diff --git a/README.md b/README.md
index 434a5f4..73afab3 100644
--- a/README.md
+++ b/README.md
@@ -1198,7 +1198,7 @@ Companion runtime helper:
   - shared `bootstrap()` helper (`register` + `getCapabilities`) for startup handshakes
   - shared `publishHeartbeat()` helper for periodic `node.status.set` updates with safe defaults
   - optional `defaultSessionId` for canvas helper calls so `sessionId` can be omitted per call
-- `src/companion/heartbeatLoop.ts` provides `CompanionHeartbeatLoop` for periodic heartbeat scheduling (`publishHeartbeat`) with start/stop safety and error hooks.
+- `src/companion/heartbeatLoop.ts` provides `CompanionHeartbeatLoop` for periodic heartbeat scheduling (`publishHeartbeat`) with start/stop safety, error hooks, and optional auto-stop after repeated failures.
 
 ## Canvas / A2UI Foundation
 
diff --git a/docs/plans/state.json b/docs/plans/state.json
index b805496..23e06ad 100644
--- a/docs/plans/state.json
+++ b/docs/plans/state.json
@@ -286,6 +286,19 @@
       ],
       "test_status": "pnpm test:run src/companion/platformClients.test.ts src/companion/platformClients.integration.test.ts + pnpm typecheck passing"
     },
+    "companion-heartbeat-loop-failure-threshold": {
+      "status": "completed",
+      "date": "2026-02-17",
+      "updated": "2026-02-17",
+      "summary": "Extended `CompanionHeartbeatLoop` with failure-threshold controls (`maxConsecutiveFailures`) and `onFailureLimitReached` callback support so companion runtimes can auto-stop noisy loops after repeated heartbeat failures.",
+      "files_modified": [
+        "src/companion/heartbeatLoop.ts",
+        "src/companion/heartbeatLoop.test.ts",
+        "README.md",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/companion/heartbeatLoop.test.ts src/companion/platformClients.test.ts + pnpm typecheck passing"
+    },
     "browser-tools-activation-clarity": {
       "status": "completed",
       "date": "2026-02-17",
diff --git a/src/companion/heartbeatLoop.test.ts b/src/companion/heartbeatLoop.test.ts
index e237cf6..7aa6a40 100644
--- a/src/companion/heartbeatLoop.test.ts
+++ b/src/companion/heartbeatLoop.test.ts
@@ -100,4 +100,34 @@ describe('CompanionHeartbeatLoop', () => {
     expect(publishHeartbeat).toHaveBeenCalledTimes(1);
     expect(loop.running).toBe(false);
   });
+
+  it('stops when maxConsecutiveFailures threshold is reached', async () => {
+    const publishHeartbeat = vi
+      .fn<() => Promise<NodeStatusSetResult>>()
+      .mockRejectedValue(new Error('persistent-failure'));
+    const onError = vi.fn();
+    const onFailureLimitReached = vi.fn();
+    const loop = new CompanionHeartbeatLoop(
+      { publishHeartbeat },
+      {
+        intervalMs: 300,
+        onError,
+        maxConsecutiveFailures: 2,
+        onFailureLimitReached,
+      },
+    );
+
+    loop.start();
+    await Promise.resolve();
+    expect(loop.running).toBe(true);
+
+    await vi.advanceTimersByTimeAsync(300);
+    expect(loop.running).toBe(false);
+    expect(onError).toHaveBeenCalledTimes(2);
+    expect(onFailureLimitReached).toHaveBeenCalledTimes(1);
+    expect(onFailureLimitReached).toHaveBeenCalledWith(expect.any(Error), 2);
+
+    await vi.advanceTimersByTimeAsync(1000);
+    expect(publishHeartbeat).toHaveBeenCalledTimes(2);
+  });
 });
diff --git a/src/companion/heartbeatLoop.ts b/src/companion/heartbeatLoop.ts
index c165085..b040941 100644
--- a/src/companion/heartbeatLoop.ts
+++ b/src/companion/heartbeatLoop.ts
@@ -9,6 +9,8 @@ export interface CompanionHeartbeatLoopOptions {
   intervalMs?: number;
   buildHeartbeat?: () => HeartbeatStatusInput | Promise<HeartbeatStatusInput>;
   onError?: (error: Error) => void;
+  maxConsecutiveFailures?: number;
+  onFailureLimitReached?: (error: Error, consecutiveFailures: number) => void;
 }
 
 /**
@@ -20,16 +22,21 @@ export class CompanionHeartbeatLoop {
   private readonly intervalMs: number;
   private readonly buildHeartbeat?: () => HeartbeatStatusInput | Promise<HeartbeatStatusInput>;
   private readonly onError?: (error: Error) => void;
+  private readonly maxConsecutiveFailures: number;
+  private readonly onFailureLimitReached?: (error: Error, consecutiveFailures: number) => void;
 
   private timer: NodeJS.Timeout | null = null;
   private started = false;
   private inFlight = false;
+  private consecutiveFailures = 0;
 
   constructor(publisher: HeartbeatPublisher, options: CompanionHeartbeatLoopOptions = {}) {
     this.publisher = publisher;
     this.intervalMs = options.intervalMs ?? 30_000;
     this.buildHeartbeat = options.buildHeartbeat;
     this.onError = options.onError;
+    this.maxConsecutiveFailures = options.maxConsecutiveFailures ?? Number.POSITIVE_INFINITY;
+    this.onFailureLimitReached = options.onFailureLimitReached;
   }
 
   get running(): boolean {
@@ -41,6 +48,7 @@ export class CompanionHeartbeatLoop {
       return;
     }
     this.started = true;
+    this.consecutiveFailures = 0;
 
     if (runImmediately) {
       void this.tick();
@@ -74,9 +82,16 @@ export class CompanionHeartbeatLoop {
     try {
       const payload = this.buildHeartbeat ? await this.buildHeartbeat() : undefined;
       await this.publisher.publishHeartbeat(payload);
+      this.consecutiveFailures = 0;
     } catch (error) {
       const err = error instanceof Error ? error : new Error(String(error));
+      this.consecutiveFailures += 1;
       this.onError?.(err);
+      if (this.consecutiveFailures >= this.maxConsecutiveFailures) {
+        this.onFailureLimitReached?.(err, this.consecutiveFailures);
+        this.stop();
+        return;
+      }
     } finally {
       this.inFlight = false;
       this.scheduleNext();