diff --git a/server-check.php b/server-check.php
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+++ b/server-check.php
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+<?php
+/**
+ * Server Diagnostic Script
+ * Visit this page to see what's wrong with the deployment
+ */
+
+header('Content-Type: text/html; charset=utf-8');
+?>
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Server Diagnostic - Nano Banana Pro</title>
+    <style>
+        body { font-family: monospace; background: #000; color: #0f0; padding: 20px; }
+        .section { background: #1a1a1a; padding: 15px; margin: 10px 0; border-left: 4px solid #0f0; }
+        .error { border-left-color: #f00; color: #f00; }
+        .warning { border-left-color: #ff0; color: #ff0; }
+        .success { border-left-color: #0f0; color: #0f0; }
+        h1 { color: #0ff; }
+        h2 { color: #ff0; }
+        pre { margin: 5px 0; }
+    </style>
+</head>
+<body>
+    <h1>=== NANO BANANA PRO SERVER DIAGNOSTIC ===</h1>
+
+    <div class="section">
+        <h2>1. PHP Information</h2>
+        <pre>PHP Version: <?php echo phpversion(); ?></pre>
+        <pre>Server: <?php echo $_SERVER['SERVER_SOFTWARE'] ?? 'Unknown'; ?></pre>
+        <pre>Document Root: <?php echo $_SERVER['DOCUMENT_ROOT'] ?? 'Unknown'; ?></pre>
+        <pre>Current Directory: <?php echo __DIR__; ?></pre>
+    </div>
+
+    <div class="section <?php echo file_exists(__DIR__ . '/vendor') ? 'success' : 'error'; ?>">
+        <h2>2. Composer Dependencies (vendor/)</h2>
+        <?php if (file_exists(__DIR__ . '/vendor')): ?>
+            <pre>✓ vendor/ directory EXISTS</pre>
+            <pre>✓ Autoload: <?php echo file_exists(__DIR__ . '/vendor/autoload.php') ? 'EXISTS' : 'MISSING'; ?></pre>
+            <pre>✓ Firebase JWT: <?php echo file_exists(__DIR__ . '/vendor/firebase') ? 'INSTALLED' : 'MISSING'; ?></pre>
+        <?php else: ?>
+            <pre>✗ vendor/ directory MISSING</pre>
+            <pre>✗ FIX: Run 'composer install' on the server</pre>
+        <?php endif; ?>
+    </div>
+
+    <div class="section <?php echo file_exists(__DIR__ . '/config.php') ? 'success' : 'error'; ?>">
+        <h2>3. Configuration Files</h2>
+        <pre>config.php: <?php echo file_exists(__DIR__ . '/config.php') ? '✓ EXISTS' : '✗ MISSING'; ?></pre>
+        <pre>.env: <?php echo file_exists(__DIR__ . '/.env') ? '✓ EXISTS' : '⚠ MISSING (optional)'; ?></pre>
+        <pre>.env.example: <?php echo file_exists(__DIR__ . '/.env.example') ? '✓ EXISTS' : '✗ MISSING'; ?></pre>
+    </div>
+
+    <div class="section">
+        <h2>4. Critical Files Check</h2>
+        <?php
+        $criticalFiles = [
+            'index.php',
+            'api.php',
+            'auth.php',
+            'AuthMiddleware.php',
+            'JWTValidator.php',
+            'session_manager.php',
+            'env_loader.php',
+            'enhance_prompt.php'
+        ];
+        foreach ($criticalFiles as $file):
+        ?>
+        <pre><?php echo $file; ?>: <?php echo file_exists(__DIR__ . '/' . $file) ? '✓' : '✗ MISSING'; ?></pre>
+        <?php endforeach; ?>
+    </div>
+
+    <div class="section">
+        <h2>5. Directory Permissions</h2>
+        <?php
+        $uploads = __DIR__ . '/uploads';
+        $sessions = __DIR__ . '/uploads/sessions';
+        ?>
+        <pre>uploads/: <?php echo is_dir($uploads) ? (is_writable($uploads) ? '✓ Writable' : '⚠ Not writable') : '✗ Missing'; ?></pre>
+        <pre>uploads/sessions/: <?php echo is_dir($sessions) ? (is_writable($sessions) ? '✓ Writable' : '⚠ Not writable') : '✗ Missing'; ?></pre>
+    </div>
+
+    <div class="section">
+        <h2>6. Testing File Loads</h2>
+        <?php
+        echo "<pre>Testing env_loader.php...</pre>";
+        try {
+            if (file_exists(__DIR__ . '/env_loader.php')) {
+                require_once __DIR__ . '/env_loader.php';
+                echo "<pre class='success'>✓ env_loader.php loaded successfully</pre>";
+            } else {
+                echo "<pre class='error'>✗ env_loader.php missing</pre>";
+            }
+        } catch (Exception $e) {
+            echo "<pre class='error'>✗ Error: " . htmlspecialchars($e->getMessage()) . "</pre>";
+        }
+
+        echo "<pre>Testing config.php...</pre>";
+        try {
+            if (file_exists(__DIR__ . '/config.php')) {
+                require_once __DIR__ . '/config.php';
+                echo "<pre class='success'>✓ config.php loaded successfully</pre>";
+                echo "<pre>  GEMINI_API_KEY: " . (defined('GEMINI_API_KEY') && !empty(GEMINI_API_KEY) ? '✓ SET' : '✗ NOT SET') . "</pre>";
+                echo "<pre>  SSO_ENABLED: " . (defined('SSO_ENABLED') ? (SSO_ENABLED ? 'TRUE' : 'FALSE') : '✗ NOT SET') . "</pre>";
+            } else {
+                echo "<pre class='error'>✗ config.php missing</pre>";
+            }
+        } catch (Exception $e) {
+            echo "<pre class='error'>✗ Error: " . htmlspecialchars($e->getMessage()) . "</pre>";
+        }
+
+        echo "<pre>Testing AuthMiddleware.php...</pre>";
+        try {
+            if (file_exists(__DIR__ . '/AuthMiddleware.php')) {
+                require_once __DIR__ . '/AuthMiddleware.php';
+                echo "<pre class='success'>✓ AuthMiddleware.php loaded successfully</pre>";
+            } else {
+                echo "<pre class='error'>✗ AuthMiddleware.php missing</pre>";
+            }
+        } catch (Exception $e) {
+            echo "<pre class='error'>✗ Error: " . htmlspecialchars($e->getMessage()) . "</pre>";
+        }
+        ?>
+    </div>
+
+    <div class="section">
+        <h2>7. Next Steps</h2>
+        <?php if (!file_exists(__DIR__ . '/vendor')): ?>
+        <pre class="error">ACTION REQUIRED: Run 'composer install' on the server</pre>
+        <?php endif; ?>
+        <?php if (!file_exists(__DIR__ . '/config.php')): ?>
+        <pre class="error">ACTION REQUIRED: Copy config.example.php to config.php and add API key</pre>
+        <?php endif; ?>
+        <?php if (file_exists(__DIR__ . '/vendor') && file_exists(__DIR__ . '/config.php')): ?>
+        <pre class="success">✓ All critical files present - check error logs for specific PHP error</pre>
+        <?php endif; ?>
+    </div>
+
+    <h2>Deployment Checklist:</h2>
+    <pre>
+    1. git pull origin master
+    2. composer install
+    3. cp config.example.php config.php
+    4. Edit config.php (add Gemini API key)
+    5. cp .env.example .env
+    6. mkdir -p uploads/sessions
+    7. chmod 755 uploads/sessions
+    8. Visit index.php
+    </pre>
+
+</body>
+</html>
