diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7aaac5a7..9bc163f04 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 
 ### Fixes
 - Auto-reply: prefer `RawBody` for command/directive parsing (WhatsApp + Discord) and prevent fallback runs from clobbering concurrent session updates. (#643) — thanks @mcinteerj.
+- Cron: `wakeMode: "now"` waits for heartbeat completion (and retries when the main lane is busy). (#666) — thanks @roshanasingh4.
 - Agents/OpenAI: fix Responses tool-only → follow-up turn handling (avoid standalone `reasoning` items that trigger 400 “required following item”).
 - Auth: update Claude Code keychain credentials in-place during refresh sync; share JSON file helpers; add CLI fallback coverage.
 - Auth: throttle external CLI credential syncs (Claude/Codex), reduce Keychain reads, and skip sync when cached credentials are still fresh.
diff --git a/src/cron/service.test.ts b/src/cron/service.test.ts
index 34762abd8..03364e9cd 100644
--- a/src/cron/service.test.ts
+++ b/src/cron/service.test.ts
@@ -4,6 +4,7 @@ import path from "node:path";
 
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
+import type { HeartbeatRunResult } from "../infra/heartbeat-wake.js";
 import { CronService } from "./service.js";
 
 const noopLogger = {
@@ -78,6 +79,68 @@ describe("CronService", () => {
     await store.cleanup();
   });
 
+  it("wakeMode now waits for heartbeat completion when available", async () => {
+    const store = await makeStorePath();
+    const enqueueSystemEvent = vi.fn();
+    const requestHeartbeatNow = vi.fn();
+
+    let now = 0;
+    const nowMs = () => {
+      now += 10;
+      return now;
+    };
+
+    let resolveHeartbeat: ((res: HeartbeatRunResult) => void) | null = null;
+    const runHeartbeatOnce = vi.fn(
+      async () =>
+        await new Promise<HeartbeatRunResult>((resolve) => {
+          resolveHeartbeat = resolve;
+        }),
+    );
+
+    const cron = new CronService({
+      storePath: store.storePath,
+      cronEnabled: true,
+      log: noopLogger,
+      nowMs,
+      enqueueSystemEvent,
+      requestHeartbeatNow,
+      runHeartbeatOnce,
+      runIsolatedAgentJob: vi.fn(async () => ({ status: "ok" })),
+    });
+
+    await cron.start();
+    const job = await cron.add({
+      name: "wakeMode now waits",
+      enabled: true,
+      schedule: { kind: "at", atMs: 1 },
+      sessionTarget: "main",
+      wakeMode: "now",
+      payload: { kind: "systemEvent", text: "hello" },
+    });
+
+    const runPromise = cron.run(job.id, "force");
+    for (let i = 0; i < 10; i++) {
+      if (runHeartbeatOnce.mock.calls.length > 0) break;
+      // Let the locked() chain progress.
+      await Promise.resolve();
+    }
+
+    expect(runHeartbeatOnce).toHaveBeenCalledTimes(1);
+    expect(requestHeartbeatNow).not.toHaveBeenCalled();
+    expect(enqueueSystemEvent).toHaveBeenCalledWith("hello");
+    expect(job.state.runningAtMs).toBeTypeOf("number");
+
+    resolveHeartbeat?.({ status: "ran", durationMs: 123 });
+    await runPromise;
+
+    expect(job.state.lastStatus).toBe("ok");
+    expect(job.state.lastDurationMs).toBeGreaterThan(0);
+
+    cron.stop();
+    await store.cleanup();
+  });
+
   it("runs an isolated job and posts summary to main", async () => {
     const store = await makeStorePath();
     const enqueueSystemEvent = vi.fn();
diff --git a/src/cron/service.ts b/src/cron/service.ts
index 620ebd16f..870e56675 100644
--- a/src/cron/service.ts
+++ b/src/cron/service.ts
@@ -1,5 +1,6 @@
 import crypto from "node:crypto";
 
