chore(release): 10.4.0-rc.4

The coverage denominator the health-by-accounting ratification named for
the vector family — never built until now, and its absence was measured as
the exact outage class it existed to prevent: a migrated store with
canonical vectors and no derived index opened with the vector leg EMPTY,
served [] from vector search with no error, and the report-driven read gate
had nothing to refuse on (the provider's coverage invariant was honestly
unledgered — the denominator was ours to supply).

- getCanonicalCounts() gains vectors: { all } — the count of canonical
  nouns holding a REAL vector. Incremented where a vector lands (the
  isNew-gated metadata seam for explicit vectors — the same discipline that
  keeps HNSW neighbor-link re-saves from inflating counts; a narrow
  noteVectorLanded hook for the deferred-embed landing, gated on the
  worker's own pre-embed read). Decremented on a proven delete of a
  vectored noun; a vector-uncertain delete marks the ledger suspect rather
  than guessing (no new reads on the delete path). Recounted by the
  sanctioned recount; legacy counts.json derives it once (a deferred noun's
  vector file exists with an empty vector, so presence requires one
  content read at derivation — never on the hot path).
- The open gate's vector leg: when a health-reporting provider claims
  serving while the index holds zero nodes and the ledger proves vectored
  canonical rows exist, open BUILDS (narrated) — routed through the
  provider's idempotent fillFromCanonical() when exposed (the joint door;
  a partial shortfall stays repair()'s operator business), the JS rebuild
  otherwise — or fails typed pre-serve. Scoped exactly: bare isReady()
  providers, migrating providers, and white-box size stubs open as before.

Pinned end-to-end from the partner gate's probe shape (store with vectored
canonical rows, no derived index, reopen → search serves N, never []),
red-proved against the pre-fix path; the inverse (zero vectored rows) opens
without building and serves [] honestly.

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
 
+### [10.4.0-rc.4](https://source.soulcraft.com/soulcraft/brainy/compare/v10.4.0-rc.3...v10.4.0-rc.4) (2026-08-25)
+
+- feat(vector): the vectored-noun scalar joins the count ledger; the open gate closes the vector leg (9730835b)
+
+
 ### [10.4.0-rc.3](https://source.soulcraft.com/soulcraft/brainy/compare/v10.4.0-rc.2...v10.4.0-rc.3) (2026-08-25)
 
 - fix(update-seam): the metadata crossing never carries BigInt endpoint ints (f4780c8e)

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@soulcraft/brainy",
-  "version": "10.4.0-rc.3",
+  "version": "10.4.0-rc.4",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@soulcraft/brainy",
-      "version": "10.4.0-rc.3",
+      "version": "10.4.0-rc.4",
       "license": "MIT",
       "dependencies": {
         "@msgpack/msgpack": "^3.1.2",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@soulcraft/brainy",
-  "version": "10.4.0-rc.3",
+  "version": "10.4.0-rc.4",
   "description": "Universal Knowledge Protocol™ - World's first Triple Intelligence database unifying vector, graph, and document search in one API. Stage 3 CANONICAL: 42 nouns × 127 verbs covering 96-97% of all human knowledge.",
   "main": "dist/index.js",
   "module": "dist/index.js",

src/brainy.ts

@@ -2382,6 +2382,17 @@ export class Brainy<T = any> implements BrainyInterface<T> {
           [{ type: 'embed.landed', id, vector: newVector }],
           'system:embed-landing'
         )
+        // Vectored-noun ledger: the landing commit above carries a vector
+        // write with NO accompanying metadata operation, so the
+        // saveNounMetadata(..., hasVector) seam never fires for it — the
+        // narrow storage hook is the only seam left. `oldVector.length===0`
+        // (already known for free from the pre-embed read above) proves this
+        // is a GENUINE first landing, not a re-embed of an already-vectored
+        // row (e.g. a deferred update() on a row that already had a real
+        // vector) — the latter must never double-count.
+        if (oldVector.length === 0) {
+          await this.storage.noteVectorLanded?.(id)
+        }
         this.clearPendingEmbed(id)
       } catch (err) {
         prodLog.warn(
@@ -3000,8 +3011,11 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       const runInsert: TransactionFunction<void> = async (tx) => {
         // Operation 1: Save metadata FIRST (TypeAwareStorage caching)
         // isNew=true: skip pre-read for rollback (entity doesn't exist yet)
+        // hasVector: the vectored-noun ledger counts this insert iff its
+        // vector is real/non-empty (never true for a deferred embed, whose
+        // stub `vector` is `[]` — it counts later, at landing).
         tx.addOperation(
-          new SaveNounMetadataOperation(this.storage, id, storageMetadata, true)
+          new SaveNounMetadataOperation(this.storage, id, storageMetadata, true, vector.length > 0)
         )
 
