refactor(8.0): final cleanup — drop HnswProvider alias + config.hnsw + 'hnsw' surface (scaffold step 6)

Step 6 of the brainy 8.0 rename scaffolding. Removes every legacy 'hnsw'-
flavoured public name introduced as a compat shim in steps 1-5. The
algorithm-neutral surface is now the only surface.

REMOVED — PHASE A (type aliases)

src/plugin.ts
- Removed `export type HnswProvider = VectorIndexProvider` alias.
- Removed `export type DiskAnnProvider = VectorIndexProvider` alias.

src/index.ts
- Removed `export const HNSWIndex = JsHnswVectorIndex` alias.

src/types/brainy.types.ts
- Removed `BrainyStats.indexHealth.hnsw` field (the new `vector` field
  carries the same boolean).

src/brainy.ts
- `stats()` no longer emits the legacy `hnsw` field on `indexHealth`.

REMOVED — PHASE B (storage adapter rename, 8 adapters)

Repo-wide rename: `saveHNSWData` → `saveVectorIndexData` and
`getHNSWData` → `getVectorIndexData` across:

- src/storage/adapters/baseStorageAdapter.ts (abstract declarations)
- src/storage/adapters/fileSystemStorage.ts
- src/storage/adapters/gcsStorage.ts
- src/storage/adapters/r2Storage.ts
- src/storage/adapters/s3CompatibleStorage.ts
- src/storage/adapters/azureBlobStorage.ts
- src/storage/adapters/opfsStorage.ts
- src/storage/adapters/memoryStorage.ts
- src/storage/adapters/historicalStorageAdapter.ts
- src/brainy.ts (call sites)
- src/hnsw/hnswIndex.ts + src/hnsw/typeAwareHNSWIndex.ts (call sites)

The default-delegation wrappers added in scaffold step 4 are removed
(would have been duplicate declarations after the rename).

REMOVED — PHASE C (cache category 'hnsw')

src/utils/unifiedCache.ts
- Cache-category union narrowed from
    'hnsw' | 'vectors' | 'metadata' | 'embedding' | 'other'
  to
    'vectors' | 'metadata' | 'embedding' | 'other'
- typeAccessCounts, typeSizes, typeCounts, accessRatios, sizeRatios,
  and the fairness-check iterator all drop the 'hnsw' key.
- Per planning § 2.5: pre-8.0 'hnsw' cache entries are an in-memory
  category. Cache is rebuildable; entries naturally don't exist after
  a restart, so no migration path is needed.

src/hnsw/hnswIndex.ts
- 3 cache.set() call sites migrated from category 'hnsw' to 'vectors'.
- Cache key prefix `hnsw:vector:` → `vector:`.
- typeCounts/typeSizes/typeAccessCounts accessor renames
  `.hnsw` → `.vectors`.

tests/unit/utils/unifiedCache-eviction.test.ts
- Test fixtures updated: cache.set(..., 'hnsw', ...) → cache.set(..., 'vectors', ...).
- Stats assertion `stats.typeSizes.hnsw` → `stats.typeSizes.vectors`.

REMOVED — PHASE D (config.hnsw)

src/types/brainy.types.ts
- Removed `BrainyConfig.hnsw` field entirely. The 8.0 surface is
  `BrainyConfig.vector.{recall, quantization, vectorStorage, advanced}`.

src/brainy.ts
- normalizeConfig() no longer emits a `hnsw` field on Required<BrainyConfig>.
- setupIndex() rewired:
  - Reads from `this.config.vector` (not `this.config.hnsw`).
  - Calls `resolveJsHnswConfig(this.config.vector)` to translate the
    `recall` preset into M / efConstruction / efSearch knobs (with
    `advanced.hnsw` overrides winning when supplied).
- Imports `resolveJsHnswConfig` from './utils/recallPreset.js'.

