diff --git a/src/__tests__/cli-device-status.test.ts b/src/__tests__/cli-device-status.test.ts
index abea55afd..188aae2dc 100644
--- a/src/__tests__/cli-device-status.test.ts
+++ b/src/__tests__/cli-device-status.test.ts
@@ -2,10 +2,38 @@ import assert from 'node:assert/strict';
 import fs from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
-import { test } from 'vitest';
+import { test, vi } from 'vitest';
 import { readCurrentOwnerIdentity } from '../utils/owner-identity.ts';
 import { runCliCapture } from './cli-capture.ts';
 
+// readProcessStartTime shells out to `ps` with a 1s timeout (see
+// utils/host-process.ts). This file's fixtures read our own start time once
+// to build a "live" claim, then production re-reads it during classification
+// to confirm identity; under full-suite CPU contention that second `ps` call
+// can miss its deadline and return null, mismatching the cached value and
+// flipping a genuinely-live claim to 'owner-process-dead'. Cache our own
+// pid's start time after the first (real) read so every later read is
+// self-consistent with the fixtures instead of racing a fresh `ps` call.
+// isProcessAlive is left real (a plain `kill(pid, 0)` syscall, not a
+// subprocess), so the fabricated-dead-pid fixtures below still classify as
+// stale through that real, non-flaky check.
+vi.mock('../utils/host-process.ts', async () => {
+  const actual = await vi.importActual<typeof import('../utils/host-process.ts')>(
+    '../utils/host-process.ts',
+  );
+  let cachedOwnStartTime: string | null | undefined;
+  return {
+    ...actual,
+    readProcessStartTime: (pid: number) => {
+      if (pid !== process.pid) return null;
+      if (cachedOwnStartTime === undefined) {
+        cachedOwnStartTime = actual.readProcessStartTime(process.pid);
+      }
+      return cachedOwnStartTime;
+    },
+  };
+});
+
 test('device status is daemonless and does not send a daemon request', async () => {
   const result = await runCliCapture(['device', 'status', '--json']);
   assert.equal(result.code, null);
diff --git a/src/platforms/apple/core/__tests__/runner-session.test.ts b/src/platforms/apple/core/__tests__/runner-session.test.ts
index a401e900c..c29d31541 100644
--- a/src/platforms/apple/core/__tests__/runner-session.test.ts
+++ b/src/platforms/apple/core/__tests__/runner-session.test.ts
@@ -24,6 +24,7 @@ const {
   mockIsProcessAlive,
   mockIsProcessGroupAlive,
   mockPrepareXctestrunWithEnv,
+  mockReadProcessStartTime,
   mockResolveExpectedRunnerCacheMetadata,
   mockResolveRunnerDerivedPath,
   mockRunAppleToolCommand,
@@ -40,6 +41,12 @@ const {
   mockIsProcessAlive: vi.fn(),
   mockIsProcessGroupAlive: vi.fn(),
   mockPrepareXctestrunWithEnv: vi.fn(),
+  // Non-empty default: RUNNER_OWNER_START_TIME below is computed at module
+  // load (before beforeEach), and readProcessStartTime's real implementation
+  // shells out to `ps` with a 1s timeout that can miss under CPU contention,
+  // flipping a live owner to 'owner-process-dead'. Deterministic value, no
+  // shell-out; identity is still enforced by pid in beforeEach below.
+  mockReadProcessStartTime: vi.fn((_pid: number) => 'fixed-test-owner-start-time' as string | null),
   mockResolveExpectedRunnerCacheMetadata: vi.fn(),
   mockResolveRunnerDerivedPath: vi.fn(),
   mockRunAppleToolCommand: vi.fn(),
@@ -68,6 +75,7 @@ vi.mock('../../../../utils/host-process.ts', async () => {
     ...actual,
     isProcessAlive: mockIsProcessAlive,
     isProcessGroupAlive: mockIsProcessGroupAlive,
+    readProcessStartTime: mockReadProcessStartTime,
   };
 });
 