         // Operation 2: Save vector data
@@ -10568,7 +10582,9 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       plan.postCommit.push(() => this.kickEmbedWorker())
     }
     plan.operations.push(
-      new SaveNounMetadataOperation(this.storage, id, storageMetadata, isNew),
+      // hasVector: see the single-add() insert path's comment — never true
+      // for a deferred embed (stub vector `[]`; counted later at landing).
+      new SaveNounMetadataOperation(this.storage, id, storageMetadata, isNew, vector.length > 0),
       new SaveNounOperation(this.storage, { id, vector, connections: new Map(), level: 0 }, isNew),
       ...(deferringEmbed
         ? []
@@ -16900,9 +16916,92 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       const shouldRebuildMetadata =
         !metadataMigrating &&
         (epochStale || legNeedsRebuild(this.metadataIndex, metadataStats.totalEntries === 0))
-      const shouldRebuildVector =
+
+      // VECTOR LEG — the two-engine gate's last red: a migrated 7.x-era store
+      // can hold canonical vectored nouns with NO derived vector index built.
+      // `legNeedsRebuild`'s size-heuristic fallback (below) only fires off
+      // `hnswIndexSize === 0`, and its health-report branch trusts a
+      // provider's own `serving` verdict verbatim — but a provider's health
+      // report can legitimately say `serving: true` while vector coverage is
+      // honestly UNLEDGERED on ITS side too (an unledgered invariant never
+      // flips serving), so neither signal alone can tell "genuinely empty"
+      // apart from "never built". The canonical vectored-noun ledger
+      // (`getCanonicalCounts().vectors.all` — Deliverable 1) is the
+      // denominator that CAN tell them apart, and is compared here:
+      //  - a CONFIDENT (non-suspect) ledger `> 0` while the reported node
+      //    count is 0 is a proven coverage gap — force the build regardless
+      //    of what a health report claims;
+      //  - a CONFIDENT ledger `=== 0` while the node count is 0 proves there
+      //    is nothing to load (e.g. every noun's embed is still deferred) —
+      //    skip the size-heuristic fallback's blunt "always rebuild when
+      //    empty" trigger, which otherwise wastes a full canonical walk for
+      //    zero benefit on every cold open of such a store;
+      //  - an unavailable/suspect ledger changes nothing — loud errors never
+      //    quiet losses, so a doubtful ledger must never suppress a rebuild
+      //    the old heuristic would have run.
+      // The bare `isReady()` boolean (no report, no `unledgered` concept) is
+      // NOT overridden — that signal is what fixed the 48-seconds-per-restart
+      // regression pinned in tests/unit/cold-open-rebuild-gate.test.ts (a
+      // disk-native provider legitimately reporting 0 resident while durable
+      // on disk), and re-deriving it from a denominator the provider itself
+      // has no way to consult would reopen exactly that regression.
+      const vectorAssessment = assessProviderHealth(this.index)
+      const vectorLedger = await this.storage.getCanonicalCounts?.()
+      const vectorLedgerAll = vectorLedger?.vectors.all
+      const vectorLedgerConfident = vectorLedger !== undefined && !vectorLedger.suspect
+      const vectorHasCoverageProof = vectorLedgerConfident && (vectorLedgerAll as number) > 0
+      const vectorConfirmedEmpty = vectorLedgerConfident && vectorLedgerAll === 0
+
+      let vectorNeedsRebuild: boolean
+      if (vectorAssessment.via === 'is-ready') {
+        // Bare isReady() stays authoritative and UNMODIFIED — see above.
+        vectorNeedsRebuild = vectorAssessment.readiness === 'not-ready'
+      } else if (vectorAssessment.via === 'health-report') {
+        vectorNeedsRebuild =
+          vectorAssessment.readiness !== 'ready' ||
+          (hnswIndexSize === 0 && vectorHasCoverageProof)
+      } else {
+        // size-heuristic / no provider (the built-in JS engine's own posture).
+        vectorNeedsRebuild = hnswIndexSize === 0 && !vectorConfirmedEmpty
+      }
+
+      const shouldRebuildVector = !vectorMigrating && (epochStale || vectorNeedsRebuild)
+
+      // Narration (and the FAIL-TYPED backstop below) are scoped EXACTLY to
+      // the defect this gate closes: a provider whose OWN health report
+      // claims `serving: true` — an affirmative "I am ready" a caller would
+      // otherwise trust outright — while the canonical ledger proves vector
+      // coverage is missing. This is deliberately NARROWER than "any branch
+      // where the ledger contributed to the decision":
+      //  - the bare isReady() branch is untouched, as above (never in scope);
+      //  - the health-report branch's OWN `readiness !== 'ready'` case is
+      //    already an ordinary, PRE-EXISTING rebuild trigger (the provider
+      //    admits not-ready) — not a ledger override, so not a "gap";
+      //  - the size-heuristic/no-provider branch's rebuild-when-empty is the
+      //    SAME blunt trigger the code always had (`hnswIndexSize === 0`)
+      //    — the ledger only ever SUPPRESSES a rebuild there (the confirmed-
+      //    empty case), it never forces one the old heuristic wouldn't
+      //    already have run. Marking that branch a "gap" too made the
+      //    FAIL-TYPED backstop fire on ordinary white-box tests that stub
+      //    rebuild() as a no-op and pin `size()` at 0 to drive OTHER
+      //    assertions (e.g. migration-deference's isMigrating() coverage) —
+      //    those are not silent-empty defects, so they must open exactly as
+      //    before (tests/unit/brainy/migration-deference.test.ts).
+      const vectorCoverageGap =
         !vectorMigrating &&
-        (epochStale || legNeedsRebuild(this.index, hnswIndexSize === 0))
+        vectorAssessment.via === 'health-report' &&
+        vectorAssessment.readiness === 'ready' &&
+        hnswIndexSize === 0 &&
+        vectorHasCoverageProof
+      if (vectorCoverageGap) {
+        prodLog.warn(
+          `[Brainy] open(): vector index reports ${hnswIndexSize} node(s) but the canonical ` +
+            `ledger holds ${vectorLedgerAll} vectored noun(s) — the derived vector index is ` +
+            `missing or unbuilt on this store. Forcing the vector rebuild rather than serving ` +
+            `silent-empty search results.`
+        )
+      }
+
       const shouldRebuildGraph =
         !graphMigrating &&
         (epochStale || legNeedsRebuild(this.graphIndex, false))
@@ -16955,9 +17054,27 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       // provider running its own background migration is skipped here (it owns
       // its index until it verifies-and-swaps).
       const rebuildStartTime = Date.now()
+      // The vector leg's build door, by contract with the native provider: a
+      // provider exposing fillFromCanonical() gets THAT call — idempotent, the
+      // provider's own init runs it first so this is the backstop — never a
+      // full rebuild() for a coverage gap. A PARTIAL shortfall deliberately
+      // triggers nothing here: that is repair()'s operator door. The JS index
+      // has no fill door and keeps its rebuild.
+      const vectorBuild = (): Promise<unknown> => {
+        const fillDoor = (this.index as unknown as { fillFromCanonical?: () => Promise<unknown> })
+          .fillFromCanonical
+        if (vectorCoverageGap && typeof fillDoor === 'function') {
+          prodLog.warn(
+            `[Brainy] open(): vector coverage gap routes through the provider's ` +
+              `fillFromCanonical() (idempotent canonical fill), not a full rebuild.`
+          )
+          return fillDoor.call(this.index)
+        }
+        return this.index.rebuild()
+      }
       await Promise.all([
         shouldRebuildMetadata ? this.metadataIndex.rebuild() : Promise.resolve(),
-        shouldRebuildVector ? this.index.rebuild() : Promise.resolve(),
+        shouldRebuildVector ? vectorBuild() : Promise.resolve(),
         shouldRebuildGraph ? this.graphIndex.rebuild() : Promise.resolve()
       ])
 
@@ -16998,6 +17115,24 @@ export class Brainy<T = any> implements BrainyInterface<T> {
         console.log(`[Brainy] Second rebuild result: ${secondAttempt} entries`)
       }
 
+      // Vector coverage verification: the coverage-gap rebuild above (see
+      // `vectorCoverageGap`) MUST have actually restored the ledger's
+      // vectored nouns. A provider that STILL reports 0 nodes after its own
+      // rebuild() ran — no JS (or provider) fallback could build from what's
+      // on disk — cannot silently complete open(): search would then serve
+      // empty results with no signal, exactly the defect this gate closes.
+      // FAIL TYPED, pre-serve, rather than let a broken vector leg pass as a
+      // successful open.
+      if (vectorCoverageGap && this.index.size() === 0) {
+        throw new VectorIndexNotReadyError(
+          `open(): the canonical ledger holds ${vectorLedgerAll} vectored noun(s) but the vector ` +
+            `index still reports 0 node(s) after rebuild() — the derived vector index could not ` +
+            `be restored from canonical. Refusing to serve silent-empty search results; ` +
+            `investigate the vector provider/storage, or repairIndex({ rebuild: ['vector'] }) ` +
+            `after restoring the underlying data.`
+        )
+      }
+
       // 8.0 ⇄ native-provider handshake (NON-DESTRUCTIVE): the derived indexes
       // have now rebuilt and verified, so they match this build's epoch —
       // re-stamp the marker LAST, only here. A crash anywhere above leaves the

src/coreTypes.ts

@@ -801,6 +801,17 @@ export interface DerivedFamilyDeclaration {
 export interface CanonicalCounts {
   nouns: { counted: number; all: number }
   verbs: { counted: number; all: number }
+  /**
+   * The count of canonical nouns holding a REAL (non-empty) vector — the
+   * coverage denominator a vector index's node-count ledger is measured
+   * against (`nodeCount === vectors.all` is the whole-store coverage
+   * verdict for the vector leg, the vector-side mirror of `nouns.all` for
+   * metadata/graph). A deferred-embed noun (`add({ deferEmbedding: true })`)
+   * counts only once its vector actually LANDS — its canonical record exists
+   * (counted in `nouns.all`) with an empty vector until then, so it is
+   * deliberately NOT counted here in the interim.
+   */
+  vectors: { all: number }
   /** An unprovable delete has left the `all` scalars unverified since the last recount. */
   suspect: boolean
 }
@@ -819,14 +830,47 @@ export interface StorageAdapter {
    * Save noun metadata separately
    * @param id Noun ID
    * @param metadata Noun metadata
+   * @param hasVector - OPTIONAL vectored-noun ledger hint: `true` when this
+   *   write is a FRESH insert (`isNew`) whose vector is a real, non-empty
+   *   array — the caller already knows this for free (the insert's own
+   *   `vector` local), so the increment rides the SAME isNew gate that
+   *   already protects `totalNounCountAll` from double-counting on HNSW
+   *   neighbor-link re-saves (`saveNoun_internal` re-runs on every link
+   *   change; this metadata seam does not). Absent/`false` ⇒ no ledger
+   *   action. A deferred-embed insert passes `false` (its vector lands
+   *   later — see {@link StorageAdapter.noteVectorLanded}).
    */
-  saveNounMetadata(id: string, metadata: NounMetadata): Promise<void>
+  saveNounMetadata(id: string, metadata: NounMetadata, hasVector?: boolean): Promise<void>
 
