fix(copilot): RPC DataError reconstruction, chat stream reconnection

Fix two issues:

1. RPC DataError deserialization crash: When the database-manager
   returns a 400 for a Prisma DataError/UniqueViolationError, the
   client-side reconstruction crashes because DataError.__init__
   expects a dict but exc.args only contains a string message.
   Wrap the string in the expected dict structure so the exception
   is properly caught by callers (e.g. workspace file overwrites).

2. Chat stream reconnection on page refresh: The AI SDK's built-in
   resume:true fires before message hydration completes, causing
   hydrated messages to overwrite the resumed stream. Replace with
   manual resumeStream() called after hydration + active_stream
   detection. Show the stop button immediately when an active stream
   is detected (isReconnecting flag) and prevent sending new messages
   until reconnected.

autogpt_platform/backend/backend/util/service.py

@@ -599,6 +599,15 @@ def get_service_client(
                 if error_response and error_response.type in EXCEPTION_MAPPING:
                     exception_class = EXCEPTION_MAPPING[error_response.type]
                     args = error_response.args or [str(e)]
+
+                    # Prisma DataError subclasses expect a dict `data` arg,
+                    # but RPC serialization only preserves the string message
+                    # from exc.args.  Wrap it in the expected structure so
+                    # the constructor doesn't crash on `.get()`.
+                    if issubclass(exception_class, DataError):
+                        msg = str(args[0]) if args else str(e)
+                        raise exception_class({"user_facing_error": {"message": msg}})
+
                     raise exception_class(*args)
 
                 # Otherwise categorize by HTTP status code

autogpt_platform/backend/backend/util/service_test.py

@@ -6,6 +6,7 @@ from unittest.mock import Mock
 
 import httpx
 import pytest
+from prisma.errors import DataError, UniqueViolationError
 
 from backend.util.service import (
     AppService,
@@ -447,6 +448,39 @@ class TestHTTPErrorRetryBehavior:
 
         assert "Invalid parameter value" in str(exc_info.value)
 
+    def test_prisma_data_error_reconstructed_correctly(self):
+        """Test that DataError subclasses (e.g. UniqueViolationError) are
+        reconstructed without crashing.
+
+        Prisma's DataError.__init__ expects a dict `data` arg with
+        a 'user_facing_error' key.  RPC serialization only preserves the
+        string message via exc.args, so the client must wrap it in the
+        expected dict structure.
+        """
+        for exc_type in [DataError, UniqueViolationError]:
+            mock_response = Mock()
+            mock_response.status_code = 400
+            mock_response.json.return_value = {
+                "type": exc_type.__name__,
+                "args": ["Unique constraint failed on the fields: (`path`)"],
+            }
+            mock_response.raise_for_status.side_effect = httpx.HTTPStatusError(
+                "400 Bad Request", request=Mock(), response=mock_response
+            )
+
+            client = get_service_client(ServiceTestClient)
+
+            with pytest.raises(exc_type) as exc_info:
+                client._handle_call_method_response(  # type: ignore[attr-defined]
+                    response=mock_response, method_name="test_method"
+                )
+
+            # The exception should have the message preserved
+            assert "Unique constraint" in str(exc_info.value)
+            # And should have the expected data structure (not crash)
+            assert hasattr(exc_info.value, "data")
+            assert isinstance(exc_info.value.data, dict)
+
     def test_client_error_status_codes_coverage(self):
         """Test that various 4xx status codes are all wrapped as HTTPClientError."""
         client_error_codes = [400, 401, 403, 404, 405, 409, 422, 429]

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

@@ -23,6 +23,7 @@ export function CopilotPage() {
     status,
     error,
     stop,
+    isReconnecting,
     createSession,
     onSend,
     isLoadingSession,
@@ -71,6 +72,7 @@ export function CopilotPage() {
             sessionId={sessionId}
             isLoadingSession={isLoadingSession}
             isCreatingSession={isCreatingSession}
+            isReconnecting={isReconnecting}
             onCreateSession={createSession}
             onSend={onSend}
             onStop={stop}

