Add Kling AI video generation engine alongside Veo 3.1

Integrates Kling AI as a second video engine in the Video Gen tab with
three cinema-relevant workflows: Generate (T2V/I2V with camera control),
Extend (video extension up to 3 min), and Lip Sync (image + audio).

Backend: New kling_api.php with pure PHP JWT auth, all workflows, async
status polling, and CDN video download. Env files updated with Kling
credential placeholders.

Frontend: Engine selector toggle, workflow-specific settings panels,
Kling polling, engine badges in ProjectsTab, rerun support.

Also includes image model toggle changes (Gemini Pro/Flash).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/.env.example

@@ -19,6 +19,13 @@ BACKEND_PORT=5015
 # Get your API key from: https://aistudio.google.com/app/apikey
 GEMINI_API_KEY=your-api-key-here
 
+# ----------------------------------------------------------------------------
+# Kling AI API Credentials (https://platform.klingai.com)
+# ----------------------------------------------------------------------------
+# Get credentials from: https://platform.klingai.com
+KLING_ACCESS_KEY=your-kling-access-key-here
+KLING_SECRET_KEY=your-kling-secret-key-here
+
 # ----------------------------------------------------------------------------
 # Frontend URL for CORS (REQUIRED)
 # ----------------------------------------------------------------------------

backend/.env.local

@@ -17,6 +17,13 @@ BACKEND_PORT=5015
 # Get your API key from: https://aistudio.google.com/app/apikey
 # GEMINI_API_KEY=AIzaSyCMKLSJJYEx4c6-TtBACnjdULrLzsr_fts
 GEMINI_API_KEY=AIzaSyDs7EKdC9NLM5UqWlGUqeQO96TmSA-kos8
+
+# ----------------------------------------------------------------------------
+# Kling AI API Credentials (https://platform.klingai.com)
+# ----------------------------------------------------------------------------
+KLING_ACCESS_KEY=
+KLING_SECRET_KEY=
+
 # ----------------------------------------------------------------------------
 # Frontend URL for CORS (REQUIRED)
 # ----------------------------------------------------------------------------

backend/.env.production

@@ -13,6 +13,12 @@
 GEMINI_API_KEY=AIzaSyDs7EKdC9NLM5UqWlGUqeQO96TmSA-kos8
 # AIzaSyCMKLSJJYEx4c6-TtBACnjdULrLzsr_fts
 
+# ----------------------------------------------------------------------------
+# Kling AI API Credentials (https://platform.klingai.com)
+# ----------------------------------------------------------------------------
+KLING_ACCESS_KEY=
+KLING_SECRET_KEY=
+
 # ----------------------------------------------------------------------------
 # Frontend URL for CORS (REQUIRED)
 # ----------------------------------------------------------------------------

backend/api.php

@@ -57,10 +57,17 @@ try {
 class NanoBananaProAPI {
     private $apiKey;
     private $baseUrl = 'https://generativelanguage.googleapis.com/v1beta/models';
-    private $model = 'gemini-3-pro-image-preview';
+    private $model;
 
-    public function __construct($apiKey) {
+    // Available models
+    private static $models = [
+        'pro' => 'gemini-3-pro-image-preview',
+        'flash' => 'gemini-3.1-flash-image-preview'
+    ];
+
+    public function __construct($apiKey, $modelType = 'pro') {
         $this->apiKey = $apiKey;
+        $this->model = self::$models[$modelType] ?? self::$models['pro'];
     }
 
     public function generateImage($prompt, $aspectRatio = '16:9', $imageSize = '2K', $inputImage = null, $referenceImages = []) {
@@ -296,6 +303,12 @@ try {
             error_log("Received " . count($referenceImages) . " reference images from frontend");
         }
 
+        // Read and validate model type
+        $modelType = $_POST['modelType'] ?? 'pro';
+        if (!in_array($modelType, ['pro', 'flash'])) {
+            $modelType = 'pro';
+        }
+
         // Check if API key is configured
         if (!defined('GEMINI_API_KEY') || empty(GEMINI_API_KEY)) {
             throw new Exception('API key not configured. Please set GEMINI_API_KEY in config.php');
@@ -307,7 +320,7 @@ try {
         }
 
