feat(vector): the vectored-noun scalar joins the count ledger; the open gate closes the vector leg

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.

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()
       }