refactor(copilot): Extract DeleteChatDialog to own component

Move delete confirmation dialog from ChatSidebar to reusable component:
- Create DeleteChatDialog under app/copilot/components
- Clean props interface: session, isDeleting, onConfirm, onCancel
- Update ChatSidebar to use new component
- All existing tests pass

autogpt_platform/frontend/src/app/(platform)/copilot/CopilotPage.tsx

@@ -1,8 +1,8 @@
 "use client";
 
+import { Button } from "@/components/atoms/Button/Button";
+import { Dialog } from "@/components/molecules/Dialog/Dialog";
 import { SidebarProvider } from "@/components/ui/sidebar";
-// TODO: Replace with modern Dialog component when available
-import DeleteConfirmDialog from "@/components/__legacy__/delete-confirm-dialog";
 import { ChatContainer } from "./components/ChatContainer/ChatContainer";
 import { ChatSidebar } from "./components/ChatSidebar/ChatSidebar";
 import { MobileDrawer } from "./components/MobileDrawer/MobileDrawer";
@@ -97,13 +97,47 @@ export function CopilotPage() {
       )}
       {/* Delete confirmation dialog - rendered at top level for proper z-index on mobile */}
       {isMobile && (
-        <DeleteConfirmDialog
-          entityType="chat"
-          entityName={sessionToDelete?.title || "Untitled chat"}
-          open={!!sessionToDelete}
-          onOpenChange={(open) => !open && handleCancelDelete()}
-          onDoDelete={handleConfirmDelete}
-        />
+        <Dialog
+          title="Delete chat"
+          controlled={{
+            isOpen: !!sessionToDelete,
+            set: async (open) => {
+              if (!open && !isDeleting) {
+                handleCancelDelete();
+              }
+            },
+          }}
+          onClose={handleCancelDelete}
+        >
+          <Dialog.Content>
+            <p className="text-neutral-600">
+              Are you sure you want to delete{" "}
+              <span className="font-medium">
+                &quot;{sessionToDelete?.title || "Untitled chat"}&quot;
+              </span>
+              ? This action cannot be undone.
+            </p>
+            <Dialog.Footer>
+              <Button
+                variant="ghost"
+                size="small"
+                onClick={handleCancelDelete}
+                disabled={isDeleting}
+              >
+                Cancel
+              </Button>
+              <Button
+                variant="primary"
+                size="small"
+                onClick={handleConfirmDelete}
+                loading={isDeleting}
+                className="bg-red-600 hover:bg-red-700"
+              >
+                Delete
+              </Button>
+            </Dialog.Footer>
+          </Dialog.Content>
+        </Dialog>
       )}
     </SidebarProvider>
   );

autogpt_platform/frontend/src/app/(platform)/copilot/components/ChatSidebar/ChatSidebar.tsx

@@ -8,8 +8,7 @@ import { Button } from "@/components/atoms/Button/Button";
 import { LoadingSpinner } from "@/components/atoms/LoadingSpinner/LoadingSpinner";
 import { Text } from "@/components/atoms/Text/Text";
 import { toast } from "@/components/molecules/Toast/use-toast";
-// TODO: Replace with modern Dialog component when available
-import DeleteConfirmDialog from "@/components/__legacy__/delete-confirm-dialog";
+import { DeleteChatDialog } from "../DeleteChatDialog";
 import {
   Sidebar,
   SidebarContent,
@@ -92,6 +91,12 @@ export function ChatSidebar() {
     }
   }
 
+  function handleCancelDelete() {
+    if (!isDeleting) {
+      setSessionToDelete(null);
+    }
+  }
+
   function formatDate(dateString: string) {
     const date = new Date(dateString);
     const now = new Date();
@@ -257,12 +262,11 @@ export function ChatSidebar() {
         )}
       </Sidebar>
 