         // Initialize API
-        $api = new NanoBananaProAPI(GEMINI_API_KEY);
+        $api = new NanoBananaProAPI(GEMINI_API_KEY, $modelType);
 
         // Determine input image for editing:
         // 1. Frontend sends uploadedImage when editing from library or a displayed image
@@ -347,7 +360,7 @@ try {
                 'aspectRatio' => $aspectRatio,
                 'imageSize' => $imageSize,
                 'actionType' => $inputImage ? 'edit' : 'generate',
-                'model' => 'Gemini 3 Pro Image'
+                'model' => $modelType === 'flash' ? 'Nano Banana 2 (Flash)' : 'Nano Banana Pro'
             ];
 
             logImageGeneration($prompt, $imageData['base64'], $imageData['mime_type'], $webhookSettings, $userEmail, $inputImage ? 'edit' : 'generate');

backend/kling_api.php

@@ -0,0 +1,628 @@
+<?php
+/**
+ * Kling AI Video Generation API for Lux Studio
+ * Handles Kling video generation: Text-to-Video, Image-to-Video, Video Extension, Lip Sync
+ */
+
+// Suppress HTML error output to prevent breaking JSON responses
+error_reporting(E_ALL);
+ini_set('display_errors', 0);
+ini_set('log_errors', 1);
+set_time_limit(600);
+ini_set('memory_limit', '512M');
+ini_set('post_max_size', '100M');
+ini_set('upload_max_filesize', '100M');
+
+header('Content-Type: application/json');
+header('Access-Control-Allow-Origin: *');
+header('Access-Control-Allow-Methods: POST, GET, OPTIONS');
+header('Access-Control-Allow-Headers: Content-Type');
+
+// Handle preflight requests
+if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
+    http_response_code(200);
+    exit;
+}
+
+// Load configuration
+require_once 'config.php';
+
+class KlingAPI {
+    private $accessKey;
+    private $secretKey;
+    private $baseUrl = 'https://api-singapore.klingai.com';
+
+    public function __construct($accessKey, $secretKey) {
+        $this->accessKey = $accessKey;
+        $this->secretKey = $secretKey;
+    }
+
+    /**
+     * Generate HS256 JWT token for Kling API authentication
+     * Pure PHP implementation - no external libraries required
+     */
+    private function generateJWT() {
+        $header = json_encode(['alg' => 'HS256', 'typ' => 'JWT']);
+        $now = time();
+        $payload = json_encode([
+            'iss' => $this->accessKey,
+            'exp' => $now + 1800,  // 30 minute expiry
+            'nbf' => $now - 5     // Valid from 5 seconds ago (clock skew tolerance)
+        ]);
+
+        $b64Header = $this->base64UrlEncode($header);
+        $b64Payload = $this->base64UrlEncode($payload);
+
+        $signature = hash_hmac('sha256', "$b64Header.$b64Payload", $this->secretKey, true);
+        $b64Signature = $this->base64UrlEncode($signature);
+
+        return "$b64Header.$b64Payload.$b64Signature";
+    }
+
+    /**
+     * URL-safe Base64 encoding
+     */
+    private function base64UrlEncode($data) {
+        return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');
+    }
+
+    /**
+     * Make an authenticated request to the Kling API
+     */
+    private function makeRequest($method, $endpoint, $payload = null) {
+        $url = $this->baseUrl . $endpoint;
+        $jwt = $this->generateJWT();
+
+        $headers = [
+            'Content-Type: application/json',
+            'Authorization: Bearer ' . $jwt
+        ];
+
+        $ch = curl_init($url);
+        curl_setopt_array($ch, [
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_FOLLOWLOCATION => true,
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_TIMEOUT => 120,
+            CURLOPT_HTTPHEADER => $headers
+        ]);
+
+        if ($method === 'POST') {
+            curl_setopt($ch, CURLOPT_POST, true);
+            if ($payload !== null) {
+                curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
+            }
+        }
+
+        $response = curl_exec($ch);
+        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        $curlError = curl_error($ch);
+        curl_close($ch);
+
+        if ($curlError) {
+            throw new Exception("Kling API connection error: $curlError");
+        }
+
+        $decoded = json_decode($response, true);
+
