Memory: make QMD cache eviction callback idempotent

src/memory/search-manager.test.ts

@@ -114,4 +114,35 @@ describe("getMemorySearchManager caching", () => {
     // eslint-disable-next-line @typescript-eslint/unbound-method
     expect(QmdMemoryManager.create).toHaveBeenCalledTimes(2);
   });
+
+  it("does not evict a newer cached wrapper when closing an older failed wrapper", async () => {
+    const retryAgentId = "retry-agent-close";
+    const cfg = {
+      memory: { backend: "qmd", qmd: {} },
+      agents: { list: [{ id: retryAgentId, default: true, workspace: "/tmp/workspace" }] },
+    } as const;
+
+    mockPrimary.search.mockRejectedValueOnce(new Error("qmd query failed"));
+
+    const first = await getMemorySearchManager({ cfg, agentId: retryAgentId });
+    expect(first.manager).toBeTruthy();
+    if (!first.manager) {
+      throw new Error("manager missing");
+    }
+    await first.manager.search("hello");
+
+    const second = await getMemorySearchManager({ cfg, agentId: retryAgentId });
+    expect(second.manager).toBeTruthy();
+    if (!second.manager) {
+      throw new Error("manager missing");
+    }
+    expect(second.manager).not.toBe(first.manager);
+
+    await first.manager.close?.();
+
+    const third = await getMemorySearchManager({ cfg, agentId: retryAgentId });
+    expect(third.manager).toBe(second.manager);
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(QmdMemoryManager.create).toHaveBeenCalledTimes(2);
+  });
 });

src/memory/search-manager.ts

@@ -68,6 +68,7 @@ class FallbackMemoryManager implements MemorySearchManager {
   private fallback: MemorySearchManager | null = null;
   private primaryFailed = false;
   private lastError?: string;
+  private cacheEvicted = false;
 
   constructor(
     private readonly deps: {
@@ -90,7 +91,7 @@ class FallbackMemoryManager implements MemorySearchManager {
         log.warn(`qmd memory failed; switching to builtin index: ${this.lastError}`);
         await this.deps.primary.close?.().catch(() => {});
         // Evict the failed wrapper so the next request can retry QMD with a fresh manager.
-        this.onClose?.();
+        this.evictCacheEntry();
       }
     }
     const fallback = await this.ensureFallback();
@@ -175,7 +176,7 @@ class FallbackMemoryManager implements MemorySearchManager {
   async close() {
     await this.deps.primary.close?.();
     await this.fallback?.close?.();
-    this.onClose?.();
+    this.evictCacheEntry();
   }
 
   private async ensureFallback(): Promise<MemorySearchManager | null> {
@@ -190,6 +191,14 @@ class FallbackMemoryManager implements MemorySearchManager {
     this.fallback = fallback;
     return this.fallback;
   }
+
+  private evictCacheEntry(): void {
+    if (this.cacheEvicted) {
+      return;
+    }
+    this.cacheEvicted = true;
+    this.onClose?.();
+  }
 }
 
 function buildQmdCacheKey(agentId: string, config: ResolvedQmdConfig): string {