perf: optimize markdown file link detection

Only mark existing files as openable links
Avoid file-link behavior while messages stream
Limit file existence checks to 4 concurrent requests

packages/ui/src/components/chat/MarkdownRendererImpl.tsx

@@ -992,10 +992,15 @@ interface MarkdownRendererProps {
   disableStreamAnimation?: boolean;
   variant?: MarkdownVariant;
   onShowPopup?: (content: ToolPopupContent) => void;
+  enableFileReferences?: boolean;
 }
 
 const MERMAID_BLOCK_SELECTOR = '[data-markdown="mermaid-block"]';
 const FILE_LINK_SELECTOR = '[data-openchamber-file-link="true"]';
+const FILE_REFERENCE_STAT_CONCURRENCY = 4;
+const FILE_REFERENCE_STAT_CACHE = new Map<string, Promise<boolean>>();
+let activeFileReferenceStatCount = 0;
+const pendingFileReferenceStats: Array<() => void> = [];
 
 type ParsedFileReference = {
   path: string;
@@ -1262,6 +1267,44 @@ const getResolvedReference = (rawValue: string, effectiveDirectory: string): (Pa
   };
 };
 
+const fileReferenceExists = (resolvedPath: string): Promise<boolean> => {
+  const normalizedPath = normalizePath(resolvedPath);
+  if (!normalizedPath) {
+    return Promise.resolve(false);
+  }
+
+  const cached = FILE_REFERENCE_STAT_CACHE.get(normalizedPath);
+  if (cached) {
+    return cached;
+  }
+
+  const request = new Promise<boolean>((resolve) => {
+    const run = () => {
+      activeFileReferenceStatCount += 1;
+      void fetch(`/api/fs/stat?path=${encodeURIComponent(normalizedPath)}`, {
+        method: 'GET',
+        cache: 'no-store',
+      })
+        .then((response) => resolve(response.ok))
+        .catch(() => resolve(false))
+        .finally(() => {
+          activeFileReferenceStatCount = Math.max(0, activeFileReferenceStatCount - 1);
+          pendingFileReferenceStats.shift()?.();
+        });
+    };
+
+    if (activeFileReferenceStatCount < FILE_REFERENCE_STAT_CONCURRENCY) {
+      run();
+      return;
+    }
+
+    pendingFileReferenceStats.push(run);
+  });
+
+  FILE_REFERENCE_STAT_CACHE.set(normalizedPath, request);
+  return request;
+};
+
 const getContextDirectory = (effectiveDirectory: string, resolvedPath: string): string => {
   const normalizedDirectory = normalizePath(effectiveDirectory);
   if (normalizedDirectory) {
@@ -1278,11 +1321,13 @@ const useFileReferenceInteractions = ({
   effectiveDirectory,
   editor,
   preferRuntimeEditor,
+  enabled,
 }: {
   containerRef: React.RefObject<HTMLDivElement | null>;
   effectiveDirectory: string;
   editor?: EditorAPI;
   preferRuntimeEditor?: boolean;
+  enabled: boolean;
 }) => {
   const annotationDebounceRef = React.useRef<number | null>(null);
 
@@ -1291,6 +1336,20 @@ const useFileReferenceInteractions = ({
     if (!container) {
       return;
     }
+    let cancelled = false;
+
+    const clearFileLinkAttributes = (candidate: HTMLElement) => {
+      candidate.removeAttribute('data-openchamber-file-link');
+      candidate.removeAttribute('data-openchamber-file-ref');
+      candidate.removeAttribute('data-openchamber-file-path');
+      if (candidate.getAttribute('title') === 'Open file') {
+        candidate.removeAttribute('title');
+      }
+      if (candidate.tagName.toLowerCase() !== 'a') {
+        candidate.removeAttribute('role');
+        candidate.removeAttribute('tabindex');
+      }
+    };
 
     const annotateFileLinks = () => {
       const candidates = container.querySelectorAll<HTMLElement>('[data-markdown="inline-code"], a');
@@ -1298,28 +1357,32 @@ const useFileReferenceInteractions = ({
       for (const candidate of Array.from(candidates)) {
         const rawCandidate = extractPathCandidateFromElement(candidate);
         const resolved = getResolvedReference(rawCandidate, effectiveDirectory);
-        if (!resolved) {
-          candidate.removeAttribute('data-openchamber-file-link');
-          candidate.removeAttribute('data-openchamber-file-ref');
-          candidate.removeAttribute('data-openchamber-file-path');
-          if (candidate.getAttribute('title') === 'Open file') {
-            candidate.removeAttribute('title');
-          }
-          if (candidate.tagName.toLowerCase() !== 'a') {
-            candidate.removeAttribute('role');
-            candidate.removeAttribute('tabindex');
-          }
+        clearFileLinkAttributes(candidate);
+
+        if (!enabled || !resolved) {
           continue;
         }
 
