Session Projection
Domain: Sessions & Persistence
Motivation
dsh-session-projection serves current per-session state — todos, goals, conversation statistics — to clients without replaying the raw event log. Domain plugins register a projection unit (key, state schema, initial state, and a synchronous apply(state, event)), and carriers receive complete, schema-validated JSON values through snapshots and change notifications.
Concrete Example
snapshot(session) returns { asOfSeq, values }, where asOfSeq is the seq of the last event every value reflects; onChanged(listener) subscribes to per-change notifications.
Analogy
A live dashboard computed from the event feed instead of re-reading the database.