mobile: start new agents on Sonnet at medium effort

The create screen opened with model and effort blank, so the easy path
was picking from the full catalog, expensive models included. A fresh
setup now starts on the first Sonnet model the catalog offers, at medium
effort when supported. A draft link's own model still wins when offered,
a resumed setup keeps its saved choice, and anything the catalog lacks is
left for the user to choose.

Co-authored-by: Carl <c217fe6b9d958f41c3a5e030dccc7f626775a923089cb6491305eade75ea1f1b@buzz.block.builderlab.xyz>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: morgmart <98432065+morgmart@users.noreply.github.com>

mobile/lib/features/agents/agent_model_picker.dart

@@ -117,3 +117,27 @@ bool validAgentModelSelection(
           (entry) => entry.id == model && entry.efforts.contains(effort),
         ) ==
         true;
+
+/// The model and effort a new agent starts with, so the easy path is a
+/// capable but affordable choice rather than a blank (or the priciest) one.
+/// A draft's own model wins when the catalog offers it; otherwise the first
+/// Sonnet model, at medium effort when supported. Anything the catalog
+/// doesn't offer is left for the user to choose.
+(String?, String?) startingAgentModel(
+  List<RemoteAgentModel> catalog, {
+  String? draftModel,
+  String? draftEffort,
+}) {
+  final drafted = catalog.where((entry) => entry.id == draftModel).firstOrNull;
+  if (drafted != null) {
+    return (
+      drafted.id,
+      drafted.efforts.contains(draftEffort) ? draftEffort : null,
+    );
+  }
+  final fallback = catalog
+      .where((entry) => entry.id.toLowerCase().contains('sonnet'))
+      .firstOrNull;
+  if (fallback == null) return (null, null);
+  return (fallback.id, fallback.efforts.contains('medium') ? 'medium' : null);
+}

mobile/lib/features/agents/create_agent_page.dart

@@ -1,7 +1,10 @@
 import 'agent_avatar_hero.dart';
 import 'agent_character_artwork.dart';
+
 import 'dart:math';
+
 import 'agent_model_picker.dart';
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
@@ -57,26 +60,25 @@ class CreateAgentPage extends HookConsumerWidget {
     final draft = controller.pending == null ? initialDraft : null;
     final model = useState(controller.pending?['model_id'] as String?);
     final effort = useState(controller.pending?['reasoning_effort'] as String?);
-    // Draft model hints apply to the first catalog that loads (after a failed
+    // A fresh setup starts from the first catalog that loads (after a failed
-    // load, the one Retry fetches), and only if it offers them.
+    // load, the one Retry fetches): the draft's model if offered, otherwise
-    final hintsApplied = useRef(false);
+    // the default. A resumed setup keeps its saved choice.
+    final startApplied = useRef(controller.pending != null);
     useEffect(() {
       final entries = catalog.data;
-      if (draft == null ||
+      if (startApplied.value ||
-          hintsApplied.value ||
           catalog.connectionState != ConnectionState.done ||
           entries == null) {
         return null;
       }
-      hintsApplied.value = true;
+      startApplied.value = true;
-      final match = entries
+      final (startModel, startEffort) = startingAgentModel(
-          .where((entry) => entry.id == draft.modelId)
+        entries,
-          .firstOrNull;
+        draftModel: draft?.modelId,
-      if (match == null) return null;
+        draftEffort: draft?.reasoningEffort,
-      model.value = match.id;
+      );
-      effort.value = match.efforts.contains(draft.reasoningEffort)
+      model.value = startModel;
-          ? draft.reasoningEffort
+      effort.value = startEffort;
-          : null;
       return null;
     }, [catalog.connectionState]);
     final name = useTextEditingController(

