feat(chat): scroll-to-latest button + panic hold-progress ring (v1.10.0+14)

B6 scroll-to-latest: ScrollController on the timeline; a small
  arrow-down FAB fades in once scrolled >400px up and animates back
  to the newest message on tap (overlaid on the list, not the FAB slot)
B5 panic hold-ring: 700ms AnimationController drives a red progress
  ring around the panic icon; haptic + fire on completion, silent
  reset on early release; tap-hint and configured guard preserved

Panic ring verified in-browser (ring fills, alert fires to the room).
Scroll-to-latest verified with a deterministic widget test because the
CanvasKit surface rejects synthetic scroll input in headless Chromium.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

help4bis-claude-notes/decisions.md

@@ -114,3 +114,12 @@
 - **Verified in headless Chromium on production build:** grouping renders (Sam's 3-run collapsed to tight blue bubbles; Alex's 2-run shows name once + avatar on last bubble only, amber deterministic disc), "Today" chip renders, quick-react row renders with all six presets + picker button, tapping ❤️ sent a real m.reaction (confirmed via server /messages). Long-press context menu still fires (all of Reply/React/Copy/Edit/Delete intact).
 - **Note:** cross-day separators are logic-only verified (can't backdate events without an appservice); the same-day "Today" chip confirms the render path.
 - **Status:** built + deployed app2.m8chat.au v1.9.0+13 (backup pre190 tarball). Analyze clean, format clean, tests pass.
+
+### 2026-07-04 08:30 — Scroll-to-latest + panic hold-ring (v1.10.0+14)
+- **B6 scroll-to-latest:** _Timeline converted ConsumerWidget → ConsumerStatefulWidget with a ScrollController. When offset > 400 (reverse list, newest at 0), an AnimatedScale FloatingActionButton.small(arrow_downward) fades in at Positioned(right:12,bottom:12) inside a Stack around the ListView (NOT the Scaffold FAB slot). Tap → animateTo(0, 200ms, easeOut).
+- **B5 panic hold-ring:** panic_button.dart → onLongPressDown starts a 700ms AnimationController; a red CircularProgressIndicator(value: controller.value) fills around the emergency_share icon; on completion HapticFeedback.heavyImpact + fire; early release resets silently. onTap still shows the hint; configured guard + _sending state preserved.
+- **Verified:**
+  - Panic ring: headless Chromium screenshot mid-hold shows the red arc ~half-filled; completing the hold fired the alert (🚨 text landed in the SES Emergency room; location correctly skipped when geolocation not granted, proving the alert-before-location safeguard).
+  - Scroll-to-latest: the Flutter CanvasKit surface would NOT accept synthetic scroll input from Playwright (mouse wheel and drag both no-op on the canvas; input field steals focus). Verified instead with a deterministic widget test (test/scroll_to_latest_test.dart): 40 messages, starts at offset 0, drag up → offset > 400 + button appears, tap → offset back to 0. Passes.
+- **Note for future:** getTimeline() only yields the ~10-event sync window and there is no scroll-back history pagination, so on a normal phone the timeline rarely exceeds ~1 screen and the jump button seldom shows in practice. Wiring requestHistory() on near-top scroll would make both the button and long-scrollback genuinely useful. Flagged, not built.
+- **Status:** built + deployed app2.m8chat.au v1.10.0+14 (backup pre1100 tarball). Analyze clean, 4 tests pass.

lib/core/config/app_config.dart

@@ -11,7 +11,7 @@ abstract final class AppConfig {
     'turns:matrix.m8chat.au:5349',
   ];
   static const String appName = 'M8Chat';
-  static const String appVersion = '1.9.0';
+  static const String appVersion = '1.10.0';
 
   // Jitsi conferencing
   static const String jitsiDomain = 'conf.m8chat.au';

lib/features/chat/presentation/chat_screen.dart

@@ -1,4 +1,4 @@
-// Version: 1.5.0 | Created: 2026-04-01 | Updated: 2026-07-04
+// Version: 1.6.0 | Created: 2026-04-01 | Updated: 2026-07-04
 // Full chat screen — timeline + input + typing indicators + read receipts
 // + long-press context menu (quick reactions, reply, react, copy, edit,
 // delete) + day separators + same-sender message grouping + room options.
@@ -128,15 +128,57 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
 // Timeline
 // ---------------------------------------------------------------------------
 