@@ -156,6 +164,12 @@ beforeEach(async () => {
   mockRunAppleToolCommand.mockResolvedValue({ exitCode: 0, stdout: '', stderr: '' });
   mockIsProcessAlive.mockReturnValue(true);
   mockIsProcessGroupAlive.mockReturnValue(false);
+  // Our pid reads back its fixed start time; any other pid reads as
+  // not-found, same as a real `ps` miss. Dead-lease tests use fabricated
+  // pids already rejected by mockIsProcessAlive before this is consulted.
+  mockReadProcessStartTime.mockImplementation((pid: number) =>
+    pid === process.pid ? RUNNER_OWNER_START_TIME : null,
+  );
   mockWaitForRunner.mockResolvedValue(runnerResponse({ uptimeMs: 1 }));
 });
 
diff --git a/src/utils/__tests__/daemon-client.test.ts b/src/utils/__tests__/daemon-client.test.ts
index 1594d31b7..3b67f90af 100644
--- a/src/utils/__tests__/daemon-client.test.ts
+++ b/src/utils/__tests__/daemon-client.test.ts
@@ -1,4 +1,4 @@
-import { test } from 'vitest';
+import { test, vi } from 'vitest';
 import assert from 'node:assert/strict';
 import http from 'node:http';
 import net from 'node:net';
@@ -36,6 +36,36 @@ import {
 import { stopProcessForTakeover } from '../../daemon/daemon-process.ts';
 import { findProjectRoot, readVersion } from '../version.ts';
 
+// readProcessStartTime/readProcessCommand shell out to `ps` with a 1s
+// timeout (see host-process.ts). isAgentDeviceDaemonProcess re-reads both for
+// every liveness check, so a spawned-daemon fixture that is proven live once
+// (a real read, right after the process starts) can still be misclassified
+// as dead later if a *subsequent* `ps` call happens to miss its deadline
+// under full-suite CPU contention. mockReadProcessStartTime/mockReadProcessCommand
+// default to `undefined`, which falls through to the real implementation for
+// every pid in every test in this file; only the one test below that needs a
+// stable answer for its spawned pid configures an override, and clears it
+// afterward.
+const { mockReadProcessStartTime, mockReadProcessCommand } = vi.hoisted(() => ({
+  mockReadProcessStartTime: vi.fn<(pid: number) => string | null | undefined>(),
+  mockReadProcessCommand: vi.fn<(pid: number) => string | null | undefined>(),
+}));
+
+vi.mock('../host-process.ts', async () => {
+  const actual = await vi.importActual<typeof import('../host-process.ts')>('../host-process.ts');
+  return {
+    ...actual,
+    readProcessStartTime: (pid: number) => {
+      const overridden = mockReadProcessStartTime(pid);
+      return overridden !== undefined ? overridden : actual.readProcessStartTime(pid);
+    },
+    readProcessCommand: (pid: number) => {
+      const overridden = mockReadProcessCommand(pid);
+      return overridden !== undefined ? overridden : actual.readProcessCommand(pid);
+    },
+  };
+});
+
 type MockHttpResponse = EventEmitter & {
   headers?: Record<string, string>;
   statusCode?: number;
@@ -413,11 +443,25 @@ test('cleanupFailedDaemonStartupMetadata retains live startup daemon on timeout'
 
   try {
     await new Promise((resolve) => setTimeout(resolve, 50));
+    // Read the spawned daemon's real identity once (ground truth: it is
+    // genuinely alive, with this real start time and command line), then
+    // pin readProcessStartTime/readProcessCommand to keep returning these
+    // same proven-real values for this pid. isAgentDeviceDaemonProcess reads
+    // both again internally on every call inside cleanupFailedDaemonStartupMetadata;
+    // without pinning, a second real `ps` call could miss its 1s timeout
+    // under load and misclassify this genuinely-live daemon as dead.
     const processStartTime = readProcessStartTime(pid) ?? undefined;
-    if (readProcessCommand(pid) === null || processStartTime === undefined) {
+    const command = readProcessCommand(pid);
+    if (command === null || processStartTime === undefined) {
       t.skip('process command/start inspection is unavailable in this environment');
       return;
     }
+    mockReadProcessStartTime.mockImplementation((queriedPid: number) =>
+      queriedPid === pid ? processStartTime : undefined,
+    );
+    mockReadProcessCommand.mockImplementation((queriedPid: number) =>
+      queriedPid === pid ? command : undefined,
+    );
 
     const paths = resolveDaemonPaths(stateDir);
     fs.mkdirSync(paths.baseDir, { recursive: true });
@@ -450,6 +494,8 @@ test('cleanupFailedDaemonStartupMetadata retains live startup daemon on timeout'
     assert.equal(fs.existsSync(paths.infoPath), true);
     assert.equal(fs.existsSync(paths.lockPath), true);
   } finally {
+    mockReadProcessStartTime.mockReset();
+    mockReadProcessCommand.mockReset();
     if (isProcessAlive(pid)) {
       process.kill(pid, 'SIGKILL');
       await waitForProcessExit(pid, 1_500);