diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab09adc2209..2be9e346e5f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -107,6 +107,7 @@ Docs: https://docs.openclaw.ai
 - Telegram/Empty final replies: skip outbound send for null/undefined final text payloads without media so Telegram typing indicators do not linger on `text must be non-empty` errors. Landed from contributor PR #30969 by @haosenwang1018. Thanks @haosenwang1018.
 - Routing/Binding peer-kind parity: treat `peer.kind` `group` and `channel` as equivalent for binding scope matching (while keeping `direct` separate) so Slack/public channel bindings do not silently fall through. Landed from contributor PR #31135 by @Sid-Qin. Thanks @Sid-Qin.
 - Agents/FS workspace default: honor documented host file-tool default `tools.fs.workspaceOnly=false` when unset so host `write`/`edit` calls are not incorrectly workspace-restricted unless explicitly enabled. Landed from contributor PR #31128 by @SaucePackets. Thanks @SaucePackets.
+- Cron/Timer hot-loop guard: enforce a minimum timer re-arm delay when stale past-due jobs would otherwise trigger repeated `setTimeout(0)` loops, preventing event-loop saturation and log-flood behavior. (#29853) Thanks @FlamesCN.
 - Gateway/CLI session recovery: handle expired CLI session IDs gracefully by clearing stale session state and retrying without crashing gateway runs. Landed from contributor PR #31090 by @frankekn. Thanks @frankekn.
 - Slack/Subagent completion delivery: stop forcing bound conversation IDs into `threadId` so Slack completion announces do not send invalid `thread_ts` for DMs/top-level channels. Landed from contributor PR #31105 by @stakeswky. Thanks @stakeswky.
 - Signal/Loop protection: evaluate own-account detection before sync-message filtering (including UUID-only `accountUuid` configs) so `sentTranscript` sync events cannot bypass loop protection and self-reply loops. Landed from contributor PR #31093 by @kevinWangSheng. Thanks @kevinWangSheng.
diff --git a/src/cron/service.armtimer-tight-loop.test.ts b/src/cron/service.armtimer-tight-loop.test.ts
new file mode 100644
index 00000000000..a82aa36fbb2
--- /dev/null
+++ b/src/cron/service.armtimer-tight-loop.test.ts
@@ -0,0 +1,184 @@
+import fs from "node:fs/promises";
+import path from "node:path";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { createNoopLogger, createCronStoreHarness } from "./service.test-harness.js";
+import { createCronServiceState } from "./service/state.js";
+import { armTimer, onTimer } from "./service/timer.js";
+import type { CronJob } from "./types.js";
+
+const noopLogger = createNoopLogger();
+const { makeStorePath } = createCronStoreHarness({ prefix: "openclaw-cron-tight-loop-" });
+
+/**
+ * Create a cron job that is past-due AND has a stuck `runningAtMs` marker.
+ * This combination causes `findDueJobs` to return `[]` (blocked by
+ * `runningAtMs`) while `nextWakeAtMs` still returns the past-due timestamp,
+ * which before the fix resulted in a `setTimeout(0)` tight loop.
+ */
+function createStuckPastDueJob(params: { id: string; nowMs: number; pastDueMs: number }): CronJob {
+  const pastDueAt = params.nowMs - params.pastDueMs;
+  return {
+    id: params.id,
+    name: "stuck-job",
+    enabled: true,
+    deleteAfterRun: false,
+    createdAtMs: pastDueAt - 60_000,
+    updatedAtMs: pastDueAt - 60_000,
+    schedule: { kind: "cron", expr: "*/15 * * * *" },
+    sessionTarget: "isolated",
+    wakeMode: "next-heartbeat",
+    payload: { kind: "agentTurn", message: "monitor" },
+    delivery: { mode: "none" },
+    state: {
+      nextRunAtMs: pastDueAt,
+      // Stuck: set from a previous execution that was interrupted.
+      // Not yet old enough for STUCK_RUN_MS (2 h) to clear it.
+      runningAtMs: pastDueAt + 1,
+    },
+  };
+}
+
+describe("CronService - armTimer tight loop prevention", () => {
+  beforeEach(() => {
+    noopLogger.debug.mockClear();
+    noopLogger.info.mockClear();
+    noopLogger.warn.mockClear();
+    noopLogger.error.mockClear();
+  });
+
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("enforces a minimum delay when the next wake time is in the past", () => {
+    const timeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const now = Date.parse("2026-02-28T12:32:00.000Z");
+    const pastDueMs = 17 * 60 * 1000; // 17 minutes past due
+
+    const state = createCronServiceState({
+      storePath: "/tmp/test-cron/jobs.json",
+      cronEnabled: true,
+      log: noopLogger,
+      nowMs: () => now,
+      enqueueSystemEvent: vi.fn(),
+      requestHeartbeatNow: vi.fn(),
+      runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok" }),
+    });
+    state.store = {
+      version: 1,
+      jobs: [createStuckPastDueJob({ id: "monitor", nowMs: now, pastDueMs })],
+    };
+
+    armTimer(state);
+
+    expect(state.timer).not.toBeNull();
+    const delays = timeoutSpy.mock.calls
+      .map(([, delay]) => delay)
+      .filter((d): d is number => typeof d === "number");
+
+    // Before the fix, delay would be 0 (tight loop).
