test(expo): boot each iOS lane without its background services on CI

.changeset/slim-expo-e2e-simulators.md

@@ -0,0 +1,2 @@
+---
+---

.claude/skills/verify-clerk-expo/SKILL.md

@@ -23,6 +23,7 @@ Set up each machine once.
 2. Create the iOS template simulator, which the CLI clones to make each simulator it drives, with `xcrun simctl create "Clerk Verify Template iOS" "iPhone Air"`. That makes a new simulator that holds only the system's apps. Do not clone a simulator you already use: a clone holds every app of the original, and those apps show on the home screen at the start of a video. Boot the template once and shut it down: a clone of a template that never booted takes about twenty seconds longer to boot. `doctor` says when a system HTTPS proxy needs its CA trusted there. Android needs no template: the first `up --platform android` writes the `Clerk_Verify_Pixel` AVD.
 3. Give the machine the team's Clerk Platform API key. Set `CLERK_PLATFORM_API_KEY` to the key. Or set `CLERK_PLATFORM_API_KEY_FILE` to a file that holds it and that only you can read (mode 0600). Or set `VERIFY_PLATFORM_KEY_REFERENCE` to the key's 1Password secret reference, which the 1Password CLI reads once a person approves the request in the 1Password app, within 60 seconds. Never put the key or the reference in a file inside a repository.
 4. Install ffmpeg (`brew install ffmpeg`), which `attach --video` uses to cut the video to the part that `host.evidence` marks. Without it, `attach` posts the whole video and says that ffmpeg is not installed.
+5. Install simslim (`brew install mobai-app/tap/simslim`), so that each local iOS simulator boots without its background services and uses about a quarter of the memory. `doctor` says whether it is installed. Set `VERIFY_SIMSLIM=0` to boot stock simulators.
 
 Then, in each worktree:
 

.github/workflows/verify-e2e.yml

@@ -123,10 +123,25 @@ jobs:
       - name: Wait for the device image
         wait: device-image
 
+      - name: Install simslim
+        if: matrix.platform == 'ios'
+        run: |
+          set -euo pipefail
+          archive="$RUNNER_TEMP/simslim.tar.gz"
+          curl --fail --silent --show-error --location --retry 3 --output "$archive" \
+            https://github.com/MobAI-App/simslim/releases/download/v0.12.2/simslim-v0.12.2-macos-arm64.tar.gz
+          echo "b47302da6fb83b8b4c21f4fdd61507469770c07b0ff07fd1f48207bda4270887  $archive" | shasum -a 256 -c -
+          mkdir -p "$RUNNER_TEMP/bin"
+          tar -xzf "$archive" -C "$RUNNER_TEMP/bin" simslim
+          echo "$RUNNER_TEMP/bin" >> "$GITHUB_PATH"
+
       - name: Build the fixture and boot a device
         timeout-minutes: 30
         env:
           CLERK_PLATFORM_API_KEY: ${{ secrets.MOBILE_VERIFICATION_PLATFORM_API_KEY }}
+          VERIFY_SIMSLIM: ${{ matrix.platform == 'ios' && '1' || '' }}
+          SIMSLIM_BOOT_TIMEOUT: 15m
+          SIMSLIM_SPAWN_TIMEOUT: 5m
         run: |
           "$CLI" up --platform "$PLATFORM" --backend local
 

integration/expo-native/src/platform/ios/local.ts

@@ -10,6 +10,7 @@ import {
   type AcquireRequest,
   type DeviceBackend,
   type DoctorCheck,
+  type DoctorCheckId,
   type EvidencePath,
   type LocalLease,
   type Recording,
@@ -41,6 +42,47 @@ async function simctl(args: readonly string[], what: string): Promise<string> {
   return result.stdout;
 }
 
