Fix markdown preview to show full file content instead of diff snippet

packages/desktop/src/executors/base/DiffMetadataExtractor.ts

@@ -54,7 +54,7 @@ export class DiffMetadataExtractor {
     return null;
   }
 
-  private extractClaudeEdit(metadata: Record<string, unknown>): DiffMetadata[] | null {
+  private async extractClaudeEdit(metadata: Record<string, unknown>): Promise<DiffMetadata[] | null> {
     const input = metadata.input as Record<string, unknown> | undefined;
     if (!input) return null;
 
@@ -64,6 +64,23 @@ export class DiffMetadataExtractor {
 
     if (!filePath || oldString === undefined || newString === undefined) return null;
 
+    // Read the current file content to get the full file after edit
+    const currentContent = await this.readFileIfExists(filePath);
+
+    // If we can read the file, the edit has been applied, so currentContent is the new full content
+    // We need to reconstruct the old full content by reversing the edit
+    if (currentContent !== null) {
+      // The file now contains newString where oldString used to be
+      // Reconstruct old content: replace newString back with oldString
+      const fullOldContent = currentContent.replace(newString, oldString);
+      return [{
+        filePath,
+        oldString: fullOldContent,
+        newString: currentContent,
+      }];
+    }
+
+    // Fallback: return the partial strings if file can't be read
     return [{
       filePath,
       oldString,