ci(preflight): use host-GPU auto-no-window for local api37 emulator

Change the api37_e2e.py emulator launch from `-gpu swiftshader_indirect`
to `-gpu auto-no-window`. For a LOCAL run the host GPU is faster and
auto-no-window is the mode that boots cleanly on this machine; CI's
e2e-preview keeps swiftshader_indirect for headless-runner determinism.
This is now the single deliberate divergence from e2e-preview; the image
string, provisioning, boot sequence, and every other emulator flag stay
in lockstep. Updated the script comments/docstring, SKILL.md, CLAUDE.md,
and the build.gradle.kts managed-devices comment to document it.

Syntax-only change (python -m py_compile clean); emulator not run.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.claude/skills/preflight/SKILL.md

@@ -64,17 +64,20 @@ Managed Device — its only published system image is the nonstandard `android-3
 `google_apis_ps16k` pairing, which neither `ManagedVirtualDevice`'s `apiLevel` (Int) nor
 `apiPreview` (codename) DSL resolves (see the comment above `testOptions.managedDevices` in
 `app/build.gradle.kts`), so there is no `api37DebugAndroidTest` task. The script hand-provisions
-it exactly the way CI's `e2e-preview` job does — installs the image with `sdkmanager`, creates
-the AVD with `avdmanager`, cold-boots it headless with the same emulator flags, waits for
-`sys.boot_completed`, runs `:app:connectedDebugAndroidTest`, then kills the emulator and deletes
-the AVD. Because it mirrors `e2e-preview`, local preflight == CI on API 37.
+it essentially the way CI's `e2e-preview` job does — installs the image with `sdkmanager`,
+creates the AVD with `avdmanager`, cold-boots it headless, waits for `sys.boot_completed`, runs
+`:app:connectedDebugAndroidTest`, then kills the emulator and deletes the AVD. The emulator flags
+match `e2e-preview` with one deliberate local exception: the **GPU mode**. CI uses
+`-gpu swiftshader_indirect` (software rendering, deterministic on a headless CI runner); the
+local run uses `-gpu auto-no-window`, which renders on the host GPU — faster, and the mode that
+boots cleanly on a dev machine.
 
 All three levels are the E2E that preflight runs locally and all three must pass; CI fans the
 same suite out across the whole matrix (API 29–36 in `e2e`, plus API 37 in `e2e-preview`). Keep
 `api35DebugAndroidTest` / `api36DebugAndroidTest` in lockstep with the top of the managed-device
 list in `app/build.gradle.kts`, and keep `api37_e2e.py` in lockstep with the `e2e-preview` job in
-`.github/workflows/ci.yml` (same image string + emulator flags) — when a newer API level is added
-there, run the new top levels instead.
+`.github/workflows/ci.yml` (same image string + emulator flags, apart from the intentional GPU-mode
+difference noted above) — when a newer API level is added there, run the new top levels instead.
 
 ## Reporting
 

.claude/skills/preflight/api37_e2e.py

@@ -11,9 +11,11 @@ API 37's only published system image is the nonstandard "android-37.0" / google_
 "android-<apiLevel:Int>" package id (apiLevel = 37 -> "android-37") or an
 "android-<apiPreview:codename>" one -- neither resolves to "android-37.0" -- so there is NO
 api37DebugAndroidTest task to run. This script custom-provisions the emulator with
-sdkmanager / avdmanager / emulator directly, mirroring CI's `e2e-preview` job in
-.github/workflows/ci.yml EXACTLY (same system image string, same emulator flags, same
-provisioning/boot sequence) so that local preflight == CI. Keep the two in lockstep: when a
+sdkmanager / avdmanager / emulator directly, closely mirroring CI's `e2e-preview` job in
+.github/workflows/ci.yml (same system image string, same provisioning/boot sequence, same
+emulator flags EXCEPT the GPU mode -- CI uses `-gpu swiftshader_indirect` for headless
+determinism, while this local run uses `-gpu auto-no-window` to render on the host GPU, which
+is faster; see start_emulator). Keep the two in lockstep on everything but that GPU flag: when a
 stable, GMD-compatible API 37 image ships, delete this script, fold api37 into
 testOptions.managedDevices, and fold 37 into CI's `e2e` matrix (dropping the `e2e-preview` job).
 
