diff --git a/src/infra/heartbeat-runner-execution.ts b/src/infra/heartbeat-runner-execution.ts
index afd71e19a219..0e3d868f47ff 100644
--- a/src/infra/heartbeat-runner-execution.ts
+++ b/src/infra/heartbeat-runner-execution.ts
@@ -184,6 +184,14 @@ export async function resolveHeartbeatWakeStage(opts: HeartbeatRunOptions) {
     wakeSource !== "cron" &&
     !isWithinActiveHours(cfg, heartbeat, startedAt)
   ) {
+    // Documented observable skip (`system heartbeat last` / troubleshooting
+    // docs promise reason=quiet-hours); every sibling skip past this point
+    // emits, so a silent return here hides the window from operators.
+    emitHeartbeatEvent({
+      status: "skipped",
+      reason: "quiet-hours",
+      durationMs: Date.now() - startedAt,
+    });
     return { kind: "skipped", reason: "quiet-hours" } as const;
   }
 
diff --git a/src/infra/heartbeat-runner.returns-default-unset.test.ts b/src/infra/heartbeat-runner.returns-default-unset.test.ts
index 4cb0a858ed55..7e58af8a909f 100644
--- a/src/infra/heartbeat-runner.returns-default-unset.test.ts
+++ b/src/infra/heartbeat-runner.returns-default-unset.test.ts
@@ -23,6 +23,7 @@ import {
 } from "../test-utils/channel-plugins.js";
 import { typedCases } from "../test-utils/typed-cases.js";
 import { normalizeSessionDeliveryState } from "../utils/delivery-context.shared.js";
+import { getLastHeartbeatEvent, resetHeartbeatEventsForTest } from "./heartbeat-events.js";
 import {
   type HeartbeatDeps,
   isHeartbeatEnabledForAgent,
@@ -337,6 +338,7 @@ beforeAll(async () => {
 
 beforeEach(() => {
   resetSystemEventsForTest();
+  resetHeartbeatEventsForTest();
   if (testRegistry) {
     setActivePluginRegistry(testRegistry);
   }
@@ -862,6 +864,8 @@ describe("runHeartbeatOnce", () => {
     if (res.status === "skipped") {
       expect(res.reason).toBe("quiet-hours");
     }
+    // Documented observable skip: `system heartbeat last` must show the window.
+    expect(getLastHeartbeatEvent()).toMatchObject({ status: "skipped", reason: "quiet-hours" });
   });
 
   it("skips a routeless interval poll before the agent run", async () => {