fix(chat): scroll to target lines in file references

apps/desktop/src/components/workpanel/FilesTab.tsx

@@ -126,7 +126,7 @@ function HighlightedText({ path, content }: { path: string; content: string }) {
     <pre className="file-viewer-code">
       {tokens
         ? tokens.tokens.map((row, i) => (
-            <div className="file-viewer-line" key={i}>
+            <div className="file-viewer-line" data-line={i + 1} key={i}>
               {row.length === 0
                 ? "\n"
                 : row.map((token, j) => (
@@ -137,7 +137,7 @@ function HighlightedText({ path, content }: { path: string; content: string }) {
             </div>
           ))
         : visible.split("\n").map((line, i) => (
-            <div className="file-viewer-line" key={i}>
+            <div className="file-viewer-line" data-line={i + 1} key={i}>
               {line || "\n"}
             </div>
           ))}
@@ -163,8 +163,10 @@ export function FilesTab() {
   const [expanded, setExpanded] = useState<Set<string>>(new Set());
   const [selected, setSelected] = useState<string | null>(null);
   const [selectedMimeType, setSelectedMimeType] = useState<string | undefined>();
+  const [selectedLine, setSelectedLine] = useState<number | undefined>();
   const [file, setFile] = useState<FsReadResult | null>(null);
   const [fileError, setFileError] = useState(false);
+  const viewerBodyRef = useRef<HTMLDivElement>(null);
 
   // Workspace switches reset all browsing state. Guarded so it only fires on
   // an actual root change: an unconditional [root] effect also runs on the
@@ -178,6 +180,7 @@ export function FilesTab() {
     setExpanded(new Set());
     setSelected(null);
     setSelectedMimeType(undefined);
+    setSelectedLine(undefined);
     setFile(null);
     setFileError(false);
   }, [root]);
@@ -215,17 +218,32 @@ export function FilesTab() {
     [dirs, loadDir],
   );
 
-  const openFile = useCallback(async (rel: string, mimeType?: string) => {
-    setSelected(rel);
-    setSelectedMimeType(mimeType);
-    setFile(null);
-    setFileError(false);
-    try {
-      setFile(await api.fsRead(rel, mimeType));
-    } catch {
-      setFileError(true);
-    }
-  }, []);
+  const openFile = useCallback(
+    async (rel: string, mimeType?: string, position?: { line?: number; column?: number }) => {
+      setSelected(rel);
+      setSelectedMimeType(mimeType);
+      setSelectedLine(position?.line);
+      setFile(null);
+      setFileError(false);
+      try {
+        setFile(await api.fsRead(rel, mimeType));
+      } catch {
+        setFileError(true);
+      }
+    },
+    [],
+  );
+
+  useEffect(() => {
+    if (!file || selectedLine == null) return;
+    const frame = requestAnimationFrame(() => {
+      const lineNode = viewerBodyRef.current?.querySelector(
+        `[data-line="${selectedLine}"]`,
+      );
+      lineNode?.scrollIntoView({ block: "center" });
+    });
+    return () => cancelAnimationFrame(frame);
+  }, [file, selectedLine]);
 
   const openMp4 = useCallback(async () => {
     if (!selected) return;
@@ -260,7 +278,10 @@ export function FilesTab() {
       setExpanded((prev) => new Set([...prev, ...ancestors]));
       for (const dir of ancestors) void loadDir(dir);
     }
-    void openFile(path, fileRequest.mimeType);
+    void openFile(path, fileRequest.mimeType, {
+      line: fileRequest.line,
+      column: fileRequest.column,
+    });
   }, [fileRequest, root, loadDir, openFile]);
 
