Phase 4 checkpoint: chat-screen perf refactor + retryable blast-failure + repo-wide dispose-ref guardrail

Chat-screen performance (customer + mitra):
- Parent screens have zero `ref.watch` — only `ref.listen` for side effects
- Body extracted into its own `ConsumerStatefulWidget`; AppBar parts split
  into narrow `.select` consumers (mode, sensitivity, timer)
- Per-second timer ticks routed to dedicated providers
  (`chatRemainingSecondsProvider` + new `mitraChatRemainingSecondsProvider`)
  so WS `session_tick` frames don't invalidate the rest of the chat state

Dispose-in-ref bug fix:
- `home_screen.dart`, `payment_screen.dart`, `mitra_chat_screen.dart` —
  ref-using cleanup moved from `dispose()` to `deactivate()`. Modern
  Riverpod invalidates `ref` the moment `dispose()` runs; the resulting
  silent error corrupts the widget-tree finalize and the next screen
  appears frozen
- `halo_lints` package added at repo root with `no_ref_in_dispose` rule
  to catch this pattern in CI / IDE analysis
- `custom_lint` activated in both apps' `analysis_options.yaml`
  (was installed but never wired in — also brings `riverpod_lint`'s
  `avoid_ref_inside_state_dispose` online)
- CLAUDE.md Pitfalls section added to client_app + mitra_app

Phase 4 §3 retryable blast-failure (Option A):
- Backend `expirePairingRequest` + all-rejected use
  `recordIntermediateFailure` instead of `failPaymentSession` so the
  payment session stays `confirmed` for re-blast
- WS `pairing_failed` payload carries `is_terminal: false` on the
  retryable paths; client parses the flag and exposes `retryBlast()`
- "Coba cari lagi" CTA on S7 Timeout now re-blasts on the same payment
- Pairing service test updated to reflect the new semantics

Customer waiting-payment screen navigation patch:
- `_navigateTerminal` uses `Future.microtask` + `addPostFrameCallback`
  redundancy after a release-mode bug where polling stopped but
  `context.go` never fired, leaving the screen visually stuck on
  "menunggu pembayaran"

See requirement/resume-2026-05-15.md for next-day pickup checklist
(mitra release rebuild + S21 Ultra install + retest is the gating item).

Bundles unrelated in-flight Phase 4 §2.x work that was already on disk
(ESP screen removal, USP one-time gate scaffolding, bestie-availability
public route, OTP service edits, Maestro flow tweaks) — kept together
to avoid a partial-rebase mess.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

