feat(FN-2843): auto-select quick chat default model

- Extend /models API responses to include optional defaultProvider/defaultModelId from global settings, including empty and error paths
- Update QuickChatFAB to prefer the configured default model on load and fall back to first-model selection only when no agents exist
- Move quick chat model tag/title-wrap inline styles into QuickChatFAB.css using dashboard design tokens
- Add QuickChatFAB tests covering default-model auto-selection with and without agents and legacy behavior when no default is configured

packages/dashboard/app/api/legacy.ts

@@ -1114,6 +1114,8 @@ export interface ModelsResponse {
   models: ModelInfo[];
   favoriteProviders: string[];
   favoriteModels: string[];
+  defaultProvider?: string;
+  defaultModelId?: string;
 }
 
 /** Fetch available AI models from the model registry along with favoriteProviders */

packages/dashboard/app/components/QuickChatFAB.css

@@ -188,6 +188,28 @@
   color: var(--text);
 }
 
+.quick-chat-panel-title-wrap {
+  display: flex;
+  align-items: center;
+  gap: var(--space-sm);
+  min-width: 0;
+}
+
+.quick-chat-model-tag {
+  display: inline-flex;
+  align-items: center;
+  max-width: 18ch;
+  padding: var(--space-xs) var(--space-sm);
+  border-radius: var(--radius-pill);
+  border: 1px solid color-mix(in srgb, var(--todo) 35%, var(--border));
+  background: color-mix(in srgb, var(--todo) 14%, transparent);
+  color: var(--text);
+  font-size: 0.75rem;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
 .quick-chat-panel-header-actions {
   display: inline-flex;
   align-items: center;

packages/dashboard/app/components/QuickChatFAB.tsx

@@ -46,29 +46,6 @@ interface ParsedModelSelection {
   modelId: string;
 }
 
-const modelTagStyle = {
-  display: "inline-flex",
-  alignItems: "center",
-  maxWidth: "180px",
-  padding: "var(--space-xs) var(--space-sm)",
-  borderRadius: "var(--radius-pill)",
-  border: "1px solid color-mix(in srgb, var(--todo) 35%, var(--border))",
-  background: "color-mix(in srgb, var(--todo) 14%, transparent)",
-  color: "var(--text)",
-  fontSize: "11px",
-  whiteSpace: "nowrap",
-  overflow: "hidden",
-  textOverflow: "ellipsis",
-} as const;
-
-const headerTitleWrapStyle = {
-  display: "flex",
-  alignItems: "center",
-  gap: "var(--space-sm)",
-  minWidth: 0,
-} as const;
-
-
 function getAgentLabel(agent: Agent): string {
   const base = agent.name?.trim() || agent.id;
   return `${base} (${agent.role})`;
@@ -807,8 +784,27 @@ export function QuickChatFAB({
       .then((response) => {
         const loadedModels = response.models ?? [];
         setModels(loadedModels);
-        // Auto-select first model when no agents exist and no model selected yet
+
-        if (agents.length === 0 && loadedModels.length > 0 && !selectedModel) {
+        if (selectedModel || loadedModels.length === 0) {
+          return;
+        }
+
+        const defaultProvider = response.defaultProvider;
+        const defaultModelId = response.defaultModelId;
+        if (defaultProvider && defaultModelId) {
+          const defaultSelection = `${defaultProvider}/${defaultModelId}`;
+          const hasDefaultModel = loadedModels.some(
+            (model) => `${model.provider}/${model.id}` === defaultSelection,
+          );
+          if (hasDefaultModel) {
+            setSelectedModel(defaultSelection);
+            setChatMode("model");
+            return;
+          }
+        }
+
+        // Fallback: auto-select first model only when no agents exist.
+        if (agents.length === 0) {
           const firstModel = loadedModels[0];
           if (firstModel) {
             setSelectedModel(`${firstModel.provider}/${firstModel.id}`);
@@ -1353,10 +1349,10 @@ export function QuickChatFAB({
           )}
 
           <div className="quick-chat-panel-header">
-            <div style={headerTitleWrapStyle}>
+            <div className="quick-chat-panel-title-wrap">
               <h3>Quick Chat</h3>
               {selectedModelTag && (
-                <span style={modelTagStyle} data-testid="quick-chat-model-tag" title={selectedModelTag}>
+                <span className="quick-chat-model-tag" data-testid="quick-chat-model-tag" title={selectedModelTag}>
                   {selectedModelTag}
                 </span>
               )}

packages/dashboard/app/components/__tests__/ActivityLogModal.test.tsx

@@ -487,6 +487,7 @@ describe("ActivityLogModal", () => {
 
     await waitFor(() => {
       expect(screen.getByTestId("activity-log-modal")).toBeTruthy();
+      expect(screen.getAllByTestId("activity-entry").length).toBeGreaterThan(0);
     });
 
     // Verify key structural classes that the mobile CSS targets

packages/dashboard/app/components/__tests__/QuickChatFAB.test.tsx

@@ -164,6 +164,8 @@ describe("QuickChatFAB", () => {
       models: mockModels,
       favoriteProviders: [],
       favoriteModels: [],
+      defaultProvider: undefined,
+      defaultModelId: undefined,
     });
     createMockStreamResponse();
   });
@@ -185,6 +187,63 @@ describe("QuickChatFAB", () => {
     expect(screen.queryByTestId("quick-chat-agent-select")).toBeNull();
   });
 