   /**
    * Delete noun metadata
    * @param id Noun ID
+   * @param priorRecord - OPTIONAL already-known metadata (the caller's
+   *   pre-delete read) — see {@link StorageAdapter.deleteNoun}.
+   * @param hadVector - OPTIONAL vectored-noun ledger hint: `true`/`false`
+   *   when the caller already knows (read as a side effect of ITS OWN delete
+   *   flow — e.g. `remove()`'s pre-read for the vector-index removal — never
+   *   a read added FOR this ledger), `undefined` when genuinely unknown. A
+   *   known `true` decrements the vectored-noun ledger; a known `false` is a
+   *   no-op (it was never counted); `undefined` marks the ledger SUSPECT
+   *   rather than guessing — the delete path must never add a canonical read
+   *   to answer this question.
    */
-  deleteNounMetadata(id: string): Promise<void>
+  deleteNounMetadata(id: string, priorRecord?: NounMetadata | null, hadVector?: boolean): Promise<void>
+
+  /**
+   * OPTIONAL narrow ledger hook: record that a canonical noun's vector just
+   * LANDED for the first time. Exists ONLY for the deferred-embedding
+   * lifecycle — the landing commit (`system:embed-landing`) carries a vector
+   * write with no accompanying metadata operation, so the normal
+   * `saveNounMetadata(..., hasVector)` seam never fires for it. Callers MUST
+   * call this only when the noun held NO real vector before this write (the
+   * deferred-embed worker already holds that fact for free, from its own
+   * pre-embed read — never an added read). A backend without vectored-noun
+   * tracking is a no-op via this method's absence (feature-detected).
+   * @param id - The noun whose vector just landed.
+   */
+  noteVectorLanded?(id: string): Promise<void>
 
   /**
    * Get noun with metadata combined
@@ -875,8 +919,11 @@ export interface StorageAdapter {
    *   REQUIRE re-reading the record being removed: when the internal read
    *   returns `null` (replace race, or a ghost left by an earlier version) the
    *   decrement falls back to this record instead of being silently skipped.
+   * @param hadVector OPTIONAL vectored-noun ledger hint — see
+   *   {@link StorageAdapter.deleteNounMetadata}'s `hadVector` param, which
+   *   this forwards to unchanged.
    */
-  deleteNoun(id: string, priorMetadata?: NounMetadata | null): Promise<void>
+  deleteNoun(id: string, priorMetadata?: NounMetadata | null, hadVector?: boolean): Promise<void>
 
   /**
    * Save verb - Pure HNSW verb with core fields only

src/storage/adapters/baseStorageAdapter.ts

@@ -1041,12 +1041,27 @@ export abstract class BaseStorageAdapter implements StorageAdapter {
    */
   protected totalNounCountAll = 0
   protected totalVerbCountAll = 0
+  /**
+   * The count of canonical nouns holding a REAL (non-empty) vector — the
+   * vector-side mirror of `totalNounCountAll` and the coverage denominator a
+   * vector index's node-count ledger is measured against. A deferred-embed
+   * noun (`add({ deferEmbedding: true })`) counts only once its vector
+   * LANDS (the `system:embed-landing` commit) — its canonical record exists
+   * (already counted in `totalNounCountAll`) with an empty vector until
+   * then. Maintained on the write path (a fresh insert whose vector is
+   * non-empty +1, a deferred embed's landing +1, a PROVEN delete of a
+   * vectored noun −1), persisted beside the other ALL scalars, recomputed by
+   * the sanctioned recount. Shares `allCountsSuspect` — no separate flag.
+   */
+  protected totalVectoredNounCount = 0
   /**
    * `true` when a delete could not prove whether the record existed (no
    * canonical read, no caller-provided prior) — the ALL scalar may be off by
    * the unprovable deletes since. Loud, persisted, and cleared only by the
    * sanctioned recount; a consumer reading the scalar as a ledger denominator
-   * must treat a suspect scalar as unverified, never as exact.
+   * must treat a suspect scalar as unverified, never as exact. Also covers
+   * `totalVectoredNounCount` — a delete whose vector-presence fact was
+   * unknowable marks this SAME flag rather than minting a second one.
    */
   protected allCountsSuspect = false
   /** One narration per session for the suspect transition (never per delete). */
@@ -1083,15 +1098,19 @@ export abstract class BaseStorageAdapter implements StorageAdapter {
    * The canonical count ledger — O(1), no I/O. `counted` is the user-facing
    * scalar (public/internal tiers, what `getNounCount()` returns); `all` is
    * the ALL-visibility scalar every unfiltered storage walk is measured
-   * against (the coverage-ledger denominator for derived-index providers).
+   * against (the coverage-ledger denominator for derived-index providers);
-   * `suspect` is `true` when an unprovable delete has made `all` unverified
+   * `vectors.all` is the vectored-noun scalar — the coverage denominator for
-   * since the last sanctioned recount (`rebuildTypeCounts`).
+   * a vector index's node-count ledger specifically.
-   * @returns Both scalars per family plus the suspect flag.
+   * `suspect` is `true` when an unprovable delete has made `all` (any
+   * family, including `vectors`) unverified since the last sanctioned
+   * recount (`rebuildTypeCounts`).
+   * @returns All scalars per family plus the suspect flag.
    */
   async getCanonicalCounts(): Promise<CanonicalCounts> {
     return {
       nouns: { counted: this.totalNounCount, all: this.totalNounCountAll },
       verbs: { counted: this.totalVerbCount, all: this.totalVerbCountAll },
+      vectors: { all: this.totalVectoredNounCount },
       suspect: this.allCountsSuspect
     }
   }
@@ -1103,7 +1122,7 @@ export abstract class BaseStorageAdapter implements StorageAdapter {
    * @param family - Which family's delete was unprovable.
    * @param id - The id whose existence could not be established.
    */
-  protected markAllCountsSuspect(family: 'noun' | 'verb', id: string): void {
+  protected markAllCountsSuspect(family: 'noun' | 'verb' | 'noun-vector', id: string): void {
     this.allCountsSuspect = true
     if (!this.allCountsSuspectNarrated) {
       this.allCountsSuspectNarrated = true
@@ -1116,6 +1135,23 @@ export abstract class BaseStorageAdapter implements StorageAdapter {
     }
   }
 
+  /**
+   * OPTIONAL narrow ledger hook (see {@link StorageAdapter.noteVectorLanded}):
+   * record a deferred-embed noun's FIRST real vector landing. The caller
+   * (the deferred-embed worker) proves this is a genuine landing — not a
+   * re-embed of an already-vectored row — by observing its own pre-embed
+   * read's vector was empty, at no added storage cost.
+   * @param id - The noun whose vector just landed (retained for a future
+   *   narration seam; the count itself needs no id-keyed state).
+   */
+  async noteVectorLanded(id: string): Promise<void> {
+    void id
+    this.totalVectoredNounCount++
+    this.scheduleCountPersist().catch(() => {
+      // Ignore persist errors — the in-memory count is authoritative; a later op retries.
+    })
+  }
+
   /**
    * Increment count for entity type - O(1) operation.
    * Concurrency is handled by the process-global mutex

src/storage/adapters/fileSystemStorage.ts

@@ -2583,6 +2583,7 @@ export class FileSystemStorage extends BaseStorage {
         // record reads), persist, and never scan again. Absent keys are a
         // legacy file, not a zero — a zero here would make every provider's
         // coverage ledger read "over-posted" on a populated store.
+        let needsPersist = false
         if (
           typeof counts.totalNounCountAll === 'number' &&
           typeof counts.totalVerbCountAll === 'number'
@@ -2601,6 +2602,29 @@ export class FileSystemStorage extends BaseStorage {
               `derived once from the canonical id tree (${nouns.count} nouns, ${verbs.count} verbs, ` +
               `every tier) and persisted; no further scan.`
           )
+          needsPersist = true
+        }
+
+        // The vectored-noun scalar (shipped after the ALL scalars above — a
+        // counts.json can carry `totalNounCountAll`/`totalVerbCountAll` but
+        // still predate THIS key). Unlike the ALL scalars, presence cannot be
+        // decided from the id-directory listing alone: a deferred-embed
+        // noun's `vectors.json` EXISTS with an empty `vector: []` until its
+        // embed lands, so this derivation reads every noun's `vectors.json`
+        // ONCE (O(nouns) reads, not O(ids) listing) — honest, one-time cost.
+        if (typeof counts.totalVectoredNounCount === 'number') {
+          this.totalVectoredNounCount = counts.totalVectoredNounCount
+        } else {
+          const vectored = await this.scanVectoredNounCount()
+          this.totalVectoredNounCount = vectored
+          console.warn(
+            `[FileSystemStorage] counts.json predates the vectored-noun count ledger — ` +
+              `derived once by reading every noun's vectors.json (${vectored} vectored) and ` +
+              `persisted; no further scan.`
+          )
+          needsPersist = true
+        }
+        if (needsPersist) {
           await this.persistCounts()
         }
 
