri triggers after BEAM restart: When a subscription already existed in Khepri (persisted from a previous run), reregister_subscriber only updated the subscriber PID but did NOT re-register the Khepri trigger. The trigger's stored procedure (an Erlang fun/closure) becomes stale after a BEAM restart, so new events written to the store would never fire the notification mechanism. This caused subscription-based event delivery to silently stop working after daemon restarts. Fixed: reregister_subscriber now also re-creates the filter and re-registers the Khepri trigger, ensuring the stored procedure is fresh.

[1.4.4] - 2026-03-06

Fixed

• Telemetry handler crash on subscription created: handle_event(?SUBSCRIPTION_CREATED, ...) pattern-matched on #{subscription_id := _} but the metadata from subscribe/5 sends subscription_name instead. This caused a badmatch that detached the telemetry logger handler for the entire session. Fixed: use maps:get/3 with fallback.

[1.4.3] - 2026-03-06

Fixed

• Crash in update_subscriber_pid on re-subscribe: reckon_db_subscriptions_store:get/2 returns subscription() | undefined, not {ok, subscription()} | {error, _}. The re-registration code from v1.4.2 pattern-matched on {ok, Existing} which caused a case_clause crash, killing the gateway worker and preventing all subscriptions from being set up on that store. Fixed: match on the record directly with is_record guard.

[1.4.2] - 2026-03-06

Fixed

• Subscriptions not re-registering subscriber PID after restart: When a projection re-subscribes on startup, the subscription already exists in Khepri (persisted from the previous BEAM instance). Previously this returned {error, {already_exists, _}} and the new subscriber PID was never registered. The emitter pool delivered events to the dead PID from the previous run, so projections never received events and read models stayed empty/stale after restart. Fix: when a subscription already exists and a new subscriber_pid is provided, update the stored subscription with the new PID and return {ok, Key}.

Changed

• Eliminated all deep case/if nesting across codebase: Refactored ~50 instances of depth-2+ nesting across 25 source files to max depth 1. Extracted helper functions, used pattern matching on function heads, and pipeline patterns. No behavioral changes.

[1.4.1] - 2026-03-06

Fixed

• Subscription health monitor kills valid subscriptions after restart: The health monitor treated subscriptions with dead subscriber_pid as stale and deleted them, even when the emitter pool was running and actively serving events. After a daemon restart, ALL persisted subscriptions have dead PIDs (from the previous BEAM instance), so the health checker would kill every domain subscription ~2 minutes after boot. This left projections without event feeds and read models empty/stale. Fix: subscriptions with dead subscriber_pid but a running emitter pool are now treated as healthy (restarted subscription from a previous BEAM instance).

• App-level telemetry crashes handler on startup: emit_start_telemetry() fired [reckon_db, store, started] with app-level metadata (#{application => reckon_db, version => ...}) instead of the expected #{store_id := ...}. This caused a badmatch in reckon_db_telemetry:handle_event/4, which detached the entire telemetry logger handler for the rest of the session. Removed the mistyped app-level telemetry events (per-store telemetry in reckon_db_store is unaffected).

• Stale RECKON_DB_VERSION macro: Updated from "0.1.0" to "1.4.1".

[1.4.0] - 2026-03-06

Fixed

• Per-store Ra system isolation: Each ReckonDB store now creates its own dedicated Ra system with separate WAL, segments, and DETS files. Previously, all stores shared the default khepri Ra system, causing all event data from every bounded context to be written into a single WAL file (whichever store started first owned the shared WAL directory). This affected both single and cluster modes.

[1.3.3] - 2026-03-05

Fixed

• Late subscription event delivery: Subscriptions registered after leader activation had Khepri triggers but no emitter workers, silently dropping events until the health monitor detected missing pools (up to 2 minutes). setup_event_notification now eagerly starts the emitter pool when the emitter supervisor is available, using pattern matching on whereis/1 to avoid a gen_server:call deadlock when called from within the leader worker during default subscription setup.

Added

• late_subscribe_starts_pool_immediately integration test in reckon_db_emitter_autostart_SUITE verifying that the emitter pool exists immediately after subscribe/5 returns when the leader is active.