-      <DeleteConfirmDialog
-        entityType="chat"
-        entityName={sessionToDelete?.title || "Untitled chat"}
-        open={!!sessionToDelete}
-        onOpenChange={(open) => !open && setSessionToDelete(null)}
-        onDoDelete={handleConfirmDelete}
+      <DeleteChatDialog
+        session={sessionToDelete}
+        isDeleting={isDeleting}
+        onConfirm={handleConfirmDelete}
+        onCancel={handleCancelDelete}
       />
     </>
   );

autogpt_platform/frontend/src/app/(platform)/copilot/components/ChatSidebar/__tests__/ChatSidebar.test.tsx

@@ -0,0 +1,350 @@
+import { expect, test, describe, vi, beforeEach, afterEach } from "vitest";
+import {
+  render,
+  screen,
+  waitFor,
+  fireEvent,
+  cleanup,
+} from "@testing-library/react";
+import { ChatSidebar } from "../ChatSidebar";
+import { server } from "@/mocks/mock-server";
+import {
+  getGetV2ListSessionsMockHandler,
+  getDeleteV2DeleteSessionMockHandler204,
+  getDeleteV2DeleteSessionMockHandler422,
+} from "@/app/api/__generated__/endpoints/chat/chat.msw";
+import { SidebarProvider } from "@/components/ui/sidebar";
+import { NuqsTestingAdapter } from "nuqs/adapters/testing";
+import { http, HttpResponse, delay } from "msw";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { BackendAPIProvider } from "@/lib/autogpt-server-api/context";
+
+// Mock sessions data
+const mockSessions = {
+  sessions: [
+    {
+      id: "session-1",
+      title: "First Chat",
+      created_at: new Date().toISOString(),
+      updated_at: new Date().toISOString(),
+    },
+    {
+      id: "session-2",
+      title: "Second Chat",
+      created_at: new Date(Date.now() - 86400000).toISOString(),
+      updated_at: new Date(Date.now() - 86400000).toISOString(),
+    },
+    {
+      id: "session-3",
+      title: null,
+      created_at: new Date(Date.now() - 172800000).toISOString(),
+      updated_at: new Date(Date.now() - 172800000).toISOString(),
+    },
+  ],
+  total: 3,
+};
+
+function createTestQueryClient() {
+  return new QueryClient({
+    defaultOptions: {
+      queries: {
+        retry: false,
+      },
+    },
+  });
+}
+
+function TestWrapper({
+  children,
+  searchParams = "",
+  onUrlUpdate,
+}: {
+  children: React.ReactNode;
+  searchParams?: string;
+  onUrlUpdate?: (event: { queryString: string }) => void;
+}) {
+  const queryClient = createTestQueryClient();
+  return (
+    <QueryClientProvider client={queryClient}>
+      <BackendAPIProvider>
+        <NuqsTestingAdapter
+          searchParams={searchParams}
+          hasMemory
+          onUrlUpdate={onUrlUpdate}
+        >
+          <SidebarProvider defaultOpen={true}>{children}</SidebarProvider>
+        </NuqsTestingAdapter>
+      </BackendAPIProvider>
+    </QueryClientProvider>
+  );
+}
+
+function renderChatSidebar(
+  searchParams = "",
+  onUrlUpdate?: (event: { queryString: string }) => void,
+) {
+  return render(
+    <TestWrapper searchParams={searchParams} onUrlUpdate={onUrlUpdate}>
+      <ChatSidebar />
+    </TestWrapper>,
+  );
+}
+
+describe("ChatSidebar", () => {
+  beforeEach(() => {
+    server.use(
+      getGetV2ListSessionsMockHandler(() => mockSessions),
+      getDeleteV2DeleteSessionMockHandler204(),
+    );
+  });
+
+  afterEach(() => {
+    cleanup();
+  });
+
+  describe("Sessions List", () => {
+    test("renders session list correctly", async () => {
+      renderChatSidebar();
+
+      // Use getAllByText since component may render multiple times
+      await waitFor(() => {
+        const elements = screen.getAllByText("First Chat");
+        expect(elements.length).toBeGreaterThan(0);
+      });
+
+      expect(screen.getAllByText("Second Chat").length).toBeGreaterThan(0);
+      expect(screen.getAllByText("Untitled chat").length).toBeGreaterThan(0);
+    });
+
+    test("shows empty state when no sessions", async () => {
+      server.use(
+        getGetV2ListSessionsMockHandler(() => ({
+          sessions: [],
+          total: 0,
+        })),
+      );
+
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(
+          screen.getAllByText("No conversations yet").length,
+        ).toBeGreaterThan(0);
+      });
+    });
+
+    test("formats dates correctly", async () => {
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      expect(screen.getAllByText("Today").length).toBeGreaterThan(0);
+      expect(screen.getAllByText("Yesterday").length).toBeGreaterThan(0);
+      expect(screen.getAllByText("2 days ago").length).toBeGreaterThan(0);
+    });
+  });
+
+  describe("Delete Dialog", () => {
+    test("opens delete dialog when trash button is clicked", async () => {
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      // Find and click the delete button for the first session
+      const deleteButtons = screen.getAllByLabelText("Delete chat");
+      fireEvent.click(deleteButtons[0]);
+
+      // Dialog should appear with confirmation text
+      await waitFor(() => {
+        expect(
+          screen.getByText(/Are you sure you want to delete/),
+        ).toBeDefined();
+      });
+    });
+