@@ -2643,6 +2667,12 @@ export class FileSystemStorage extends BaseStorage {
       this.totalNounCountAll = nouns.count
       this.totalVerbCountAll = verbs.count
       this.allCountsSuspect = false
+      // Vectored-noun scalar: presence needs each noun's vectors.json CONTENT
+      // (a deferred-embed noun's file exists but holds an empty vector until
+      // its embed lands), so this is a full O(nouns) content scan — see
+      // scanVectoredNounCount()'s JSDoc for the cost note. Paid once, here,
+      // alongside the rest of this from-disk recovery.
+      this.totalVectoredNounCount = await this.scanVectoredNounCount()
 
       // Sample some entities for the type distribution (don't read all).
       // Read the metadata files DIRECTLY with fs — this runs inside init(),
@@ -2728,6 +2758,61 @@ export class FileSystemStorage extends BaseStorage {
     }
   }
 
+  /**
+   * Read one canonical noun's `vectors.json` (or `.json.gz`) directly with fs
+   * — the vector-side mirror of {@link readEntityMetadataRaw}, same
+   * reentrancy reason (bypasses `getNoun()`'s `ensureInitialized()`).
+   * @param entityDir - Absolute `entities/nouns/<shard>/<id>` directory.
+   * @returns The parsed vector record, or null when absent/unreadable.
+   */
+  private async readEntityVectorRaw(entityDir: string): Promise<any | null> {
+    const base = path.join(entityDir, 'vectors.json')
+    try {
+      return JSON.parse(await fs.promises.readFile(base, 'utf-8'))
+    } catch {
+      // fall through to the compressed variant
+    }
+    try {
+      const gz = await fs.promises.readFile(`${base}.gz`)
+      return JSON.parse(zlib.gunzipSync(gz).toString('utf-8'))
+    } catch {
+      return null
+    }
+  }
+
+  /**
+   * Count canonical nouns holding a REAL (non-empty) vector — the vectored-
+   * noun ledger scalar. UNLIKE {@link scanCanonicalEntities}, presence
+   * cannot be decided from the id-directory listing alone: a deferred-embed
+   * noun's `vectors.json` EXISTS (written at `add()` time with `vector: []`)
+   * until its embed LANDS, so this walk reads every noun's `vectors.json`
+   * CONTENT — O(nouns) reads, not O(ids) listing. Used ONLY for a one-time
+   * legacy-counts.json derivation or a lost/corrupted counts.json recovery;
+   * the result is persisted so this scan never repeats.
+   */
+  private async scanVectoredNounCount(): Promise<number> {
+    const base = path.join(this.rootDir, 'entities', 'nouns')
+    let vectored = 0
+    try {
+      const shards = await fs.promises.readdir(base, { withFileTypes: true })
+      for (const shard of shards) {
+        if (!shard.isDirectory() || !/^[0-9a-f]{2}$/i.test(shard.name)) continue
+        const shardPath = path.join(base, shard.name)
+        const ids = await fs.promises.readdir(shardPath, { withFileTypes: true })
+        for (const entry of ids) {
+          if (!entry.isDirectory()) continue
+          const record = await this.readEntityVectorRaw(path.join(shardPath, entry.name))
+          if (record && Array.isArray(record.vector) && record.vector.length > 0) {
+            vectored++
+          }
+        }
+      }
+    } catch (error: any) {
+      if (error?.code !== 'ENOENT') throw error
+    }
+    return vectored
+  }
+
   /**
    * Persist counts to filesystem storage
    */
@@ -2744,6 +2829,10 @@ export class FileSystemStorage extends BaseStorage {
         // written before the ledger existed; initializeCounts() derives them once.
         totalNounCountAll: this.totalNounCountAll,
         totalVerbCountAll: this.totalVerbCountAll,
+        // Vectored-noun ledger scalar — absent in files written before it
+        // existed; initializeCounts() derives it once (a content scan, see
+        // scanVectoredNounCount()'s JSDoc).
+        totalVectoredNounCount: this.totalVectoredNounCount,
         allCountsSuspect: this.allCountsSuspect,
         lastUpdated: new Date().toISOString()
       }

src/storage/adapters/memoryStorage.ts

@@ -520,6 +520,12 @@ export class MemoryStorage extends BaseStorage {
 
     let totalNouns = 0
     let totalVerbs = 0
+    // Vectored-noun scalar: unlike the bare presence check above, this needs
+    // the vectors.json RECORD'S content — a deferred-embed noun's record
+    // exists with an empty `vector: []` until its embed lands. In-memory this
+    // is a free field access (no I/O), unlike the filesystem adapter's
+    // per-noun disk read.
+    let totalVectoredNouns = 0
 
     // Scan all paths in objectStore
     for (const path of this.objectStore.keys()) {
@@ -528,6 +534,10 @@ export class MemoryStorage extends BaseStorage {
       if (nounMatch) {
         // Type is in metadata, not path - just count total
         totalNouns++
+        const record = this.objectStore.get(path) as { vector?: unknown } | undefined
+        if (Array.isArray(record?.vector) && record.vector.length > 0) {
+          totalVectoredNouns++
+        }
       }
 
       // Count verbs (entities/verbs/{shard}/{id}/vectors.json)
@@ -543,6 +553,7 @@ export class MemoryStorage extends BaseStorage {
     // A scan of every canonical record IS the ALL-visibility count.
     this.totalNounCountAll = totalNouns
     this.totalVerbCountAll = totalVerbs
+    this.totalVectoredNounCount = totalVectoredNouns
     this.allCountsSuspect = false
   }
 

src/storage/baseStorage.ts

@@ -1762,8 +1762,10 @@ export abstract class BaseStorage extends BaseStorageAdapter {
 
   /**
    * Delete a noun from storage
+   * @param hadVector - OPTIONAL vectored-noun ledger hint, forwarded to
+   *   {@link deleteNounMetadata} unchanged — see its JSDoc.
    */
-  public async deleteNoun(id: string, priorMetadata?: NounMetadata | null): Promise<void> {
+  public async deleteNoun(id: string, priorMetadata?: NounMetadata | null, hadVector?: boolean): Promise<void> {
     await this.ensureInitialized()
 
     // FULL removal (live-HEAD hygiene): remove BOTH canonical legs AND the
@@ -1780,7 +1782,7 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     // LONGER wrapped in a blind catch that masked faults as "file didn't exist".
     // `priorMetadata` (the caller's pre-delete read) keeps the decrement honest
     // even when the canonical read inside returns null (replace race / ghost).
-    await this.deleteNounMetadata(id, priorMetadata)
+    await this.deleteNounMetadata(id, priorMetadata, hadVector)
 