Changed

• Bumped reckon_gater dependency to ~> 1.1.3 (includes debug_info for dialyzer)

[1.3.2] - 2026-02-21

Fixed

• pg scope process dies silently: pg:start_link(?RECKON_DB_PG_SCOPE) was called from reckon_db_app:start/2, creating an unsupervised pg process linked only to the application master. When it died, no supervisor restarted it, silently breaking ALL event delivery (emitter workers join pg groups for subscription routing). Moved pg scope startup into reckon_db_sup:init/1 as the first supervised child with restart => permanent, ensuring it is always restarted on failure.

Added

• reckon_db_pg_scope_SUITE integration tests verifying pg scope supervision, automatic restart after crash, and full event delivery after scope restart.

[1.3.0] - 2026-02-20

Fixed

• Leader detection in single mode: reckon_db_node_monitor used a one-shot leader check in single mode that never rescheduled. If Ra leader election hadn't completed by the first check, the LeaderWorker never activated and emitter pools never started. Fixed to retry until leader is detected, then stop polling (no leadership changes in single-node mode).
• Node monitor placement: Moved reckon_db_node_monitor from cluster_sup (cluster mode only) to system_sup (all modes). The node monitor must run in single mode too to detect Ra leader and activate leader responsibilities.
• Supervisor strategies: Changed notification_sup and leader_sup from one_for_one to rest_for_one. If leader_sup crashes, emitter_sup must restart to prevent stale emitter pools running without leader coordination. If leader_tracker crashes, leader_worker must restart to re-establish dependency on tracking infrastructure.

Added

• Subscription health monitor (reckon_db_subscription_health): Periodic health checks (default 60s) that detect and clean up stale subscriptions (dead subscriber), orphaned emitter pools (pool without subscription), and missing emitter pools (subscription without pool). Only performs cleanup on the Ra leader node. Includes on-demand health_check/1 API returning a health report map.
• Dead subscriber cleanup in emitter: When an emitter worker detects its subscriber PID is dead during event delivery, it now asynchronously stops the emitter pool (matching ex-esdb's send_or_kill_pool pattern). Previously dead subscribers accumulated silently.
• Emitter autostart integration tests: New CT suite reckon_db_emitter_autostart_SUITE with 13 end-to-end tests covering leader activation, subscription lifecycle, event delivery, dead subscriber cleanup, and health monitor operation.

[1.2.7] - 2026-02-18

Fixed

• Persistence worker crash on undefined options: get_persistence_interval/1 called maps:get/3 on the options field of store_config, which crashed with {badmap, undefined} when options was not explicitly set. Fixed by adding a guard clause for is_map(Options) and a fallback clause that returns the default persistence interval. Also set the default value of options in the store_config record to #{} (empty map) to prevent this class of bug in other code paths.

[1.2.6] - 2026-02-13

Fixed

• Subscription id not populated: subscribe/5 created the #subscription{} record without setting the id field, leaving it as undefined. The subscription key was computed and used for Khepri storage and trigger registration, but the subscription record passed to notify_created (and thus to the leader_tracker and emitter pool) still had id = undefined. This caused emitter workers to join pg group {StoreId, undefined, emitters} while Khepri triggers broadcast to {StoreId, CorrectKey, emitters} — a different group. Events were silently dropped because no emitters were found in the broadcast group. Fixed by setting Subscription#subscription{id = Key} before passing to downstream consumers.

[1.2.5] - 2026-02-13

Fixed

• Stream subscription filter path mismatch: by_stream/1 was stripping the category prefix from stream IDs (e.g., <<"test$delivery-001">> became <<"delivery-001">>), creating Khepri trigger filters that never matched stored events. This caused ALL stream-based subscriptions to silently fail — triggers never fired, subscribers never received events. Fixed to use the full stream ID in the filter path.
• Event type filter record matching: by_event_type/1 used a map pattern (#{event_type => Type}) to match stored events, but events are stored as #event{} records (tuples). Map patterns cannot match records. Fixed to use proper record pattern matching with #event{event_type = Type, _ = '_'}.

Added

• Subscription delivery integration tests: New CT suite reckon_db_subscription_delivery_SUITE with 5 end-to-end tests verifying the full subscribe → append → trigger → emitter → deliver pipeline.