+  it("auto-selects configured default model when no agents exist", async () => {
+    mockAgentsHook([]);
+    mockFetchModels.mockResolvedValue({
+      models: mockModels,
+      favoriteProviders: [],
+      favoriteModels: [],
+      defaultProvider: "openai",
+      defaultModelId: "gpt-4o",
+    });
+
+    render(<QuickChatFAB addToast={addToast} />);
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    await waitFor(() => {
+      expect(screen.getByTestId("quick-chat-model-tag")).toHaveTextContent("GPT-4o");
+    });
+  });
+
+  it("auto-selects configured default model and switches to model mode when agents exist", async () => {
+    mockAgentsHook(mockAgents);
+    mockFetchModels.mockResolvedValue({
+      models: mockModels,
+      favoriteProviders: [],
+      favoriteModels: [],
+      defaultProvider: "openai",
+      defaultModelId: "gpt-4o",
+    });
+
+    render(<QuickChatFAB addToast={addToast} />);
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    await waitFor(() => {
+      expect(screen.getByTestId("quick-chat-model-select")).toBeDefined();
+      expect(screen.getByTestId("quick-chat-model-tag")).toHaveTextContent("GPT-4o");
+    });
+  });
+
+  it("preserves existing behavior when no default model is configured and agents exist", async () => {
+    mockAgentsHook(mockAgents);
+    mockFetchModels.mockResolvedValue({
+      models: mockModels,
+      favoriteProviders: [],
+      favoriteModels: [],
+      defaultProvider: undefined,
+      defaultModelId: undefined,
+    });
+
+    render(<QuickChatFAB addToast={addToast} />);
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    await waitFor(() => {
+      expect(screen.getByTestId("quick-chat-agent-select")).toBeDefined();
+    });
+    expect(screen.queryByTestId("quick-chat-model-select")).toBeNull();
+    expect(screen.queryByTestId("quick-chat-model-tag")).toBeNull();
+  });
+
   it("renders FAB button when agents exist", () => {
     render(<QuickChatFAB addToast={addToast} />);
 

packages/dashboard/src/routes/register-model-routes.ts

@@ -5,10 +5,40 @@ export const registerModelRoutes: ApiRouteRegistrar = (ctx) => {
   const { router, options, store, runtimeLogger } = ctx;
 
   router.get("/models", async (_req, res) => {
+    // Get favoriteProviders/favoriteModels and default model from global settings.
+    let favoriteProviders: string[] = [];
+    let favoriteModels: string[] = [];
+    let defaultProvider: string | undefined;
+    let defaultModelId: string | undefined;
+    let useClaudeCli = false;
+    if (store) {
+      try {
+        const globalStore = store.getGlobalSettingsStore();
+        const globalSettings = await globalStore.getSettings();
+        favoriteProviders = globalSettings.favoriteProviders ?? [];
+        favoriteModels = globalSettings.favoriteModels ?? [];
+        defaultProvider = globalSettings.defaultProvider;
+        defaultModelId = globalSettings.defaultModelId;
+        useClaudeCli = globalSettings.useClaudeCli === true;
+      } catch {
+        // Silently ignore settings errors - just return empty favorites/default model
+      }
+    }
+
+    const defaultModelResponse =
+      defaultProvider && defaultModelId
+        ? { defaultProvider, defaultModelId }
+        : {};
+
     // Always return 200 with empty array instead of 404 when no models available.
     // This ensures the frontend can handle empty states gracefully.
     if (!options?.modelRegistry) {
-      res.json({ models: [], favoriteProviders: [], favoriteModels: [] });
+      res.json({
+        models: [],
+        favoriteProviders,
+        favoriteModels,
+        ...defaultModelResponse,
+      });
       return;
     }
 
@@ -22,22 +52,6 @@ export const registerModelRoutes: ApiRouteRegistrar = (ctx) => {
         contextWindow: m.contextWindow,
       }));
 
-      // Get favoriteProviders and favoriteModels from global settings
-      let favoriteProviders: string[] = [];
-      let favoriteModels: string[] = [];
-      let useClaudeCli = false;
-      if (store) {
-        try {
-          const globalStore = store.getGlobalSettingsStore();
-          const globalSettings = await globalStore.getSettings();
-          favoriteProviders = globalSettings.favoriteProviders ?? [];
-          favoriteModels = globalSettings.favoriteModels ?? [];
-          useClaudeCli = globalSettings.useClaudeCli === true;
-        } catch {
-          // Silently ignore settings errors - just return empty favorites
-        }
-      }
-
       // The vendored pi-claude-cli extension registers its provider as
       // "pi-claude-cli" (distinct from "anthropic") whenever it loads.
       // When the toggle is OFF, hide those entries from pickers so users
@@ -48,14 +62,24 @@ export const registerModelRoutes: ApiRouteRegistrar = (ctx) => {
         models = models.filter((m) => m.provider !== "pi-claude-cli");
       }
 
-      res.json({ models, favoriteProviders, favoriteModels });
+      res.json({
+        models,
+        favoriteProviders,
+        favoriteModels,
+        ...defaultModelResponse,
+      });
     } catch (err: unknown) {
       if (err instanceof ApiError) {
         throw err;
       }
       const message = err instanceof Error ? err.message : String(err);
       runtimeLogger.child("models").warn(`Failed to load models: ${message}`);
-      res.json({ models: [], favoriteProviders: [], favoriteModels: [] });
+      res.json({
+        models: [],
+        favoriteProviders,
+        favoriteModels,
+        ...defaultModelResponse,
+      });
     }
   });
 };