requirement/resume-2026-05-15.md

@@ -0,0 +1,78 @@
+# Resume — 2026-05-15
+
+> Cross-device pickup note. Mirror of the local Claude memory `project_resume_next.md` so this is reachable on any machine that clones the repo. Delete this file when fully resumed.
+
+Paused **2026-05-14 evening**. Chat-screen perf refactor done in code on both apps; release rebuild + install + retest on mitra is the gating step that didn't complete (S21 Ultra unplugged before the final build could finish).
+
+## What needs doing tomorrow — in order
+
+### 1. Rebuild + install mitra release on S21 Ultra
+
+Code is on disk in `mitra_app/lib/features/chat/screens/mitra_chat_screen.dart` (full refactor) and `mitra_app/lib/core/chat/mitra_chat_notifier.dart` (timer-extraction provider). The APK currently on the S21 Ultra only has the timer-extraction fix — NOT the full body/AppBar split.
+
+```bash
+# Plug the S21 Ultra, authorize USB debugging if needed:
+adb devices    # confirm device shows as `device`, not `unauthorized`
+
+# Build + install + run:
+cd mitra_app
+flutter run -d <S21_DEVICE_ID> --release --dart-define=API_BASE_URL=http://<DEV_MACHINE_IP>:3000
+```
+
+Yesterday's IDs (will differ on a new host):
+- S21 Ultra: `RRCR100NN7Z`
+- Customer SM-A530F: `52002a5db8e0c46b`
+- Dev machine static IP: `192.168.88.247`
+
+Backend dev server (`cd backend && npm run dev`) needs to be running first. The dev `API_BASE_URL` defaults to production if you forget the dart-define.
+
+### 2. Test mitra chat under release
+
+After install: open a chat session, send a few messages, watch the partner type. Expected:
+- Timer ticks every 1s rebuild ONLY the timer pill in the AppBar.
+- Sending/receiving messages rebuilds ONLY the body widget.
+- Typing pulses don't cause whole-screen flicker.
+
+Bar: it should feel as snappy as the customer app does now (which is the reference point).
+
+### 3. Verify customer waiting_payment_screen navigation patch
+
+Yesterday the customer app got stuck on "menunggu pembayaran" after a payment was confirmed (polling stopped but `addPostFrameCallback(context.go(...))` never fired). Patched with belt-and-suspenders in `waiting_payment_screen.dart::_navigateTerminal` — `Future.microtask` + `addPostFrameCallback` redundancy.
+
+End-to-end test path:
+1. Customer app: tap "aku mau curhat" → pick tier → create payment.
+2. SQL-confirm the payment (or use the dev confirm endpoint).
+3. Watch the waiting screen — should advance off "menunggu pembayaran" into notif-gate → searching within ~3s (one poll cycle).
+
+If still stuck: I added `print` instrumentation would surface debug-mode only; consider running customer in debug to capture log output.
+
+### 4. If mitra chat is still laggy after #1
+
+Next suspect: message-list rebuilds on every state change re-iterate visible ListView.builder items. Try:
+- Convert `_MessageBubble` to `const` constructor (immutable inputs).
+- Wrap bubbles in `RepaintBoundary` to isolate paint.
+
+Don't touch until #1 confirms whether the body-extraction refactor was sufficient.
+
+## What landed today (already on disk / committed)
+
+- **Dispose-in-ref fix** in `home_screen.dart`, `payment_screen.dart` (customer), `mitra_chat_screen.dart` (mitra). Pattern: ref-using cleanup goes in `deactivate()`, not `dispose()`. Symptom of regression: next screen looks frozen after navigation, even though app is alive.
+- **`halo_lints`** package at repo root with `no_ref_in_dispose` rule. Wired into both apps' `analysis_options.yaml`. Also activates the already-installed `riverpod_lint` package (which ships `avoid_ref_inside_state_dispose` for the same case).
+- **CLAUDE.md Pitfalls section** added to `client_app/CLAUDE.md` and `mitra_app/CLAUDE.md` documenting the dispose-ref landmine.
+- **Customer chat refactor** — `chat_screen.dart` split into `_ChatHeader` + `_ChatBodySection` + `_TimerBanner`. Parent has zero `ref.watch`.
+- **Mitra chat refactor** — `mitra_chat_screen.dart` mirrors customer pattern: `_MitraChatBodyContent`, `_MitraChatTopicToggle`, `_MitraChatVoicePill`, `_MitraChatTimerAction`. Plus the `mitraChatRemainingSecondsProvider` for per-second ticks.
+- **Customer waiting screen nav** — `Future.microtask` + `addPostFrameCallback` redundancy at terminal status.
+- **Phase 4 Option A retryable blast-failure** — backend `expirePairingRequest` + all-rejected use `recordIntermediateFailure` instead of `failPaymentSession`; WS payload has `is_terminal: false`; client carries `topicSensitivity` through `PairingFailedData`; "coba cari lagi" CTA re-blasts on the same payment via `retryBlast()`. Test updated to match new semantics.
+
+## Hazards / gotchas to remember
+
+- **Release mode is the bar.** Debug-mode JIT on both phones (SM-A530F + S21 Ultra) was unusably laggy. Always rebuild release to test real perf.
+- **`node --watch` doesn't pick up newly-added module files.** When you add a brand-new route file or service, kill + restart the backend dev server. Don't trust the auto-reload for new files.
+- **AVD on the dev host is unusable for interactive rendering** — use the physical devices.
+- **`.claude/settings.local.json` + `.claude/agent-memory/` + `client_app/devtools_options.yaml`** stay modified — local-only, never commit.
+
+## Decisions explicitly deferred
+
+- **CI integration** — user raised the topic but we punted. Scope to gather when resuming: GitHub Actions vs other; per-PR triggers; which projects (backend vitest + control_center playwright + client/mitra flutter analyze + dart run custom_lint); APK build artifacts; Maestro Cloud or self-hosted device runner.
+- **Phase 4 §2.1 real-device verification** — still pending from before today. See `requirement/phase3.4-testing.md` §1.5.1 for the runbook.
+- **`backend/test/services/session-timer.service.test.js`** — 2 pre-existing failures (uuid-string fixture bug). Unrelated to anything we touched.