[1.2.4] - 2026-02-13

Fixed

• Subscription Filter Error Handling: create_filter/2 errors no longer crash the gateway worker. Invalid stream names (e.g., missing $ separator) now return {error, {invalid_filter, Reason}} instead of propagating to khepri_evf:wrap/1 which caused a function_clause crash.
• Gateway Worker Resilience: handle_cast for save_subscription now matches the result and logs a warning on failure instead of crashing. Previously, a single invalid subscription could crash the worker and lose all 28+ pending subscription messages in its queue.

[1.2.3] - 2026-02-06

Fixed

• Subscription Filter Types: Fixed create_filter/2 function_clause error
  • Added support for gater-style subscription types: by_stream, by_event_type, by_event_pattern, by_event_payload, by_tags
  • Maintains backward compatibility with evoq-style types
  • Required for reckon_evoq_adapter type translation through the gater layer

[1.2.2] - 2026-02-01

Documentation

• Event Envelope Documentation: Improved event structure documentation
  • Added note about evoq event envelope in guides/event_sourcing.md
  • Documented metadata standardization (required vs optional fields)
  • Cross-referenced evoq Event Envelope Guide
  • Clarified simplified vs full envelope formats

[1.2.1] - 2026-01-21

Fixed

• Documentation: Corrected asset paths for hexdocs SVG rendering
  • Changed ../assets/ to assets/ in all guides

[1.2.0] - 2026-01-21

Added

• Distributed Store Registry: Cluster-wide store discovery using pg groups
  • reckon_db_store_registry GenServer with pg-based distributed membership
  • Automatic store announcement/unannouncement on start/stop
  • Cross-node store visibility via broadcast mechanism
  • list_stores/0 - List all stores in the cluster
  • get_store_info/1 - Get detailed info about a specific store
  • list_stores_on_node/1 - List stores on a specific node
  • 11 new unit tests for store registry
  • Gateway worker calls registry directly (no facade layer)

[1.1.1] - 2026-01-21

Added

• Documentation: Added Event Sourcing Paradigms guide to hexdocs
  • Entity-Centric (Traditional DDD)
  • Relationship-Centric (DCB - Dynamic Consistency Boundaries)
  • Process-Centric (Dossier metaphor with tags)

[1.1.0] - 2026-01-21

Added

• Tag-Based Querying: Cross-stream event queries using tags
  • read_by_tags/4 - Query events by tags across all streams
  • Support for any (union) and all (intersection) matching modes
  • Tags field added to event records and storage
  • 15 new unit tests for tag filtering
  • Tags are for QUERY purposes only, NOT for concurrency control

Changed

• Dependencies: Updated reckon_gater from ~> 1.0.3 to ~> 1.1.0 for tags support

[1.0.3] - 2026-01-19

Changed

• Dependencies: Updated reckon_gater from exact 1.0.0 to ~> 1.0.3 to include critical double-wrapping bugfix

[1.0.2] - 2026-01-09

Fixed

• Documentation: Minor documentation improvements

[1.0.0] - 2026-01-03

Changed

• Stable Release: First stable release of reckon-db under reckon-db-org
• All APIs considered stable and ready for production use
• Updated Dockerfile with correct package names (reckon_db)
• Fixed guide asset paths for hexdocs compatibility

[0.4.6] - 2025-12-26

Fixed

• Dependency conflict: Removed direct ra dependency (khepri provides it). Updated to reckon_db_gater ~> 0.6.5 which removed stale ra from its lock file.

[0.4.5] - 2025-12-26

Fixed

• Dependency conflict: Updated ra dependency from exact 2.16.12 to ~> 2.17.1 to resolve conflict with reckon_db_gater ~> 0.6.4 which requires ra ~> 2.17.1

[0.4.4] - 2025-12-22

Added

• Configuration Guide: Comprehensive configuration documentation
  • Store configuration options (data_dir, mode, pool sizes)
  • Health probing configuration
  • Consistency checking and persistence intervals
  • Erlang (sys.config) and Elixir (config.exs) examples
  • Complete development/staging/production examples
  • Performance tuning recommendations
  • Telemetry events reference

[0.4.3] - 2025-12-22

Added

• Gateway Worker Handlers:
  • delete_stream - Delete streams via gateway
  • read_by_event_types - Native Khepri type filtering via gateway
  • get_subscription - Get subscription details including checkpoint

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

[0.4.2] - 2025-12-22

Added

• Cluster Consistency Checker (reckon_db_consistency_checker.erl):

  • Split-brain detection via membership consensus verification
  • Leader consensus verification across all cluster nodes
  • Raft log consistency checks (term and commit index)
  • Quorum status monitoring with margin calculation
  • Four status levels: healthy, degraded, split_brain, no_quorum
  • Configurable check intervals (default: 5000ms)
  • Status change callbacks for alerting
  • Telemetry events: [reckon_db, consistency, ...]

