diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d22b0d3..69885cda 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@
 - Added `toggle_connect_hardware_keyboard` tool to toggle the iOS Simulator hardware keyboard connection ([#346](https://github.com/getsentry/XcodeBuildMCP/issues/346)).
 - Fixed `xcode_tools_bridge_disconnect` immediately re-syncing proxied tools after a manual disconnect ([#343](https://github.com/getsentry/XcodeBuildMCP/issues/343)).
 - Stopped suggesting an unsupported `--device-id`/`deviceId` argument in the `device list` next-step hint for `device build`/`build_device`; device targeting flows through session defaults ([#350](https://github.com/getsentry/XcodeBuildMCP/pull/350) by [@MukundaKatta](https://github.com/MukundaKatta)).
+- Fixed simulator defaults refresh to reconcile stale `simulatorId` values in memory when both `simulatorId` and `simulatorName` are configured, while still avoiding config write-back churn across contributors ([#357](https://github.com/getsentry/XcodeBuildMCP/issues/357)).
 
 ## [2.3.2]
 
diff --git a/src/utils/__tests__/simulator-defaults-refresh.test.ts b/src/utils/__tests__/simulator-defaults-refresh.test.ts
new file mode 100644
index 00000000..bb39e8f2
--- /dev/null
+++ b/src/utils/__tests__/simulator-defaults-refresh.test.ts
@@ -0,0 +1,168 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+const {
+  persistSessionDefaultsPatchMock,
+  resolveSimulatorNameToIdMock,
+  resolveSimulatorIdToNameMock,
+  inferPlatformMock,
+  logMock,
+} = vi.hoisted(() => ({
+  persistSessionDefaultsPatchMock: vi.fn(),
+  resolveSimulatorNameToIdMock: vi.fn(),
+  resolveSimulatorIdToNameMock: vi.fn(),
+  inferPlatformMock: vi.fn(),
+  logMock: vi.fn(),
+}));
+
+vi.mock('../config-store.ts', () => ({
+  persistSessionDefaultsPatch: persistSessionDefaultsPatchMock,
+}));
+
+vi.mock('../simulator-resolver.ts', () => ({
+  resolveSimulatorNameToId: resolveSimulatorNameToIdMock,
+  resolveSimulatorIdToName: resolveSimulatorIdToNameMock,
+}));
+
+vi.mock('../infer-platform.ts', () => ({
+  inferPlatform: inferPlatformMock,
+}));
+
+vi.mock('../logger.ts', () => ({
+  log: logMock,
+}));
+
+import { sessionStore } from '../session-store.ts';
+import { scheduleSimulatorDefaultsRefresh } from '../simulator-defaults-refresh.ts';
+
+describe('scheduleSimulatorDefaultsRefresh', () => {
+  const originalNodeEnv = process.env.NODE_ENV;
+  const originalVitestEnv = process.env.VITEST;
+
+  beforeEach(() => {
+    sessionStore.clearAll();
+    persistSessionDefaultsPatchMock.mockReset();
+    resolveSimulatorNameToIdMock.mockReset();
+    resolveSimulatorIdToNameMock.mockReset();
+    inferPlatformMock.mockReset();
+    logMock.mockReset();
+
+    process.env.NODE_ENV = 'development';
+    delete process.env.VITEST;
+
+    inferPlatformMock.mockResolvedValue({
+      platform: 'iOS Simulator',
+      source: 'simulator-runtime',
+    });
+  });
+
+  afterEach(() => {
+    process.env.NODE_ENV = originalNodeEnv;
+    if (originalVitestEnv == null) {
+      delete process.env.VITEST;
+    } else {
+      process.env.VITEST = originalVitestEnv;
+    }
+
+    vi.useRealTimers();
+  });
+
+  async function runRefresh(options: { simulatorId?: string; simulatorName?: string }) {
+    vi.useFakeTimers();
+
+    const defaults = {
+      ...(options.simulatorId != null ? { simulatorId: options.simulatorId } : {}),
+      ...(options.simulatorName != null ? { simulatorName: options.simulatorName } : {}),
+    };
+    sessionStore.setDefaults(defaults);
+    const expectedRevision = sessionStore.getRevision();
+
+    const scheduled = scheduleSimulatorDefaultsRefresh({
+      expectedRevision,
+      reason: 'startup-hydration',
+      profile: null,
+      persist: false,
+      simulatorId: options.simulatorId,
+      simulatorName: options.simulatorName,