+        if ($httpCode === 401 || (isset($decoded['code']) && $decoded['code'] >= 1000 && $decoded['code'] <= 1004)) {
+            throw new Exception('Kling API authentication failed. Check your KLING_ACCESS_KEY and KLING_SECRET_KEY in .env');
+        }
+
+        if ($httpCode === 429 || (isset($decoded['code']) && $decoded['code'] >= 1302 && $decoded['code'] <= 1304)) {
+            throw new Exception('Kling API rate limit or concurrent task limit exceeded. Please wait and try again.');
+        }
+
+        if (isset($decoded['code']) && $decoded['code'] >= 1200 && $decoded['code'] <= 1201) {
+            $detail = $decoded['message'] ?? 'Unknown parameter error';
+            throw new Exception("Kling API invalid parameters: $detail");
+        }
+
+        if ($httpCode >= 500) {
+            throw new Exception('Kling server error. Please try again.');
+        }
+
+        if ($httpCode !== 200 && $httpCode !== 201) {
+            $msg = $decoded['message'] ?? "HTTP $httpCode";
+            throw new Exception("Kling API error: $msg");
+        }
+
+        return $decoded;
+    }
+
+    /**
+     * Text-to-Video generation
+     */
+    public function textToVideo($prompt, $opts = []) {
+        $payload = [
+            'prompt' => $prompt,
+            'model_name' => $opts['model_name'] ?? 'kling-v2-6',
+            'mode' => $opts['mode'] ?? 'std',
+            'duration' => $opts['duration'] ?? '5',
+            'aspect_ratio' => $opts['aspect_ratio'] ?? '16:9',
+            'cfg_scale' => floatval($opts['cfg_scale'] ?? 0.5)
+        ];
+
+        if (!empty($opts['negative_prompt'])) {
+            $payload['negative_prompt'] = $opts['negative_prompt'];
+        }
+
+        if (!empty($opts['sound']) && $opts['sound'] === 'on') {
+            $payload['sound'] = 'on';
+        }
+
+        // Camera control - only include if a preset is selected
+        if (!empty($opts['camera_control']) && $opts['camera_control'] !== 'none') {
+            $payload['camera_control'] = [
+                'type' => 'predefined',
+                'config' => $opts['camera_control']
+            ];
+        }
+
+        error_log("Kling T2V request: model={$payload['model_name']}, mode={$payload['mode']}, duration={$payload['duration']}");
+
+        $response = $this->makeRequest('POST', '/v1/videos/text2video', $payload);
+
+        return $this->extractTaskInfo($response, 'text2video');
+    }
+
+    /**
+     * Image-to-Video generation
+     */
+    public function imageToVideo($images, $prompt, $opts = []) {
+        $payload = [
+            'model_name' => $opts['model_name'] ?? 'kling-v2-6',
+            'mode' => $opts['mode'] ?? 'std',
+            'duration' => $opts['duration'] ?? '5',
+            'aspect_ratio' => $opts['aspect_ratio'] ?? '16:9',
+            'cfg_scale' => floatval($opts['cfg_scale'] ?? 0.5)
+        ];
+
+        if (!empty($prompt)) {
+            $payload['prompt'] = $prompt;
+        }
+
+        if (!empty($opts['negative_prompt'])) {
+            $payload['negative_prompt'] = $opts['negative_prompt'];
+        }
+
+        if (!empty($opts['sound']) && $opts['sound'] === 'on') {
+            $payload['sound'] = 'on';
+        }
+
+        // Camera control
+        if (!empty($opts['camera_control']) && $opts['camera_control'] !== 'none') {
+            $payload['camera_control'] = [
+                'type' => 'predefined',
+                'config' => $opts['camera_control']
+            ];
+        }
+
+        // Start frame image (required)
+        if (isset($images[0])) {
+            $imageData = $this->cleanBase64($images[0]['data']);
+            $payload['image'] = $imageData;
+        }
+
+        // Optional end frame image
+        if (isset($images[1])) {
+            $tailData = $this->cleanBase64($images[1]['data']);
+            $payload['image_tail'] = $tailData;
+        }
+
+        error_log("Kling I2V request: model={$payload['model_name']}, images=" . count($images));
+
+        $response = $this->makeRequest('POST', '/v1/videos/image2video', $payload);
+
+        return $this->extractTaskInfo($response, 'image2video');
+    }
+
+    /**
