Plan: Realtime Database presence for online friends

docs/plans/rtdb-presence.md

@@ -0,0 +1,49 @@
+# Plan — Realtime Database presence for online friends
+
+- **Status:** Proposed
+- **Effort:** Small
+- **Firebase services:** Realtime Database, Authentication
+- **Touches:** `lib/friends_screen.dart`, `lib/user_profile_page.dart`, new `lib/services/presence_service.dart`
+
+## Overview
+
+Show a small "online now" dot on friend cards and the profile page. Presence is ephemeral and high-churn, which makes Realtime Database (RTDB) `onDisconnect` a better fit than Firestore for cost and latency.
+
+## User flow
+
+1. User opens the Friends tab.
+2. Friends who have the app in the foreground show a green dot next to their avatar; recently-active (<5 min background) show a grey dot.
+3. Profile page mirrors the status in the header.
+
+## Technical approach
+
+- Add RTDB to the Firebase project (new database in the same region as Firestore, e.g. `europe-west1`).
+- On auth state change to signed-in, `PresenceService` writes `/status/{uid}` = `{ state: "online", lastChanged: ServerValue.TIMESTAMP }` and registers `onDisconnect().set({ state: "offline", lastChanged: ServerValue.TIMESTAMP })`.
+- On `AppLifecycleState.paused` set `state: "background"`; on `resumed` set `state: "online"`.
+- Mirror to Firestore only on transitions via an RTDB-triggered Cloud Function (`functions/src/presence.ts` → `onValueWritten`), so Firestore-only clients can still read a coarse status.
+- Friends screen subscribes directly to `/status/{friendUid}` refs for each friend in a batched `ValueEventListener`.
+
+## Data model
+
+- RTDB `/status/{uid}`: `{ state: "online" | "background" | "offline", lastChanged: number }`.
+- Optional Firestore mirror at `users/{uid}.presence` for non-listening contexts.
+
+## Security rules
+
+- RTDB rules: `/status/{uid}` write-restricted to `auth.uid == $uid`; read restricted to signed-in users who are friends (enforce via Cloud Function mirror if RTDB rule complexity grows).
+
+## Rollout
+
+- Gate behind Remote Config flag `feature_presence_enabled` (default false).
+- Ship dot UI behind the flag; enable for internal testers first.
+
+## Risks
+
+- RTDB adds a second datastore — keep logic thin, treat Firestore as source of truth.
+- `onDisconnect` can fire late on mobile networks; treat "offline" as eventually consistent.
+- Privacy: hide presence if the user toggles a "invisible mode" preference in settings.
+
+## Testing
+
+- Unit test `PresenceService` lifecycle transitions with a fake RTDB.
+- Manual two-device test: sign in on both, kill one, verify the other sees offline within ~30 s.

lib/claim.dart

@@ -125,11 +125,14 @@ class _ClaimState extends State<Claim> with TickerProviderStateMixin {
         postboxes[entry.key as String] =
             Map<String, dynamic>.from(entry.value as Map);
       }
+      // Cloud Functions serialise JS numbers as either int or double;
+      // assigning a double to a typed int field throws, so normalise via num.
+      int asInt(dynamic v) => (v as num?)?.toInt() ?? 0;
       setState(() {
-        _count = counts['total'] ?? 0;
-        _maxPoints = points['max'] ?? 0;
-        _minPoints = points['min'] ?? 0;
-        _claimedToday = counts['claimedToday'] ?? 0;
+        _count = asInt(counts['total']);
+        _maxPoints = asInt(points['max']);
+        _minPoints = asInt(points['min']);
+        _claimedToday = asInt(counts['claimedToday']);
         _postboxes = postboxes;
         currentStage = _count > 0 ? ClaimStage.results : ClaimStage.empty;
       });