   const renderDir = (rel: string, depth: number): React.ReactNode => {
@@ -337,6 +358,7 @@ export function FilesTab() {
             onClick={() => {
               setSelected(null);
               setSelectedMimeType(undefined);
+              setSelectedLine(undefined);
               setFile(null);
             }}
           >
@@ -356,12 +378,15 @@ export function FilesTab() {
             <IconExternal size={14} />
           </TooltipButton>
         </div>
-        <div className="file-viewer-body">
+        <div className="file-viewer-body" ref={viewerBodyRef}>
           {fileError ? (
             <WorkTabEmpty icon={IconFileText} title={t("panel.files.error")} />
           ) : !file ? (
             <div className="file-tree-note">{t("panel.files.loading")}</div>
-          ) : file.kind === "text" && isMarkdownPath(selected) ? (
+          ) :
+          file.kind === "text" &&
+          isMarkdownPath(selected) &&
+          selectedLine === undefined ? (
             <div className="file-viewer-markdown prose-chat">
               <Markdown source={file.content ?? ""} baseDir={fileDirOf(selected)} />
             </div>

apps/desktop/src/features/chat/transcript/shared.tsx

@@ -423,13 +423,22 @@ export function FileRefChip({
   kind,
   mimeType,
   onOpen,
+  line,
+  column,
   ...position
 }: {
   name: string;
   path: string;
   kind?: "image" | "file";
   mimeType?: string;
-  onOpen: (path: string, baseDir?: string, mimeType?: string) => void;
+  onOpen: (
+    path: string,
+    baseDir?: string,
+    mimeType?: string,
+    position?: { line?: number; column?: number },
+  ) => void;
+  line?: number;
+  column?: number;
 } & SourcePositionProps) {
   const { t } = useTranslation();
   const Icon = fileChipIcon(name, kind);
@@ -443,7 +452,7 @@ export function FileRefChip({
         {...position}
         title={`${html ? t("chat.previewUrl") : t("chat.openFile")} — ${path}`}
         aria-label={`${name} — ${path}`}
-        onClick={() => onOpen(path, undefined, mimeType)}
+        onClick={() => onOpen(path, undefined, mimeType, { line, column })}
         onContextMenu={(event) => openFileMenu(event, { path })}
       >
         <span className="composer-chip-icon" aria-hidden>
@@ -556,6 +565,8 @@ export function LinkifiedText({ text, attachments }: { text: string; attachments
             key={index}
             name={segment.label}
             path={segment.target.path}
+            line={segment.target.line}
+            column={segment.target.column}
             onOpen={openFileRef}
             {...position}
           />

apps/desktop/src/hooks/use-preview-target.ts

@@ -27,7 +27,12 @@ export function useOpenPreviewTarget() {
   const openFileRef = useOpenChatFileRef();
   return useCallback(
     (target: ChatPreviewTarget) =>
-      target.kind === "file" ? openFileRef(target.path) : openHttpUrl(target.url),
+      target.kind === "file"
+        ? openFileRef(target.path, undefined, undefined, {
+            line: target.line,
+            column: target.column,
+          })
+        : openHttpUrl(target.url),
     [openFileRef],
   );
 }
@@ -131,10 +136,13 @@ function useResolveChatFileRef() {
  * Open a file reference the conversation mentioned.
  *
  * A workspace `.html` page in the primary folder stays with the side browser
- * (ADR 0163): it is a page to run, not a file to read. A project file opens in
- * the bundled file view when that view is installed and on the host file tab
- * otherwise; scratch and attachment files live outside the project and always
- * take the host file tab.
+ * (ADR 0163): it is a page to run, not a file to read. A plain project file
+ * opens in the bundled file view when available; a positioned `path:line`
+ * reference uses the host file tab, which can scroll to the requested line.
+ * The plugin view accepts opaque path locations and has no line-navigation
+ * contract, so positioned references keep their path unchanged and use the
+ * host viewer's existing scroll support. Scratch and attachment files also use
+ * the host file tab.
  */
 export function useOpenChatFileRef() {
   const resolveRef = useResolveChatFileRef();
@@ -149,11 +157,20 @@ export function useOpenChatFileRef() {
   );
 