+    // After the fix, delay must be >= MIN_REFIRE_GAP_MS (2000 ms).
+    expect(delays.length).toBeGreaterThan(0);
+    for (const d of delays) {
+      expect(d).toBeGreaterThanOrEqual(2_000);
+    }
+
+    timeoutSpy.mockRestore();
+  });
+
+  it("does not add extra delay when the next wake time is in the future", () => {
+    const timeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const now = Date.parse("2026-02-28T12:32:00.000Z");
+
+    const state = createCronServiceState({
+      storePath: "/tmp/test-cron/jobs.json",
+      cronEnabled: true,
+      log: noopLogger,
+      nowMs: () => now,
+      enqueueSystemEvent: vi.fn(),
+      requestHeartbeatNow: vi.fn(),
+      runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok" }),
+    });
+    state.store = {
+      version: 1,
+      jobs: [
+        {
+          id: "future-job",
+          name: "future-job",
+          enabled: true,
+          deleteAfterRun: false,
+          createdAtMs: now,
+          updatedAtMs: now,
+          schedule: { kind: "cron", expr: "*/15 * * * *" },
+          sessionTarget: "isolated" as const,
+          wakeMode: "next-heartbeat" as const,
+          payload: { kind: "agentTurn" as const, message: "test" },
+          delivery: { mode: "none" as const },
+          state: { nextRunAtMs: now + 10_000 }, // 10 seconds in the future
+        },
+      ],
+    };
+
+    armTimer(state);
+
+    const delays = timeoutSpy.mock.calls
+      .map(([, delay]) => delay)
+      .filter((d): d is number => typeof d === "number");
+
+    // The natural delay (10 s) should be used, not the floor.
+    expect(delays).toContain(10_000);
+
+    timeoutSpy.mockRestore();
+  });
+
+  it("breaks the onTimer→armTimer hot-loop with stuck runningAtMs", async () => {
+    const timeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const store = await makeStorePath();
+    const now = Date.parse("2026-02-28T12:32:00.000Z");
+    const pastDueMs = 17 * 60 * 1000;
+
+    await fs.mkdir(path.dirname(store.storePath), { recursive: true });
+    await fs.writeFile(
+      store.storePath,
+      JSON.stringify(
+        {
+          version: 1,
+          jobs: [createStuckPastDueJob({ id: "monitor", nowMs: now, pastDueMs })],
+        },
+        null,
+        2,
+      ),
+      "utf-8",
+    );
+
+    const state = createCronServiceState({
+      storePath: store.storePath,
+      cronEnabled: true,
+      log: noopLogger,
+      nowMs: () => now,
+      enqueueSystemEvent: vi.fn(),
+      requestHeartbeatNow: vi.fn(),
+      runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok" }),
+    });
+
+    // Simulate the onTimer path: it will find no runnable jobs (blocked by
+    // runningAtMs) and re-arm the timer in its finally block.
+    await onTimer(state);
+
+    expect(state.running).toBe(false);
+    expect(state.timer).not.toBeNull();
+
+    // The re-armed timer must NOT use delay=0. It should use at least
+    // MIN_REFIRE_GAP_MS to prevent the hot-loop.
+    const allDelays = timeoutSpy.mock.calls
+      .map(([, delay]) => delay)
+      .filter((d): d is number => typeof d === "number");
+
+    // The last setTimeout call is from the finally→armTimer path.
+    const lastDelay = allDelays[allDelays.length - 1];
+    expect(lastDelay).toBeGreaterThanOrEqual(2_000);
+
+    timeoutSpy.mockRestore();
+    await store.cleanup();
+  });
+});
diff --git a/src/cron/service/timer.ts b/src/cron/service/timer.ts
index 333caabbfb1..4d38e7c33f1 100644
--- a/src/cron/service/timer.ts
+++ b/src/cron/service/timer.ts
@@ -446,9 +446,18 @@ export function armTimer(state: CronServiceState) {
   }
   const now = state.deps.nowMs();
   const delay = Math.max(nextAt - now, 0);
+  // Floor: when the next wake time is in the past (delay === 0), enforce a
+  // minimum delay to prevent a tight setTimeout(0) loop.  This can happen
+  // when a job has a stuck runningAtMs marker and a past-due nextRunAtMs:
+  // findDueJobs skips the job (blocked by runningAtMs), while
+  // recomputeNextRunsForMaintenance intentionally does not advance the
+  // past-due nextRunAtMs (per #13992).  The finally block in onTimer then
+  // re-invokes armTimer with delay === 0, creating an infinite hot-loop
+  // that saturates the event loop and fills the log file to its size cap.
+  const flooredDelay = delay === 0 ? MIN_REFIRE_GAP_MS : delay;
   // Wake at least once a minute to avoid schedule drift and recover quickly
   // when the process was paused or wall-clock time jumps.
-  const clampedDelay = Math.min(delay, MAX_TIMER_DELAY_MS);
+  const clampedDelay = Math.min(flooredDelay, MAX_TIMER_DELAY_MS);
   // Intentionally avoid an `async` timer callback:
   // Vitest's fake-timer helpers can await async callbacks, which would block
   // tests that simulate long-running jobs. Runtime behavior is unchanged.