feat(profile): generated default avatars (boring-avatars beam) from pubkey

People without a photo or seed illustration now get a deterministic
pattern avatar drawn from their pubkey (flutter_boring_avatars, MIT),
in an earthy seed-tone palette, replacing the coloured-initial disc.
Same pubkey renders the same picture on every device with nothing shared.

apps/app_seeds/lib/ui/avatar.dart

@@ -6,7 +6,7 @@ import 'seed_glyph.dart';
 ///    media server, like offer photos);
 ///  - `tane:seed:<name>` — one of our own seed illustrations (for people who'd
 ///    rather not put a real photo — pseudonymity stays the default);
-///  - empty — the deterministic coloured disc with the name's initial.
+///  - empty — a pattern avatar generated deterministically from the pubkey.
 const avatarGlyphPrefix = 'tane:seed:';
 
 /// The seed illustrations offered as ready-made avatars. Names are the stable

apps/app_seeds/lib/ui/peer_avatar.dart

@@ -1,15 +1,27 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_boring_avatars/flutter_boring_avatars.dart';
 
 import '../services/offer_thumbnail.dart' show decodeDataUri;
 import '../services/profile_cache.dart';
 import 'avatar.dart';
 import 'seed_glyph.dart';
+import 'theme.dart';
+
+/// Palette for the generated default avatars — earthy seed-and-leaf tones so
+/// the fallback art sits inside the app's palette rather than fighting it.
+const _generatedAvatarPalette = BoringAvatarPalette([
+  seedGreen,
+  seedRating, // warm amber
+  Color(0xFFB5541F), // terracotta pot
+  Color(0xFF6B4F2A), // seed-coat brown
+  Color(0xFFD3E8C8), // pale leaf
+]);
 
 /// A small round avatar for a person. When they've set an avatar ([picture] — a
 /// `data:` photo thumbnail or a `tane:seed:<glyph>` illustration) it's shown;
-/// otherwise it falls back to a deterministic disc coloured from their [pubkey],
-/// with the first letter of their [name] (else a person glyph). Same pubkey →
-/// same colour on every device, so a person stays visually recognizable.
+/// otherwise it falls back to a generated pattern drawn deterministically from
+/// their [pubkey] (boring-avatars "beam"). Same pubkey → same picture on every
+/// device, so a person stays visually recognizable without sharing anything.
 class PeerAvatar extends StatelessWidget {
   const PeerAvatar({
     required this.pubkey,
@@ -46,35 +58,25 @@ class PeerAvatar extends StatelessWidget {
       }
     }
 
-    final letter = _initial(name);
-    return CircleAvatar(
-      radius: radius,
-      backgroundColor: peerAvatarColor(pubkey),
-      child: letter == null
-          ? Icon(Icons.person_outline, size: radius, color: Colors.white)
-          : Text(
-              letter,
-              style: TextStyle(
-                color: Colors.white,
-                fontSize: radius,
-                fontWeight: FontWeight.w600,
-              ),
-            ),
+    return Semantics(
+      label: name,
+      image: true,
+      child: SizedBox.square(
+        dimension: radius * 2,
+        child: BoringAvatar(
+          name: pubkey,
+          type: BoringAvatarType.beam,
+          palette: _generatedAvatarPalette,
+          shape: const OvalBorder(),
+        ),
+      ),
     );
   }
-
-  static String? _initial(String? name) {
-    if (name == null) return null;
-    final trimmed = name.trim();
-    if (trimmed.isEmpty) return null;
-    // characters.first handles emoji/combining marks safely.
-    return trimmed.characters.first.toUpperCase();
-  }
 }
 
