fix(chat): verify thread existence in backend to prevent fk violations and gracefully reset route state on client loading failures

Author: SH20RAJ

apps/website/src/app/api/chat/route.ts

@@ -38,7 +38,27 @@ export async function POST(req: Request) {
   const question = lastUserMessage?.content || "";
 
   let threadId = body.threadId;
-  if (!threadId) {
+  let threadExists = false;
+
+  if (threadId) {
+    const [existingThread] = await db
+      .select({ id: chatThreads.id })
+      .from(chatThreads)
+      .where(
+        and(
+          eq(chatThreads.id, threadId),
+          eq(chatThreads.userId, user.id),
+          eq(chatThreads.workspaceId, workspaceId),
+        ),
+      )
+      .limit(1);
+
+    if (existingThread) {
+      threadExists = true;
+    }
+  }
+
+  if (!threadId || !threadExists) {
     threadId = newId("thr");
     await db.insert(chatThreads).values({
       id: threadId,
@@ -49,6 +69,7 @@ export async function POST(req: Request) {
     });
   }
 
+
   // Persist user message to DB
   await db.insert(chatMessages).values({
     id: newId("msg"),

apps/website/src/components/chat/chat-page.tsx

@@ -125,9 +125,15 @@ export function ChatPage() {
           router.replace(`/dashboard/chat?threadId=${threadId}`);
         }
       }
-    } catch {
-      toast.error("Failed to load thread details.");
+    } catch (err) {
+      console.error("Failed to load thread:", err);
+      toast.error("Conversation not found or failed to load.");
+      setActiveThreadId(null);
+      setMessages([]);
+      router.replace("/dashboard/chat");
     }
+
+
   }, [router, setMessages, stop]);
 
   // Sync thread when URL params change