+    test("closes dialog when cancel is clicked", async () => {
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      const deleteButtons = screen.getAllByLabelText("Delete chat");
+      fireEvent.click(deleteButtons[0]);
+
+      await waitFor(() => {
+        expect(
+          screen.getByText(/Are you sure you want to delete/),
+        ).toBeDefined();
+      });
+
+      const cancelButton = screen.getByRole("button", { name: "Cancel" });
+      fireEvent.click(cancelButton);
+
+      await waitFor(() => {
+        expect(
+          screen.queryByText(/Are you sure you want to delete/),
+        ).toBeNull();
+      });
+    });
+
+    test("calls delete API when delete button is clicked", async () => {
+      const deleteMock = vi.fn();
+      server.use(
+        http.delete(
+          "http://localhost:3000/api/proxy/api/chat/sessions/:sessionId",
+          async ({ params }) => {
+            deleteMock(params.sessionId);
+            return new HttpResponse(null, { status: 204 });
+          },
+        ),
+      );
+
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      const deleteButtons = screen.getAllByLabelText("Delete chat");
+      fireEvent.click(deleteButtons[0]);
+
+      await waitFor(() => {
+        expect(
+          screen.getByText(/Are you sure you want to delete/),
+        ).toBeDefined();
+      });
+
+      const deleteButton = screen.getByRole("button", { name: "Delete" });
+      fireEvent.click(deleteButton);
+
+      await waitFor(() => {
+        expect(deleteMock).toHaveBeenCalledWith("session-1");
+      });
+    });
+
+    test("closes dialog after successful deletion", async () => {
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      const deleteButtons = screen.getAllByLabelText("Delete chat");
+      fireEvent.click(deleteButtons[0]);
+
+      await waitFor(() => {
+        expect(
+          screen.getByText(/Are you sure you want to delete/),
+        ).toBeDefined();
+      });
+
+      const deleteButton = screen.getByRole("button", { name: "Delete" });
+      fireEvent.click(deleteButton);
+
+      await waitFor(() => {
+        expect(
+          screen.queryByText(/Are you sure you want to delete/),
+        ).toBeNull();
+      });
+    });
+
+    test("handles deletion error gracefully", async () => {
+      server.use(getDeleteV2DeleteSessionMockHandler422());
+
+      renderChatSidebar();
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      const deleteButtons = screen.getAllByLabelText("Delete chat");
+      fireEvent.click(deleteButtons[0]);
+
+      await waitFor(() => {
+        expect(
+          screen.getByText(/Are you sure you want to delete/),
+        ).toBeDefined();
+      });
+
+      const deleteButton = screen.getByRole("button", { name: "Delete" });
+      fireEvent.click(deleteButton);
+
+      // Dialog should close even on error
+      await waitFor(() => {
+        expect(
+          screen.queryByText(/Are you sure you want to delete/),
+        ).toBeNull();
+      });
+    });
+  });
+
+  describe("Session Selection", () => {
+    test("highlights currently selected session", async () => {
+      renderChatSidebar("?sessionId=session-1");
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      // Find the session with selected styling (text-zinc-600 indicates selected)
+      const selectedSessions = screen.getAllByText("First Chat");
+      const hasSelectedStyle = selectedSessions.some(
+        (el) =>
+          el.className.includes("text-zinc-600") ||
+          el.closest("div")?.className.includes("bg-zinc-100"),
+      );
+      expect(hasSelectedStyle).toBe(true);
+    });
+
+    test("selects session when clicked", async () => {
+      const urlUpdateSpy = vi.fn();
+
+      renderChatSidebar("", urlUpdateSpy);
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      // Find a session button and click it
+      const sessionElements = screen.getAllByText("First Chat");
+      const sessionButton = sessionElements[0].closest("button");
+      if (sessionButton) {
+        fireEvent.click(sessionButton);
+      }
+
+      await waitFor(() => {
+        expect(urlUpdateSpy).toHaveBeenCalled();
+        const lastCall =
+          urlUpdateSpy.mock.calls[urlUpdateSpy.mock.calls.length - 1];
+        expect(lastCall[0].queryString).toContain("sessionId=session-1");
+      });
+    });
+  });
+
+  describe("New Chat", () => {
+    test("clears session selection when new chat button is clicked", async () => {
+      const urlUpdateSpy = vi.fn();
+
+      renderChatSidebar("?sessionId=session-1", urlUpdateSpy);
+
+      await waitFor(() => {
+        expect(screen.getAllByText("First Chat").length).toBeGreaterThan(0);
+      });
+
+      const newChatButton = screen.getByRole("button", { name: "New Chat" });
+      fireEvent.click(newChatButton);
+
+      await waitFor(() => {
+        expect(urlUpdateSpy).toHaveBeenCalled();
+        const lastCall =
+          urlUpdateSpy.mock.calls[urlUpdateSpy.mock.calls.length - 1];
+        expect(lastCall[0].queryString).not.toContain("sessionId=session-1");
+      });
+    });
+  });
+});