 /// A [PeerAvatar] that looks the person's published avatar up from the
-/// [ProfileCache] (their kind:0 `picture`), falling back to the coloured-initial
-/// disc while it loads or when none is cached / no cache is available. Use at
+/// [ProfileCache] (their kind:0 `picture`), falling back to the generated
+/// pattern while it loads or when none is cached / no cache is available. Use at
 /// list/row sites (one avatar each); for many avatars of the same few people
 /// (chat bubbles) resolve the picture once into state instead.
 class CachedAvatar extends StatelessWidget {

apps/app_seeds/pubspec.yaml

@@ -78,6 +78,7 @@ dependencies:
   # while the app is foregrounded. Mobile/Linux/macOS only; a no-op on web and
   # Windows. Foreground-only by design — background/push is a later concern.
   flutter_local_notifications: ^18.0.1
+  flutter_boring_avatars: ^2.1.0
 
 dev_dependencies:
   flutter_test:

apps/app_seeds/test/ui/chat_message_list_test.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:commons_core/commons_core.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:flutter_boring_avatars/flutter_boring_avatars.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:tane/domain/chat_timeline.dart';
@@ -124,14 +125,14 @@ void main() {
     await tester.pumpWidget(host(cubit));
     await tester.pump();
 
-    // Both sides carry an avatar, and the two people are different colours —
+    // Both sides carry an avatar, each generated from its own pubkey —
     // so you can tell who said what at a glance.
     expect(find.byType(PeerAvatar), findsNWidgets(2));
-    final discs = tester
-        .widgetList<CircleAvatar>(find.byType(CircleAvatar))
+    final generated = tester
+        .widgetList<BoringAvatar>(find.byType(BoringAvatar))
         .toList();
-    expect(discs, hasLength(2));
-    expect(discs.first.backgroundColor, isNot(discs.last.backgroundColor));
+    expect(generated, hasLength(2));
+    expect(generated.first.name, isNot(generated.last.name));
   });
 
   testWidgets('a new message lands in view at the bottom, not below the fold', (

apps/app_seeds/test/ui/peer_avatar_test.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_boring_avatars/flutter_boring_avatars.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:tane/services/profile_cache.dart';
 import 'package:tane/ui/avatar.dart';
@@ -37,19 +38,20 @@ void main() {
       home: Scaffold(body: Center(child: child)),
     );
 
-    testWidgets('shows the name initial when known', (tester) async {
-      await tester.pumpWidget(host(PeerAvatar(pubkey: 'aa', name: 'rosa')));
-      expect(find.text('R'), findsOneWidget); // uppercased first letter
-    });
-
-    testWidgets('falls back to a glyph when the name is unknown', (
+    testWidgets('falls back to a generated pattern keyed by pubkey', (
       tester,
     ) async {
-      await tester.pumpWidget(host(const PeerAvatar(pubkey: 'aa')));
-      expect(find.byIcon(Icons.person_outline), findsOneWidget);
+      await tester.pumpWidget(host(PeerAvatar(pubkey: 'aa', name: 'rosa')));
+      final generated = tester.widget<BoringAvatar>(find.byType(BoringAvatar));
+      expect(generated.name, 'aa'); // pubkey, not name → stable across renames
       expect(find.byType(Text), findsNothing);
     });
 
+    testWidgets('generates it even when the name is unknown', (tester) async {
+      await tester.pumpWidget(host(const PeerAvatar(pubkey: 'aa')));
+      expect(find.byType(BoringAvatar), findsOneWidget);
+    });
+
     testWidgets('renders a seed illustration when the avatar is a token', (
       tester,
     ) async {
@@ -74,19 +76,19 @@ void main() {
       expect(find.byType(SeedGlyph), findsOneWidget);
     });
 
-    testWidgets('falls back to the initial when nothing is cached', (
+    testWidgets('falls back to the generated pattern when nothing is cached', (
       tester,
     ) async {
       final cache = ProfileCache(InMemorySecretStore());
       await tester.pumpWidget(host(
           CachedAvatar(pubkey: 'peer2', name: 'Bea', cache: cache)));
       await tester.pumpAndSettle();
-      expect(find.text('B'), findsOneWidget);
+      expect(find.byType(BoringAvatar), findsOneWidget);
     });
 
-    testWidgets('no cache → the coloured-initial disc', (tester) async {
+    testWidgets('no cache → the generated pattern', (tester) async {
       await tester.pumpWidget(host(const CachedAvatar(pubkey: 'x', name: 'Bea')));
-      expect(find.text('B'), findsOneWidget);
+      expect(find.byType(BoringAvatar), findsOneWidget);
     });
   });
 }