Add Cache primtive

benchmarks/storage.ts

@@ -1,5 +1,6 @@
 import { AESKey } from '../src/crypto/aes-key.js';
 import { StorageMemory, EncryptedStorage, type BaseStorage } from '../src/storage/index.js';
+import { BTreeCache, KvCache } from '../src/cache/index.js';
 
 // ---------------------------------------------------------------------------
 // Helpers
@@ -161,9 +162,19 @@ const DOC_COUNTS = [1_000, 10_000, 50_000];
 for (const count of DOC_COUNTS) {
   const docs = generateDocs(count);
 
-  // Indexes on id, name, AND age — range queries on age use B+ Tree.
-  const indexedWithAge = StorageMemory.from<Doc>(['id', 'name', 'age']);
-  await benchmarkStorage('StorageMemory (indexed: id,name,age)', indexedWithAge, docs, { hasAgeIndex: true });
+  // Indexes on id, name, AND age with explicit B+ Tree cache.
+  const indexedWithAgeBTree = StorageMemory.from<Doc>(
+    ['id', 'name', 'age'],
+    new BTreeCache(),
+  );
+  await benchmarkStorage('StorageMemory (B+Tree cache, indexed: id,name,age)', indexedWithAgeBTree, docs, { hasAgeIndex: true });
+
+  // Same indexes, but KV cache (no range support).
+  const indexedWithAgeKv = StorageMemory.from<Doc>(
+    ['id', 'name', 'age'],
+    new KvCache(),
+  );
+  await benchmarkStorage('StorageMemory (KV cache, indexed: id,name,age)', indexedWithAgeKv, docs);
 
   // Indexes on id, name only — range queries on age fall back to full scan.
   const indexed = StorageMemory.from<Doc>(['id', 'name']);