fix(FN-2011): keep chat input responsive during streaming

- Make useChat and useQuickChat sendMessage synchronous and update consumers to call it without awaiting
- Allow ChatView and QuickChatFAB inputs to remain editable while responses stream
- Keep quick chat send disabled during active streaming to prevent concurrent sends
- Add hook and component tests for synchronous sendMessage and non-blocking input behavior

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

@@ -5,7 +5,7 @@
 
 import fs from "node:fs";
 import path from "node:path";
-import { render, screen, waitFor, within } from "@testing-library/react";
+import { fireEvent, render, screen, waitFor, within } from "@testing-library/react";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { userEvent } from "@testing-library/user-event";
 import { ChatView } from "../ChatView";
@@ -742,6 +742,41 @@ describe("ChatView", () => {
     expect(sendButton).toBeDisabled();
   });
 
+  it("textarea is enabled during streaming", () => {
+    setupMockChat({
+      activeSession: { id: "session-001", agentId: "agent-001", status: "active", title: "Test Chat", updatedAt: "2026-04-08T00:00:00.000Z" },
+      messages: [
+        { id: "msg-001", sessionId: "session-001", role: "user", content: "Hello", createdAt: "2026-04-08T00:00:00.000Z" },
+      ],
+      isStreaming: true,
+      streamingText: "Thinking...",
+    });
+
+    render(<ChatView projectId="proj-123" addToast={vi.fn()} />);
+
+    const textarea = screen.getByTestId("chat-input");
+    expect(textarea).not.toBeDisabled();
+  });
+
+  it("user can type while streaming", async () => {
+    setupMockChat({
+      activeSession: { id: "session-001", agentId: "agent-001", status: "active", title: "Test Chat", updatedAt: "2026-04-08T00:00:00.000Z" },
+      messages: [
+        { id: "msg-001", sessionId: "session-001", role: "user", content: "Hello", createdAt: "2026-04-08T00:00:00.000Z" },
+      ],
+      isStreaming: true,
+      streamingText: "Thinking...",
+    });
+
+    render(<ChatView projectId="proj-123" addToast={vi.fn()} />);
+
+    const textarea = screen.getByTestId("chat-input");
+
+    // User should be able to type in the textarea while streaming
+    fireEvent.change(textarea, { target: { value: "Second message" } });
+    expect((textarea as HTMLTextAreaElement).value).toBe("Second message");
+  });
+
   it("shows streaming indicator when isStreaming is true", () => {
     setupMockChat({
       activeSession: { id: "session-001", agentId: "agent-001", status: "active", title: "Test Chat", updatedAt: "2026-04-08T00:00:00.000Z" },

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

@@ -423,7 +423,7 @@ describe("QuickChatFAB", () => {
     });
   });
 
-  it("streaming state shows streaming message and disables input", async () => {
+  it("streaming state shows streaming message and keeps input enabled", async () => {
     render(<QuickChatFAB addToast={addToast} projectId="proj-123" />);
 
     fireEvent.click(screen.getByTestId("quick-chat-fab"));
@@ -437,11 +437,38 @@ describe("QuickChatFAB", () => {
     fireEvent.change(input, { target: { value: "Hello" } });
     fireEvent.click(screen.getByTestId("quick-chat-send"));
 
-    // Input should be cleared and disabled during streaming
+    // Input should be cleared but NOT disabled during streaming
     await waitFor(() => {
       expect((screen.getByTestId("quick-chat-input") as HTMLInputElement).value).toBe("");
     });
-    expect(screen.getByTestId("quick-chat-input")).toBeDisabled();
+    expect(screen.getByTestId("quick-chat-input")).not.toBeDisabled();
+
+    // Send button should be disabled during streaming
+    expect(screen.getByTestId("quick-chat-send")).toBeDisabled();
+  });
+
+  it("user can type while streaming", async () => {
+    render(<QuickChatFAB addToast={addToast} projectId="proj-123" />);
+
+    fireEvent.click(screen.getByTestId("quick-chat-fab"));
+
+    // Wait for session initialization
+    await waitFor(() => {
+      expect(mockFetchChatSessions).toHaveBeenCalled();
+    });
+
+    const input = await screen.findByTestId("quick-chat-input");
+    fireEvent.change(input, { target: { value: "Hello" } });
+    fireEvent.click(screen.getByTestId("quick-chat-send"));
+
+    // Input should be cleared after send
+    await waitFor(() => {
+      expect((screen.getByTestId("quick-chat-input") as HTMLInputElement).value).toBe("");
+    });
+
+    // User should still be able to type in the input while streaming
+    fireEvent.change(input, { target: { value: "Second message" } });
+    expect((screen.getByTestId("quick-chat-input") as HTMLInputElement).value).toBe("Second message");
   });
 
   it("after streaming completes, assistant message is shown", async () => {
@@ -483,17 +510,22 @@ describe("QuickChatFAB", () => {
     fireEvent.change(input, { target: { value: "Hello" } });
     fireEvent.click(screen.getByTestId("quick-chat-send"));
 
-    // Wait for streaming to complete
-    await waitFor(() => {
-      expect(screen.getByTestId("quick-chat-input")).not.toBeDisabled();
-    });
+    // Wait for streaming to complete and assistant response to appear
+    await waitFor(
+      () => {
+        expect(screen.getByText(/Here's my response/)).toBeDefined();
+      },
+      { timeout: 5000 },
+    );
 
     // Check that user's "Hello" message is preserved
     expect(screen.getByText("Hello")).toBeDefined();
 
-    // Check that assistant response is shown (mock concatenates thinking + text)
-    // The mock sends "Thinking..." then "Here's my response." which concatenates
-    expect(screen.getByText(/Here's my response/)).toBeDefined();
+    // Input should be enabled after streaming completes
+    expect(screen.getByTestId("quick-chat-input")).not.toBeDisabled();
+
+    // Send button should be enabled after streaming completes (input is empty so still disabled)
+    expect(screen.getByTestId("quick-chat-send")).toBeDisabled();
   });
 
   it("switching agents creates a new session for the selected agent", async () => {