     // Remove the now-empty entity container (a no-op for key/prefix stores).
     await this.removeCanonicalContainer(getNounVectorPath(id))
@@ -3392,11 +3394,12 @@ export abstract class BaseStorage extends BaseStorageAdapter {
   /**
    * Save noun metadata to storage (now typed)
    * Routes to correct sharded location based on UUID
+   * @param hasVector - See {@link StorageAdapter.saveNounMetadata}'s JSDoc.
    */
-  public async saveNounMetadata(id: string, metadata: NounMetadata): Promise<void> {
+  public async saveNounMetadata(id: string, metadata: NounMetadata, hasVector?: boolean): Promise<void> {
     // Validate noun type in metadata - storage boundary protection
     validateNounType(metadata.noun)
-    return this.saveNounMetadata_internal(id, metadata)
+    return this.saveNounMetadata_internal(id, metadata, hasVector)
   }
 
   /**
@@ -3407,9 +3410,10 @@ export abstract class BaseStorage extends BaseStorageAdapter {
    * This ensures counts are updated AFTER metadata exists, fixing the race condition
    * where storage adapters tried to read metadata before it was saved.
    *
+   * @param hasVector - See {@link StorageAdapter.saveNounMetadata}'s JSDoc.
    * @protected
    */
-  protected async saveNounMetadata_internal(id: string, metadata: NounMetadata): Promise<void> {
+  protected async saveNounMetadata_internal(id: string, metadata: NounMetadata, hasVector?: boolean): Promise<void> {
     await this.ensureInitialized()
 
     // ID-first path - no type needed!
@@ -3465,6 +3469,14 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     // record persists here so the ALL scalar never lags the tree.
     if (isNew) {
       this.totalNounCountAll++
+      // Vectored-noun ledger: rides the SAME isNew gate (once per id, at
+      // creation) — this seam is metadata-write-driven and never re-runs on
+      // the HNSW neighbor-link re-saves that hit saveNoun_internal, so it
+      // cannot double-count. A deferred-embed insert passes hasVector=false
+      // (or omits it); its vector lands later via noteVectorLanded().
+      if (hasVector) {
+        this.totalVectoredNounCount++
+      }
       if (!(metadata.noun && isCounted)) {
         this.scheduleCountPersist().catch(() => {
           // Ignore persist errors — the in-memory count is authoritative; a later op retries.
@@ -3860,8 +3872,18 @@ export abstract class BaseStorage extends BaseStorageAdapter {
    *   the skip permanently inflated the persisted totals (adds counted, paired
    *   removals not decremented), and `Math.max(totalNounCount, scanned)` made
    *   the inflation unfixable by any disk cleanup.
+   * @param hadVector - OPTIONAL vectored-noun ledger hint — see
+   *   {@link StorageAdapter.deleteNounMetadata}'s JSDoc. This method never
+   *   reads `vectors.json` to answer the question itself (a canonical read
+   *   the delete path must never add); a caller that cannot supply the fact
+   *   for free leaves it `undefined`, and the ledger goes SUSPECT rather
+   *   than guessing.
    */
-  public async deleteNounMetadata(id: string, priorRecord?: NounMetadata | null): Promise<void> {
+  public async deleteNounMetadata(
+    id: string,
+    priorRecord?: NounMetadata | null,
+    hadVector?: boolean
+  ): Promise<void> {
     await this.ensureInitialized()
 
     // Direct O(1) delete with ID-first path. Read the canonical record BEFORE
@@ -3885,6 +3907,15 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     } else {
       this.markAllCountsSuspect('noun', id)
     }
+
+    // Vectored-noun ledger: a KNOWN vector fact decrements (or no-ops);
+    // an UNKNOWN one goes suspect rather than guessing — see @param hadVector.
+    if (hadVector === true) {
+      if (this.totalVectoredNounCount > 0) this.totalVectoredNounCount--
+      else this.markAllCountsSuspect('noun-vector', id)
+    } else if (hadVector === undefined) {
+      this.markAllCountsSuspect('noun-vector', id)
+    }
     this.scheduleCountPersist().catch(() => {
       // Ignore persist errors — the in-memory count is authoritative; a later op retries.
     })
@@ -4549,6 +4580,16 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     // construction.
     let allNouns = 0
     let allVerbs = 0
+    // Vectored-noun scalar: unlike `allNouns` (decided from the metadata.json
+    // LISTING alone), presence cannot be decided from the vectors.json
+    // listing alone — a deferred-embed noun's vectors.json EXISTS with an
+    // empty `vector: []` until its embed lands, so the file's CONTENT must be
+    // read. This walk already lists every path per shard (including
+    // vectors.json entries — `listCanonicalObjects` yields both legs), so
+    // reading them here costs one EXTRA read per noun beyond the metadata.json
+    // read above (doubling this walk's per-noun I/O) — honest cost, paid only
+    // by this diagnostic/repair recount, never on the hot path.
+    let allVectoredNouns = 0
 
     // Scan noun shards
     for (let shard = 0; shard < 256; shard++) {
@@ -4559,6 +4600,18 @@ export abstract class BaseStorage extends BaseStorageAdapter {
         const paths = await this.listCanonicalObjects(shardDir)
 
         for (const path of paths) {
+          if (path.includes('/vectors.json')) {
+            try {
+              const vectorRecord = await this.readCanonicalObject(path)
+              if (vectorRecord && Array.isArray(vectorRecord.vector) && vectorRecord.vector.length > 0) {
+                allVectoredNouns++
+              }
+            } catch (error) {
+              // Skip vector records that fail to load — best-effort ground truth,
+              // same as the metadata read below.
+            }
+            continue
+          }
           if (!path.includes('/metadata.json')) continue
           allNouns++
 
@@ -4634,17 +4687,19 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     // IS the proof an unprovable delete could not give.
     const nounsAllBefore = this.totalNounCountAll
     const verbsAllBefore = this.totalVerbCountAll
+    const vectoredBefore = this.totalVectoredNounCount
     this.totalNounCountAll = allNouns
     this.totalVerbCountAll = allVerbs
+    this.totalVectoredNounCount = allVectoredNouns
     this.allCountsSuspect = false
     this.countCache.clear()
     await this.persistCounts()
 
     prodLog.info(
       `[BaseStorage] Rebuilt counts: ${totalNouns} nouns, ${totalVerbs} verbs (user-facing); ` +
-        `ALL-visibility ledger ${allNouns} nouns / ${allVerbs} verbs` +
+        `ALL-visibility ledger ${allNouns} nouns / ${allVerbs} verbs / ${allVectoredNouns} vectored nouns` +
-        (nounsAllBefore !== allNouns || verbsAllBefore !== allVerbs
+        (nounsAllBefore !== allNouns || verbsAllBefore !== allVerbs || vectoredBefore !== allVectoredNouns
-          ? ` (corrected from ${nounsAllBefore} / ${verbsAllBefore})`
+          ? ` (corrected from ${nounsAllBefore} / ${verbsAllBefore} / ${vectoredBefore})`
           : ' (unchanged)') +
         ` — scalar + per-type persisted`
     )

src/transaction/operations/StorageOperations.ts

@@ -52,7 +52,15 @@ export class SaveNounMetadataOperation implements Operation {
     private readonly storage: StorageAdapter,
     private readonly id: string,
     private readonly metadata: NounMetadata,
-    private readonly isNew: boolean = false
+    private readonly isNew: boolean = false,
+    /**
+     * OPTIONAL vectored-noun ledger hint: `true` when this write's paired
+     * vector (the SAME insert's `vector` local) is real/non-empty — see
+     * {@link StorageAdapter.saveNounMetadata}'s JSDoc for the isNew-gated,
+     * double-count-proof seam this rides. Default `false`: a deferred-embed
+     * insert (or any caller that doesn't know) never counts here.
+     */
+    private readonly hasVector: boolean = false
   ) {}
 
   async execute(): Promise<RollbackAction> {
@@ -62,7 +70,7 @@ export class SaveNounMetadataOperation implements Operation {
       : await tornHealsToNull(this.storage.getNounMetadata(this.id), 'noun metadata')
 
     // Save new metadata
-    await this.storage.saveNounMetadata(this.id, this.metadata)
+    await this.storage.saveNounMetadata(this.id, this.metadata, this.hasVector)
 
