fix: unify panic room code format and validate room join id

src/app/api/room/[id]/join/route.test.ts

@@ -74,11 +74,11 @@ describe("POST /api/room/[id]/join", () => {
   it("returns 404 when room not found", async () => {
     mockAtomicUpdate.mockResolvedValue(null);
 
-    const req = createRequest("/api/room/NONEXIST/join", {
+    const req = createRequest("/api/room/ABC123/join", {
       method: "POST",
       body: { userId: "user-1" },
     });
-    const ctx = createRouteContext({ id: "NONEXIST" });
+    const ctx = createRouteContext({ id: "ABC123" });
     const res = await POST(req, ctx);
     expect(res.status).toBe(404);
   });
@@ -92,4 +92,14 @@ describe("POST /api/room/[id]/join", () => {
     const res = await POST(req, ctx);
     expect(res.status).toBe(401);
   });
+
+  it("returns 400 when room id format is invalid", async () => {
+    const req = createRequest("/api/room/1234/join", {
+      method: "POST",
+      body: { userId: "user-1" },
+    });
+    const ctx = createRouteContext({ id: "1234" });
+    const res = await POST(req, ctx);
+    expect(res.status).toBe(400);
+  });
 });

src/app/api/room/[id]/join/route.ts

@@ -2,14 +2,16 @@ import { NextResponse } from "next/server";
 import { atomicUpdateRoom } from "@/lib/roomRepository";
 import { notify } from "@/lib/roomEvents";
 import { apiHandler, ApiError, requireUserId } from "@/lib/api";
+import { validatePanicRoomId } from "@/lib/validation";
 
 export const POST = apiHandler(async (req, { params }) => {
   const { id } = await params;
+  const roomId = validatePanicRoomId(id);
   const { userId } = await req.json();
 
   requireUserId(userId);
 
-  const updated = await atomicUpdateRoom(id, (data) => {
+  const updated = await atomicUpdateRoom(roomId, (data) => {
     if (data.kickedUsers.includes(userId)) {
       throw new ApiError("你已被移出该房间", 403);
     }
@@ -24,10 +26,10 @@ export const POST = apiHandler(async (req, { params }) => {
 
   if (!updated) throw new ApiError("房间不存在或已过期", 404);
 
-  notify(id);
+  notify(roomId);
 
   return NextResponse.json({
-    roomId: id,
+    roomId,
     userCount: updated.users.length,
   });
 });