+     * Extend an existing Kling video
+     */
+    public function extendVideo($videoId, $opts = []) {
+        $payload = [
+            'video_id' => $videoId
+        ];
+
+        if (!empty($opts['prompt'])) {
+            $payload['prompt'] = $opts['prompt'];
+        }
+
+        if (!empty($opts['negative_prompt'])) {
+            $payload['negative_prompt'] = $opts['negative_prompt'];
+        }
+
+        if (isset($opts['cfg_scale'])) {
+            $payload['cfg_scale'] = floatval($opts['cfg_scale']);
+        }
+
+        error_log("Kling Extend request: videoId=$videoId");
+
+        $response = $this->makeRequest('POST', '/v1/videos/video-extend', $payload);
+
+        return $this->extractTaskInfo($response, 'video-extend');
+    }
+
+    /**
+     * Lip Sync generation (image + audio → talking head video)
+     */
+    public function lipSync($imageData, $audioData, $opts = []) {
+        $payload = [
+            'image' => $this->cleanBase64($imageData),
+            'sound_file' => $this->cleanBase64($audioData)
+        ];
+
+        if (!empty($opts['prompt'])) {
+            $payload['prompt'] = $opts['prompt'];
+        }
+
+        if (!empty($opts['mode'])) {
+            $payload['mode'] = $opts['mode'];
+        }
+
+        error_log("Kling Lip Sync request: mode=" . ($opts['mode'] ?? 'std'));
+
+        $response = $this->makeRequest('POST', '/v1/videos/avatar', $payload);
+
+        return $this->extractTaskInfo($response, 'avatar');
+    }
+
+    /**
+     * Check the status of a Kling task
+     */
+    public function checkStatus($taskId, $taskType) {
+        // Map task types to their status endpoints
+        $endpointMap = [
+            'text2video' => '/v1/videos/text2video/',
+            'image2video' => '/v1/videos/image2video/',
+            'video-extend' => '/v1/videos/video-extend/',
+            'avatar' => '/v1/videos/avatar/'
+        ];
+
+        $endpoint = ($endpointMap[$taskType] ?? '/v1/videos/text2video/') . $taskId;
+
+        $response = $this->makeRequest('GET', $endpoint);
+
+        return $response;
+    }
+
+    /**
+     * Download a video from Kling CDN and save locally
+     */
+    public function downloadAndSaveVideo($url) {
+        $ch = curl_init($url);
+        curl_setopt_array($ch, [
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_FOLLOWLOCATION => true,
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_TIMEOUT => 120
+        ]);
+
+        $videoData = curl_exec($ch);
+        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        $curlError = curl_error($ch);
+        curl_close($ch);
+
+        if ($curlError || $httpCode !== 200 || !$videoData) {
+            throw new Exception("Failed to download video from Kling CDN: HTTP $httpCode");
+        }
+
+        $filename = 'video_' . date('Ymd_His') . '_' . bin2hex(random_bytes(4)) . '.mp4';
+        $videoDir = __DIR__ . '/generated_videos';
+
+        if (!is_dir($videoDir)) {
+            mkdir($videoDir, 0755, true);
+        }
+
+        $filepath = $videoDir . '/' . $filename;
+        file_put_contents($filepath, $videoData);
+
+        return $filename;
+    }
+
+    /**
+     * Extract task ID and type from Kling API response
+     */
+    private function extractTaskInfo($response, $taskType) {
+        // Kling API returns: { "code": 0, "message": "...", "request_id": "...", "data": { "task_id": "...", "task_status": "submitted" } }
+        if (isset($response['data']['task_id'])) {
+            return [
+                'taskId' => $response['data']['task_id'],
+                'taskType' => $taskType,
+                'status' => $response['data']['task_status'] ?? 'submitted'
+            ];
+        }
+
+        // Also check for task_id at top level
+        if (isset($response['task_id'])) {
+            return [
+                'taskId' => $response['task_id'],
+                'taskType' => $taskType,
+                'status' => $response['task_status'] ?? 'submitted'
+            ];
+        }
+
+        throw new Exception('Kling API returned unexpected response: ' . json_encode($response));
+    }
+
+    /**
+     * Clean base64 data - remove data URI prefix and whitespace