@@ -117,12 +119,16 @@ def create_avd(avdmanager: str, emulator: str) -> None:
 
 def start_emulator(emulator: str, emu_log: Path, attempt: int) -> subprocess.Popen:
     print(f"Starting API 37 emulator (attempt {attempt})...")
-    # Flags mirror .github/workflows/ci.yml e2e-preview EXACTLY (cold headless boot, SwiftShader
-    # GPU, hardware accel required, no cameras). Keep in lockstep with that job.
+    # Flags mirror .github/workflows/ci.yml e2e-preview (cold headless boot, hardware accel
+    # required, no cameras), with ONE deliberate LOCAL exception -- the GPU mode. CI uses
+    # `-gpu swiftshader_indirect` (software rendering, deterministic on a headless CI runner);
+    # locally we use `-gpu auto-no-window`, which renders on the host GPU: faster, and the mode
+    # that boots cleanly on a dev machine. Keep everything except the GPU mode in lockstep with
+    # that job.
     flags = [
         "-avd", AVD_NAME,
         "-no-window", "-no-audio", "-no-boot-anim", "-no-snapshot", "-accel", "on",
-        "-gpu", "swiftshader_indirect", "-camera-back", "none", "-camera-front", "none",
+        "-gpu", "auto-no-window", "-camera-back", "none", "-camera-front", "none",
     ]
     log = open(emu_log, "wb")  # noqa: SIM115 - handed to the child; closed in the parent below
     try:

CLAUDE.md

@@ -39,8 +39,9 @@ top two stable API levels in the E2E matrix, each via its own Gradle Managed Dev
 and tears down each emulator automatically). API 37 (preview) has no Gradle Managed Device — its
 only image is the nonstandard `android-37.0` / `google_apis_ps16k` pairing (see the comment above
 `testOptions.managedDevices` in `app/build.gradle.kts`) — so `api37_e2e.py` hand-provisions it,
-mirroring CI's `e2e-preview` job (same image + emulator flags), boots it headless, runs
-`connectedDebugAndroidTest`, and tears it down. Running all three levels locally is required; the
+mirroring CI's `e2e-preview` job (same image + emulator flags, except it uses host-GPU
+`-gpu auto-no-window` locally vs CI's headless `-gpu swiftshader_indirect`), boots it headless,
+runs `connectedDebugAndroidTest`, and tears it down. Running all three levels locally is required; the
 rest of the multi-API matrix (API 29–34) stays CI's job. Emulators need a free hardware
 hypervisor (VT-x/WHPX), so shut down VirtualBox/other VMs first or the AVD hangs at 0% CPU.
 

app/build.gradle.kts

@@ -159,9 +159,10 @@ android {
         // (docs/perf/issue-124-unified-inbox-paging.md) independently corroborates this: its API 37
         // cross-check used a physical Pixel, not an emulator/AVD. Locally, preflight covers API 37
         // by hand-provisioning it with .claude/skills/preflight/api37_e2e.py, which mirrors the
-        // e2e-preview job (same image + emulator flags). Once a managed-device-compatible image is
-        // published, add `api37` here (and to the CI matrix), delete that script, and drop the
-        // e2e-preview job.
+        // e2e-preview job (same image + emulator flags, except it renders on the host GPU via
+        // `-gpu auto-no-window` locally instead of CI's headless `-gpu swiftshader_indirect`). Once
+        // a managed-device-compatible image is published, add `api37` here (and to the CI matrix),
+        // delete that script, and drop the e2e-preview job.
         managedDevices {
             localDevices {
                 listOf(29, 30, 31, 32, 33, 34, 35, 36).forEach { api ->