+import type { HeartbeatRunResult } from "../infra/heartbeat-wake.js";
 import { truncateUtf16Safe } from "../utils.js";
 import { migrateLegacyCronPayload } from "./payload-migration.js";
 import { computeNextRunAtMs } from "./schedule.js";
@@ -37,11 +38,9 @@ export type CronServiceDeps = {
   cronEnabled: boolean;
   enqueueSystemEvent: (text: string) => void;
   requestHeartbeatNow: (opts?: { reason?: string }) => void;
-  runHeartbeatOnce?: (opts?: { reason?: string }) => Promise<{
-    status: "ran" | "skipped" | "failed";
-    durationMs: number;
+  runHeartbeatOnce?: (opts?: {
     reason?: string;
-  }>;
+  }) => Promise<HeartbeatRunResult>;
   runIsolatedAgentJob: (params: { job: CronJob; message: string }) => Promise<{
     status: "ok" | "error" | "skipped";
     summary?: string;
@@ -50,6 +49,10 @@ export type CronServiceDeps = {
   onEvent?: (evt: CronEvent) => void;
 };
 
+type CronServiceDepsInternal = Omit<CronServiceDeps, "nowMs"> & {
+  nowMs: () => number;
+};
+
 const STUCK_RUN_MS = 2 * 60 * 60 * 1000;
 const MAX_TIMEOUT_MS = 2 ** 31 - 1;
 
@@ -104,8 +107,7 @@ function normalizePayloadToSystemText(payload: CronPayload) {
 }
 
 export class CronService {
-  private readonly deps: Required<Omit<CronServiceDeps, "onEvent">> &
-    Pick<CronServiceDeps, "onEvent">;
+  private readonly deps: CronServiceDepsInternal;
   private store: CronStoreFile | null = null;
   private timer: NodeJS.Timeout | null = null;
   private running = false;
@@ -116,7 +118,6 @@ export class CronService {
     this.deps = {
       ...deps,
       nowMs: deps.nowMs ?? (() => Date.now()),
-      onEvent: deps.onEvent,
     };
   }
 
@@ -520,25 +521,36 @@ export class CronService {
         }
         this.deps.enqueueSystemEvent(text);
         if (job.wakeMode === "now" && this.deps.runHeartbeatOnce) {
-          const heartbeatResult = await this.deps.runHeartbeatOnce({
-            reason: `cron:${job.id}`,
-          });
-          // Map heartbeat status to cron status
+          const reason = `cron:${job.id}`;
+          const delay = (ms: number) =>
+            new Promise<void>((resolve) => setTimeout(resolve, ms));
+          const maxWaitMs = 2 * 60_000;
+          const waitStartedAt = this.deps.nowMs();
+
+          let heartbeatResult: HeartbeatRunResult;
+          for (;;) {
+            heartbeatResult = await this.deps.runHeartbeatOnce({ reason });
+            if (
+              heartbeatResult.status !== "skipped" ||
+              heartbeatResult.reason !== "requests-in-flight"
+            ) {
+              break;
+            }
+            if (this.deps.nowMs() - waitStartedAt > maxWaitMs) {
+              heartbeatResult = {
+                status: "skipped",
+                reason: "timeout waiting for main lane to become idle",
+              };
+              break;
+            }
+            await delay(250);
+          }
+
           if (heartbeatResult.status === "ran") {
             await finish("ok", undefined, text);
-          } else if (heartbeatResult.status === "skipped") {
-            await finish(
-              "skipped",
-              heartbeatResult.reason ?? "heartbeat skipped",
-              text,
-            );
-          } else if (heartbeatResult.status === "failed") {
-            await finish(
-              "error",
-              heartbeatResult.reason ?? "heartbeat failed",
-              text,
-            );
-          }
+          } else if (heartbeatResult.status === "skipped")
+            await finish("skipped", heartbeatResult.reason, text);
+          else await finish("error", heartbeatResult.reason, text);
         } else {
           // wakeMode is "next-heartbeat" or runHeartbeatOnce not available
           this.deps.requestHeartbeatNow({ reason: `cron:${job.id}` });
diff --git a/src/gateway/server.ts b/src/gateway/server.ts
index caabc1517..a56f07605 100644
--- a/src/gateway/server.ts
+++ b/src/gateway/server.ts
@@ -723,7 +723,7 @@ export async function startGatewayServer(
         return await runHeartbeatOnce({
           cfg: runtimeConfig,
           reason: opts?.reason,
-          deps: { runtime },
+          deps: { ...deps, runtime: defaultRuntime },
         });
       },
       runIsolatedAgentJob: async ({ job, message }) => {