Promotes `subtype?: string` to a top-level standard field on every entity,
alongside `type` / `confidence` / `weight`. Flat string, no hierarchy — the
consumer-chosen vocabulary for sub-classifying entities within a NounType
(Person → employee/customer, Document → invoice/contract, etc.).
Layer 1 — subtype field + rollup
- HNSWNounWithMetadata.subtype + STANDARD_ENTITY_FIELDS entry
- Entity / Result / AddParams / UpdateParams / FindParams threading
- add()/update() persist subtype on storageMetadata + entityForIndexing
- get()/find() route through the standard-field fast path
- subtypeCountsByType (Map<NounTypeIdx, Map<subtype, count>>) on
BaseStorage, mirrored after nounCountsByType with the same self-heal
rebuild and persisted to _system/subtype-statistics.json
- brain.counts.bySubtype(type, subtype?) — O(1) point + breakdown
- brain.counts.topSubtypes(type, n) — top-N by count
- brain.subtypesOf(type) — distinct subtypes seen
- find({ type, subtype }) and find({ subtype: ['a','b'] }) on the fast path
Layer 2 — trackField for other facets
- brain.trackField(name, { perType?, values? }) registers a field for
cardinality + per-NounType breakdown stats. Backed by the aggregation
engine (auto-defines __fieldCounts__<name>), backfill-on-define applies.
- brain.counts.byField(name, { type? }) returns value frequencies
- Optional vocabulary whitelist rejects off-vocabulary writes at add/update
Layer 3 — generic migrateField
- brain.migrateField({ from, to, readBoth?, batchSize?, onProgress? })
streams every entity, copies the value from one path to another, and
(unless readBoth) clears the source. Supports top-level standard fields,
metadata.X, and data.X paths. Idempotent — safe to re-run.
Docs
- New guide: docs/guides/subtypes-and-facets.md (Layer 1 + 2 + 3)
- README, DATA_MODEL, QUERY_OPERATORS, api/README, finite-type-system,
quick-start all treat subtype as a core primitive with anonymous example
vocabularies (employee/customer/invoice/milestone).
Tests
- 26 new integration tests covering write/read/update/delete round-trips,
counts rollup decrement + re-route on mutation, trackField + byField
with and without perType, vocabulary whitelist enforcement, and
migrateField for metadata.X → subtype and data.X → subtype paths
including readBoth deprecation-window semantics.
Unit suite: 1468/1468 passing. Type-check + build clean.