   return useCallback(
-    (path: string, baseDir?: string, mimeType?: string) => {
+    (
+      path: string,
+      baseDir?: string,
+      mimeType?: string,
+      position?: { line?: number; column?: number },
+    ) => {
+      const line = position?.line;
+      const column = position?.column;
       void (async () => {
         const resolved = await resolveRef(path, baseDir);
         if (!resolved) return;
+        const hasPosition = line !== undefined || column !== undefined;
         if (
+          !hasPosition &&
           resolved.inProject &&
           resolved.primary &&
           resolved.relativePath &&
@@ -162,11 +179,15 @@ export function useOpenChatFileRef() {
           openUrl(resolved.relativePath);
           return;
         }
-        if (resolved.inProject && fileViewAvailable) {
+        if (
+          resolved.inProject &&
+          fileViewAvailable &&
+          !hasPosition
+        ) {
           openTab(fileManagerPluginTab(resolved.path));
           return;
         }
-        openFile(resolved.path, mimeType);
+        openFile(resolved.path, mimeType, { line, column });
       })();
     },
     [fileViewAvailable, openFile, openTab, openUrl, resolveRef],

apps/desktop/src/lib/chat-links.ts

@@ -52,6 +52,21 @@ function stripLineRef(path: string): string {
   return path.replace(/:\d+(?::\d+)?$/, "");
 }
 
+/** Trailing `:line[:col]` on a file token, if any. */
+export function parseFileRefPosition(
+  text: string,
+): { line: number; column?: number } | null {
+  const token = text.trim().replace(/[.,!?;:，。！？；：]+$/u, "");
+  const match = token.match(/:(\d+)(?::(\d+))?$/);
+  if (!match) return null;
+  const line = Number(match[1]);
+  if (!Number.isFinite(line) || line < 1) return null;
+  const column = match[2] !== undefined ? Number(match[2]) : undefined;
+  return column !== undefined && Number.isFinite(column) && column >= 1
+    ? { line, column }
+    : { line };
+}
+
 function leafName(path: string): string {
   const normalized = path.replaceAll("\\", "/").replace(/\/+$/, "");
   return normalized.slice(normalized.lastIndexOf("/") + 1) || path;
@@ -188,7 +203,7 @@ export function toWorkspaceRel(
 }
 
 export type ChatPreviewTarget =
-  | { kind: "file"; path: string }
+  | { kind: "file"; path: string; line?: number; column?: number }
   | { kind: "url"; url: string };
 
 /** Resolve one raw chat token into a previewable target, or null. */
@@ -199,17 +214,24 @@ export function resolvePreviewTarget(
 ): ChatPreviewTarget | null {
   const trimmed = text.trim();
   if (isHttpUrl(trimmed)) return { kind: "url", url: trimmed };
-  const at = unwrapAtFileRef(trimmed);
+  const position = parseFileRefPosition(trimmed);
+  const pathText = position
+    ? trimmed.replace(/[.,!?;:，。！？；：]+$/u, "")
+    : trimmed;
+  const at = unwrapAtFileRef(pathText);
   if (at) {
-    if (isAbsoluteFilePath(at)) return { kind: "file", path: at };
-    const rel = toWorkspaceRel(at, root, baseDir);
-    return rel ? { kind: "file", path: rel } : null;
+    const cleaned = stripLineRef(at);
+    if (isAbsoluteFilePath(cleaned)) {
+      return { kind: "file", path: cleaned, ...(position ?? {}) };
+    }
+    const rel = toWorkspaceRel(cleaned, root, baseDir);
+    return rel ? { kind: "file", path: rel, ...(position ?? {}) } : null;
   }
-  const file = parseFileRef(trimmed);
+  const file = parseFileRef(pathText);
   if (!file) return null;
-  if (isAbsoluteFilePath(file)) return { kind: "file", path: file };
+  if (isAbsoluteFilePath(file)) return { kind: "file", path: file, ...(position ?? {}) };
   const rel = toWorkspaceRel(file, root, baseDir);
-  return rel ? { kind: "file", path: rel } : null;
+  return rel ? { kind: "file", path: rel, ...(position ?? {}) } : null;
 }
 
