feat(FN-4739): complete Step 3 — add room transcript clear route

Fusion-Task-Id: FN-4739
Fusion-Task-Lineage: fc120dfa-d1b2-4065-9595-d0bc6304d2af

packages/dashboard/src/__tests__/chat-room-routes.test.ts

@@ -269,6 +269,32 @@ describe("Chat Room API Routes", () => {
     expect(del2.status).toBe(404);
   });
 
+  it("clears all messages in a room", async () => {
+    const room = chatStore.createRoom({ name: "Clear API" });
+    chatStore.addRoomMessage(room.id, { role: "user", content: "one" });
+    chatStore.addRoomMessage(room.id, { role: "assistant", content: "two" });
+    chatStore.addRoomMessage(room.id, { role: "user", content: "three" });
+
+    const res = await request(app, "DELETE", `/api/chat/rooms/${room.id}/messages`);
+    expect(res.status).toBe(200);
+    expect(res.body).toEqual({ success: true, deletedCount: 3 });
+    expect(chatStore.getRoomMessages(room.id)).toEqual([]);
+  });
+
+  it("returns 404 when clearing messages for an unknown room", async () => {
+    const res = await request(app, "DELETE", "/api/chat/rooms/room-missing/messages");
+    expect(res.status).toBe(404);
+  });
+
+  it("keeps per-message delete route behavior after adding room-clear endpoint", async () => {
+    const room = chatStore.createRoom({ name: "Route ordering" });
+    const message = chatStore.addRoomMessage(room.id, { role: "user", content: "one" });
+
+    const res = await request(app, "DELETE", `/api/chat/rooms/${room.id}/messages/${message.id}`);
+    expect(res.status).toBe(200);
+    expect(chatStore.getRoomMessage(message.id)).toBeUndefined();
+  });
+
   it("handles message attachments route", async () => {
     const room = chatStore.createRoom({ name: "Files" });
     const message = chatStore.addRoomMessage(room.id, { role: "user", content: "hello" });

packages/dashboard/src/routes/register-chat-room-routes.ts

@@ -332,6 +332,21 @@ export function registerChatRoomRoutes(ctx: ApiRoutesContext): void {
     }
   });
 
+  router.delete("/chat/rooms/:id/messages", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
+    try {
+      const roomId = String(req.params.id);
+      const { chatStore } = await resolveRoomScopedServices(req, getRequestedProjectId(req));
+      const room = chatStore.getRoom(roomId);
+      if (!room) throw notFound(`Chat room ${roomId} not found`);
+
+      const deletedCount = chatStore.clearRoomMessages(roomId);
+      res.json({ success: true, deletedCount });
+    } catch (err: unknown) {
+      if (err instanceof ApiError) throw err;
+      rethrowAsApiError(err, "Failed to clear chat room messages");
+    }
+  });
+
   router.post("/chat/rooms/:id/messages/:messageId/attachments", rateLimit(RATE_LIMITS.mutation), async (req, res) => {
     try {
       const roomId = String(req.params.id);
@@ -371,6 +386,7 @@ export function registerChatRoomRoutes(ctx: ApiRoutesContext): void {
       "GET /chat/rooms/:id/messages",
       "POST /chat/rooms/:id/messages",
       "DELETE /chat/rooms/:id/messages/:messageId",
+      "DELETE /chat/rooms/:id/messages",
       "POST /chat/rooms/:id/messages/:messageId/attachments",
     ];
     chatLogger.info("room routes registered", { chatRoomRoutes });