feat(FN-4017): add /new command alias for task creation in quick chat

Added a `/new` slash command alias across the chat interface, with interception in ChatView, support in the QuickChatFAB, corresponding tests, and documentation in the dashboard guide.

Fusion-Task-Id: FN-4017

packages/dashboard/app/components/ChatView.tsx

@@ -1244,7 +1244,7 @@ export function ChatView({ projectId, addToast, experimentalFeatures }: ChatView
     const files = pendingAttachments.map((attachment) => attachment.file);
     if ((!trimmed && files.length === 0) || !activeSession) return;
 
-    if (trimmed === "/clear") {
+    if (trimmed === "/clear" || trimmed === "/new") {
       clearComposerState();
       stopStreaming();
       clearPendingMessage();

packages/dashboard/app/components/QuickChatFAB.tsx

@@ -1673,7 +1673,7 @@ export function QuickChatFAB({
       return;
     }
 
-    if (trimmed === "/clear") {
+    if (trimmed === "/clear" || trimmed === "/new") {
       stopStreaming();
       clearPendingMessage();
       attachmentsToSend.forEach((attachment) => {
@@ -2382,7 +2382,7 @@ export function QuickChatFAB({
                 ))}
                 {helpMessageVisible && (
                   <div className="quick-chat-panel-message quick-chat-panel-message--received" data-testid="quick-chat-help-message">
-                    {renderAssistantMessageContent("Available commands:\n- `/clear` — Clear conversation and start fresh\n- `/skill:{name}` — Use a specific skill\n- `/help` — Show this help")}
+                    {renderAssistantMessageContent("Available commands:\n- `/new` or `/clear` — Clear conversation and start fresh\n- `/skill:{name}` — Use a specific skill\n- `/help` — Show this help")}
                   </div>
                 )}
                 <div
@@ -2436,7 +2436,7 @@ export function QuickChatFAB({
                 ))}
                 {helpMessageVisible && (
                   <div className="quick-chat-panel-message quick-chat-panel-message--received" data-testid="quick-chat-help-message">
-                    {renderAssistantMessageContent("Available commands:\n- `/clear` — Clear conversation and start fresh\n- `/skill:{name}` — Use a specific skill\n- `/help` — Show this help")}
+                    {renderAssistantMessageContent("Available commands:\n- `/new` or `/clear` — Clear conversation and start fresh\n- `/skill:{name}` — Use a specific skill\n- `/help` — Show this help")}
                   </div>
                 )}
               </>

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

@@ -1093,6 +1093,51 @@ describe("ChatView", () => {
     expect(clearPendingMessage).toHaveBeenCalledTimes(1);
   });
 
+  it("intercepts exact /new and starts a fresh session instead of sending message", async () => {
+    const sendMessage = vi.fn();
+    const createSession = vi.fn().mockResolvedValue({ id: "session-new", agentId: "agent-001" });
+    const stopStreaming = vi.fn();
+    const clearPendingMessage = vi.fn();
+
+    setupMockChat({
+      activeSession: activeSessionFixture,
+      messages: [],
+      sendMessage,
+      createSession,
+      stopStreaming,
+      clearPendingMessage,
+    });
+
+    render(<ChatView projectId="proj-123" addToast={vi.fn()} />);
+
+    const textarea = screen.getByTestId("chat-input");
+    await userEvent.type(textarea, "  /new  {enter}");
+
+    expect(sendMessage).not.toHaveBeenCalled();
+    expect(createSession).toHaveBeenCalledWith({ agentId: "agent-001" });
+    expect(stopStreaming).toHaveBeenCalledTimes(1);
+    expect(clearPendingMessage).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not intercept non-exact /new text", async () => {
+    const sendMessage = vi.fn();
+    const createSession = vi.fn();
+    setupMockChat({
+      activeSession: activeSessionFixture,
+      messages: [],
+      sendMessage,
+      createSession,
+    });
+
+    render(<ChatView projectId="proj-123" addToast={vi.fn()} />);
+
+    const textarea = screen.getByTestId("chat-input");
+    await userEvent.type(textarea, "/new now{enter}");
+
+    expect(sendMessage).toHaveBeenCalledWith("/new now", []);
+    expect(createSession).not.toHaveBeenCalled();
+  });
+
   it("does not intercept non-exact /clear text", async () => {
     const sendMessage = vi.fn();
     const createSession = vi.fn();

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

@@ -231,6 +231,44 @@ describe("QuickChatFAB session-first UX", () => {
     expect(mockStreamChatResponse).not.toHaveBeenCalled();
   });
 
+  it("intercepts exact /new and starts a fresh session for the active target", async () => {
+    render(<QuickChatFAB addToast={vi.fn()} projectId="proj-1" />);
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    const input = await screen.findByTestId("quick-chat-input");
+    await waitFor(() => expect(input).not.toBeDisabled());
+    fireEvent.change(input, { target: { value: " /new " } });
+    fireEvent.click(screen.getByTestId("quick-chat-send"));
+
+    await waitFor(() => {
+      expect(mockCreateChatSession).toHaveBeenCalledWith(
+        { agentId: "__fn_agent__", modelProvider: "openai", modelId: "gpt-4o" },
+        "proj-1",
+      );
+    });
+    expect(mockStreamChatResponse).not.toHaveBeenCalled();
+  });
+
+  it("does not intercept non-exact /new prompts", async () => {
+    render(<QuickChatFAB addToast={vi.fn()} projectId="proj-1" />);
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    const input = await screen.findByTestId("quick-chat-input");
+    await waitFor(() => expect(input).not.toBeDisabled());
+    fireEvent.change(input, { target: { value: "/new now" } });
+    fireEvent.click(screen.getByTestId("quick-chat-send"));
+
+    await waitFor(() => {
+      expect(mockStreamChatResponse).toHaveBeenCalledWith(
+        "session-model",
+        "/new now",
+        expect.any(Object),
+        [],
+        "proj-1",
+      );
+    });
+  });
+
   it("does not intercept non-exact /clear prompts", async () => {
     render(<QuickChatFAB addToast={vi.fn()} projectId="proj-1" />);
     fireEvent.click(screen.getByTestId("quick-chat-fab"));
@@ -312,7 +350,10 @@ describe("QuickChatFAB session-first UX", () => {
     fireEvent.change(input, { target: { value: "/help" } });
     fireEvent.click(screen.getByTestId("quick-chat-send"));
 
-    expect(await screen.findByTestId("quick-chat-help-message")).toBeInTheDocument();
+    const helpMessage = await screen.findByTestId("quick-chat-help-message");
+    expect(helpMessage).toBeInTheDocument();
+    expect(helpMessage).toHaveTextContent("/new");
+    expect(helpMessage).toHaveTextContent("/clear");
     expect(mockStreamChatResponse).not.toHaveBeenCalled();
   });