lib/nearby.dart

@@ -113,23 +113,26 @@ class _NearbyState extends State<Nearby> {
       final claimedCompass = data['claimedCompass'] != null
           ? Map<String, dynamic>.from(data['claimedCompass'] as Map)
           : <String, dynamic>{};
+      // Cloud Functions serialise JS numbers as either int or double; assigning
+      // a double to a typed int field throws, so normalise every count via num.
+      int asInt(dynamic v) => (v as num?)?.toInt() ?? 0;
       setState(() {
-        _count = counts['total'] ?? 0;
-        _maxPoints = pts['max'] ?? 0;
-        _minPoints = pts['min'] ?? 0;
+        _count = asInt(counts['total']);
+        _maxPoints = asInt(pts['max']);
+        _minPoints = asInt(pts['min']);
         currentStage = NearbyStage.results;
         for (final dir in const [
           'N', 'NNE', 'NE', 'ENE', 'E', 'ESE',
           'SE', 'SSE', 'S', 'SSW', 'SW', 'WSW',
           'W', 'WNW', 'NW', 'NNW',
         ]) {
-          _compassCounts[dir] = compass[dir] ?? 0;
-          _claimedCompassCounts[dir] = claimedCompass[dir] ?? 0;
+          _compassCounts[dir] = asInt(compass[dir]);
+          _claimedCompassCounts[dir] = asInt(claimedCompass[dir]);
         }
-        _claimedToday = counts['claimedToday'] ?? 0;
+        _claimedToday = asInt(counts['claimedToday']);
         for (final cipher in MonarchInfo.all) {
-          _cipherTotals[cipher] = counts[cipher] ?? 0;
-          _cipherClaimed[cipher] = counts['${cipher}_claimed'] ?? 0;
+          _cipherTotals[cipher] = asInt(counts[cipher]);
+          _cipherClaimed[cipher] = asInt(counts['${cipher}_claimed']);
         }
         _lastScanned = DateTime.now();
       });

lib/wear/wear_claim_page.dart

@@ -52,8 +52,10 @@ class _WearClaimPageState extends State<WearClaimPage> {
       });
       if (!mounted) return;
       final counts = result.data['counts'] ?? {};
-      final total = (counts['total'] as int?) ?? 0;
-      final claimed = (counts['claimedToday'] as int?) ?? 0;
+      // Cloud Functions serialise JS numbers as either int or double; `as int?`
+      // would throw on a double, so normalise via num.
+      final total = (counts['total'] as num?)?.toInt() ?? 0;
+      final claimed = (counts['claimedToday'] as num?)?.toInt() ?? 0;
       _postboxes = Map<String, dynamic>.from(result.data['postboxes'] ?? {});
       setState(() {
         _count = total;

lib/wear/wear_compass_page.dart

@@ -75,8 +75,13 @@ class _WearCompassPageState extends State<WearCompassPage> {
       final counts = result.data['counts'] ?? {};
       final compassRaw = result.data['compass'] ?? {};
       setState(() {
-        _totalCount = (counts['total'] as int?) ?? 0;
-        _compassCounts = Map<String, int>.from(compassRaw);
+        // Cloud Functions serialise JS numbers as either int or double;
+        // `as int?` would throw on a double, so normalise via num.
+        _totalCount = (counts['total'] as num?)?.toInt() ?? 0;
+        _compassCounts = {
+          for (final e in (compassRaw as Map).entries)
+            e.key as String: (e.value as num).toInt(),
+        };
         _stage = _CompassStage.results;
       });
       // Haptic pulse to signal scan complete.
@@ -206,7 +211,13 @@ class _WearCompassPageState extends State<WearCompassPage> {
               angle: -rotation,
               child: CustomPaint(
                 size: Size(size, size),
-                painter: FuzzyCompassPainter(sectors: sectorValues),
+                // Pass rotation so the painter counter-rotates the 'N' label;
+                // otherwise it spins with the canvas and is unreadable whenever
+                // the watch is not pointing north.
+                painter: FuzzyCompassPainter(
+                  sectors: sectorValues,
+                  rotation: rotation,
+                ),
               ),
             ),
             // Centre count overlay (doesn't rotate)

lib/wear/wear_status_page.dart

@@ -18,10 +18,14 @@ class WearStatusPage extends StatefulWidget {
 class _WearStatusPageState extends State<WearStatusPage> {
   final StreakService _streakService = StreakService();
   late final Stream<int?> _streakStream = _streakService.streakStream();
+  // Cache so the StreamBuilder doesn't re-subscribe (and briefly show empty
+  // stats) on every rebuild. Computed once in initState from the uid at mount.
+  late final Stream<DocumentSnapshot<Map<String, dynamic>>>? _userDocStream =
+      _buildUserDocStream();
 
   String? get _displayName => FirebaseAuth.instance.currentUser?.displayName;
 
-  Stream<DocumentSnapshot<Map<String, dynamic>>>? _userDocStream() {
+  Stream<DocumentSnapshot<Map<String, dynamic>>>? _buildUserDocStream() {
     final uid = FirebaseAuth.instance.currentUser?.uid;
     if (uid == null) return null;
     return FirebaseFirestore.instance.collection('users').doc(uid).snapshots();
@@ -71,7 +75,7 @@ class _WearStatusPageState extends State<WearStatusPage> {
 
               // Lifetime points
               StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
-                stream: _userDocStream(),
+                stream: _userDocStream,
                 builder: (context, snap) {
                   final data = snap.data?.data();
                   final lifetimePoints =