fix: cover discord thread starter cache TTL (#5274) (thanks @webvijayi)

CHANGELOG.md

@@ -64,6 +64,7 @@ Docs: https://docs.openclaw.ai
 - Agents: prevent file descriptor leaks in child process cleanup. (#13565) Thanks @KyleChen26.
 - Agents: prevent double compaction caused by cache TTL bypassing guard. (#13514) Thanks @taw0002.
 - Agents: use last API call's cache tokens for context display instead of accumulated sum. (#13805) Thanks @akari-musubi.
+- Discord: add TTL/LRU eviction to the thread starter cache to prevent unbounded growth. (#5274) Thanks @webvijayi.
 - Discord tests: use a partial @buape/carbon mock in slash command coverage. (#13262) Thanks @arosstale.
 - Tests: update thread ID handling in Slack message collection tests. (#14108) Thanks @swizzmagik.
 

src/discord/monitor/threading.test.ts

@@ -1,10 +1,12 @@
-import type { Client } from "@buape/carbon";
-import { describe, expect, it } from "vitest";
+import { ChannelType, type Client } from "@buape/carbon";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import { buildAgentSessionKey } from "../../routing/resolve-route.js";
 import {
+  __resetDiscordThreadStarterCacheForTest,
   resolveDiscordAutoThreadContext,
   resolveDiscordAutoThreadReplyPlan,
   resolveDiscordReplyDeliveryPlan,
+  resolveDiscordThreadStarter,
 } from "./threading.js";
 
 describe("resolveDiscordAutoThreadContext", () => {
@@ -142,3 +144,45 @@ describe("resolveDiscordAutoThreadReplyPlan", () => {
     expect(plan.autoThreadContext).toBeNull();
   });
 });
+
+describe("resolveDiscordThreadStarter cache", () => {
+  afterEach(() => {
+    vi.useRealTimers();
+    __resetDiscordThreadStarterCacheForTest();
+  });
+
+  it("expires cached entries after TTL", async () => {
+    vi.useFakeTimers();
+    const baseTime = new Date("2026-02-12T00:00:00Z").getTime();
+    vi.setSystemTime(baseTime);
+
+    const restGet = vi.fn(async () => ({
+      content: "starter",
+      author: { username: "starter", id: "user-1" },
+      timestamp: "2026-02-12T00:00:00Z",
+    }));
+    const client = { rest: { get: restGet } } as unknown as Client;
+
+    const params = {
+      channel: { id: "thread-1" },
+      client,
+      parentId: "parent-1",
+      parentType: ChannelType.GuildText,
+      resolveTimestampMs: () => baseTime,
+    };
+
+    const first = await resolveDiscordThreadStarter(params);
+    expect(first?.text).toBe("starter");
+    expect(restGet).toHaveBeenCalledTimes(1);
+
+    vi.setSystemTime(baseTime + 60_000);
+    const second = await resolveDiscordThreadStarter(params);
+    expect(second).toEqual(first);
+    expect(restGet).toHaveBeenCalledTimes(1);
+
+    vi.setSystemTime(baseTime + 60_000 + 5 * 60_000 + 1);
+    const third = await resolveDiscordThreadStarter(params);
+    expect(third).toEqual(first);
+    expect(restGet).toHaveBeenCalledTimes(2);
+  });
+});