fix(snapshot): Handle teardown shutdown races

Treat an already-shut-down simulator as successful cleanup and align compiler-failure fixtures with the emitted result shape.

Author: cameroncooke

src/snapshot-tests/__fixtures__/cli/json/device/test--error-compiler.json

@@ -20,17 +20,11 @@
     "summary": {
       "status": "FAILED",
       "durationMs": 1234,
-      "counts": {
-        "passed": 0,
-        "failed": 0,
-        "skipped": 0
-      },
       "target": "device"
     },
     "artifacts": {
       "deviceId": "<UUID>",
-      "buildLogPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/logs/test_device_<TIMESTAMP>_pid<PID>.log",
-      "xcresultPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/result-bundles/test_device_<TIMESTAMP>_pid<PID>.xcresult"
+      "buildLogPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/logs/test_device_<TIMESTAMP>_pid<PID>.log"
     },
     "tests": {
       "selected": [

src/snapshot-tests/__fixtures__/mcp/json/device/test--error-compiler.json

@@ -7,17 +7,11 @@
     "summary": {
       "status": "FAILED",
       "durationMs": 1234,
-      "counts": {
-        "passed": 0,
-        "failed": 0,
-        "skipped": 0
-      },
       "target": "device"
     },
     "artifacts": {
       "deviceId": "<UUID>",
-      "buildLogPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/logs/test_device_<TIMESTAMP>_pid<PID>.log",
-      "xcresultPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/result-bundles/test_device_<TIMESTAMP>_pid<PID>.xcresult"
+      "buildLogPath": "~/Library/Developer/XcodeBuildMCP/workspaces/XcodeBuildMCP-<HASH>/logs/test_device_<TIMESTAMP>_pid<PID>.log"
     },
     "tests": {
       "selected": [

src/snapshot-tests/preflight/__tests__/simulator.test.ts

@@ -100,6 +100,40 @@ describe('simulator app preflight ownership', () => {
     ]);
   });
 
+  it('tolerates a cleanup shutdown that loses a race', async () => {
+    const cleanup = new CleanupStack();
+    const runner = vi
+      .fn<ExternalCommandRunner>()
+      .mockResolvedValueOnce(
+        commandResult(
+          JSON.stringify({
+            devices: { runtime: [{ udid: 'SIM-1', name: 'iPhone 17', state: 'Shutdown' }] },
+          }),
+        ),
+      )
+      .mockResolvedValueOnce(commandResult())
+      .mockResolvedValueOnce(commandResult())
+      .mockResolvedValueOnce(commandResult('', { exitCode: 2, stderr: 'Already shutdown' }))
+      .mockResolvedValueOnce(
+        commandResult(
+          JSON.stringify({
+            devices: { runtime: [{ udid: 'SIM-1', name: 'iPhone 17', state: 'Shutdown' }] },
+          }),
+        ),
+      );
+
+    await ensureSimulatorBooted('SIM-1', cleanup, runner);
+    await expect(cleanup.cleanup()).resolves.toBeUndefined();
+
+    expect(runner.mock.calls.map(([, args]) => args)).toEqual([
+      ['simctl', 'list', 'devices', 'available', '--json'],
+      ['simctl', 'boot', 'SIM-1'],
+      ['simctl', 'bootstatus', 'SIM-1', '-b'],
+      ['simctl', 'shutdown', 'SIM-1'],
+      ['simctl', 'list', 'devices', 'available', '--json'],
+    ]);
+  });
+
   it('replaces and cleans up a pre-existing fixture app', async () => {
     const cleanup = new CleanupStack();
     const runner = vi

src/snapshot-tests/preflight/simulator.ts

@@ -146,7 +146,13 @@ export async function ensureSimulatorBooted(
   if (options.shutdownOnCleanup !== false) {
     cleanup?.defer(`shut down simulator ${simulatorId}`, async () => {
       const result = await runner('xcrun', ['simctl', 'shutdown', simulatorId]);
-      assertExternalCommandSucceeded(result, `Shut down simulator ${simulatorId}`);
+      if (result.exitCode !== 0 || result.signal !== null || result.timedOut || result.spawnError) {
+        const currentState = (await readSimulator(simulatorId, runner)).state;
+        if (currentState === 'Shutdown') {
+          return;
+        }
+        assertExternalCommandSucceeded(result, `Shut down simulator ${simulatorId}`);
+      }
       await waitForSimulatorState(simulatorId, 'Shutdown', runner);
     });
   }