mobile/test/features/agents/agent_model_picker_test.dart

@@ -0,0 +1,66 @@
+import 'package:buzz/features/agents/agent_model_picker.dart';
+import 'package:buzz/shared/agents/remote_agents.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  const opus = RemoteAgentModel(
+    id: 'kgoose-claude-opus-4-6',
+    name: 'Opus',
+    efforts: ['low', 'medium', 'high'],
+  );
+  const sonnet = RemoteAgentModel(
+    id: 'kgoose-claude-sonnet-4-6',
+    name: 'Sonnet',
+    efforts: ['low', 'medium', 'high'],
+  );
+
+  test('defaults to Sonnet at medium effort', () {
+    expect(startingAgentModel([opus, sonnet]), (
+      'kgoose-claude-sonnet-4-6',
+      'medium',
+    ));
+  });
+
+  test('leaves effort for the user when medium is not offered', () {
+    const highOnly = RemoteAgentModel(
+      id: 'claude-sonnet-5',
+      name: 'Sonnet 5',
+      efforts: ['high'],
+    );
+    expect(startingAgentModel([opus, highOnly]), ('claude-sonnet-5', null));
+  });
+
+  test('chooses nothing when no Sonnet is offered', () {
+    expect(startingAgentModel([opus]), (null, null));
+  });
+
+  test('a draft model the catalog offers wins over the default', () {
+    expect(
+      startingAgentModel(
+        [opus, sonnet],
+        draftModel: opus.id,
+        draftEffort: 'high',
+      ),
+      (opus.id, 'high'),
+    );
+    expect(
+      startingAgentModel(
+        [opus, sonnet],
+        draftModel: opus.id,
+        draftEffort: 'max',
+      ),
+      (opus.id, null),
+    );
+  });
+
+  test('a draft model the catalog lacks falls back to the default', () {
+    expect(
+      startingAgentModel(
+        [opus, sonnet],
+        draftModel: 'gone',
+        draftEffort: 'high',
+      ),
+      (sonnet.id, 'medium'),
+    );
+  });
+}

mobile/test/features/agents/create_agent_page_test.dart

@@ -1,8 +1,10 @@
 import 'dart:io';
+
 import 'package:buzz/shared/widgets/frosted_app_bar.dart';
 import 'package:buzz/shared/widgets/preset_agent_avatar.dart';
 import 'package:buzz/shared/agents/agent_avatar_catalog.dart';
 import 'package:buzz/features/agents/agent_avatar_editor_page.dart';
+
 import 'dart:async';
 
 import 'package:buzz/shared/agents/remote_agents.dart';
@@ -228,6 +230,55 @@ void main() {
       expect(h.registry.calls, contains('publish-policy'));
     },
   );
+
+  testWidgets('a new agent starts on the affordable default model', (
+    tester,
+  ) async {
+    final h = await AgentsHarness.create();
+    h.registry.models = [
+      {
+        'id': 'premium-model',
+        'display_name': 'Premium model',
+        'supported_reasoning_efforts': ['low', 'medium', 'high'],
+      },
+      {
+        'id': 'kgoose-claude-sonnet-4-6',
+        'display_name': 'Sonnet',
+        'supported_reasoning_efforts': ['low', 'medium', 'high'],
+      },
+    ];
+    await h.open(tester, directory: [existing]);
+    if (!supportsRemoteAgents(h.community)) return;
+    await tester.tap(find.byTooltip('Add agent'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Sonnet'), findsOneWidget);
+    expect(find.text('Premium model'), findsNothing);
+    expect(find.text('medium'), findsOneWidget);
+
+    // Naming it is all that's left before Create.
+    await tester.enterText(
+      find.descendant(
+        of: find.byWidgetPredicate(
+          (widget) => widget is Semantics && widget.properties.label == 'Name',
+        ),
+        matching: find.byType(TextField),
+      ),
+      'Scout',
+    );
+    await tester.pump();
+    expect(
+      tester
+          .widget<IconButton>(
+            find.ancestor(
+              of: find.byTooltip('Create'),
+              matching: find.byType(IconButton),
+            ),
+          )
+          .onPressed,
+      isNotNull,
+    );
+  });
 }
 
 class _StalledPosterClient implements HttpClient {