diff --git a/src/infra/outbound/directory-cache.test.ts b/src/infra/outbound/directory-cache.test.ts
new file mode 100644
index 00000000000..ce7d041951e
--- /dev/null
+++ b/src/infra/outbound/directory-cache.test.ts
@@ -0,0 +1,45 @@
+import { describe, expect, it, vi } from "vitest";
+import type { OpenClawConfig } from "../../config/config.js";
+import { DirectoryCache } from "./directory-cache.js";
+
+describe("DirectoryCache", () => {
+  const cfg = {} as OpenClawConfig;
+
+  it("expires entries after ttl", () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-01-01T00:00:00.000Z"));
+    const cache = new DirectoryCache<string>(1000, 10);
+
+    cache.set("a", "value-a", cfg);
+    expect(cache.get("a", cfg)).toBe("value-a");
+
+    vi.setSystemTime(new Date("2026-01-01T00:00:02.000Z"));
+    expect(cache.get("a", cfg)).toBeUndefined();
+
+    vi.useRealTimers();
+  });
+
+  it("evicts oldest keys when max size is exceeded", () => {
+    const cache = new DirectoryCache<string>(60_000, 2);
+    cache.set("a", "value-a", cfg);
+    cache.set("b", "value-b", cfg);
+    cache.set("c", "value-c", cfg);
+
+    expect(cache.get("a", cfg)).toBeUndefined();
+    expect(cache.get("b", cfg)).toBe("value-b");
+    expect(cache.get("c", cfg)).toBe("value-c");
+  });
+
+  it("refreshes insertion order on key updates", () => {
+    const cache = new DirectoryCache<string>(60_000, 2);
+    cache.set("a", "value-a", cfg);
+    cache.set("b", "value-b", cfg);
+    cache.set("a", "value-a2", cfg);
+    cache.set("c", "value-c", cfg);
+
+    // Updating "a" should keep it and evict older "b".
+    expect(cache.get("a", cfg)).toBe("value-a2");
+    expect(cache.get("b", cfg)).toBeUndefined();
+    expect(cache.get("c", cfg)).toBe("value-c");
+  });
+});
diff --git a/src/infra/outbound/directory-cache.ts b/src/infra/outbound/directory-cache.ts
index 8dccac50ff9..97aca418eb4 100644
--- a/src/infra/outbound/directory-cache.ts
+++ b/src/infra/outbound/directory-cache.ts
@@ -22,25 +22,35 @@ export function buildDirectoryCacheKey(key: DirectoryCacheKey): string {
 export class DirectoryCache<T> {
   private readonly cache = new Map<string, CacheEntry<T>>();
   private lastConfigRef: OpenClawConfig | null = null;
+  private readonly maxSize: number;
 
-  constructor(private readonly ttlMs: number) {}
+  constructor(
+    private readonly ttlMs: number,
+    maxSize = 2000,
+  ) {
+    this.maxSize = Math.max(1, Math.floor(maxSize));
+  }
 
   get(key: string, cfg: OpenClawConfig): T | undefined {
     this.resetIfConfigChanged(cfg);
+    this.pruneExpired(Date.now());
     const entry = this.cache.get(key);
     if (!entry) {
       return undefined;
     }
-    if (Date.now() - entry.fetchedAt > this.ttlMs) {
-      this.cache.delete(key);
-      return undefined;
-    }
     return entry.value;
   }
 
   set(key: string, value: T, cfg: OpenClawConfig): void {
     this.resetIfConfigChanged(cfg);
-    this.cache.set(key, { value, fetchedAt: Date.now() });
+    const now = Date.now();
+    this.pruneExpired(now);
+    // Refresh insertion order so active keys are less likely to be evicted.
+    if (this.cache.has(key)) {
+      this.cache.delete(key);
+    }
+    this.cache.set(key, { value, fetchedAt: now });
+    this.evictToMaxSize();
   }
 
   clearMatching(match: (key: string) => boolean): void {
@@ -64,4 +74,25 @@ export class DirectoryCache<T> {
     }
     this.lastConfigRef = cfg;
   }
+
+  private pruneExpired(now: number): void {
+    if (this.ttlMs <= 0) {
+      return;
+    }
+    for (const [cacheKey, entry] of this.cache.entries()) {
+      if (now - entry.fetchedAt > this.ttlMs) {
+        this.cache.delete(cacheKey);
+      }
+    }
+  }
+
+  private evictToMaxSize(): void {
+    while (this.cache.size > this.maxSize) {
+      const oldestKey = this.cache.keys().next().value;
+      if (typeof oldestKey !== "string") {
+        break;
+      }
+      this.cache.delete(oldestKey);
+    }
+  }
 }