diff --git a/git-ai/src/commands/InitCommand.ts b/git-ai/src/commands/InitCommand.ts
index 655831b..23398e1 100644
--- a/git-ai/src/commands/InitCommand.ts
+++ b/git-ai/src/commands/InitCommand.ts
@@ -12,7 +12,6 @@ import { logger } from '../utils/logger.js';
 async function readSecretInput(rl: readline.Interface, prompt: string): Promise<string> {
   const rlAny = rl as any;
   const originalWrite = rlAny._writeToOutput;
-  // Suppress character echoing: only allow the initial prompt to be written
   let promptWritten = false;
   rlAny._writeToOutput = function _writeToOutput(str: string) {
     if (!promptWritten) {
@@ -29,6 +28,28 @@ async function readSecretInput(rl: readline.Interface, prompt: string): Promise<
   }
 }
 
+/**
+ * Atomically writes content to filePath using a temp file + fsync + rename,
+ * ensuring the file has permissions 0o600.
+ */
+function atomicWriteFileSync(filePath: string, content: string): void {
+  const dir = path.dirname(filePath);
+  const tempPath = path.join(dir, `.tmp-${process.pid}-${Date.now()}`);
+  const fd = fs.openSync(tempPath, fs.constants.O_CREAT | fs.constants.O_EXCL | fs.constants.O_WRONLY, 0o600);
+  try {
+    try {
+      fs.writeFileSync(fd, content);
+      fs.fsyncSync(fd);
+    } finally {
+      fs.closeSync(fd);
+    }
+    fs.renameSync(tempPath, filePath);
+  } catch (error) {
+    try { fs.unlinkSync(tempPath); } catch { /* best-effort cleanup */ }
+    throw error;
+  }
+}
+
 export async function initCommand() {
   const rl = readline.createInterface({
     input: process.stdin,
@@ -38,6 +59,7 @@ export async function initCommand() {
   console.log('🚀 Welcome to AI-Git-Terminal Setup\n');
 
   try {
+    // --- Step 1: Read API Key ---
     let apiKey = '';
     while (!apiKey) {
       const apiKeyInput = await readSecretInput(rl, '🔑 Enter your Gemini API Key: ');
@@ -47,56 +69,65 @@ export async function initCommand() {
       }
     }
 
+    // --- Step 2: Read model name ---
     const modelInput = await rl.question('🤖 Enter model name (default: gemini-1.5-flash): ');
     const model = modelInput.trim() || 'gemini-1.5-flash';
 
+    // --- Step 3: Build config object ---
     const newConfig: Config = {
-      ai: {
-        provider: 'gemini',
-        apiKey,
-        model: model,
-      },
-      git: {
-        autoStage: false,
-      },
-      ui: {
-        theme: 'dark',
-        showIcons: true,
-      },
+      ai: { provider: 'gemini', apiKey, model },
+      git: { autoStage: false },
+      ui: { theme: 'dark', showIcons: true },
     };
 
-    // Validate with Zod and persist with restricted permissions (mode 0o600)
+    // Validate with Zod
     ConfigSchema.parse(newConfig);
 
     const configPath = path.join(os.homedir(), '.aigitrc');
 
-    if (fs.existsSync(configPath)) {
-      const overwriteChoice = (await rl.question(
-        '⚠️ Existing config found. Choose [o]verwrite, [b]ackup then replace, or [c]ancel: '
-      )).trim().toLowerCase();
-
-      if (overwriteChoice === 'b' || overwriteChoice === 'backup') {
-        const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
-        const backupPath = `${configPath}.bak-${timestamp}`;
-        fs.renameSync(configPath, backupPath);
-        console.log(`📦 Existing config backed up to ${backupPath}`);
-      } else if (overwriteChoice === 'o' || overwriteChoice === 'overwrite') {
-        console.log('📝 Overwriting existing config file.');
-      } else {
-        console.log('🚫 Initialization canceled. Existing config left unchanged.');
-        return;
+    // --- Step 4: Attempt atomic creation ---
+    try {
+      const fd = fs.openSync(configPath, fs.constants.O_CREAT | fs.constants.O_EXCL | fs.constants.O_RDWR, 0o600);
+      try {
+        fs.writeFileSync(fd, JSON.stringify(newConfig, null, 2));
+        fs.fsyncSync(fd);
+      } finally {
+        fs.closeSync(fd);
       }
+      console.log(`\n✅ Configuration saved to ${configPath}`);
+      console.log('Try running: ai-git commit');
+      return;
+    } catch (err: any) {
+      if (err.code !== 'EEXIST') throw err;
+      // File already exists, proceed to backup/overwrite prompt
     }
 
-    fs.writeFileSync(configPath, JSON.stringify(newConfig, null, 2), { mode: 0o600 });
-    fs.chmodSync(configPath, 0o600);
+    // --- Step 5: Handle existing file ---
+    const overwriteChoice = (await rl.question(
+      '⚠️ Existing config found. Choose [o]verwrite, [b]ackup then replace, or [c]ancel: '
+    )).trim().toLowerCase();
+
+    if (overwriteChoice === 'b' || overwriteChoice === 'backup') {
+      const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
+      const backupPath = `${configPath}.bak-${timestamp}`;
+      fs.renameSync(configPath, backupPath);
+      console.log(`📦 Existing config backed up to ${backupPath}`);
+      atomicWriteFileSync(configPath, JSON.stringify(newConfig, null, 2));
+    } else if (overwriteChoice === 'o' || overwriteChoice === 'overwrite') {
+      atomicWriteFileSync(configPath, JSON.stringify(newConfig, null, 2));
+      console.log('📝 Overwriting existing config file.');
+    } else {
+      console.log('🚫 Initialization canceled. Existing config left unchanged.');
+      return;
+    }
 
     console.log(`\n✅ Configuration saved to ${configPath}`);
     console.log('Try running: ai-git commit');
+
   } catch (error) {
     logger.error('Failed to save configuration: ' + (error instanceof Error ? error.message : String(error)));
     console.error('\n❌ Invalid input or failed to write config file.');
   } finally {
     rl.close();
   }
-}
\ No newline at end of file
+}
diff --git a/git-ai/src/services/ConfigService.ts b/git-ai/src/services/ConfigService.ts
index 16d7453..a2de320 100644
--- a/git-ai/src/services/ConfigService.ts
+++ b/git-ai/src/services/ConfigService.ts
@@ -55,7 +55,21 @@ export class ConfigService {
 
   public saveConfig(newConfig: Config): void {
     const validated = ConfigSchema.parse(newConfig);
-    fs.writeFileSync(ConfigService.CONFIG_PATH, JSON.stringify(validated, null, 2), { mode: 0o600 });
+    const configPath = ConfigService.CONFIG_PATH;
+    const tempPath = path.join(path.dirname(configPath), `.tmp-${process.pid}-${Date.now()}`);
+    const fd = fs.openSync(tempPath, fs.constants.O_CREAT | fs.constants.O_EXCL | fs.constants.O_WRONLY, 0o600);
+    try {
+      try {
+        fs.writeFileSync(fd, JSON.stringify(validated, null, 2));
+        fs.fsyncSync(fd);
+      } finally {
+        fs.closeSync(fd);
+      }
+      fs.renameSync(tempPath, configPath);
+    } catch (error) {
+      try { fs.unlinkSync(tempPath); } catch { /* best-effort cleanup */ }
+      throw error;
+    }
     this.config = validated;
   }
 }
\ No newline at end of file