autogpt_platform/frontend/src/app/(platform)/copilot/components/DeleteChatDialog/DeleteChatDialog.tsx

@@ -0,0 +1,66 @@
+"use client";
+
+import { Button } from "@/components/atoms/Button/Button";
+import { Dialog } from "@/components/molecules/Dialog/Dialog";
+
+interface DeleteChatDialogProps {
+  /** The session to delete, or null if dialog should be closed */
+  session: { id: string; title: string | null | undefined } | null;
+  /** Whether deletion is in progress */
+  isDeleting: boolean;
+  /** Called when user confirms deletion */
+  onConfirm: () => void;
+  /** Called when user cancels (only works when not deleting) */
+  onCancel: () => void;
+}
+
+export function DeleteChatDialog({
+  session,
+  isDeleting,
+  onConfirm,
+  onCancel,
+}: DeleteChatDialogProps) {
+  return (
+    <Dialog
+      title="Delete chat"
+      controlled={{
+        isOpen: !!session,
+        set: async (open) => {
+          if (!open && !isDeleting) {
+            onCancel();
+          }
+        },
+      }}
+      onClose={onCancel}
+    >
+      <Dialog.Content>
+        <p className="text-neutral-600">
+          Are you sure you want to delete{" "}
+          <span className="font-medium">
+            &quot;{session?.title || "Untitled chat"}&quot;
+          </span>
+          ? This action cannot be undone.
+        </p>
+        <Dialog.Footer>
+          <Button
+            variant="ghost"
+            size="small"
+            onClick={onCancel}
+            disabled={isDeleting}
+          >
+            Cancel
+          </Button>
+          <Button
+            variant="primary"
+            size="small"
+            onClick={onConfirm}
+            loading={isDeleting}
+            className="bg-red-600 hover:bg-red-700"
+          >
+            Delete
+          </Button>
+        </Dialog.Footer>
+      </Dialog.Content>
+    </Dialog>
+  );
+}

autogpt_platform/frontend/src/app/(platform)/copilot/components/DeleteChatDialog/index.ts

@@ -0,0 +1 @@
+export { DeleteChatDialog } from "./DeleteChatDialog";