-class _Timeline extends ConsumerWidget {
+class _Timeline extends ConsumerStatefulWidget {
   const _Timeline({required this.roomId, required this.onReply});
 
   final String roomId;
   final void Function(MessageModel) onReply;
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<_Timeline> createState() => _TimelineState();
-    final timelineAsync = ref.watch(chatTimelineProvider(roomId));
+}
+
+class _TimelineState extends ConsumerState<_Timeline> {
+  final _scrollController = ScrollController();
+
+  /// The list is reverse:true, so the newest message sits at offset 0.
+  /// Show the jump-to-latest button once the user scrolls up past this.
+  static const _showButtonThreshold = 400.0;
+  bool _showScrollToLatest = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _scrollController.addListener(_onScroll);
+  }
+
+  @override
+  void dispose() {
+    _scrollController.removeListener(_onScroll);
+    _scrollController.dispose();
+    super.dispose();
+  }
+
+  void _onScroll() {
+    if (!_scrollController.hasClients) return;
+    final show = _scrollController.offset > _showButtonThreshold;
+    if (show != _showScrollToLatest) {
+      setState(() => _showScrollToLatest = show);
+    }
+  }
+
+  void _scrollToLatest() {
+    if (!_scrollController.hasClients) return;
+    _scrollController.animateTo(
+      0,
+      duration: const Duration(milliseconds: 200),
+      curve: Curves.easeOut,
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final timelineAsync = ref.watch(chatTimelineProvider(widget.roomId));
 
     return timelineAsync.when(
       loading: () => const Center(child: CircularProgressIndicator()),
@@ -158,7 +200,10 @@ class _Timeline extends ConsumerWidget {
           );
         }
 
-        return ListView.builder(
+        return Stack(
+          children: [
+            ListView.builder(
+              controller: _scrollController,
               reverse: true,
               padding: const EdgeInsets.symmetric(vertical: 8),
               itemCount: messages.length,
@@ -188,8 +233,8 @@ class _Timeline extends ConsumerWidget {
 
                 final bubble = _MessageWithGestures(
                   message: message,
-              roomId: roomId,
+                  roomId: widget.roomId,
-              onReply: () => onReply(message),
+                  onReply: () => widget.onReply(message),
                   isFirstInGroup: isFirstInGroup,
                   isLastInGroup: isLastInGroup,
                 );
@@ -203,6 +248,22 @@ class _Timeline extends ConsumerWidget {
                   ],
                 );
               },
+            ),
+            Positioned(
+              right: 12,
+              bottom: 12,
+              child: AnimatedScale(
+                duration: const Duration(milliseconds: 150),
+                scale: _showScrollToLatest ? 1 : 0,
+                child: FloatingActionButton.small(
+                  heroTag: 'scrollToLatest',
+                  onPressed: _scrollToLatest,
+                  tooltip: 'Jump to latest',
+                  child: const Icon(Icons.arrow_downward),
+                ),
+              ),
+            ),
+          ],
         );
       },
     );

lib/features/panic/presentation/panic_button.dart

@@ -1,9 +1,11 @@
-// Version: 1.0.0 | Created: 2026-07-04
+// Version: 1.1.0 | Created: 2026-07-04 | Updated: 2026-07-04
-// Panic trigger button for the rooms AppBar. Push-to-talk style:
+// Panic trigger button for the rooms AppBar. Push-to-talk style: HOLD for
-// HOLD to fire the alert; a plain tap only shows the hint. Only rendered
+// 700ms to fire the alert, with a filling ring showing progress so a brush
-// when a panic configuration exists in account data.
+// cannot fire it and the user sees exactly when it sends. A plain tap only
+// shows the hint. Only rendered when a panic configuration exists.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../data/panic_repository.dart';
@@ -15,9 +17,47 @@ class PanicButton extends ConsumerStatefulWidget {
   ConsumerState<PanicButton> createState() => _PanicButtonState();
 }
 
-class _PanicButtonState extends ConsumerState<PanicButton> {
+class _PanicButtonState extends ConsumerState<PanicButton>
+    with SingleTickerProviderStateMixin {
+  static const _holdDuration = Duration(milliseconds: 700);
+
+  late final AnimationController _holdController;
   bool _sending = false;
 
+  @override
+  void initState() {
+    super.initState();
+    _holdController = AnimationController(vsync: this, duration: _holdDuration)
+      ..addStatusListener(_onHoldStatus);
+  }
+
+  @override
+  void dispose() {
+    _holdController.dispose();
+    super.dispose();
+  }
+
+  void _onHoldStatus(AnimationStatus status) {
+    // The ring filled all the way: the hold completed, fire the alert.
+    if (status == AnimationStatus.completed) {
+      HapticFeedback.heavyImpact();
+      _trigger();
+      _holdController.reset();
+    }
+  }
+
+  void _onHoldStart() {
+    if (_sending) return;
+    _holdController.forward(from: 0);
+  }
+
+  void _onHoldCancelled() {
+    // Released before the ring filled: cancel silently.
+    if (_holdController.status == AnimationStatus.forward) {
+      _holdController.reset();
+    }
+  }
+
   Future<void> _trigger() async {
     if (_sending) return;
     setState(() => _sending = true);
@@ -32,9 +72,15 @@ class _PanicButtonState extends ConsumerState<PanicButton> {
     messenger.showSnackBar(
       SnackBar(
         backgroundColor: error == null ? Colors.green.shade800 : null,
-        content: Text(
+        content: Text(error ?? 'Emergency alert sent with your location.'),
-          error ?? 'Emergency alert sent with your location.',
       ),
+    );
+  }
+
+  void _showHint() {
+    ScaffoldMessenger.of(context).showSnackBar(
+      const SnackBar(
+        content: Text('Hold the button to send the emergency alert.'),
       ),
     );
   }
@@ -47,24 +93,55 @@ class _PanicButtonState extends ConsumerState<PanicButton> {
     if (!configured) return const SizedBox.shrink();
 
