diff --git a/packages/coding-agent/src/modes/components/tool-execution.ts b/packages/coding-agent/src/modes/components/tool-execution.ts
index 859a361f8..fddc637f5 100644
--- a/packages/coding-agent/src/modes/components/tool-execution.ts
+++ b/packages/coding-agent/src/modes/components/tool-execution.ts
@@ -317,6 +317,19 @@ function unregisterSpinnerBlock(block: ToolExecutionComponent): void {
 	}
 }
 
+/** Stop the shared spinner ticker and drop every registered live block.
+ *  Called on interactive-mode teardown so a stray live block cannot keep the
+ *  process-wide 80ms interval alive past shutdown (lingering event-loop
+ *  handles pin the process; cf. `postmortem.quit`). Test files that assert on
+ *  ticker arming also use this to start from a clean slate. */
+export function stopSharedSpinnerTicker(): void {
+	liveSpinnerBlocks.clear();
+	if (sharedSpinnerTimer) {
+		clearInterval(sharedSpinnerTimer);
+		sharedSpinnerTimer = undefined;
+	}
+}
+
 // Stable per-instance counter so each tool execution's inline images get a
 // graphics id that survives child re-creation (the image budget keys off it).
 let toolExecutionInstanceSeq = 0;
diff --git a/packages/coding-agent/src/modes/interactive-mode.ts b/packages/coding-agent/src/modes/interactive-mode.ts
index 3837eaca1..22eb1ec46 100644
--- a/packages/coding-agent/src/modes/interactive-mode.ts
+++ b/packages/coding-agent/src/modes/interactive-mode.ts
@@ -166,7 +166,7 @@ import type { HookInputComponent } from "./components/hook-input";
 import type { HookSelectorComponent, HookSelectorSlider } from "./components/hook-selector";
 import { type PlanReviewAnnotationState, PlanReviewOverlay } from "./components/plan-review-overlay";
 import { StatusLineComponent } from "./components/status-line";
-import type { ToolExecutionHandle } from "./components/tool-execution";
+import { stopSharedSpinnerTicker, type ToolExecutionHandle } from "./components/tool-execution";
 import { TranscriptContainer } from "./components/transcript-container";
 import { WelcomeComponent, type LspServerInfo as WelcomeLspServerInfo } from "./components/welcome";
 import { BtwController } from "./controllers/btw-controller";
@@ -4160,6 +4160,9 @@ export class InteractiveMode implements InteractiveModeContext {
 			this.#stopLoadingAnimation(false);
 		}
 		this.#cleanupMicAnimation();
+		// Stop the shared tool-spinner ticker: a live block missed by per-component
+		// stopAnimation would otherwise keep an 80ms interval pinning the process.
+		stopSharedSpinnerTicker();
 		this.#liveCommandController.dispose();
 		this.#cancelTodoAutoClearTimer();
 		this.#cancelObserverUiSyncTimer();
diff --git a/packages/coding-agent/test/agent-session-title-generation-dispose.test.ts b/packages/coding-agent/test/agent-session-title-generation-dispose.test.ts
index f425c62fc..6feda7822 100644
--- a/packages/coding-agent/test/agent-session-title-generation-dispose.test.ts
+++ b/packages/coding-agent/test/agent-session-title-generation-dispose.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, it, vi } from "bun:test";
+import { afterEach, beforeEach, describe, expect, it, vi } from "bun:test";
 import { Agent } from "@oh-my-pi/pi-agent-core";
 import * as ai from "@oh-my-pi/pi-ai";
 import { createMockModel } from "@oh-my-pi/pi-ai/providers/mock";
@@ -12,8 +12,19 @@ import { createAssistantMessage } from "./helpers/agent-session-setup";
 
 let session: AgentSession | undefined;
 let authStorage: AuthStorage | undefined;
+// Earlier full-suite files that boot main() in ACP/RPC mode set PI_NO_TITLE=1
+// process-wide (main.ts) and never restore it; maybeStartTitleGeneration gates
+// on it, so these tests would silently skip titling and time out.
+let previousNoTitle: string | undefined;
+
+beforeEach(() => {
+	previousNoTitle = Bun.env.PI_NO_TITLE;
+	delete Bun.env.PI_NO_TITLE;
+});
 
 afterEach(async () => {
+	if (previousNoTitle === undefined) delete Bun.env.PI_NO_TITLE;
+	else Bun.env.PI_NO_TITLE = previousNoTitle;
 	vi.restoreAllMocks();
 	await session?.dispose();
 	authStorage?.close();
diff --git a/packages/coding-agent/test/modes/components/tool-execution-spinner.test.ts b/packages/coding-agent/test/modes/components/tool-execution-spinner.test.ts
index 6a8d95b2c..52932a85d 100644
--- a/packages/coding-agent/test/modes/components/tool-execution-spinner.test.ts
+++ b/packages/coding-agent/test/modes/components/tool-execution-spinner.test.ts
@@ -1,7 +1,8 @@
-import { afterEach, beforeAll, describe, expect, it, vi } from "bun:test";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "bun:test";
 import { stripVTControlCharacters } from "node:util";
 import {
 	SPINNER_RENDER_INTERVAL_MS,
+	stopSharedSpinnerTicker,
 	ToolExecutionComponent,
 } from "@oh-my-pi/pi-coding-agent/modes/components/tool-execution";
 import { TranscriptContainer } from "@oh-my-pi/pi-coding-agent/modes/components/transcript-container";
@@ -17,6 +18,13 @@ describe("ToolExecutionComponent live preview spinners", () => {
 		await initTheme();
 	});
 
+	// Earlier test files may leak live blocks (components never stopAnimation'd),
+	// which keeps the shared ticker armed on a REAL interval and makes these
+	// fake-timer assertions observe a pre-existing timer instead of a fresh one.
+	beforeEach(() => {
+		stopSharedSpinnerTicker();
+	});
+
 	afterEach(() => {
 		vi.useRealTimers();
 		vi.restoreAllMocks();