Implemented atomic writes for json database

server/db.js

@@ -72,15 +72,21 @@ function getDefaultSettings() {
 
 // Write lock to prevent concurrent writes from corrupting db.json
 let writeQueue = Promise.resolve();
+const tmpPath = dbPath + '.tmp';
 
 async function saveDb(data) {
   // Queue this write operation - each write waits for the previous one
   writeQueue = writeQueue.then(async () => {
     try {
       const jsonString = JSON.stringify(data, null, 2);
-      await fs.writeFile(dbPath, jsonString);
+      // Atomic write: write to temp file, then rename
+      // Rename is atomic on most filesystems, preventing corruption on crash
+      await fs.writeFile(tmpPath, jsonString);
+      await fs.rename(tmpPath, dbPath);
     } catch (err) {
       console.error('Error writing database:', err);
+      // Clean up temp file if it exists
+      try { await fs.unlink(tmpPath); } catch { /* ignore */ }
       throw err;
     }
   }).catch(err => {