+// VERIFY_SIMSLIM=1 requires simslim and VERIFY_SIMSLIM=0 turns it off; otherwise a lane is slimmed
+// whenever simslim is installed.
+export function laneBoot(flag: string | undefined, simslimInstalled: boolean): 'slim' | 'stock' {
+  if (flag === '1') return 'slim';
+  if (flag === '0') return 'stock';
+  return simslimInstalled ? 'slim' : 'stock';
+}
+
+async function simslimVersion(): Promise<string | null> {
+  const probe = await run('simslim', ['--version']);
+  return probe.code === 0 ? probe.stdout.trim().replace(/^simslim\s+/, '') : null;
+}
+
+// A clone does not inherit simslim's overrides, so each lane is slimmed before its first boot, when
+// the background services it turns off would otherwise keep the host's cores busy for minutes.
+async function boot(udid: string, name: string): Promise<void> {
+  if (laneBoot(process.env.VERIFY_SIMSLIM, (await simslimVersion()) !== null) === 'stock') {
+    await simctl(['boot', udid], `simctl boot ${name}`);
+    await simctl(['bootstatus', udid, '-b'], `simctl bootstatus ${name}`);
+    return;
+  }
+  const slim = await run('simslim', ['on', udid]);
+  if (slim.code !== 0) {
+    throw new VerifyFailure('NOT_READY', `simslim on ${name} failed: ${slim.stderr.trim() || slim.stdout.trim()}`, 'install simslim, or set VERIFY_SIMSLIM=0');
+  }
+}
+
+async function simslimCheck(): Promise<DoctorCheck> {
+  // The shared DoctorCheckId union has no simslim entry yet.
+  const id = 'simslim' as DoctorCheckId;
+  const version = await simslimVersion();
+  if (version === null) {
+    return process.env.VERIFY_SIMSLIM === '1'
+      ? { id, ok: false, detail: 'VERIFY_SIMSLIM=1 needs simslim, and it is not installed', fix: 'brew install mobai-app/tap/simslim, or unset VERIFY_SIMSLIM' }
+      : { id, ok: true, state: 'warning', detail: 'not installed; lanes boot stock (brew install mobai-app/tap/simslim)' };
+  }
+  return laneBoot(process.env.VERIFY_SIMSLIM, true) === 'slim'
+    ? { id, ok: true, detail: `slim on (simslim ${version})` }
+    : { id, ok: true, state: 'warning', detail: `simslim ${version} is installed; VERIFY_SIMSLIM=0 keeps lanes stock` };
+}
+
 function simulatorDataDir(udid: string): string {
   return join(homedir(), 'Library', 'Developer', 'CoreSimulator', 'Devices', udid, 'data');
 }
@@ -116,8 +158,7 @@ export function localIosBackend(options: { readonly os?: NodeJS.Platform } = {})
         await deleteSimulators((d) => d.name === claim.deviceName);
         request.progress(`device  ${claim.deviceName}  cloning ${TEMPLATE_NAME}`);
         udid = (await simctl(['clone', template.udid, claim.deviceName], `simctl clone ${claim.deviceName}`)).trim();
-        await simctl(['boot', udid], `simctl boot ${claim.deviceName}`);
-        await simctl(['bootstatus', udid, '-b'], `simctl bootstatus ${claim.deviceName}`);
+        await boot(udid, claim.deviceName);
       } catch (error) {
         await clearSlot(claim, request.worktree).catch(() => undefined);
         throw error;
@@ -228,6 +269,7 @@ export function localIosBackend(options: { readonly os?: NodeJS.Platform } = {})
         xcode.code === 0
           ? { id: 'xcode', ok: true, detail: xcode.stdout.split('\n')[0]?.replace('Xcode ', '') ?? '' }
           : { id: 'xcode', ok: false, detail: 'xcodebuild is not available', fix: 'install Xcode and run `sudo xcode-select -s /Applications/Xcode.app`' },
+        await simslimCheck(),
       ];
       const template = xcode.code === 0 ? (await listSimulators()).find((d) => d.name === TEMPLATE_NAME) : undefined;
       const device: DoctorCheck[] = [

integration/expo-native/test/ios-doctor.test.ts

@@ -4,7 +4,7 @@ import { chmodSync, mkdtempSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { describe, it } from 'node:test';
-import { localIosBackend } from '../src/platform/ios/local.ts';
+import { laneBoot, localIosBackend } from '../src/platform/ios/local.ts';
 
 describe('iOS doctor', () => {
   it('reports the missing Xcode rather than failing when xcrun simctl cannot run', async () => {
@@ -17,10 +17,18 @@ describe('iOS doctor', () => {
     process.env.PATH = bin;
     try {
       const { toolchain, device } = await localIosBackend({ os: 'darwin' }).doctorChecks({ live: false, worktree: '/nowhere', progress: () => undefined });
-      assert.deepEqual(toolchain.map(({ id, ok }) => ({ id, ok })), [{ id: 'xcode', ok: false }]);
+      assert.deepEqual(toolchain.map(({ id, ok }) => ({ id, ok })), [{ id: 'xcode', ok: false }, { id: 'simslim', ok: true }]);
+      assert.deepEqual(toolchain[1], { id: 'simslim', ok: true, state: 'warning', detail: 'not installed; lanes boot stock (brew install mobai-app/tap/simslim)' });
       assert.deepEqual(device.find((check) => check.id === 'lane-ports'), { id: 'lane-ports', ok: true, state: 'not-run', detail: 'not run: needs xcode' });
     } finally {
       process.env.PATH = path;
     }
   });
+
+  it('slims a lane whenever simslim is installed, unless VERIFY_SIMSLIM says otherwise', () => {
+    assert.equal(laneBoot(undefined, true), 'slim');
+    assert.equal(laneBoot(undefined, false), 'stock');
+    assert.equal(laneBoot('0', true), 'stock');
+    assert.equal(laneBoot('1', false), 'slim');
+  });
 });