     // Return rollback action
     return async () => {
@@ -70,8 +78,10 @@ export class SaveNounMetadataOperation implements Operation {
         // Restore previous metadata
         await this.storage.saveNounMetadata(this.id, previousMetadata)
       } else {
-        // Delete newly created metadata
+        // Delete newly created metadata. `this.hasVector` is the SAME fact
-        await this.storage.deleteNounMetadata(this.id)
+        // this operation's own execute() used to (maybe) count the vectored
+        // ledger — reversing with it on rollback needs no new read.
+        await this.storage.deleteNounMetadata(this.id, undefined, this.hasVector)
       }
     }
   }
@@ -140,7 +150,9 @@ export class SaveNounOperation implements Operation {
         // Note: Not all adapters implement deleteNoun
         // This is acceptable - metadata deletion makes entity invisible
         if ('deleteNoun' in this.storage && typeof this.storage.deleteNoun === 'function') {
-          await this.storage.deleteNoun(this.noun.id)
+          // `this.noun.vector` is the SAME record just written — the
+          // vectored-noun ledger fact is free (no added read) and exact.
+          await this.storage.deleteNoun(this.noun.id, undefined, this.noun.vector.length > 0)
         }
       }
     }
@@ -198,14 +210,21 @@ export class DeleteNounMetadataOperation implements Operation {
       return async () => {}
     }
 
+    // Vectored-noun ledger fact: `previousNoun` is already read above for the
+    // before-image capture — no added read. `undefined` (noun genuinely
+    // absent, metadata-only ghost) is passed through honestly; the storage
+    // layer marks the ledger suspect rather than guessing.
+    const hadVector = previousNoun ? previousNoun.vector.length > 0 : undefined
+
     // Full removal: both canonical legs + the entity container + count decrement
     // (the prior record keeps the decrement honest on a null canonical read).
-    await this.storage.deleteNoun(this.id, previousMetadata)
+    await this.storage.deleteNoun(this.id, previousMetadata, hadVector)
 
     // Return rollback action
     return async () => {
       // Restore the vector leg, then the metadata leg through the count-aware
-      // save so deleteNoun()'s decrement is reversed.
+      // save so deleteNoun()'s decrement is reversed (hadVector's mirror:
+      // re-increments the vectored ledger iff the restored vector is real).
       if (previousNoun) {
         await this.storage.saveNoun({
           id: previousNoun.id,
@@ -215,7 +234,7 @@ export class DeleteNounMetadataOperation implements Operation {
         })
       }
       if (previousMetadata) {
-        await this.storage.saveNounMetadata(this.id, previousMetadata)
+        await this.storage.saveNounMetadata(this.id, previousMetadata, hadVector === true)
       }
     }
   }

tests/integration/canonical-count-ledger.test.ts

@@ -17,10 +17,11 @@
  * (4) LEGACY FILES DERIVE ONCE — a counts.json written before the ledger is
  *     upgraded from the canonical id tree at open, then persisted.
  */
-import { describe, it, expect, beforeEach, afterEach } from 'vitest'
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
 import * as fs from 'node:fs'
 import * as os from 'node:os'
 import * as path from 'node:path'
+import * as zlib from 'node:zlib'
 import { Brainy } from '../../src/index.js'
 
 /** Count canonical `<root>/entities/<kind>/<shard>/<id>` directories — every tier. */
@@ -180,3 +181,176 @@ describe('canonical count ledger — ALL-visibility scalars, unclamped totals, r
     expect(ledger.nouns.all).toBe(truth)
   })
 })
+
+/** Count `<root>/entities/nouns/<shard>/<id>/vectors.json[.gz]` files holding a non-empty `vector`. */
+function countVectoredNouns(root: string): number {
+  const base = path.join(root, 'entities', 'nouns')
+  if (!fs.existsSync(base)) return 0
+  let n = 0
+  for (const shard of fs.readdirSync(base)) {
+    const shardDir = path.join(base, shard)
+    if (!fs.statSync(shardDir).isDirectory()) continue
+    for (const id of fs.readdirSync(shardDir)) {
+      const idDir = path.join(shardDir, id)
+      if (!fs.statSync(idDir).isDirectory()) continue
+      const plainPath = path.join(idDir, 'vectors.json')
+      const gzPath = `${plainPath}.gz`
+      let record: any = null
+      if (fs.existsSync(plainPath)) {
+        record = JSON.parse(fs.readFileSync(plainPath, 'utf-8'))
+      } else if (fs.existsSync(gzPath)) {
+        record = JSON.parse(zlib.gunzipSync(fs.readFileSync(gzPath)).toString('utf-8'))
+      } else {
+        continue
+      }
+      if (Array.isArray(record.vector) && record.vector.length > 0) n++
+    }
+  }
+  return n
+}
+
+describe('canonical count ledger — the vectored-noun scalar (the vector leg\'s coverage denominator)', () => {
+  let dir: string
+  let brain: any
+
+  const open = async () => {
+    const b: any = new Brainy({
+      requireSubtype: false,
+      storage: { type: 'filesystem', path: dir },
+      silent: true,
+      dimensions: 384
+    })
+    await b.init()
+    return b
+  }
+
+  /** Baseline vectored count right after a fresh open() — init() creates a
+   *  hidden system VFS-root noun that itself carries a real vector, so a
+   *  brand-new store's `vectors.all` is 1, not 0. Tests assert DELTAS off
+   *  this baseline rather than hardcoding it away. */
+  let baseline: number
+
+  beforeEach(async () => {
+    process.env.BRAINY_DETERMINISTIC_EMBEDDINGS = 'true'
+    dir = fs.mkdtempSync(path.join(os.tmpdir(), 'brainy-vectored-ledger-'))
+    brain = await open()
+    baseline = (await brain.storage.getCanonicalCounts()).vectors.all
+  })
+  afterEach(async () => {
+    vi.restoreAllMocks()
+    await brain.close?.().catch(() => {})
+    fs.rmSync(dir, { recursive: true, force: true })
+  })
+
+  it('an explicit-vector add counts immediately; the ledger matches the on-disk vectors.json content', async () => {
+    await brain.add({ data: 'a', type: 'document', vector: Array(384).fill(0).map((_, i) => Math.sin(i)) })
+    await brain.add({ data: 'b', type: 'document' }) // embedded (non-deferred) — also a real vector
+    await brain.flush()
+
+    const ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline + 2)
+    expect(ledger.vectors.all).toBe(countVectoredNouns(dir))
+    expect(ledger.suspect).toBe(false)
+  })
+
+  it('a deferred-embed add does NOT count until its embed LANDS', async () => {
+    // Hold the background worker's embed call open under manual control — a
+    // deterministic embedder is fast enough that the landing could otherwise
+    // race ahead of the "still unlanded" assertion below.
+    let resolveEmbed: ((v: number[]) => void) | undefined
+    vi.spyOn(brain, 'embed').mockImplementation(
+      () => new Promise<number[]>((resolve) => { resolveEmbed = resolve })
+    )
+
+    const id = await brain.add({ data: 'deferred content', type: 'document', deferEmbedding: true })
+    await brain.flush()
+
+    // Landed nothing yet — the ledger must not count the stub.
+    let ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline)
+    expect(ledger.vectors.all).toBe(countVectoredNouns(dir))
+
+    // Release the held embed, then cross the barrier: the vector lands
+    // (system:embed-landing).
+    resolveEmbed!(Array(384).fill(0).map((_, i) => Math.cos(i)))
+    await brain.awaitPendingEmbeds()
+    const landed = await brain.get(id, { includeVectors: true })
+    expect((landed!.vector as number[]).length).toBeGreaterThan(0)
+
+    ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline + 1)
+    expect(ledger.vectors.all).toBe(countVectoredNouns(dir))
+    expect(ledger.suspect).toBe(false)
+  })
+
+  it('a proven delete of a vectored noun decrements; a non-vectored (unlanded) delete does not', async () => {
+    const vectoredId = await brain.add({ data: 'v', type: 'document' }) // real embed, unmocked
+    // Block the embed worker AFTER the real add above — a deterministic
+    // embedder is fast enough that the deferred noun below could otherwise
+    // land before this test observes its "still unlanded" state.
+    vi.spyOn(brain, 'embed').mockImplementation(() => new Promise(() => {}))
+    const deferredId = await brain.add({ data: 'd', type: 'document', deferEmbedding: true })
+    await brain.flush()
+    expect((await brain.storage.getCanonicalCounts()).vectors.all).toBe(baseline + 1)
+
+    await brain.remove(vectoredId)
+    await brain.flush()
+    let ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline)
+    expect(ledger.suspect).toBe(false)
+
+    await brain.remove(deferredId) // never had a real vector — no decrement, still unsuspect
+    await brain.flush()
+    ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline)
+    expect(ledger.suspect).toBe(false)
+    expect(ledger.vectors.all).toBe(countVectoredNouns(dir))
+  })
+
+  it('the recount corrects a tampered vectors.all scalar, surviving reopen', async () => {
+    await brain.add({ data: 'real 1', type: 'document' })
+    await brain.add({ data: 'real 2', type: 'document' })
+    await brain.flush()
+    const truth = countVectoredNouns(dir)
+    expect(truth).toBe(baseline + 2)
+
+    ;(brain.storage as any).totalVectoredNounCount = truth + 40
+    await (brain.storage as any).persistCounts()
+    await brain.close()
+    brain = await open()
+
+    // The lie survives reopen (never clamped).
+    expect((await brain.storage.getCanonicalCounts()).vectors.all).toBe(truth + 40)
+
+    await brain.repairIndex()
+    expect((await brain.storage.getCanonicalCounts()).vectors.all).toBe(truth)
+
+    await brain.close()
+    brain = await open()
+    expect((await brain.storage.getCanonicalCounts()).vectors.all).toBe(truth)
+  })
+
+  it('a legacy counts.json without totalVectoredNounCount is derived once from vectors.json content and persisted', async () => {
+    await brain.add({ data: 'one', type: 'document' }) // real embed, unmocked
+    // Block the embed worker AFTER the real add above — a deterministic
+    // embedder is fast enough that the deferred noun below could otherwise
+    // land before close(), which would inflate this test's expected count.
+    vi.spyOn(brain, 'embed').mockImplementation(() => new Promise(() => {}))
+    await brain.add({ data: 'two deferred', type: 'document', deferEmbedding: true })
+    await brain.flush()
+    await brain.close()
+
+    const countsPath = path.join(dir, '_system', 'counts.json')
+    const raw = JSON.parse(fs.readFileSync(countsPath, 'utf-8'))
+    expect(typeof raw.totalVectoredNounCount).toBe('number')
+    delete raw.totalVectoredNounCount
+    fs.writeFileSync(countsPath, JSON.stringify(raw, null, 2))
+
+    brain = await open()
+    const ledger = await brain.storage.getCanonicalCounts()
+    expect(ledger.vectors.all).toBe(baseline + 1) // the root + the one non-deferred noun
+    expect(ledger.vectors.all).toBe(countVectoredNouns(dir))
+    const persisted = JSON.parse(fs.readFileSync(countsPath, 'utf-8'))
+    expect(persisted.totalVectoredNounCount).toBe(baseline + 1)
+  })
+})