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

@@ -14,6 +14,8 @@ export interface ChatContainerProps {
   sessionId: string | null;
   isLoadingSession: boolean;
   isCreatingSession: boolean;
+  /** True when backend has an active stream but we haven't reconnected yet. */
+  isReconnecting?: boolean;
   onCreateSession: () => void | Promise<string>;
   onSend: (message: string) => void | Promise<void>;
   onStop: () => void;
@@ -26,11 +28,13 @@ export const ChatContainer = ({
   sessionId,
   isLoadingSession,
   isCreatingSession,
+  isReconnecting,
   onCreateSession,
   onSend,
   onStop,
   headerSlot,
 }: ChatContainerProps) => {
+  const isBusy = status === "streaming" || !!isReconnecting;
   const inputLayoutId = "copilot-2-chat-input";
 
   return (
@@ -56,8 +60,8 @@ export const ChatContainer = ({
                 <ChatInput
                   inputId="chat-input-session"
                   onSend={onSend}
-                  disabled={status === "streaming"}
-                  isStreaming={status === "streaming"}
+                  disabled={isBusy}
+                  isStreaming={isBusy}
                   onStop={onStop}
                   placeholder="What else can I help with?"
                 />

autogpt_platform/frontend/src/app/(platform)/copilot/useChatSession.ts

@@ -50,6 +50,14 @@ export function useChatSession() {
     );
   }, [sessionQuery.data, sessionId]);
 
+  // Expose active_stream info so the caller can trigger manual resume
+  // after hydration completes (rather than relying on AI SDK's built-in
+  // resume which fires before hydration).
+  const hasActiveStream = useMemo(() => {
+    if (sessionQuery.data?.status !== 200) return false;
+    return !!sessionQuery.data.data.active_stream;
+  }, [sessionQuery.data]);
+
   const { mutateAsync: createSessionMutation, isPending: isCreatingSession } =
     usePostV2CreateSession({
       mutation: {
@@ -102,6 +110,7 @@ export function useChatSession() {
     sessionId,
     setSessionId,
     hydratedMessages,
+    hasActiveStream,
     isLoadingSession: sessionQuery.isLoading,
     createSession,
     isCreatingSession,

autogpt_platform/frontend/src/app/(platform)/copilot/useCopilotPage.ts

@@ -29,6 +29,7 @@ export function useCopilotPage() {
     sessionId,
     setSessionId,
     hydratedMessages,
+    hasActiveStream,
     isLoadingSession,
     createSession,
     isCreatingSession,
@@ -91,10 +92,20 @@ export function useCopilotPage() {
     [sessionId],
   );
 
-  const { messages, sendMessage, stop, status, error, setMessages } = useChat({
+  const {
+    messages,
+    sendMessage,
+    stop,
+    status,
+    error,
+    setMessages,
+    resumeStream,
+  } = useChat({
     id: sessionId ?? undefined,
     transport: transport ?? undefined,
-    resume: true,
+    // Don't use resume: true — it fires before hydration completes, causing
+    // the hydrated messages to overwrite the resumed stream.  Instead we
+    // call resumeStream() manually after hydration + active_stream detection.
   });
 
   // Abort the stream if the backend doesn't start sending data within 12s.
@@ -115,13 +126,31 @@ export function useCopilotPage() {
     return () => clearTimeout(timer);
   }, [status]);
 
+  // Hydrate messages from the REST session endpoint.
+  // Skip hydration while streaming to avoid overwriting the live stream.
   useEffect(() => {
     if (!hydratedMessages || hydratedMessages.length === 0) return;
+    if (status === "streaming" || status === "submitted") return;
     setMessages((prev) => {
       if (prev.length >= hydratedMessages.length) return prev;
       return hydratedMessages;
     });
-  }, [hydratedMessages, setMessages]);
+  }, [hydratedMessages, setMessages, status]);
+
+  // Resume an active stream AFTER hydration completes.
+  // The backend returns active_stream info when a task is still running.
+  // We wait for hydration so the AI SDK has the conversation history
+  // before the resumed stream appends the in-progress assistant message.
+  const hasResumedRef = useRef<string | null>(null);
+  useEffect(() => {
+    if (!hasActiveStream || !sessionId) return;
+    if (!hydratedMessages || hydratedMessages.length === 0) return;
+    if (status === "streaming" || status === "submitted") return;
+    // Only resume once per session to avoid re-triggering after stream ends
+    if (hasResumedRef.current === sessionId) return;
+    hasResumedRef.current = sessionId;
+    resumeStream();
+  }, [hasActiveStream, sessionId, hydratedMessages, status, resumeStream]);
 
   // Poll session endpoint when a long-running tool (create_agent, edit_agent)
   // is in progress. When the backend completes, the session data will contain
@@ -204,12 +233,18 @@ export function useCopilotPage() {
     }
   }, [isDeleting]);
 
+  // True while we know the backend has an active stream but haven't
+  // reconnected yet.  Used to disable the send button and show stop UI.
+  const isReconnecting =
+    hasActiveStream && status !== "streaming" && status !== "submitted";
+
   return {
     sessionId,
     messages,
     status,
     error,
     stop,
+    isReconnecting,
     isLoadingSession,
     isCreatingSession,
     isUserLoading,