feat: diff tool to see discrepancies

src/main/ipc/handlers.ts

@@ -1027,6 +1027,65 @@ export function registerIpcHandlers(): void {
     return engine.deleteDefinition(id);
   });
 
+  // ============ Metadata Diff Handlers ============
+
+  safeHandle('metadataDiff:getStats', async () => {
+    const { getMetadataDiffEngine } = await import('../engine/MetadataDiffEngine');
+    const engine = getMetadataDiffEngine();
+    const projectEngine = getProjectEngine();
+    const activeProject = await projectEngine.getActiveProject();
+    if (activeProject) {
+      engine.setProjectContext(activeProject.id);
+    }
+    return engine.getTableStats();
+  });
+
+  safeHandle('metadataDiff:scan', async () => {
+    const { getMetadataDiffEngine } = await import('../engine/MetadataDiffEngine');
+    const engine = getMetadataDiffEngine();
+    const projectEngine = getProjectEngine();
+    const activeProject = await projectEngine.getActiveProject();
+    if (activeProject) {
+      engine.setProjectContext(activeProject.id);
+    }
+
+    // Forward progress events to renderer
+    const taskId = `metadata-diff-scan-${Date.now()}`;
+    
+    return taskManager.runTask({
+      id: taskId,
+      name: 'Scanning for metadata differences',
+      execute: async (onProgress) => {
+        return engine.scanAllPublishedPosts((current, total, message) => {
+          const percent = total > 0 ? (current / total) * 100 : 0;
+          onProgress(percent, message);
+        });
+      },
+    });
+  });
+
+  safeHandle('metadataDiff:syncDbToFile', async (_, postIds: string[], groupLabel: string) => {
+    const { getMetadataDiffEngine } = await import('../engine/MetadataDiffEngine');
+    const engine = getMetadataDiffEngine();
+    const projectEngine = getProjectEngine();
+    const activeProject = await projectEngine.getActiveProject();
+    if (activeProject) {
+      engine.setProjectContext(activeProject.id);
+    }
+    return engine.runSyncDbToFileTask(postIds, groupLabel);
+  });
+
+  safeHandle('metadataDiff:syncFileToDb', async (_, postIds: string[], field: string, groupLabel: string) => {
+    const { getMetadataDiffEngine } = await import('../engine/MetadataDiffEngine');
+    const engine = getMetadataDiffEngine();
+    const projectEngine = getProjectEngine();
+    const activeProject = await projectEngine.getActiveProject();
+    if (activeProject) {
+      engine.setProjectContext(activeProject.id);
+    }
+    return engine.runSyncFileToDbTask(postIds, field as 'tags' | 'categories' | 'title' | 'excerpt' | 'author', groupLabel);
+  });
+
   // ============ Event Forwarding ============
   
   // Forward engine events to renderer