• Active Health Prober (reckon_db_health_prober.erl):

  • Fast failure detection via active probing (default: 2000ms intervals)
  • Three probe types: ping, rpc, khepri
  • Configurable failure threshold (default: 3 consecutive failures)
  • Node status tracking: healthy, suspect, failed, unknown
  • Recovery detection with callbacks
  • Telemetry events: [reckon_db, health, ...]

• Cluster Consistency Guide (guides/cluster_consistency.md):

  • Split-brain problem explanation and prevention strategies
  • Consistency checker usage and configuration
  • Health prober integration patterns
  • Quorum management and recovery procedures
  • Circuit breaker and load balancer integration examples

• Architecture Diagrams (SVG):

  • assets/consistency_checker.svg - Consistency checker architecture
  • assets/split_brain_detection.svg - Split-brain detection flow
  • assets/health_probing.svg - Health probing timeline

Tests

• 35 unit tests for consistency checker
• 37 unit tests for health prober
• All 72 new tests passing

[0.4.1] - 2025-12-22

Added

• Server-Side Documentation Guides:

  • guides/temporal_queries.md - Point-in-time queries, timestamp filtering, cluster behavior
  • guides/scavenging.md - Event lifecycle, archival backends, safety guarantees
  • guides/causation.md - Causation/correlation tracking, graph building, DOT export
  • guides/stream_links.md - Derived streams, filter/transform patterns
  • guides/schema_evolution.md - Schema registry, version-based upcasting, validation
  • guides/memory_pressure.md - Pressure levels, callbacks, integration patterns
  • guides/storage_internals.md - Khepri paths, version padding, cluster replication

• Architecture Diagrams (SVG):

  • assets/temporal_query_flow.svg - Temporal query processing flow
  • assets/scavenge_lifecycle.svg - Event lifecycle state machine
  • assets/causation_graph.svg - Causation chain visualization
  • assets/stream_links.svg - Stream linking architecture
  • assets/schema_upcasting.svg - Schema version upcasting flow
  • assets/memory_levels.svg - Memory pressure level thresholds
  • assets/khepri_paths.svg - Khepri storage path structure

Changed

• Documentation Improvements:
  • Replaced ASCII diagrams with professional SVG graphics
  • snapshot_recovery.svg - Performance comparison visualization
  • event_fanout.svg - Multi-subscriber event delivery diagram
  • Updated rebar.config ex_doc with new guides organized into Core Concepts, Advanced Features, and Operations sections

[0.4.0] - 2025-12-22

Added

• Enterprise Edition NIFs: High-performance Rust NIFs with pure Erlang fallbacks

  • Community Edition (hex.pm) uses pure Erlang implementations
  • Enterprise Edition (git + Rust) gets 5-100x speedups for specific operations
  • Automatic fallback detection via persistent_term

• reckon_db_crypto_nif (Phase 1):

  • nif_base58_encode/1 - Fast Base58 encoding for DIDs
  • nif_base58_decode/1 - Fast Base58 decoding
  • Uses Bitcoin alphabet, ~5x faster than pure Erlang

• reckon_db_archive_nif (Phase 2):

  • nif_compress/1,2 - Zstd compression with configurable level
  • nif_decompress/1 - Zstd decompression
  • nif_compress_batch/1,2 - Batch compression for multiple items
  • nif_decompress_batch/1 - Batch decompression
  • ~10x faster than zlib, better compression ratios

• reckon_db_hash_nif (Phase 3):

  • nif_xxhash64/1,2 - 64-bit xxHash with optional seed
  • nif_xxhash3/1 - Modern xxHash3 (SIMD optimized)
  • nif_partition_hash/2 - Hash to partition number
  • nif_stream_partition/3 - Combined store+stream routing
  • nif_partition_hash_batch/2 - Batch hashing for bulk ops
  • nif_fnv1a/1 - FNV-1a for small keys
  • nif_fast_phash/2 - Drop-in phash2 replacement

