fix: project got corrupted sometimes

src/main/engine/MediaEngine.ts

@@ -184,9 +184,19 @@ export class MediaEngine extends EventEmitter {
   }
 
   setProjectContext(projectId: string, dataDir?: string, internalDir?: string): void {
+    const nextDataDir = dataDir || null;
+    const nextInternalDir = internalDir || null;
+    if (
+      this.currentProjectId === projectId
+      && this.dataDir === nextDataDir
+      && this.internalDir === nextInternalDir
+    ) {
+      return;
+    }
+
     this.currentProjectId = projectId;
-    this.dataDir = dataDir || null;
-    this.internalDir = internalDir || null;
+    this.dataDir = nextDataDir;
+    this.internalDir = nextInternalDir;
     console.log(`[MediaEngine] setProjectContext: projectId=${projectId}, dataDir=${this.dataDir}, internalDir=${this.internalDir}`);
   }
 

src/main/engine/MetaEngine.ts

@@ -176,6 +176,7 @@ export class MetaEngine extends EventEmitter {
   private categories: Set<string> = new Set();
   private projectMetadata: ProjectMetadata | null = null;
   private initialized: boolean = false;
+  private startupSyncPromise: Promise<void> | null = null;
 
   constructor() {
     super();
@@ -218,13 +219,19 @@ export class MetaEngine extends EventEmitter {
   }
 
   setProjectContext(projectId: string, dataDir?: string): void {
+    const nextDataDir = dataDir || null;
+    if (this.currentProjectId === projectId && this.dataDir === nextDataDir) {
+      return;
+    }
+
     this.currentProjectId = projectId;
-    this.dataDir = dataDir || null;
+    this.dataDir = nextDataDir;
     // Reset in-memory cache when project changes
     this.tags.clear();
     this.categories.clear();
     this.projectMetadata = null;
     this.initialized = false;
+    this.startupSyncPromise = null;
   }
 
   getProjectContext(): string {
@@ -394,8 +401,7 @@ export class MetaEngine extends EventEmitter {
     try {
       await this.ensureMetaDirExists();
       const filePath = this.getCategoriesFilePath();
-      const content = JSON.stringify(Array.from(this.categories).sort(), null, 2);
-      await fs.writeFile(filePath, content, 'utf-8');
+      await this.writeJsonFileAtomically(filePath, Array.from(this.categories).sort());
     } catch (error) {
       console.error('[MetaEngine] Failed to save categories:', error);
       throw error;
@@ -415,8 +421,7 @@ export class MetaEngine extends EventEmitter {
         categorySettings: _categorySettings,
         ...persistedMetadata
       } = this.projectMetadata || {};
-      const content = JSON.stringify(persistedMetadata, null, 2);
-      await fs.writeFile(filePath, content, 'utf-8');
+      await this.writeJsonFileAtomically(filePath, persistedMetadata);
     } catch (error) {
       console.error('[MetaEngine] Failed to save project metadata:', error);
       throw error;
@@ -433,8 +438,7 @@ export class MetaEngine extends EventEmitter {
       const metadata = this.ensureCategoryMetadataForKnownCategories(
         this.projectMetadata?.categoryMetadata,
       );
-      const content = JSON.stringify(metadata, null, 2);
-      await fs.writeFile(filePath, content, 'utf-8');
+      await this.writeJsonFileAtomically(filePath, metadata);
     } catch (error) {
       console.error('[MetaEngine] Failed to save category metadata:', error);
       throw error;
@@ -582,6 +586,24 @@ export class MetaEngine extends EventEmitter {
     }
   }
 
