fix(chat): handle empty uploaded files case and improve artifact selection logic (#979)

* fix(chat): handle empty uploaded files case and improve artifact selection logic

* Update frontend/src/components/workspace/chats/chat-box.tsx

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fix: address code review suggestions from PR #979 (#3)

* Initial plan

* fix: address PR #979 review suggestions

- utils.ts: scope (empty) check inside <uploaded_files> tag content
- chat-box.tsx: remove stale `artifacts` from useEffect deps
- context.tsx: wrap select/deselect with useCallback for stable refs
- test: add test_empty_new_files_produces_empty_marker

Co-authored-by: foreleven <4785594+foreleven@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: foreleven <4785594+foreleven@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>
Co-authored-by: foreleven <4785594+foreleven@users.noreply.github.com>

frontend/src/components/workspace/artifacts/context.tsx

@@ -1,4 +1,10 @@
-import { createContext, useContext, useState, type ReactNode } from "react";
+import {
+  createContext,
+  useCallback,
+  useContext,
+  useState,
+  type ReactNode,
+} from "react";
 
 import { useSidebar } from "@/components/ui/sidebar";
 import { env } from "@/env";
@@ -35,20 +41,23 @@ export function ArtifactsProvider({ children }: ArtifactsProviderProps) {
   const [autoOpen, setAutoOpen] = useState(true);
   const { setOpen: setSidebarOpen } = useSidebar();
 
-  const select = (artifact: string, autoSelect = false) => {
-    setSelectedArtifact(artifact);
-    if (env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY !== "true") {
-      setSidebarOpen(false);
-    }
-    if (!autoSelect) {
-      setAutoSelect(false);
-    }
-  };
+  const select = useCallback(
+    (artifact: string, autoSelect = false) => {
+      setSelectedArtifact(artifact);
+      if (env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY !== "true") {
+        setSidebarOpen(false);
+      }
+      if (!autoSelect) {
+        setAutoSelect(false);
+      }
+    },
+    [setSidebarOpen, setSelectedArtifact, setAutoSelect],
+  );
 
-  const deselect = () => {
+  const deselect = useCallback(() => {
     setSelectedArtifact(null);
     setAutoSelect(true);
-  };
+  }, []);
 
   const value: ArtifactsContextType = {
     artifacts,

frontend/src/components/workspace/chats/chat-box.tsx

@@ -34,12 +34,19 @@ const ChatBox: React.FC<{ children: React.ReactNode; threadId: string }> = ({
     setOpen: setArtifactsOpen,
     setArtifacts,
     select: selectArtifact,
+    deselect,
     selectedArtifact,
   } = useArtifacts();
 
   const [autoSelectFirstArtifact, setAutoSelectFirstArtifact] = useState(true);
   useEffect(() => {
     setArtifacts(thread.values.artifacts);
+    if (
+      thread.values.artifacts?.length === 0 ||
+      (selectedArtifact && !thread.values.artifacts?.includes(selectedArtifact))
+    ) {
+      deselect();
+    }
     if (
       env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY === "true" &&
       autoSelectFirstArtifact
@@ -51,7 +58,9 @@ const ChatBox: React.FC<{ children: React.ReactNode; threadId: string }> = ({
     }
   }, [
     autoSelectFirstArtifact,
+    deselect,
     selectArtifact,
+    selectedArtifact,
     setArtifacts,
     thread.values.artifacts,
   ]);