fix(webui): complete temporary chat mode

webui/src/lib/temporary-chat.ts

@@ -1,17 +1,23 @@
 import type { ChatSummary } from "./types";
 
 export const TEMPORARY_CHAT_ID_PREFIX = "temporary-";
-export const TEMPORARY_CHAT_ROUTE_KEY = "__temporary_chat__";
+const WEBSOCKET_SESSION_KEY_PREFIX = "websocket:";
 
 export function isTemporaryChatId(value: string): boolean {
   return value.startsWith(TEMPORARY_CHAT_ID_PREFIX);
 }
 
+export function temporaryChatIdFromSessionKey(value: string | null): string | null {
+  if (!value?.startsWith(WEBSOCKET_SESSION_KEY_PREFIX)) return null;
+  const chatId = value.slice(WEBSOCKET_SESSION_KEY_PREFIX.length);
+  return isTemporaryChatId(chatId) ? chatId : null;
+}
+
 export function createTemporaryChatSession(): ChatSummary {
   const chatId = `${TEMPORARY_CHAT_ID_PREFIX}${crypto.randomUUID()}`;
   const now = new Date().toISOString();
   return {
-    key: `websocket:${chatId}`,
+    key: `${WEBSOCKET_SESSION_KEY_PREFIX}${chatId}`,
     channel: "websocket",
     chatId,
     createdAt: now,