diff --git a/packages/ui/src/components/chat/MarkdownRenderer.tsx b/packages/ui/src/components/chat/MarkdownRenderer.tsx
index 2a87a108..01380763 100644
--- a/packages/ui/src/components/chat/MarkdownRenderer.tsx
+++ b/packages/ui/src/components/chat/MarkdownRenderer.tsx
@@ -1022,14 +1022,14 @@ const getContextDirectory = (effectiveDirectory: string, resolvedPath: string):
 const useFileReferenceInteractions = ({
   containerRef,
   effectiveDirectory,
-  readFile,
+  statFile,
   editor,
   preferRuntimeEditor,
   deferValidationUntilIdle = false,
 }: {
   containerRef: React.RefObject<HTMLDivElement | null>;
   effectiveDirectory: string;
-  readFile?: (path: string) => Promise<{ content: string; path: string }>;
+  statFile?: (path: string) => Promise<{ path: string; isFile: boolean; size: number }>;
   editor?: EditorAPI;
   preferRuntimeEditor?: boolean;
   deferValidationUntilIdle?: boolean;
@@ -1061,10 +1061,14 @@ const useFileReferenceInteractions = ({
 
       const checkPromise = (async () => {
         try {
-          if (!readFile) {
+          if (!statFile) {
+            return false;
+          }
+          const stat = await statFile(resolvedPath);
+          if (!stat.isFile) {
+            cache.set(resolvedPath, false);
             return false;
           }
-          await readFile(resolvedPath);
           cache.set(resolvedPath, true);
           return true;
         } catch {
@@ -1289,7 +1293,7 @@ const useFileReferenceInteractions = ({
       container.removeEventListener('click', handleClick);
       container.removeEventListener('keydown', handleKeyDown);
     };
-  }, [containerRef, deferValidationUntilIdle, editor, effectiveDirectory, preferRuntimeEditor, readFile]);
+  }, [containerRef, deferValidationUntilIdle, editor, effectiveDirectory, preferRuntimeEditor, statFile]);
 };
 
 const useMermaidInlineInteractions = ({
@@ -1405,7 +1409,7 @@ export const MarkdownRenderer: React.FC<MarkdownRendererProps> = ({
   useFileReferenceInteractions({
     containerRef: streamdownContainerRef,
     effectiveDirectory,
-    readFile: files.readFile,
+    statFile: files.statFile,
     editor,
     preferRuntimeEditor: runtime.isVSCode,
     deferValidationUntilIdle: isStreaming,
@@ -1491,7 +1495,7 @@ export const SimpleMarkdownRenderer: React.FC<{
   useFileReferenceInteractions({
     containerRef: streamdownContainerRef,
     effectiveDirectory,
-    readFile: files.readFile,
+    statFile: files.statFile,
     editor,
     preferRuntimeEditor: runtime.isVSCode,
   });
diff --git a/packages/ui/src/lib/api/types.ts b/packages/ui/src/lib/api/types.ts
index a67b2496..24a6f473 100644
--- a/packages/ui/src/lib/api/types.ts
+++ b/packages/ui/src/lib/api/types.ts
@@ -490,6 +490,7 @@ export interface FilesAPI {
   listDirectory(path: string, options?: ListDirectoryOptions): Promise<DirectoryListResult>;
   search(payload: FileSearchQuery): Promise<FileSearchResult[]>;
   createDirectory(path: string): Promise<{ success: boolean; path: string }>;
+  statFile?(path: string): Promise<{ path: string; isFile: boolean; size: number }>;
   readFile?(path: string): Promise<{ content: string; path: string }>;
   readFileBinary?(path: string): Promise<{ dataUrl: string; path: string }>;
   writeFile?(path: string, content: string): Promise<{ success: boolean; path: string }>;
diff --git a/packages/vscode/src/bridge-fs-runtime.ts b/packages/vscode/src/bridge-fs-runtime.ts
index fece387c..d2827f35 100644
--- a/packages/vscode/src/bridge-fs-runtime.ts
+++ b/packages/vscode/src/bridge-fs-runtime.ts
@@ -180,6 +180,39 @@ export async function handleFsBridgeMessage(
       }
     }
 
