Add the handoff prompt for the phone-alarm session

Items 4/3/1 are their own session: new Kotlin on AGP 9 / Gradle 9 / Kotlin
2.3, an emulator that is not installed yet, and physical-device verification
at the end.

Records two prerequisites measured today rather than assumed: the app's
min/target/compileSdk are all still delegated to the Flutter plugin (no floor
to reason about full-screen-intent or foreground-service semantics), and only
/usr/bin/adb is on PATH — emulator, avdmanager and sdkmanager are absent, and
the image needs to be API 36 to match the phone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EckWmyfetYq3Mi8MAnUudh

TODO-phone-alarm-session.md

@@ -0,0 +1,96 @@
+# Next session: make the phone a real alarm (items 4, 3, 1)
+
+REMOVE ME AFTER FINISH
+
+Paste the block at the bottom into a fresh session. Everything above it is
+context for *you*, the human, deciding whether the framing is right.
+
+## Why this is its own session
+
+The PC half is done (phases 0–7, `4286fcb`..`c131923`). What is left is
+almost entirely new Kotlin + Dart on a bleeding-edge Android toolchain, needs
+an emulator that is not installed yet, and ends in physical-device
+verification. The plan calls it "biggest chunk by far. Own session."
+
+## State of the phone app, measured 2026-08-27 (not guessed)
+
+- `phone_app/lib/` has 3 screens and 7 services. **Zero alarm capability** —
+  it is a time picker that syncs a value.
+- `MainActivity.kt` exists at
+  `android/app/src/main/kotlin/com/kuhy/wake_alarm_sync/MainActivity.kt` and
+  is bare. `applicationId = "com.kuhy.wake_alarm_sync"`.
+- **`minSdk`/`targetSdk`/`compileSdk` are all delegated** to the Flutter
+  Gradle plugin (`flutter.minSdkVersion` etc.) — there is no floor, and
+  full-screen-intent and foreground-service semantics cannot be reasoned
+  about without one. Pin them first.
+- **Only `/usr/bin/adb` is on PATH.** No `emulator`, no `avdmanager`, no
+  `sdkmanager`. The emulator work in the plan needs these installed first,
+  and the emulator image must be **API 36** to match the phone — the API 34
+  image validates against semantics the target device does not have.
+
+## The prompt
+
+```
+Implement items 4, 3 and 1 from TODO-hardening-continue.md in ~/wake-alarm —
+the phone half of the wake alarm.
+
+Read first, in this order:
+  1. TODO-hardening-continue.md          (state, decisions, traps)
+  2. ~/.claude/plans/wake-alarm-still-does-witty-toucan.md, phases 4 and 5
+     (the full design, with every measured finding)
+  3. CLAUDE.md                           (repo invariants)
+
+Scope, in order:
+
+1. Prerequisites, before any feature work:
+   - Pin explicit minSdk/targetSdk/compileSdk in
+     phone_app/android/app/build.gradle.kts. They are all delegated to the
+     Flutter plugin today, so there is no floor to reason about.
+   - Install emulator/avdmanager/sdkmanager (only adb is on PATH) and create
+     an API 36 AVD. API 34 validates against semantics the phone lacks.
+
+2. Item 4 + 1 — the phone actually rings. Hand-written Kotlin behind ONE
+   MethodChannel on the existing bare MainActivity.kt, never a plugin: the
+   stack is AGP 9.0.1 / Gradle 9.1 / Kotlin 2.3.20, and a plugin that will
+   not compile breaks the build outright rather than degrading. Five files:
+   AlarmScheduler, AlarmService, AlarmActivity, BootReceiver, AlarmChannel.
+   AlarmManager.setAlarmClock(), a foreground service with a wakelock,
+   STREAM_ALARM (load-bearing — it is what ignores DND and silent mode, never
+   STREAM_MUSIC), a full-screen intent over the lockscreen, re-arm on
+   BOOT_COMPLETED *and* on dismiss.
+   Dart side: main.dart has no init seam today — it needs
+   WidgetsFlutterBinding.ensureInitialized(), a navigatorKey and a route.
+   Port the five challenge kinds from _challenges.py so both halves behave
+   identically.
+
+3. Item 3 — separate-room proofs. NFC or QR qualifies; steps alone does NOT
+   (the phone is stationary while you walk to it, so steps only accrue after
+   pickup and can be faked by shaking it in bed). Steps + elapsed time is the
+   fallback when both others fail. This is a decision already taken — do not
+   re-litigate it.
+
+Constraints:
+- 100% branch coverage, no new # noqa / type: ignore.
+- The 250-line gate fires on STAGED files. Do not edit an oversized file this
+  change does not already have to touch — that cascade cost a full revert
+  last session. A new constant goes in its single consumer.
+- Verify on the PHONE (23181JEGR08034) via the phone-deploy skill, not just
+  the emulator. A companion-app change is not done on desktop.
+- Do not touch the PC half's invariants: no [Install] on wake-alarm.service,
+  _state.py stays UTC-keyed (screen_locker mirrors that helper), the trigger
+  starts morning-routine.service.
+
+Item 8 (mutual gating) depends on this and is the session after. Item 13
+(black screen) is a different repo, host-only, and blocks nothing.
+```
+
+## After that session
+
+- **Item 8, mutual gating.** Phone challenge first, then PC, with a bounded
+  escape: if sync is unreachable ~600 s the PC gate degrades to
+  locally-solvable and logs a WARNING. Without it, a Firebase outage means you
+  can neither dismiss nor get to work. This is the phase that legitimately
+  touches `_sync.py`, so it carries that file's 371-line split.
+- **Item 13, black screen.** `~/testsAndMisc/linux_configuration` plus /boot
+  and /etc. Host-only — vmbox is BIOS/GRUB and this machine is UEFI, so a
+  guest pass there is actively misleading.