 /** Tool-call args → preview target (Read/Write/Edit paths, fetch URLs). */

apps/desktop/src/lib/work-panel-tabs.ts

@@ -15,6 +15,9 @@ export type WorkPanelTab = {
   location?: string;
   /** Stored attachment mimeType for extension-less `attachments/<sha256>` images. */
   mimeType?: string;
+  /** Optional 1-based line/column for host file tabs (chat `path:line` refs). */
+  line?: number;
+  column?: number;
 };
 
 export type WorkPanelTabsState = {
@@ -24,9 +27,30 @@ export type WorkPanelTabsState = {
 
 export type WorkPanelContext = WorkPanelTabsState & {
   open: boolean;
-  fileRequest: { path: string; seq: number; mimeType?: string } | null;
+  fileRequest: {
+    path: string;
+    seq: number;
+    mimeType?: string;
+    line?: number;
+    column?: number;
+  } | null;
 };
 
+/** Build the file-view request represented by an active file tab. */
+export function createWorkPanelFileRequest(
+  tab: WorkPanelTab,
+  seq: number,
+): WorkPanelContext["fileRequest"] {
+  if (tab.kind !== "file" || !tab.resource) return null;
+  return {
+    path: tab.resource,
+    seq,
+    ...(tab.mimeType ? { mimeType: tab.mimeType } : {}),
+    ...(tab.line != null ? { line: tab.line } : {}),
+    ...(tab.column != null ? { column: tab.column } : {}),
+  };
+}
+
 let newWorkPanelTabSequence = 0;
 
 export function emptyWorkPanelContext(): WorkPanelContext {
@@ -267,13 +291,19 @@ export function normalizeWorkPanelFilePath(path: string): string {
   return absolute ? `/${normalized}` : normalized;
 }
 
-export function fileWorkPanelTab(path: string, mimeType?: string): WorkPanelTab {
+export function fileWorkPanelTab(
+  path: string,
+  mimeType?: string,
+  position?: { line?: number; column?: number },
+): WorkPanelTab {
   const resource = normalizeWorkPanelFilePath(path);
   return {
     id: `file:${resource}`,
     kind: "file",
     resource,
     ...(mimeType ? { mimeType } : {}),
+    ...(position?.line != null ? { line: position.line } : {}),
+    ...(position?.column != null ? { column: position.column } : {}),
   };
 }
 

apps/desktop/src/stores/app-state.ts

@@ -368,7 +368,13 @@ export type AppState = {
   workPanelContexts: Record<string, WorkPanelContext>;
   workPanelWidth: number;
   /** Chat-initiated "preview this file" request consumed by the files viewer. */
-  workPanelFileRequest: { path: string; seq: number; mimeType?: string } | null;
+  workPanelFileRequest: {
+    path: string;
+    seq: number;
+    mimeType?: string;
+    line?: number;
+    column?: number;
+  } | null;
   /** Open (or activate) the transcript tab of one delegated subagent. */
   openSubagentTab: (delegationId: string, agentName?: string) => void;
   /** Abort one session's running turn, visible or not. */
@@ -392,7 +398,11 @@ export type AppState = {
   /** Hide the visible panel while retaining its session-owned context. */
   resetWorkPanelContext: () => void;
   setWorkPanelWidth: (width: number) => void;
-  openFileInWorkPanel: (path: string, mimeType?: string) => void;
+  openFileInWorkPanel: (
+    path: string,
+    mimeType?: string,
+    position?: { line?: number; column?: number },
+  ) => void;
   openUrlInWorkPanel: (url: string) => void;
   updateBrowserWorkPanelTab: (state: BrowserState) => void;
 };