ci: measure iOS simulator startup timings

.github/workflows/e2e-tests.yml

@@ -146,10 +146,10 @@ jobs:
           node-version: '24.10.0'
           cache: 'pnpm'
 
-      - name: Setup Xcode 26.4.1
+      - name: Setup Xcode 26.6
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1.7.0
         with:
-          xcode-version: '26.4.1'
+          xcode-version: '26.6'
 
       - name: Install Watchman
         run: brew install watchman

.github/workflows/ios-simulator-startup-timings.yml

@@ -0,0 +1,170 @@
+name: Simulator boot benchmark
+
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  simulator-boot:
+    strategy:
+      fail-fast: false
+      matrix:
+        runtime:
+          - iOS-26-2
+          - iOS-26-4
+          - iOS-26-5
+
+    runs-on: macos-26
+    timeout-minutes: 20
+
+    steps:
+      - name: Select Xcode 26.6
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          sudo xcode-select \
+            --switch /Applications/Xcode_26.6.app/Contents/Developer
+
+          xcodebuild -version
+
+          echo "SIMULATOR_CACHE_KEY=core-simulator-device-ios-26-5-xcode-26-6-${ImageOS}-${ImageVersion}" >> "$GITHUB_ENV"
+
+      - name: Restore iOS 26.5 simulator cache
+        id: cache-ios-26-5-restore
+        if: matrix.runtime == 'iOS-26-5'
+        uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: ~/Library/Developer/CoreSimulator/Devices/FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E
+          key: ${{ env.SIMULATOR_CACHE_KEY }}
+
+      - name: Inspect available simulators
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          xcrun simctl list runtimes
+          xcrun simctl list devices available
+
+      - name: Measure existing simulator boot
+        shell: bash
+        env:
+          RUNTIME_SUFFIX: ${{ matrix.runtime }}
+          DEVICE_NAME: iPhone 17 Pro
+        run: |
+          set -euo pipefail
+
+          RUNTIME_ID="com.apple.CoreSimulator.SimRuntime.${RUNTIME_SUFFIX}"
+          BOOT_LOG="$RUNNER_TEMP/bootstatus-${RUNTIME_SUFFIX}.log"
+
+          echo "Looking for:"
+          echo "  Runtime: $RUNTIME_ID"
+          echo "  Device:  $DEVICE_NAME"
+
+          # Verify that the requested runtime is installed.
+          if ! xcrun simctl list runtimes -j |
+            jq -e --arg runtime "$RUNTIME_ID" '
+              .runtimes[]
+              | select(
+                  .identifier == $runtime
+                  and .isAvailable == true
+                )
+            ' >/dev/null; then
+            echo "::error::Runtime $RUNTIME_ID is not available"
+            exit 1
+          fi
+
+          # Select an existing available device only.
+          UDID="$(
+            xcrun simctl list devices available -j |
+              jq -er \
+                --arg runtime "$RUNTIME_ID" \
+                --arg name "$DEVICE_NAME" '
+                  .devices[$runtime]
+                  | map(
+                      select(
+                        .name == $name
+                        and .isAvailable == true
+                      )
+                    )
+                  | .[0].udid
+                '
+          )" || {
+            echo "::error::No existing $DEVICE_NAME found for $RUNTIME_ID"
+            echo "Available devices:"
+            xcrun simctl list devices available
+            exit 1
+          }
+
+          echo "Selected existing simulator:"
+          echo "  $DEVICE_NAME"
+          echo "  $RUNTIME_ID"
+          echo "  $UDID"
+
+          # Do not erase, recreate, or delete the selected device.
+          xcrun simctl shutdown "$UDID" 2>/dev/null || true
+
+          START_SECONDS="$(date +%s)"
+
+          echo "=== Boot request ==="
+          time xcrun simctl boot "$UDID"
+
+          echo "=== Boot completion ==="
+          set +e
+          xcrun simctl bootstatus "$UDID" -b 2>&1 |
+            tee "$BOOT_LOG"
+          BOOT_STATUS="${PIPESTATUS[0]}"
+          set -e
+
+          END_SECONDS="$(date +%s)"
+          ELAPSED_SECONDS="$((END_SECONDS - START_SECONDS))"
+
+          MIGRATION_SAMPLES="$(
+            grep -c "Waiting on Data Migration" "$BOOT_LOG" || true
+          )"
+
+          {
+            echo "### Existing simulator boot result"
+            echo
+            echo "- Runtime: \`$RUNTIME_ID\`"
+            echo "- Device: \`$DEVICE_NAME\`"
+            echo "- UDID: \`$UDID\`"
+            echo "- Duration: **${ELAPSED_SECONDS}s**"
+            echo "- Migration samples: **${MIGRATION_SAMPLES}**"
+            echo "- Runner image: \`${ImageOS:-unknown}\`"
+            echo "- Image version: \`${ImageVersion:-unknown}\`"
+          } >> "$GITHUB_STEP_SUMMARY"
+
+          if [[ "$BOOT_STATUS" -ne 0 ]]; then
+            echo "::error::Simulator failed to finish booting"
+            exit "$BOOT_STATUS"
+          fi
+
+      - name: Shut down iOS 26.5 simulator before caching
+        id: shutdown-ios-26-5
+        if: always() && matrix.runtime == 'iOS-26-5'
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          UDID="FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E"
+          xcrun simctl shutdown "$UDID" || true
+
+          for _ in {1..30}; do
+            if xcrun simctl list devices | grep -F "$UDID" | grep -q '(Shutdown)'; then
+              exit 0
+            fi
+            sleep 1
+          done
+
+          echo "::error::Simulator $UDID did not shut down before caching"
+          exit 1
+
+      - name: Save iOS 26.5 simulator cache
+        if: always() && matrix.runtime == 'iOS-26-5' && steps.shutdown-ios-26-5.outcome == 'success' && steps.cache-ios-26-5-restore.outputs.cache-hit != 'true'
+        uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: ~/Library/Developer/CoreSimulator/Devices/FD9EC0F9-63AA-4C2F-B0F5-224AAE68866E
+          key: ${{ steps.cache-ios-26-5-restore.outputs.cache-primary-key }}