     return GestureDetector(
-      onLongPress: _trigger,
+      onTap: _showHint,
-      child: IconButton(
+      onLongPressDown: (_) => _onHoldStart(),
-        tooltip: 'Hold to send emergency alert',
+      onLongPressUp: _onHoldCancelled,
-        icon: _sending
+      onLongPressCancel: _onHoldCancelled,
-            ? const SizedBox(
+      child: Tooltip(
-                width: 20,
+        message: 'Hold to send emergency alert',
-                height: 20,
+        child: SizedBox(
-                child: CircularProgressIndicator(strokeWidth: 2),
+          width: 48,
-              )
+          height: 48,
-            : const Icon(Icons.emergency_share, color: Colors.red),
+          child: Center(
-        onPressed: () {
+            child: SizedBox(
-          ScaffoldMessenger.of(context).showSnackBar(
+              width: 40,
-            const SnackBar(
+              height: 40,
-              content: Text('Hold the button to send the emergency alert.'),
+              child: Stack(
+                alignment: Alignment.center,
+                children: [
+                  // Progress ring, only painted while the hold is in progress.
+                  AnimatedBuilder(
+                    animation: _holdController,
+                    builder: (context, _) {
+                      if (_holdController.value == 0) {
+                        return const SizedBox.shrink();
+                      }
+                      return SizedBox(
+                        width: 36,
+                        height: 36,
+                        child: CircularProgressIndicator(
+                          value: _holdController.value,
+                          strokeWidth: 3,
+                          color: Colors.red,
+                          backgroundColor: Colors.red.withAlpha(40),
                         ),
                       );
                     },
                   ),
+                  if (_sending)
+                    const SizedBox(
+                      width: 20,
+                      height: 20,
+                      child: CircularProgressIndicator(strokeWidth: 2),
+                    )
+                  else
+                    const Icon(Icons.emergency_share, color: Colors.red),
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
     );
   }
 }

pubspec.yaml

@@ -1,7 +1,7 @@
 name: m8chat_app
 description: "M8Chat — Matrix chat client for Android, iOS, and Web."
 publish_to: 'none'
-version: 1.9.0+13
+version: 1.10.0+14
 
 environment:
   sdk: '>=3.11.0 <4.0.0'

test/scroll_to_latest_test.dart

@@ -0,0 +1,80 @@
+// Version: 1.0.0 | Created: 2026-07-04
+// Deterministic test for the chat timeline's scroll-to-latest button.
+// Playwright cannot drive scrolling on the Flutter CanvasKit surface, so the
+// jump-to-latest behaviour is verified here against the real widget tree.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:matrix/matrix.dart';
+
+import 'package:m8chat_app/core/network/matrix_client.dart';
+import 'package:m8chat_app/features/chat/domain/message_model.dart';
+import 'package:m8chat_app/features/chat/presentation/chat_controller.dart';
+import 'package:m8chat_app/features/chat/presentation/chat_screen.dart';
+
+void main() {
+  testWidgets(
+    'jump-to-latest button appears when scrolled up and returns to bottom',
+    (tester) async {
+      const roomId = '!scrolltest:server';
+      final base = DateTime(2026, 7, 4, 8);
+      // Index 0 is the newest message (the timeline stream is newest-first).
+      final messages = [
+        for (var i = 40; i >= 1; i--)
+          MessageModel(
+            eventId: '\$e$i',
+            roomId: roomId,
+            senderId: '@me:server',
+            senderDisplayName: 'Me',
+            timestamp: base.add(Duration(seconds: i)),
+            type: MessageType.text,
+            body: 'Message $i',
+            isMine: true,
+          ),
+      ];
+
+      await tester.pumpWidget(
+        ProviderScope(
+          overrides: [
+            matrixClientProvider.overrideWithValue(Client('test-client')),
+            chatTimelineProvider(
+              roomId,
+            ).overrideWith((ref) => Stream.value(messages)),
+          ],
+          child: const MaterialApp(home: ChatScreen(roomId: roomId)),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      final listView = find.byType(ListView);
+      expect(listView, findsOneWidget);
+
+      double offset() =>
+          tester.state<ScrollableState>(find.byType(Scrollable).first)
+              .position
+              .pixels;
+
+      // Starts pinned to the newest message (offset 0 in a reverse list).
+      expect(offset(), 0);
+
+      // Scroll up toward older messages (reverse list: drag content down).
+      await tester.drag(listView, const Offset(0, 900));
+      await tester.pumpAndSettle();
+      expect(
+        offset(),
+        greaterThan(400),
+        reason: 'should have scrolled well past the button threshold',
+      );
+
+      // The jump-to-latest button is now shown; tap it.
+      final jumpButton = find.byIcon(Icons.arrow_downward);
+      expect(jumpButton, findsOneWidget);
+      await tester.tap(jumpButton);
+      await tester.pumpAndSettle();
+
+      // Back at the newest message.
+      expect(offset(), 0);
+    },
+  );
+}