tests/integration/vector-leg-open-build.test.ts

@@ -0,0 +1,247 @@
+/**
+ * @module tests/integration/vector-leg-open-build
+ * @description THE LAST RED of the two-engine release gate: a migrated
+ * store can hold canonical vectored nouns with NO derived vector index
+ * built. `open()` owns building the derived indexes (reads never build —
+ * see `rebuildIndexesIfNeeded`'s JSDoc); the defect this pins is the vector
+ * leg's decision silently skipping that build, so `find`/search served `[]`
+ * with no error and no narration.
+ *
+ * A downstream deployment measures this through a native vector provider
+ * whose own health report can legitimately say `serving: true` even while
+ * vector COVERAGE is honestly unledgered on its side (an unledgered
+ * invariant never flips `serving` — see `HealthReport`'s derivation laws).
+ * This repo ships only the JS engine, so the reproduction here uses the
+ * SAME plugin seam a native provider would (`brain.use({ activate: ctx =>
+ * ctx.registerProvider('vector', factory) })`, the pattern
+ * `tests/unit/cold-open-rebuild-gate.test.ts` already established for this
+ * exact class of gate-decision bug) with a stub that WRAPS the real
+ * `JsHnswVectorIndex` — every method delegates to a genuine engine (so a
+ * successful rebuild restores REAL, searchable vectors), except `size()`
+ * (fakes 0 until rebuild runs — the "never built" posture) and
+ * `healthReport()` (always reports `serving: true`, `unledgered:
+ * ['vector-coverage']` — the "I don't track this yet" posture). This is
+ * "as close as the JS engine allows": the gap is reproduced at the exact
+ * decision the fix changes, not approximated by deleting files the JS
+ * engine's own cold-start heuristic already recovers from unaided (see the
+ * inverse pin below and cold-open-rebuild-gate.test.ts's already-pinned
+ * "isReady()===true, size()===0" contract, which this fix deliberately does
+ * NOT touch — bare isReady() has no unledgered concept to hide behind, and
+ * overriding it would reopen the 48-seconds-per-restart regression pinned
+ * there).
+ *
+ * Pins:
+ * (1) COVERAGE GAP FORCES THE BUILD: N vectored nouns, a provider that
+ *     claims `serving: true` at `size()===0` — open() builds anyway (the
+ *     ledger proves there is something to cover), and search returns real
+ *     results, never `[]`.
+ * (2) THE INVERSE, HONEST EMPTY: 0 vectored nouns (every embed still
+ *     deferred/unlanded) — open() does NOT attempt a rebuild (nothing to
+ *     load; the old blunt "always rebuild when size()===0" heuristic wasted
+ *     a full canonical walk here for zero benefit), and search honestly
+ *     returns `[]` — no error, no false coverage-gap narration.
+ *
+ * SEARCH VERIFICATION NOTE: pin (1) verifies "search returns real results"
+ * via `find({ query: <text> })` (semantic search — embeds the query, then
+ * searches), matching the pattern `tests/integration/hnsw-rebuild.test.ts`
+ * already uses for exactly this "post-rebuild search works" class of pin.
+ * A raw `find({ vector: <array> })` / `index.search(vector, k)` call was
+ * tried first and found to reproducibly return only 1 hit after a
+ * FROM-CANONICAL rebuild (never the full requested `limit`, sometimes not
+ * even a real neighbor) — REGARDLESS of this task's changes: it reproduces
+ * identically on a plain, unwrapped, un-stubbed reopen with the stock JS
+ * engine (verified against `hnsw-rebuild.test.ts`'s own construction) and
+ * is therefore a PRE-EXISTING, orthogonal defect in the JS HNSW engine's
+ * rebuilt-graph connectivity — outside this task's two deliverables (the
+ * count ledger and the open-gate REBUILD DECISION, not rebuild()'s internal
+ * search quality). Left for a separate investigation; not touched here.
+ */
+import { describe, it, expect, afterEach, vi } from 'vitest'
+import * as fs from 'node:fs'
+import * as os from 'node:os'
+import * as path from 'node:path'
+import { Brainy } from '../../src/index.js'
+import { JsHnswVectorIndex } from '../../src/hnsw/hnswIndex.js'
+
+const tmpDirs: string[] = []
+function mkTmp(): string {
+  const d = fs.mkdtempSync(path.join(os.tmpdir(), 'brainy-vector-leg-open-'))
+  tmpDirs.push(d)
+  return d
+}
+afterEach(() => {
+  vi.restoreAllMocks()
+  for (const d of tmpDirs.splice(0)) fs.rmSync(d, { recursive: true, force: true })
+})
+
+const V = (seed: number) =>
+  Array.from({ length: 384 }, (_, i) => Math.sin((seed + 1) * 7919 + i * 131) * 0.5 + 0.5)
+
+/**
+ * Build a store with N explicit-vector (non-deferred) nouns, flush, close.
+ * Each noun also carries embeddable text (`technology`/`science`, matching
+ * the query used below) so the semantic-search verification exercises real
+ * retrieval, not a coincidental match. The default JS engine builds a fully
+ * current store — the epoch marker is stamped current at this open's
+ * completion, so a later reopen's `_indexEpochStale` is honestly false and
+ * cannot mask the ledger-gap decision under test (nothing here manufactures
+ * epoch drift).
+ */
+async function buildVectoredStore(dir: string, n: number): Promise<string[]> {
+  const brain: any = new Brainy({
+    requireSubtype: false,
+    storage: { type: 'filesystem', path: dir },
+    plugins: [],
+    silent: true,
+    dimensions: 384
+  })
+  await brain.init()
+  const ids: string[] = []
+  for (let i = 0; i < n; i++) {
+    ids.push(
+      await brain.add({
+        data: `doc ${i} about ${i % 2 === 0 ? 'technology' : 'science'}`,
+        type: 'document',
+        vector: V(i)
+      })
+    )
+  }
+  await brain.flush()
+  await brain.close()
+  return ids
+}
+
+describe('vector-leg open-build (two-engine gate, last red)', () => {
+  it('coverage gap: a provider reporting serving:true at size()===0 is overridden by the vectored-noun ledger — open() builds, search returns real results', async () => {
+    const dir = mkTmp()
+    const ids = await buildVectoredStore(dir, 12)
+
+    // Wrap the REAL JS engine so a successful rebuild restores genuine,
+    // searchable vectors — only `size()` and `healthReport()` are faked,
+    // simulating a native provider that has never built its own coverage of
+    // an unledgered invariant.
+    const calls = { rebuild: 0 }
+    const brain: any = new Brainy({
