feat(ui): open gallery when clicking images in chat messages

Clicking an image in a chat message now opens the same ImageGalleryModal
used by the attachments gallery. Matches by contentPath or assetId.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/IssueChatThread.tsx

@@ -80,6 +80,7 @@ interface IssueChatMessageContext {
   ) => Promise<void>;
   onInterruptQueued?: (runId: string) => Promise<void>;
   interruptingQueuedRunId?: string | null;
+  onImageClick?: (src: string) => void;
 }
 
 const IssueChatCtx = createContext<IssueChatMessageContext>({
@@ -184,6 +185,7 @@ interface IssueChatThreadProps {
   includeSucceededRunsWithoutOutput?: boolean;
   onInterruptQueued?: (runId: string) => Promise<void>;
   interruptingQueuedRunId?: string | null;
+  onImageClick?: (src: string) => void;
 }
 
 const DRAFT_DEBOUNCE_MS = 800;
@@ -246,8 +248,9 @@ function commentDateLabel(date: Date | string | undefined): string {
 }
 
 function IssueChatTextPart({ text, recessed }: { text: string; recessed?: boolean }) {
+  const { onImageClick } = useContext(IssueChatCtx);
   return (
-    <MarkdownBody className="text-sm leading-6" style={recessed ? { opacity: 0.55 } : undefined}>
+    <MarkdownBody className="text-sm leading-6" style={recessed ? { opacity: 0.55 } : undefined} onImageClick={onImageClick}>
       {text}
     </MarkdownBody>
   );
@@ -1604,6 +1607,7 @@ export function IssueChatThread({
   includeSucceededRunsWithoutOutput = false,
   onInterruptQueued,
   interruptingQueuedRunId = null,
+  onImageClick,
 }: IssueChatThreadProps) {
   const location = useLocation();
   const hasScrolledRef = useRef(false);
@@ -1731,6 +1735,7 @@ export function IssueChatThread({
       onVote,
       onInterruptQueued,
       interruptingQueuedRunId,
+      onImageClick,
     }),
     [
       feedbackVoteByTargetId,
@@ -1741,6 +1746,7 @@ export function IssueChatThread({
       onVote,
       onInterruptQueued,
       interruptingQueuedRunId,
+      onImageClick,
     ],
   );
 

ui/src/components/MarkdownBody.tsx

@@ -11,6 +11,8 @@ interface MarkdownBodyProps {
   style?: React.CSSProperties;
   /** Optional resolver for relative image paths (e.g. within export packages) */
   resolveImageSrc?: (src: string) => string | null;
+  /** Called when a user clicks an inline image */
+  onImageClick?: (src: string) => void;
 }
 
 let mermaidLoaderPromise: Promise<typeof import("mermaid").default> | null = null;
@@ -92,7 +94,7 @@ function MermaidDiagramBlock({ source, darkMode }: { source: string; darkMode: b
   );
 }
 
-export function MarkdownBody({ children, className, style, resolveImageSrc }: MarkdownBodyProps) {
+export function MarkdownBody({ children, className, style, resolveImageSrc, onImageClick }: MarkdownBodyProps) {
   const { theme } = useTheme();
   const components: Components = {
     pre: ({ node: _node, children: preChildren, ...preProps }) => {
@@ -132,10 +134,19 @@ export function MarkdownBody({ children, className, style, resolveImageSrc }: Ma
       );
     },
   };
-  if (resolveImageSrc) {
+  if (resolveImageSrc || onImageClick) {
     components.img = ({ node: _node, src, alt, ...imgProps }) => {
-      const resolved = src ? resolveImageSrc(src) : null;
-      return <img {...imgProps} src={resolved ?? src} alt={alt ?? ""} />;
+      const resolved = resolveImageSrc && src ? resolveImageSrc(src) : null;
+      const finalSrc = resolved ?? src;
+      return (
+        <img
+          {...imgProps}
+          src={finalSrc}
+          alt={alt ?? ""}
+          onClick={onImageClick && finalSrc ? (e) => { e.preventDefault(); onImageClick(finalSrc); } : undefined}
+          style={onImageClick ? { cursor: "pointer", ...(imgProps.style as React.CSSProperties | undefined) } : imgProps.style as React.CSSProperties | undefined}
+        />
+      );
     };
   }
 

ui/src/pages/IssueDetail.tsx

@@ -1356,6 +1356,28 @@ export function IssueDetail() {
   const attachmentList = attachments ?? [];
   const imageAttachments = attachmentList.filter(isImageAttachment);
   const nonImageAttachments = attachmentList.filter((a) => !isImageAttachment(a));
+
+  const handleChatImageClick = useCallback(
+    (src: string) => {
+      // Try exact contentPath match first
+      let idx = imageAttachments.findIndex((a) => a.contentPath === src);
+      if (idx < 0) {
+        // Try matching by asset ID extracted from /api/assets/{assetId}/content URLs
+        const assetMatch = src.match(/\/api\/assets\/([^/]+)\/content/);
+        if (assetMatch) {
+          idx = imageAttachments.findIndex((a) => a.assetId === assetMatch[1]);
+        }
+      }
+      if (idx >= 0) {
+        setGalleryIndex(idx);
+        setGalleryOpen(true);
+      } else {
+        // Image not in attachment list — open in new tab
+        window.open(src, "_blank");
+      }
+    },
+    [imageAttachments],
+  );
   const hasAttachments = attachmentList.length > 0;
   const attachmentUploadButton = (
     <>
@@ -1897,6 +1919,7 @@ export function IssueDetail() {
                   await interruptQueuedComment.mutateAsync(runningIssueRun.id);
                 }
               : undefined}
+            onImageClick={handleChatImageClick}
           />
         </TabsContent>