ctx.storage.domain opens declared domains: zod value schemas parsed at
the durable boundary, one write chain per domain (update(fn) is the only
read-modify-write), domain/changed emitted per record after durability
(new snapshot + operation, no old value, per repo event convention).
Domain-to-backend routing is configuration (default backend + per-domain
overrides); unknown names and missing facets fail loud. Ships the
MemoryStorageBackend test helper and a runtime invariant asserting every
change event matches the in-memory state.
node:sqlite DatabaseSync with the session-persistence-sqlite open
sequence (0o700 dir, exclusive 0o600 create, foreign_keys, configurable
journal mode, user_version stamp-or-reject). STRICT tables throughout:
units/unit_globals meta tables plus one document-per-row table per
declared unit table, keeping per-key durable updates precise.
Atomic whole-file replacement (same-dir temp + fsync + rename + parent
fsync); the in-memory unit state is authoritative and the file is always
the current net state, pretty-printed. Missing files open as empty units
and materialize on first write; foreign or unparsable files reject with
malformed-medium, stored-version drift with version-mismatch.
ctx.storage is a pure registration hub: multiple named backends stay
mounted side by side, data forms (domain first) mount via the
merge-extensible StorageForms map. src/backend.ts is the normative
KV-facet contract; tests/contract.ts is the shared conformance suite
every backend runs. Backends expose data-shape facets (kv now, an
append-log facet reserved for the future session-backend migration).