+    case 'api:fs:stat': {
+      const target = (payload as { path: string })?.path;
+      if (!target) {
+        return { id, type, success: false, error: 'Path is required' };
+      }
+
+      const resolution = await deps.resolveFileReadPath(target);
+      if (!resolution.ok) {
+        return { id, type, success: false, error: resolution.error };
+      }
+
+      try {
+        const stats = await fs.promises.stat(resolution.resolvedPath);
+        if (!stats.isFile()) {
+          return { id, type, success: false, error: 'Specified path is not a file' };
+        }
+
+        return {
+          id,
+          type,
+          success: true,
+          data: {
+            path: deps.normalizeFsPath(resolution.resolvedPath),
+            isFile: true,
+            size: stats.size,
+          },
+        };
+      } catch (error) {
+        const message = error instanceof Error ? error.message : 'Failed to stat file';
+        return { id, type, success: false, error: message };
+      }
+    }
+
     case 'api:fs:write': {
       const { path: targetPath, content } = (payload as { path: string; content: string }) || {};
       if (!targetPath) {
diff --git a/packages/vscode/src/bridge-localfs-proxy-runtime.ts b/packages/vscode/src/bridge-localfs-proxy-runtime.ts
index 66618ffb..b7e90aea 100644
--- a/packages/vscode/src/bridge-localfs-proxy-runtime.ts
+++ b/packages/vscode/src/bridge-localfs-proxy-runtime.ts
@@ -1,5 +1,5 @@
 import * as fs from 'fs';
-import { getFsMimeType, resolveFileReadPath, type FsReadPathResolution } from './bridge-fs-helpers-runtime';
+import { getFsMimeType, normalizeFsPath, resolveFileReadPath, type FsReadPathResolution } from './bridge-fs-helpers-runtime';
 
 type ApiProxyResponsePayload = {
   status: number;
@@ -48,7 +48,7 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
     return buildProxyJsonError(400, 'Invalid request path');
   }
 
-  if (parsed.pathname !== '/api/fs/read' && parsed.pathname !== '/api/fs/raw') {
+  if (parsed.pathname !== '/api/fs/stat' && parsed.pathname !== '/api/fs/read' && parsed.pathname !== '/api/fs/raw') {
     return null;
   }
 
@@ -68,6 +68,21 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
       return buildProxyJsonError(400, 'Specified path is not a file');
     }
 
+    if (parsed.pathname === '/api/fs/stat') {
+      return {
+        status: 200,
+        headers: {
+          'content-type': 'application/json',
+          'cache-control': 'no-store',
+        },
+        bodyBase64: base64EncodeUtf8(JSON.stringify({
+          path: normalizeFsPath(resolution.resolvedPath),
+          isFile: true,
+          size: stats.size,
+        })),
+      };
+    }
+
     if (parsed.pathname === '/api/fs/read') {
       const content = await fs.promises.readFile(resolution.resolvedPath, 'utf8');
       return {
@@ -94,6 +109,9 @@ export const tryHandleLocalFsProxy = async (method: string, requestPath: string)
     if (err?.code === 'ENOENT') {
       return buildProxyJsonError(404, 'File not found');
     }
+    if (parsed.pathname === '/api/fs/stat') {
+      return buildProxyJsonError(500, 'Unable to stat file');
+    }
     return buildProxyJsonError(500, 'Unable to read file');
   }
 };
diff --git a/packages/vscode/webview/api/files.ts b/packages/vscode/webview/api/files.ts
index bcc73d96..4232bd2a 100644
--- a/packages/vscode/webview/api/files.ts
+++ b/packages/vscode/webview/api/files.ts
@@ -71,6 +71,16 @@ export const createVSCodeFilesAPI = (): FilesAPI => ({
     };
   },
 
