fix(registry): prevent race conditions in registry file handling

Replace async file operations with sync ones during registry file creation to ensure atomicity
Add validation for empty/invalid registry files to handle edge cases

Author: moazbuilds

src/agents/monitoring/registry.ts

@@ -46,7 +46,21 @@ export class AgentRegistry {
     try {
       if (existsSync(this.registryPath)) {
         const content = await readFile(this.registryPath, 'utf-8');
+
+        // Skip empty or whitespace-only files (race condition during file creation)
+        if (!content || content.trim().length === 0) {
+          logger.debug('Registry file is empty, skipping reload');
+          return;
+        }
+
         const parsed = JSON.parse(content) as AgentRegistryData;
+
+        // Validate parsed data structure
+        if (!parsed || typeof parsed !== 'object' || !parsed.agents) {
+          logger.warn('Registry file has invalid structure, skipping reload');
+          return;
+        }
+
         this.data = parsed;
         logger.debug(`Async reloaded agent registry with ${Object.keys(parsed.agents).length} agents`);
       }
@@ -63,7 +77,21 @@ export class AgentRegistry {
     try {
       if (existsSync(this.registryPath)) {
         const content = readFileSync(this.registryPath, 'utf-8');
+
+        // Skip empty or whitespace-only files (race condition during file creation)
+        if (!content || content.trim().length === 0) {
+          logger.debug('Registry file is empty, returning default registry');
+          return { lastId: 0, agents: {} };
+        }
+
         const parsed = JSON.parse(content) as AgentRegistryData;
+
+        // Validate parsed data structure
+        if (!parsed || typeof parsed !== 'object' || !parsed.agents) {
+          logger.warn('Registry file has invalid structure, returning default registry');
+          return { lastId: 0, agents: {} };
+        }
+
         logger.debug(`Loaded agent registry with ${Object.keys(parsed.agents).length} agents`);
         return parsed;
       }

src/agents/monitoring/registryLock.ts

@@ -29,18 +29,19 @@ export class RegistryLockService {
       const lockPath = this.registryPath;
 
       // Ensure file exists before locking (proper-lockfile requires this)
-      // Create empty file if it doesn't exist
-      const { existsSync } = await import('fs');
-      const { writeFile, mkdir } = await import('fs/promises');
+      // Use synchronous operations to prevent race conditions during file creation
+      const { existsSync, mkdirSync, writeFileSync } = await import('fs');
       const { dirname } = await import('path');
 
       if (!existsSync(lockPath)) {
         const dir = dirname(lockPath);
         if (!existsSync(dir)) {
-          await mkdir(dir, { recursive: true });
+          mkdirSync(dir, { recursive: true });
         }
-        // Create minimal valid registry file
-        await writeFile(lockPath, JSON.stringify({ lastId: 0, agents: {} }, null, 2), 'utf-8');
+        // Create minimal valid registry file synchronously
+        // This ensures the file is fully written before we try to lock it
+        const initialData = JSON.stringify({ lastId: 0, agents: {} }, null, 2);
+        writeFileSync(lockPath, initialData, 'utf-8');
         logger.debug(`Created registry file for locking: ${lockPath}`);
       }