NOT IN THIS COMMIT (deliberately)

- Persisted file path migration `_system/hnsw-*.json` →
  `_system/vector-index-*.json`. Requires dual-read logic on boot
  across 8 storage adapters. Per integration doc lines 531-539:
  "Reader accepts either spelling on load; writer emits the new spelling
  only; brains self-migrate on the next persist after upgrade." This is
  a separate body of work and lands in a follow-up commit before 8.0 GA.
- `config.hnswPersistMode` top-level field is unchanged. It's not in
  the rename inventory; a future commit can fold it into
  `config.vector.persistMode` if desired.
- strictConfig enforcement wiring. The field is accepted by
  normalizeConfig() with default 'warn'; the actual warning emission at
  knob-mismatch sites lands when the config-resolution layer is touched
  for the persisted-path migration.

VERIFICATION

- npx tsc --noEmit: clean
- npm test: 1468 / 1468 unit (one test fixture updated to use the new
  category name; assertion still passes after fixture rename)
- npm run build: clean

The 8.0 PR's user-facing surface is now algorithm-neutral end-to-end:
VectorIndexProvider, config.vector.recall, JsHnswVectorIndex,
saveVectorIndexData, 'vectors' cache category, indexHealth.vector,
strictConfig — all standalone. No legacy 'hnsw' name remains in any
public type or method signature.

src/hnsw/hnswIndex.ts

@@ -61,7 +61,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
   // Optional connections codec (2.4.0 #3). When set, node-persist writes the
   // node's per-level connection sets as a single delta-varint-compressed
   // binary blob (typically ~4× smaller than the legacy JSON-UUID-array
-  // shape), plus an empty `connections: {}` in saveHNSWData as the marker.
+  // shape), plus an empty `connections: {}` in saveVectorIndexData as the marker.
   // The read path tries to load the blob first; missing blob → legacy
   // connections field. Format convergence is lazy: pre-2.4.0 nodes still
   // load via the legacy path, then write the compressed form on next dirty
@@ -139,7 +139,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
   /**
    * @description Inject (or detach) the connections codec. When set, node
    * persistence writes a delta-varint-compressed binary blob alongside an
-   * empty `connections: {}` marker in saveHNSWData; the load path reads the
+   * empty `connections: {}` marker in saveVectorIndexData; the load path reads the
    * blob and decodes. Null reverts to the legacy JSON-array path. Wiring is
    * done by brainy.ts when the `graph:compression` provider is registered
    * AND the storage adapter exposes the binary-blob primitive AND the
@@ -227,7 +227,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
    * @description Persist one node's connections. When the connections codec is
    * wired AND the storage adapter exposes `saveBinaryBlob`, the per-level
    * connection sets are encoded into a single compact buffer and stored as a
-   * binary blob; `saveHNSWData` then records the node's level and an empty
+   * binary blob; `saveVectorIndexData` then records the node's level and an empty
    * `connections: {}` as the marker. Otherwise the legacy JSON-array path is
    * taken — the format every brainy release before 2.4.0 wrote. The two are
    * intentionally NOT dual-written: one or the other, never both, so format
@@ -250,7 +250,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
     if (canCompress) {
       const encoded = this.connectionsCodec!.encode(noun.connections)
       await storageWithBlob.saveBinaryBlob!(compressedConnectionsKey(nodeId), encoded)
-      await this.storage.saveHNSWData(nodeId, {
+      await this.storage.saveVectorIndexData(nodeId, {
         level: noun.level,
         connections: {}
       })
@@ -261,7 +261,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
     for (const [level, nounIds] of noun.connections.entries()) {
       connectionsObj[level.toString()] = Array.from(nounIds)
     }
-    await this.storage.saveHNSWData(nodeId, {
+    await this.storage.saveVectorIndexData(nodeId, {
       level: noun.level,
       connections: connectionsObj
     })
@@ -1197,7 +1197,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
           this.unifiedCache.set(
             cacheKey,
             fromMmap,
-            'hnsw',
+            'vectors',
             fromMmap.length * 4,
             50
           )
@@ -1232,7 +1232,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
       this.unifiedCache.set(
         cacheKey,
         loaded,
-        'hnsw',              // Type for fairness monitoring
+        'vectors',           // Type for fairness monitoring
         loaded.length * 4,   // Size in bytes (float32)
         50                   // Rebuild cost in ms (moderate priority)
       )
@@ -1303,7 +1303,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
         const id = uncachedIds[i]
         const v = fromMmap[i]
         if (v) {
-          this.unifiedCache.set(`hnsw:vector:${id}`, v, 'hnsw', v.length * 4, 50)
+          this.unifiedCache.set(`vector:${id}`, v, 'vectors', v.length * 4, 50)
         } else {
           misses.push(id)
         }
@@ -1322,7 +1322,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
             prodLog.debug(`MmapVectorBackend write-back failed for ${id}`, error)
           }
         }
-        this.unifiedCache.set(`hnsw:vector:${id}`, vector, 'hnsw', vector.length * 4, 50)
+        this.unifiedCache.set(`vector:${id}`, vector, 'vectors', vector.length * 4, 50)
       }))
       return
     }
@@ -1335,7 +1335,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
 
