ucm-events

Append-only event store and graph projection for the Unified Context Management (UCM) engine.

ucm-events is the source of truth for every context mutation. Following the Datomic "database as a value" model, facts are only ever appended — never updated in place. The graph is always rebuildable by replaying the event log, which makes the whole system auditable and time-travelable.

What it does

EventStore — an append-only log with id and stream indexing, checkpointing (events_since_checkpoint / advance_checkpoint), time-bounded replay, and causation_chain traversal so you can reconstruct why a fact exists.
GraphProjection — deterministic, idempotent fold from &[UcmEvent] to a UcmGraph. Replay the whole log (replay_all) or apply incrementally (apply_event / apply_batch).

Quick example

use ucm_events::{EventStore, GraphProjection};

// `events` is a Vec<UcmEvent> produced by ucm-ingest adapters.
let mut store = EventStore::new();
store.append_batch(events.clone());

// Materialize the current graph by folding the entire log.
let graph = GraphProjection::replay_all(&events);

println!("events: {}, entities: {}", store.len(), graph.all_entities().len());

Where it fits

ucm-ingest adapters emit UcmEvents → ucm-events persists and projects them into a UcmGraph (defined in ucm-graph-core) → ucm-reason analyzes the materialized graph. Because state is fully replayable, ucm-observe can re-run any past analysis and verify it is deterministic.

Research foundations

Event sourcing — Martin Fowler, Event Sourcing.
Database as a value — Datomic immutable, append-only architecture.

The in-memory store has the same API surface as a durable backend would; for production, swap the storage for RocksDB with a column family per stream.

License