App 2.34.0: set the chosen drive mode again when the car starts

The car falls back to its own default mode at every start. With "Set at
start" (on by default), the service sets the mode last chosen on
Settings and confirmed by the car again, once, while the car is in P at
0 km/h, and gives up as soon as the car leaves P or after two minutes
(DriveModeWrite.atStart, unit-tested). The buttons and the start share
the write and read-back (DriveModeSetter). Not tried on the car.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhzAVaUyqcw5PkGjz4mWW6

AGENTS.md

@@ -36,10 +36,12 @@ Repository: `ssh://git@git.stinnesbeck.com:2222/nils/mg4.git` (remote `origin`),
    index for changes that are not yours (the owner works in parallel), and scan the staged diff
    for secrets before every commit. Never print a token.
 3. **Telemetry is read-only; the drive mode is the one exception.** The app writes no vehicle
-   setting except the drive mode (owner's decision, 2026-10-25): from Settings only, a tap by the
-   driver, only in P at 0 km/h with both read fresh (unreadable means no write), through
-   EVHardware's standstill gate, and the result shown is what the car reports back
-   (`DriveModeWrite`). Nothing else gets written, and nothing writes on its own. The only system
+   setting except the drive mode (owner's decision, 2026-10-25): a tap on Settings, or — with
+   "Set at start" on — once when the head unit starts, the mode last chosen there and confirmed
+   by the car, and only before the car first leaves P. Every write only in P at 0 km/h with both
+   read fresh (unreadable means no write), through EVHardware's standstill gate; the result
+   shown is what the car reports back (`DriveModeWrite`, `DriveModeSetter`). Nothing else is
+   written. The only system
    setting it touches is `policy_control`, and only to remove the CarPlay entry the withdrawn
    full-screen experiment (2.19.2–2.19.5) may have left.
 4. **A failed read is not a zero.** Unreadable values are `null`, omitted from payloads and
@@ -77,7 +79,7 @@ Repository: `ssh://git@git.stinnesbeck.com:2222/nils/mg4.git` (remote `origin`),
 | Consumption / Charging | period totals, daily log, charging sessions and curve |
 | Live data | on/off, ABRP API key and user token, upload frequency |
 | Server | URL, pairing by QR, ingest token, installation ID (read-only), config import |
-| Settings | drive mode (Eco, Normal, Sport, Snow, Custom; the lit one is what the car reports; changes only in P at a standstill, `DriveModeWrite`), full screen, voice key, Overview style with the accent colour beside it, the Mascot character (only for that style) (offered only for styles drawn in it, `OverviewStyle.usesAccent`; Retro and Terminal add "Original" for their own palette, `hasOriginal`), tyre unit, battery and charging price (one card on wide screens), version, update check, install from USB, About |
+| Settings | drive mode (Eco, Normal, Sport, Snow, Custom; the lit one is what the car reports; changes only in P at a standstill, `DriveModeWrite`; "Set at start" sets the last confirmed choice again when the service starts with the head unit), full screen, voice key, Overview style with the accent colour beside it, the Mascot character (only for that style) (offered only for styles drawn in it, `OverviewStyle.usesAccent`; Retro and Terminal add "Original" for their own palette, `hasOriginal`), tyre unit, battery and charging price (one card on wide screens), version, update check, install from USB, About |
 | Logs | signal recorder (`SignalRecorder`/`SignalRecording`: every property and vendor getter via `VendorSurfaceProbe.capture`, again and again for 3 minutes, plus steering-wheel key broadcasts; lists what changed, rarest first; saved to the app and a USB stick; how to find where the car publishes something), update log (every install step, with the platform's words), upload log |
 
 Key classes (`app/src/main/java/com/evsuite/abrp/`): `AbrpUploadService` (foreground service,