         const vector = await this.storage.getNounVector(id)
         if (vector) {
-          this.unifiedCache.set(cacheKey, vector, 'hnsw', vector.length * 4, 50)
+          this.unifiedCache.set(cacheKey, vector, 'vectors', vector.length * 4, 50)
         }
         return vector
       })
@@ -1500,7 +1500,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
         for (const nounData of result.items) {
           try {
             // Load HNSW graph data for this entity
-            const hnswData = await (this.storage as any).getHNSWData(nounData.id)
+            const hnswData = await (this.storage as any).getVectorIndexData(nounData.id)
 
             if (!hnswData) {
               // No HNSW data - skip (might be entity added before persistence)
@@ -1584,7 +1584,7 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
           for (const nounData of result.items) {
             try {
               // Load HNSW graph data for this entity
-              const hnswData = await (this.storage as any).getHNSWData(nounData.id)
+              const hnswData = await (this.storage as any).getVectorIndexData(nounData.id)
 
               if (!hnswData) {
                 // No HNSW data - skip (might be entity added before persistence)
@@ -1816,12 +1816,12 @@ export class JsHnswVectorIndex implements VectorIndexProvider {
     const estimatedVectorMemoryMB = (entityCount * bytesPerVector) / (1024 * 1024)
     const availableCacheMB = (cacheStats.maxSize * 0.8) / (1024 * 1024) // 80% threshold
 
-    // Calculate HNSW-specific cache stats
-    const vectorsInCache = cacheStats.typeCounts.hnsw || 0
-    const hnswMemoryBytes = cacheStats.typeSizes.hnsw || 0
+    // Calculate vector-index-specific cache stats
+    const vectorsInCache = cacheStats.typeCounts.vectors || 0
+    const hnswMemoryBytes = cacheStats.typeSizes.vectors || 0
 
     // Calculate fairness metrics
-    const hnswAccessCount = cacheStats.typeAccessCounts.hnsw || 0
+    const hnswAccessCount = cacheStats.typeAccessCounts.vectors || 0
     const totalAccessCount = cacheStats.totalAccessCount
     const hnswAccessPercent = totalAccessCount > 0 ? (hnswAccessCount / totalAccessCount) * 100 : 0
 

src/hnsw/typeAwareHNSWIndex.ts

@@ -551,7 +551,7 @@ export class TypeAwareHNSWIndex {
           const index = this.getIndexForType(nounType as NounType)
 
           // Load HNSW graph data
-          const hnswData = await (this.storage as any).getHNSWData(nounData.id)
+          const hnswData = await (this.storage as any).getVectorIndexData(nounData.id)
           if (!hnswData) {
             continue // No HNSW data
           }