+  async statFile(path: string): Promise<{ path: string; isFile: boolean; size: number }> {
+    const target = normalizePath(path);
+    const data = await sendBridgeMessage<{ path?: string; isFile?: boolean; size?: number }>('api:fs:stat', { path: target });
+    return {
+      path: typeof data?.path === 'string' ? normalizePath(data.path) : target,
+      isFile: Boolean(data?.isFile),
+      size: typeof data?.size === 'number' ? data.size : 0,
+    };
+  },
+
   async delete(path: string): Promise<{ success: boolean }> {
     const target = normalizePath(path);
     const data = await sendBridgeMessage<{ success: boolean }>('api:fs:delete', { path: target });
diff --git a/packages/web/server/lib/fs/routes.js b/packages/web/server/lib/fs/routes.js
index 0eaaeeed..c7c3276f 100644
--- a/packages/web/server/lib/fs/routes.js
+++ b/packages/web/server/lib/fs/routes.js
@@ -283,6 +283,54 @@ export const registerFsRoutes = (app, dependencies) => {
     }
   });
 
+  app.get('/api/fs/stat', async (req, res) => {
+    const filePath = typeof req.query.path === 'string' ? req.query.path.trim() : '';
+    if (!filePath) {
+      return res.status(400).json({ error: 'Path is required' });
+    }
+
+    try {
+      const resolved = await resolveWorkspacePathFromContext({
+        req,
+        targetPath: filePath,
+        resolveProjectDirectory,
+        path,
+        os,
+        normalizeDirectoryPath,
+        openchamberUserConfigRoot,
+      });
+      if (!resolved.ok) {
+        return res.status(400).json({ error: resolved.error });
+      }
+
+      const [canonicalPath, canonicalBase] = await Promise.all([
+        fsPromises.realpath(resolved.resolved),
+        fsPromises.realpath(resolved.base).catch(() => path.resolve(resolved.base)),
+      ]);
+
+      if (!isPathWithinRoot(canonicalPath, canonicalBase, path, os)) {
+        return res.status(403).json({ error: 'Access to file denied' });
+      }
+
+      const stats = await fsPromises.stat(canonicalPath);
+      if (!stats.isFile()) {
+        return res.status(400).json({ error: 'Specified path is not a file' });
+      }
+
+      return res.json({ path: canonicalPath, isFile: true, size: stats.size });
+    } catch (error) {
+      const err = error;
+      if (err && typeof err === 'object' && err.code === 'ENOENT') {
+        return res.status(404).json({ error: 'File not found' });
+      }
+      if (err && typeof err === 'object' && err.code === 'EACCES') {
+        return res.status(403).json({ error: 'Access to file denied' });
+      }
+      console.error('Failed to stat file:', error);
+      return res.status(500).json({ error: (error && error.message) || 'Failed to stat file' });
+    }
+  });
+
   app.get('/api/fs/read', async (req, res) => {
     const filePath = typeof req.query.path === 'string' ? req.query.path.trim() : '';
     if (!filePath) {
diff --git a/packages/web/src/api/files.ts b/packages/web/src/api/files.ts
index a1ba6f9f..349f5180 100644
--- a/packages/web/src/api/files.ts
+++ b/packages/web/src/api/files.ts
@@ -110,6 +110,23 @@ export const createWebFilesAPI = (): FilesAPI => ({
     };
   },
 
+  async statFile(path: string): Promise<{ path: string; isFile: boolean; size: number }> {
+    const target = normalizePath(path);
+    const response = await fetch(`/api/fs/stat?path=${encodeURIComponent(target)}`);
+
+    if (!response.ok) {
+      const error = await response.json().catch(() => ({ error: response.statusText }));
+      throw new Error((error as { error?: string }).error || 'Failed to stat file');
+    }
+
+    const result = await response.json().catch(() => ({}));
+    return {
+      path: typeof (result as { path?: string }).path === 'string' ? normalizePath((result as { path: string }).path) : target,
+      isFile: Boolean((result as { isFile?: boolean }).isFile),
+      size: typeof (result as { size?: number }).size === 'number' ? (result as { size: number }).size : 0,
+    };
+  },
+
   async readFile(path: string): Promise<{ content: string; path: string }> {
     const target = normalizePath(path);
     const response = await fetch(`/api/fs/read?path=${encodeURIComponent(target)}`);