+    });
+
+    expect(scheduled).toBe(true);
+    await vi.runAllTimersAsync();
+  }
+
+  it('resolves simulatorName to simulatorId once when only name is set', async () => {
+    resolveSimulatorNameToIdMock.mockResolvedValue({
+      success: true,
+      simulatorId: 'SIM-1',
+      simulatorName: 'iPhone 17 Pro',
+    });
+
+    await runRefresh({ simulatorName: 'iPhone 17 Pro' });
+
+    expect(resolveSimulatorNameToIdMock).toHaveBeenCalledTimes(1);
+    expect(resolveSimulatorIdToNameMock).not.toHaveBeenCalled();
+    expect(sessionStore.getAll()).toEqual({
+      simulatorId: 'SIM-1',
+      simulatorName: 'iPhone 17 Pro',
+      simulatorPlatform: 'iOS Simulator',
+    });
+    expect(persistSessionDefaultsPatchMock).not.toHaveBeenCalled();
+  });
+
+  it('does not patch defaults when both values are set and name resolves to same id', async () => {
+    resolveSimulatorNameToIdMock.mockResolvedValue({
+      success: true,
+      simulatorId: 'SIM-1',
+      simulatorName: 'iPhone 17 Pro',
+    });
+    inferPlatformMock.mockResolvedValue({
+      platform: 'iOS Simulator',
+      source: 'default',
+    });
+
+    await runRefresh({ simulatorId: 'SIM-1', simulatorName: 'iPhone 17 Pro' });
+
+    expect(resolveSimulatorNameToIdMock).toHaveBeenCalledTimes(1);
+    expect(sessionStore.getAll()).toEqual({
+      simulatorId: 'SIM-1',
+      simulatorName: 'iPhone 17 Pro',
+    });
+    expect(persistSessionDefaultsPatchMock).not.toHaveBeenCalled();
+  });
+
+  it('patches simulatorId in memory when both are set and name resolves to a different id', async () => {
+    resolveSimulatorNameToIdMock.mockResolvedValue({
+      success: true,
+      simulatorId: 'SIM-2',
+      simulatorName: 'iPhone 17 Pro',
+    });
+
+    await runRefresh({ simulatorId: 'SIM-1', simulatorName: 'iPhone 17 Pro' });
+
+    expect(resolveSimulatorNameToIdMock).toHaveBeenCalledTimes(1);
+    expect(sessionStore.getAll()).toEqual({
+      simulatorId: 'SIM-2',
+      simulatorName: 'iPhone 17 Pro',
+      simulatorPlatform: 'iOS Simulator',
+    });
+    expect(persistSessionDefaultsPatchMock).not.toHaveBeenCalled();
+  });
+
+  it('keeps the existing simulatorId when name lookup fails and logs a warning', async () => {
+    resolveSimulatorNameToIdMock.mockRejectedValue(new Error('simctl failed'));
+
+    await runRefresh({ simulatorId: 'SIM-1', simulatorName: 'iPhone 17 Pro' });
+
+    expect(resolveSimulatorNameToIdMock).toHaveBeenCalledTimes(1);
+    expect(sessionStore.getAll()).toEqual({
+      simulatorId: 'SIM-1',
+      simulatorName: 'iPhone 17 Pro',
+    });
+    expect(logMock).toHaveBeenCalledWith(
+      'warn',
+      expect.stringContaining(
+        'Background simulator defaults refresh failed (startup-hydration): Error: simctl failed',
+      ),
+    );
+    expect(persistSessionDefaultsPatchMock).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/utils/simulator-defaults-refresh.ts b/src/utils/simulator-defaults-refresh.ts
index 1cbad03a..fab02a32 100644
--- a/src/utils/simulator-defaults-refresh.ts
+++ b/src/utils/simulator-defaults-refresh.ts
@@ -50,15 +50,13 @@ async function refreshSimulatorDefaults(
   const executor = options.executor ?? getDefaultCommandExecutor();
 
   try {
-    if (!simulatorId && simulatorName) {
+    if (simulatorName) {
       const resolution = await resolveSimulatorNameToId(executor, simulatorName);
-      if (resolution.success) {
+      if (resolution.success && resolution.simulatorId !== simulatorId) {
         simulatorId = resolution.simulatorId;
         patch.simulatorId = resolution.simulatorId;
       }
-    }
-
-    if (!simulatorName && simulatorId) {
+    } else if (simulatorId) {
       const resolution = await resolveSimulatorIdToName(executor, simulatorId);
       if (resolution.success) {
         simulatorName = resolution.simulatorName;