Add support for loading environment variables from .env file

.claude/settings.local.json

@@ -0,0 +1,11 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(move:*)",
+      "Bash(mv:*)",
+      "Bash(node:*)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}

README.md

@@ -53,12 +53,30 @@ node bin/cli.js
 
 **Option A: Environment Variable (Recommended)**
 
+Set it in your shell's configuration file (e.g., `.bashrc`, `.zshrc`):
 ```bash
 export GEMINI_API_KEY="your-api-key-here"
 ```
 
-**Option B: Command Line Argument**
+**Option B: .env File (Local Setup)**
 
+For local development, you can create a `.env` file by copying the provided example. This method is convenient and keeps your API key out of version control.
+
+1.  **Copy the example file:**
+    ```bash
+    cp env.example .env
+    ```
+
+2.  **Edit the `.env` file:**
+    Open the newly created `.env` file and replace the placeholder with your actual API key.
+    ```dotenv
+    # .env
+    GEMINI_API_KEY="your-api-key-here"
+    ```
+
+**Option C: Command Line Argument**
+
+Pass the key directly with the `--key` option. This method overrides environment variables and `.env` files.
 ```bash
 md-translate translate -i file.md -l Spanish --key your-api-key-here
 ```

bin/cli.js

@@ -1,12 +1,21 @@
 #!/usr/bin/env node
 
 import path from 'path';
+import { fileURLToPath } from 'url';
 
 import chalk from 'chalk';
 import { Command } from 'commander';
 import fs from 'fs-extra';
 import ora from 'ora';
+import dotenv from 'dotenv';
 
+// Load environment variables from .env file
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const envPath = path.join(__dirname, '..', '.env');
+
+// Try to load .env file, but don't fail if it doesn't exist
+dotenv.config({ path: envPath });
 
 import MarkdownTranslator from '../src/translator.js';
 

package.json

@@ -29,6 +29,7 @@
     "@playcanvas/eslint-config": "2.1.0",
     "chalk": "^5.4.1",
     "commander": "^14.0.0",
+    "dotenv": "^17.2.3",
     "eslint": "^9.31.0",
     "fs-extra": "^11.2.0",
     "glob": "^11.0.3",