+  private async writeJsonFileAtomically(filePath: string, value: unknown): Promise<void> {
+    const tempPath = `${filePath}.${process.pid}.${Date.now()}.tmp`;
+    const content = JSON.stringify(value, null, 2);
+
+    await fs.writeFile(tempPath, content, 'utf-8');
+
+    try {
+      await fs.rename(tempPath, filePath);
+    } catch (error) {
+      try {
+        await fs.unlink(tempPath);
+      } catch {
+        // Ignore cleanup errors.
+      }
+      throw error;
+    }
+  }
+
   private ensureCategoryMetadataForKnownCategories(
     categoryMetadata: Record<string, CategoryMetadata> | undefined,
   ): Record<string, CategoryMetadata> {
@@ -611,6 +633,24 @@ export class MetaEngine extends EventEmitter {
    * - Project metadata: read from file or create from database
    */
   async syncOnStartup(): Promise<void> {
+    if (this.initialized) {
+      return;
+    }
+
+    if (this.startupSyncPromise) {
+      await this.startupSyncPromise;
+      return;
+    }
+
+    this.startupSyncPromise = this.performSyncOnStartup();
+    try {
+      await this.startupSyncPromise;
+    } finally {
+      this.startupSyncPromise = null;
+    }
+  }
+
+  private async performSyncOnStartup(): Promise<void> {
     console.log(`[MetaEngine] Syncing metadata for project: ${this.currentProjectId}`);
     
     await this.ensureMetaDirExists();

src/main/engine/PostMediaEngine.ts

@@ -156,6 +156,10 @@ export class PostMediaEngine extends EventEmitter {
    * Set the current project context
    */
   setProjectContext(projectId: string): void {
+    if (this.currentProjectId === projectId) {
+      return;
+    }
+
     this.currentProjectId = projectId;
     console.log(`[PostMediaEngine] setProjectContext: projectId=${projectId}`);
   }

src/main/engine/PreviewServer.ts

@@ -210,6 +210,15 @@ export class PreviewServer {
     }
 
     try {
+        const requestUrl = new URL(req.url || '/', 'http://127.0.0.1');
+        const pathname = decodeURIComponent(requestUrl.pathname.replace(/\/+$/, '') || '/');
+
+        const asset = await this.resolveAsset(pathname);
+        if (asset) {
+          this.respondAsset(res, asset.contentType, asset.body);
+          return;
+        }
+
       const context = await this.getActiveProjectContext();
       this.postEngine.setProjectContext(context.projectId, context.dataDir);
       this.mediaEngine.setProjectContext?.(context.projectId, context.dataDir, context.dataDir);
@@ -230,7 +239,6 @@ export class PreviewServer {
       const language = metadata?.mainLanguage?.trim() || 'en';
       const pageTitle = resolvePageTitle(metadata, context.projectName, context.projectDescription);
       const maxPostsPerPage = clampMaxPostsPerPage(metadata?.maxPostsPerPage);
-      const requestUrl = new URL(req.url || '/', 'http://127.0.0.1');
       const requestTheme = sanitizePicoTheme(requestUrl.searchParams.get('theme'));
       const previewThemeMode = sanitizePicoThemeMode(requestUrl.searchParams.get('mode'));
       const useDraftContent = requestUrl.searchParams.get('draft') === 'true';
@@ -238,7 +246,6 @@ export class PreviewServer {
       const appliedTheme = requestTheme ?? sanitizePicoTheme((metadata as { picoTheme?: unknown } | null)?.picoTheme);
       const picoStylesheetHref = getPicoStylesheetHref(appliedTheme);
       const htmlRewriteContext = await this.buildHtmlRewriteContext();
-      const pathname = decodeURIComponent(requestUrl.pathname.replace(/\/+$/, '') || '/');
 
       if (pathname === '/__style-preview') {
         const stylePreviewHtml = await this.renderStylePreview(htmlRewriteContext, {
@@ -252,12 +259,6 @@ export class PreviewServer {
         return;
       }
 
-      const asset = await this.resolveAsset(pathname);
-      if (asset) {
-        this.respondAsset(res, asset.contentType, asset.body);
-        return;
-      }
-
       const imageAsset = await this.resolveImageAsset(pathname);
       if (imageAsset) {
         this.respondAsset(res, imageAsset.contentType, imageAsset.body);