-        candidate.setAttribute('data-openchamber-file-link', 'true');
-        candidate.setAttribute('data-openchamber-file-ref', rawCandidate);
-        candidate.setAttribute('data-openchamber-file-path', resolved.resolvedPath);
-        candidate.setAttribute('title', 'Open file');
-        if (candidate.tagName.toLowerCase() !== 'a') {
-          candidate.setAttribute('role', 'button');
-          candidate.setAttribute('tabindex', '0');
-        }
+        void fileReferenceExists(resolved.resolvedPath).then((exists) => {
+          if (cancelled || !exists || !container.contains(candidate)) {
+            return;
+          }
+
+          const latestRawCandidate = extractPathCandidateFromElement(candidate);
+          const latestResolved = getResolvedReference(latestRawCandidate, effectiveDirectory);
+          if (!latestResolved || latestResolved.resolvedPath !== resolved.resolvedPath) {
+            return;
+          }
+
+          candidate.setAttribute('data-openchamber-file-link', 'true');
+          candidate.setAttribute('data-openchamber-file-ref', latestRawCandidate);
+          candidate.setAttribute('data-openchamber-file-path', latestResolved.resolvedPath);
+          candidate.setAttribute('title', 'Open file');
+          if (candidate.tagName.toLowerCase() !== 'a') {
+            candidate.setAttribute('role', 'button');
+            candidate.setAttribute('tabindex', '0');
+          }
+        });
       }
     };
 
@@ -1416,6 +1479,7 @@ const useFileReferenceInteractions = ({
     container.addEventListener('keydown', handleKeyDown);
 
     return () => {
+      cancelled = true;
       if (annotationDebounceRef.current !== null && typeof window !== 'undefined') {
         window.clearTimeout(annotationDebounceRef.current);
       }
@@ -1424,7 +1488,7 @@ const useFileReferenceInteractions = ({
       container.removeEventListener('click', handleClick);
       container.removeEventListener('keydown', handleKeyDown);
     };
-  }, [containerRef, editor, effectiveDirectory, preferRuntimeEditor]);
+  }, [containerRef, editor, effectiveDirectory, preferRuntimeEditor, enabled]);
 };
 
 const useMermaidInlineInteractions = ({
@@ -1531,6 +1595,7 @@ const MarkdownRendererImpl: React.FC<MarkdownRendererProps> = ({
   disableStreamAnimation = false,
   variant = 'assistant',
   onShowPopup,
+  enableFileReferences = true,
 }) => {
   const currentTheme = useCurrentMermaidTheme();
   const { editor, runtime } = useRuntimeAPIs();
@@ -1543,6 +1608,7 @@ const MarkdownRendererImpl: React.FC<MarkdownRendererProps> = ({
     effectiveDirectory,
     editor,
     preferRuntimeEditor: runtime.isVSCode,
+    enabled: enableFileReferences && !isStreaming,
   });
   useExternalLinkInteractions({ containerRef });
   const openContextPreview = useUIStore((state) => state.openContextPreview);
@@ -1615,6 +1681,7 @@ const SimpleMarkdownRendererImpl: React.FC<{
   onShowPopup?: (content: ToolPopupContent) => void;
   mermaidControls?: MermaidControlOptions;
   allowMermaidWheelZoom?: boolean;
+  enableFileReferences?: boolean;
 }> = ({
   content,
   className,
@@ -1623,6 +1690,7 @@ const SimpleMarkdownRendererImpl: React.FC<{
   stripFrontmatter = false,
   onShowPopup,
   allowMermaidWheelZoom = false,
+  enableFileReferences = true,
 }) => {
   const { editor, runtime } = useRuntimeAPIs();
   const renderedContent = React.useMemo(
@@ -1644,6 +1712,7 @@ const SimpleMarkdownRendererImpl: React.FC<{
     effectiveDirectory,
     editor,
     preferRuntimeEditor: runtime.isVSCode,
+    enabled: enableFileReferences,
   });
   useExternalLinkInteractions({ containerRef, enabled: !disableLinkSafety });
   const syntaxTheme = React.useMemo(() => generateSyntaxTheme(currentTheme), [currentTheme]);
@@ -1674,5 +1743,6 @@ export const SimpleMarkdownRenderer = React.memo(SimpleMarkdownRendererImpl, (pr
     && prev.disableLinkSafety === next.disableLinkSafety
     && prev.stripFrontmatter === next.stripFrontmatter
     && prev.onShowPopup === next.onShowPopup
-    && prev.allowMermaidWheelZoom === next.allowMermaidWheelZoom;
+    && prev.allowMermaidWheelZoom === next.allowMermaidWheelZoom
+    && prev.enableFileReferences === next.enableFileReferences;
 });

packages/ui/src/components/chat/message/parts/AssistantTextPart.tsx

@@ -84,6 +84,7 @@ const AssistantTextPart: React.FC<AssistantTextPartProps> = ({
                 isStreaming={isStreaming}
                 disableStreamAnimation={chatRenderMode === 'sorted'}
                 variant={part.type === 'reasoning' ? 'reasoning' : 'assistant'}
+                enableFileReferences={isFinalized}
             />
         </div>
     );

packages/ui/src/index.css

@@ -976,6 +976,8 @@ html:not(.dark) .chat-scroll {
   cursor: pointer;
   text-decoration: underline;
   text-underline-offset: 2px;
+  user-select: text;
+  -webkit-user-select: text;
 }
 
 .markdown-content [data-openchamber-file-link="true"]:hover {