diff --git a/server/src/services/heartbeat-run-runtime-status.test.ts b/server/src/services/heartbeat-run-runtime-status.test.ts
index 80984155eea..f75eb616444 100644
--- a/server/src/services/heartbeat-run-runtime-status.test.ts
+++ b/server/src/services/heartbeat-run-runtime-status.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import {
   clearAllHeartbeatRunRuntimeStatuses,
   clearHeartbeatRunRuntimeStatus,
@@ -12,6 +12,7 @@ import {
 describe("heartbeat run runtime status store", () => {
   afterEach(() => {
     clearAllHeartbeatRunRuntimeStatuses();
+    vi.useRealTimers();
   });
 
   it("stores scoped ephemeral status and expires stale entries", () => {
@@ -166,6 +167,43 @@ describe("heartbeat run runtime status store", () => {
     });
   });
 
+  it("cleans unread abandoned statuses on later output without polling or expiring fresh context", () => {
+    vi.useFakeTimers({ toFake: ["Date"] });
+    const start = new Date("2026-10-30T00:00:00Z");
+    vi.setSystemTime(start);
+    const write = (runId: string) => setHeartbeatRunRuntimeStatus({
+      companyId: "company-1", issueId: null, agentId: "agent-1", runId,
+      phase: "run_activity", message: "Using Bash",
+    });
+    write("abandoned");
+    write("active");
+    vi.setSystemTime(start.getTime() + 60_000);
+    touchHeartbeatRunRuntimeStatus({
+      companyId: "company-1", issueId: null, agentId: "agent-1", runId: "active",
+    });
+    vi.setSystemTime(start.getTime() + 90_000);
+    write("boundary");
+    expect(getHeartbeatRunRuntimeStatus("abandoned")).toMatchObject({ message: "Using Bash" });
+    expect(clearHeartbeatRunRuntimeStatus("boundary")).toBe(true);
+    vi.setSystemTime(start.getTime() + 90_001);
+    touchHeartbeatRunRuntimeStatus({
+      companyId: "company-1", issueId: null, agentId: "agent-1", runId: "active",
+    });
+    expect(clearHeartbeatRunRuntimeStatus("abandoned")).toBe(false);
+    expect(getHeartbeatRunRuntimeStatus("active")).toMatchObject({ message: "Using Bash" });
+    setHeartbeatRunRuntimeStatus({
+      companyId: "company-1", issueId: null, agentId: "agent-1", runId: "old-output",
+      phase: "run_activity", message: "Delayed output", updatedAt: start,
+    });
+    vi.setSystemTime(start.getTime() + 90_002);
+    write("next-output");
+    expect(clearHeartbeatRunRuntimeStatus("old-output")).toBe(true);
+    vi.setSystemTime(start.getTime() + 180_002);
+    write("new");
+    expect(clearHeartbeatRunRuntimeStatus("active")).toBe(false);
+    expect(getHeartbeatRunRuntimeStatus("new")).toMatchObject({ message: "Using Bash" });
+  });
+
   it("sweeps expired statuses without touching fresh entries", () => {
     setHeartbeatRunRuntimeStatus({
       companyId: "company-1",
diff --git a/server/src/services/heartbeat-run-runtime-status.ts b/server/src/services/heartbeat-run-runtime-status.ts
index d2995337e23..1d78b1ffb0a 100644
--- a/server/src/services/heartbeat-run-runtime-status.ts
+++ b/server/src/services/heartbeat-run-runtime-status.ts
@@ -20,6 +20,18 @@ export interface HeartbeatRunRuntimeStatus {
 }
 
 const runtimeStatusesByRunId = new Map<string, HeartbeatRunRuntimeStatus>();
+let nextWriteCleanupAt: number | null = null;
+
+function cleanupExpiredStatusesOnWrite() {
+  const now = Date.now();
+  if (nextWriteCleanupAt === null) {
+    nextWriteCleanupAt = now + HEARTBEAT_RUN_RUNTIME_STATUS_TTL_MS;
+    return;
+  }
+  if (now <= nextWriteCleanupAt) return;
+  sweepExpiredHeartbeatRunRuntimeStatuses(new Date(now));
+  nextWriteCleanupAt = now + HEARTBEAT_RUN_RUNTIME_STATUS_TTL_MS;
+}
 
 function cloneStatus(status: HeartbeatRunRuntimeStatus): HeartbeatRunRuntimeStatus {
   return {
@@ -64,6 +76,7 @@ export function setHeartbeatRunRuntimeStatus(
     lastEventAt?: Date | null;
   },
 ): HeartbeatRunRuntimeStatus | null {
+  cleanupExpiredStatusesOnWrite();
   const message = sanitizeHeartbeatRunRuntimeStatusMessage(input.message);
   if (!message) {
     clearHeartbeatRunRuntimeStatus(input.runId);
@@ -106,6 +119,7 @@ export function touchHeartbeatRunRuntimeStatus(input: {
   fallbackPhase?: HeartbeatRunStatusPhase;
   fallbackMessage?: string;
 }): HeartbeatRunRuntimeStatus | null {
+  cleanupExpiredStatusesOnWrite();
   const at = input.at ?? new Date();
   const existing = runtimeStatusesByRunId.get(input.runId);
   if (
@@ -167,6 +181,7 @@ export function clearHeartbeatRunRuntimeStatus(runId: string): boolean {
 
 export function clearAllHeartbeatRunRuntimeStatuses(): void {
   runtimeStatusesByRunId.clear();
+  nextWriteCleanupAt = null;
 }
 
 export function sweepExpiredHeartbeatRunRuntimeStatuses(