• reckon_db_aggregate_nif (Phase 3):

  • nif_aggregate_events/2 - Bulk fold with tagged value semantics
  • nif_sum_field/2 - Vectorized sum accumulation for numeric fields
  • nif_count_where/3 - Count events matching field condition
  • nif_merge_tagged_batch/1 - Batch map merge with tagged values
  • nif_finalize/1 - Unwrap tagged values ({sum, N}, {overwrite, V})
  • nif_aggregation_stats/1 - Event statistics (counts, unique fields)

• reckon_db_filter_nif (Phase 3):

  • nif_filter_events/2 - Filter events by compiled predicate
  • nif_filter_count/2 - Count matching events without collecting
  • nif_compile_predicate/1 - Pre-compile filter predicates
  • nif_partition_events/2 - Partition events by predicate (matching/non-matching)
  • nif_first_match/2 - Find first matching event
  • nif_find_all/2 - Find all matching events with indexes
  • nif_any_match/2, nif_all_match/2 - Boolean aggregate predicates

• reckon_db_graph_nif (Phase 4):

  • nif_build_edges/1 - Build edge list from event causation relationships
  • nif_find_roots/1, nif_find_leaves/1 - Find root/leaf nodes
  • nif_topo_sort/1 - Topological sort (Kahn's algorithm via petgraph)
  • nif_has_cycle/1 - Detect cycles in causation graph
  • nif_graph_stats/1 - Calculate node/edge/depth statistics
  • nif_to_dot/1,2 - Generate Graphviz DOT format
  • nif_has_path/2 - Check if path exists between nodes
  • nif_get_ancestors/2, nif_get_descendants/2 - BFS path finding

Changed

• Build profiles:
  • Added enterprise profile with Rust NIF compilation hooks
  • Added enterprise_test profile for testing with NIFs
  • Build with rebar3 as enterprise compile to enable NIFs

Documentation

• Updated README with Enterprise/Community edition information
• Added NIF function documentation with academic references

[0.3.1] - 2025-12-20

Changed

• Version padding: Increased from 6 to 12 characters (?VERSION_PADDING macro)
  • Previous: 999,999 events per stream max (~2.7 hours at 100 events/sec)
  • Now: 999,999,999,999 events per stream max (~317 years at 100 events/sec)
  • Supports long-running neuroevolution, IoT, and continuous event streams

Fixed

• EDoc errors: Removed backticks and markdown from EDoc comments (breaks hex.pm docs)

[0.3.0] - 2025-12-20

Added

• Capability-Based Security (reckon_db_capability_verifier.erl, reckon_db_revocation.erl):
  • Server-side verification of UCAN-inspired capability tokens
  • Ed25519 signature verification using issuer's public key from DID
  • Token expiration and not-before time validation
  • Resource URI pattern matching (exact, wildcard suffix, prefix)
  • Action permission checking with wildcard support
  • Token revocation management (ETS-based, gossip integration planned)
  • Issuer revocation for compromised identities
  • Content-addressed token IDs (CIDs) for revocation tracking
  • Comprehensive unit tests (13 verifier tests + 6 revocation tests)

This completes Phase 3 of the decentralized security implementation. Client-side token creation is in reckon-gater, server-side verification is here.

Changed

• Documentation: Replaced ASCII diagrams with SVG in README and guides

Fixed

• README API documentation: Fixed incorrect function signatures
  • Subscriptions: Added missing unsubscribe/3, get/2 functions
  • Snapshots: Fixed load/3 → load_at/3, delete/3 → delete_at/3, added exists/2, exists_at/3
  • Aggregator: Completely rewrote section - was showing non-existent API (foldl/4, foldl_from_snapshot/4)
• guides/snapshots.md: Fixed load/3 → load_at/3, delete/3 → delete_at/3, rewrote aggregator example
• guides/cqrs.md: Fixed subscription key usage in emitter group join
• guides/subscriptions.md: Fixed invalid map access syntax
• guides/event_sourcing.md: Fixed aggregator foldl signature (takes events list, not store/stream)

[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

• reckon-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 reckon-db, 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