perf(sqlite): use existence probes for empty memory search

src/memory/index.test.ts

@@ -216,6 +216,7 @@ describe("memory index", () => {
     vectorEnabled?: boolean;
     cacheEnabled?: boolean;
     minScore?: number;
+    onSearch?: boolean;
     hybrid?: { enabled: boolean; vectorWeight?: number; textWeight?: number };
   }): TestCfg {
     return {
@@ -229,7 +230,7 @@ describe("memory index", () => {
             store: { path: params.storePath, vector: { enabled: params.vectorEnabled ?? false } },
             // Perf: keep test indexes to a single chunk to reduce sqlite work.
             chunking: { tokens: 4000, overlap: 0 },
-            sync: { watch: false, onSessionStart: false, onSearch: true },
+            sync: { watch: false, onSessionStart: false, onSearch: params.onSearch ?? true },
             query: {
               minScore: params.minScore ?? 0,
               hybrid: params.hybrid ?? { enabled: false },
@@ -970,6 +971,25 @@ describe("memory index", () => {
     await manager.close?.();
   });
 
+  it("does not initialize the provider when searching an empty index", async () => {
+    const cfg = createCfg({
+      storePath: path.join(workspaceDir, `index-empty-${randomUUID()}.sqlite`),
+      provider: "gemini",
+      model: "gemini-embedding-2-preview",
+      outputDimensionality: 1536,
+      onSearch: false,
+    });
+
+    const result = await getMemorySearchManager({ cfg, agentId: "main" });
+    const manager = requireManager(result);
+
+    const results = await manager.search("hello");
+
+    expect(results).toEqual([]);
+    expect(providerCalls).toEqual([]);
+    await manager.close?.();
+  });
+
   it("reindexes when Gemini outputDimensionality changes", async () => {
     const base = createCfg({
       storePath: indexModelPath,

src/memory/manager.ts

@@ -436,29 +436,23 @@ export class MemoryIndexManager extends MemoryManagerEmbeddingOps implements Mem
   }
 
   private hasIndexedContent(): boolean {
-    const chunks =
-      (
-        this.db.prepare(`SELECT COUNT(*) as c FROM chunks`).get() as
-          | {
-              c: number;
-            }
-          | undefined
-      )?.c ?? 0;
-    if (chunks > 0) {
+    const chunkRow = this.db.prepare(`SELECT 1 as found FROM chunks LIMIT 1`).get() as
+      | {
+          found?: number;
+        }
+      | undefined;
+    if (chunkRow?.found === 1) {
       return true;
     }
     if (!this.fts.enabled || !this.fts.available) {
       return false;
     }
-    const ftsRows =
-      (
-        this.db.prepare(`SELECT COUNT(*) as c FROM ${FTS_TABLE}`).get() as
-          | {
-              c: number;
-            }
-          | undefined
-      )?.c ?? 0;
-    return ftsRows > 0;
+    const ftsRow = this.db.prepare(`SELECT 1 as found FROM ${FTS_TABLE} LIMIT 1`).get() as
+      | {
+          found?: number;
+        }
+      | undefined;
+    return ftsRow?.found === 1;
   }
 
   private async searchVector(