+      requireSubtype: false,
+      storage: { type: 'filesystem', path: dir },
+      plugins: [],
+      silent: true,
+      dimensions: 384
+    })
+    brain.use({
+      name: 'fake-native-vector-unledgered-coverage',
+      activate: async (ctx: any) => {
+        ctx.registerProvider('vector', (config: any, distance: any, options: any) => {
+          const real = new JsHnswVectorIndex(config, distance, options)
+          let rebuilt = false
+          const originalRebuild = real.rebuild.bind(real)
+          ;(real as any).rebuild = async (...args: any[]) => {
+            const r = await originalRebuild(...args)
+            calls.rebuild++
+            rebuilt = true
+            return r
+          }
+          const originalSize = real.size.bind(real)
+          ;(real as any).size = () => (rebuilt ? originalSize() : 0)
+          ;(real as any).healthReport = () => ({
+            provider: 'vector',
+            healthy: true,
+            serving: true,
+            invariants: [],
+            checkedAt: Date.now(),
+            durationMs: 0,
+            generation: 1,
+            unledgered: ['vector-coverage']
+          })
+          return real
+        })
+        return true
+      }
+    })
+    await brain.init()
+
+    // WITHOUT any find() first: open() itself must have built the leg.
+    expect(calls.rebuild, 'open() forced the rebuild despite serving:true').toBe(1)
+    const status = await brain.getIndexStatus()
+    expect(status.hnswIndex.size).toBeGreaterThanOrEqual(ids.length)
+
+    // Real, searchable results — never [] (see the module doc's SEARCH
+    // VERIFICATION NOTE for why this is a semantic `query`, not a raw
+    // `vector`, call).
+    const results = await brain.find({ query: 'technology document', limit: 5 })
+    expect(results.length).toBeGreaterThan(0)
+    expect(results.length).not.toBe(0)
+
+    await brain.close()
+  })
+
+  it('the inverse: only deferred (never-landed) user nouns — the ledger is never inflated by them, and search over them honestly returns []', async () => {
+    // ARCHITECTURAL NOTE (found while building this pin): every brainy store
+    // carries ONE permanent, always-vectored noun beyond user data — the VFS
+    // root (`entities/nouns/.../00000000-0000-0000-0000-000000000000`,
+    // src/vfs/VirtualFileSystem.ts). It is inserted with an explicit all-zero
+    // (but non-empty, length-384) vector on EVERY store's first open — never
+    // deferred (a deliberate WASM-cold-compile-avoidance fix, see that
+    // file's comment) — and VFS init unconditionally re-creates it if
+    // missing, before the rebuild gate ever runs. A literal "0 vectored
+    // nouns" store is therefore unreachable through the public API; a
+    // brand-new store's `vectors.all` floor is 1, not 0. This pin verifies
+    // the law the task names in the ACHIEVABLE form: nouns whose embed is
+    // still deferred/unlanded contribute NOTHING to the vectored-noun ledger
+    // — the coverage-gap comparison sees exactly the root (1), never
+    // root+deferred — and semantic search over deferred-only user content
+    // honestly returns `[]` (no error, no false "coverage restored" claim).
+    const dir = mkTmp()
+
+    const build: any = new Brainy({
+      requireSubtype: false,
+      storage: { type: 'filesystem', path: dir },
+      plugins: [],
+      silent: true,
+      dimensions: 384
+    })
+    await build.init()
+    const rootOnlyLedger = await build.storage.getCanonicalCounts()
+    // Block the embedder permanently so every add below stays deferred and
+    // unlanded for the rest of this test (a fast deterministic embedder
+    // could otherwise land it before we ever observe the "still 0 extra"
+    // state).
+    vi.spyOn(build, 'embed').mockImplementation(() => new Promise(() => {}))
+    for (let i = 0; i < 5; i++) {
+      await build.add({ data: `deferred ${i}`, type: 'document', deferEmbedding: true })
+    }
+    await build.flush()
+    const ledgerWithDeferred = await build.storage.getCanonicalCounts()
+    // The five deferred adds contributed ZERO to the vectored-noun ledger.
+    expect(ledgerWithDeferred.vectors.all).toBe(rootOnlyLedger.vectors.all)
+    await build.close()
+
+    // Reopen (default JS engine — no stub needed): the root is the ONLY
+    // thing the vector leg has to load; the deferred nouns are correctly
+    // invisible to it. Block the embedder again BEFORE init() — reopen
+    // recovers the durable pending-embed markers and kicks the worker as
+    // part of init() itself, and an unblocked deterministic embedder could
+    // land all five before this test observes the open-time ledger.
+    const brain: any = new Brainy({
+      requireSubtype: false,
+      storage: { type: 'filesystem', path: dir },
+      plugins: [],
+      silent: true,
+      dimensions: 384
+    })
+    vi.spyOn(brain, 'embed').mockImplementation(() => new Promise(() => {}))
+    await brain.init()
+    // The ledger is exactly the root — the five deferred, still-unlanded
+    // nouns (which the rebuild above DOES insert into the graph, each with
+    // its stub empty vector — `index.size()` counts EVERY canonical noun's
+    // graph node, deferred or not, so it is not the coverage metric) never
+    // inflate the VECTORED count.
+    const ledgerAfterReopen = await brain.storage.getCanonicalCounts()
+    expect(ledgerAfterReopen.vectors.all).toBe(rootOnlyLedger.vectors.all)
+
+    const results = await brain.find({ vector: V(3), limit: 5 })
+    expect(results).toEqual([])
+
+    await brain.close()
+  })
+})

tests/lifecycle/biography.test.ts

@@ -380,6 +380,12 @@ describe.sequential('lifecycle — the working store', () => {
             counted: aliveVerbs + model.vfsContainsVerbs,
             all: aliveVerbs + model.vfsContainsVerbs + model.vfsBaselineVerbs
           },
+          // Every noun this biography ever adds carries an explicit/computed
+          // vector (the harness never defers an embed), so the vectored-noun
+          // scalar tracks nouns.all exactly.
+          vectors: {
+            all: aliveEntities.length + model.vfsFileNouns + model.vfsBaselineNouns
+          },
           suspect: false
         })
       } finally {