+     */
+    private function cleanBase64($data) {
+        $data = preg_replace('/^data:[^;]+;base64,/', '', $data);
+        $data = preg_replace('/\s+/', '', $data);
+        return $data;
+    }
+}
+
+// =============================================================================
+// Request Handler
+// =============================================================================
+
+try {
+    $action = $_POST['action'] ?? $_GET['action'] ?? null;
+
+    if (!$action) {
+        throw new Exception('No action specified');
+    }
+
+    // Validate Kling credentials
+    if (!defined('KLING_ACCESS_KEY') || empty(KLING_ACCESS_KEY) || !defined('KLING_SECRET_KEY') || empty(KLING_SECRET_KEY)) {
+        throw new Exception('Kling API credentials not configured. Please set KLING_ACCESS_KEY and KLING_SECRET_KEY in your .env file.');
+    }
+
+    $api = new KlingAPI(KLING_ACCESS_KEY, KLING_SECRET_KEY);
+
+    // =========================================================================
+    // Action: generate (Text-to-Video or Image-to-Video)
+    // =========================================================================
+    if ($action === 'generate') {
+        $prompt = $_POST['prompt'] ?? '';
+        $modelName = $_POST['modelName'] ?? 'kling-v2-6';
+        $duration = $_POST['duration'] ?? '5';
+        $aspectRatio = $_POST['aspectRatio'] ?? '16:9';
+        $mode = $_POST['mode'] ?? 'std';
+        $cfgScale = $_POST['cfgScale'] ?? '0.5';
+        $sound = $_POST['sound'] ?? 'off';
+        $negativePrompt = $_POST['negativePrompt'] ?? '';
+        $cameraControl = $_POST['cameraControl'] ?? 'none';
+
+        // Validate model
+        $validModels = ['kling-v2-6', 'kling-v2-5-turbo', 'kling-v2-1-master', 'kling-v1-6'];
+        if (!in_array($modelName, $validModels)) {
+            $modelName = 'kling-v2-6';
+        }
+
+        // Validate duration
+        if (!in_array($duration, ['5', '10'])) {
+            $duration = '5';
+        }
+
+        // Validate aspect ratio
+        if (!in_array($aspectRatio, ['16:9', '9:16', '1:1'])) {
+            $aspectRatio = '16:9';
+        }
+
+        // Validate mode
+        if (!in_array($mode, ['std', 'pro'])) {
+            $mode = 'std';
+        }
+
+        $opts = [
+            'model_name' => $modelName,
+            'mode' => $mode,
+            'duration' => $duration,
+            'aspect_ratio' => $aspectRatio,
+            'cfg_scale' => $cfgScale,
+            'sound' => $sound,
+            'negative_prompt' => trim($negativePrompt),
+            'camera_control' => $cameraControl
+        ];
+
+        // Collect reference images
+        $referenceImages = [];
+        $refCount = intval($_POST['referenceImageCount'] ?? 0);
+        for ($i = 0; $i < min($refCount, 2); $i++) {
+            if (isset($_POST["referenceImage_$i"])) {
+                $referenceImages[] = [
+                    'data' => $_POST["referenceImage_$i"],
+                    'mime_type' => $_POST["referenceImageType_$i"] ?? 'image/jpeg'
+                ];
+            }
+        }
+
+        // Branch: T2V or I2V based on reference images
+        if (!empty($referenceImages)) {
+            if (empty($prompt)) {
+                $prompt = '';  // Prompt is optional for I2V
+            }
+            $result = $api->imageToVideo($referenceImages, $prompt, $opts);
+        } else {
+            if (empty($prompt)) {
+                throw new Exception('Prompt is required for text-to-video generation');
+            }
+            $result = $api->textToVideo($prompt, $opts);
+        }
+
+        echo json_encode([
+            'success' => true,
+            'status' => 'pending',
+            'taskId' => $result['taskId'],
+            'taskType' => $result['taskType'],
+            'message' => 'Kling video generation started. Polling for status.'
+        ]);
+        exit;
+    }
+
+    // =========================================================================
+    // Action: extend (Video Extension)
+    // =========================================================================
+    if ($action === 'extend') {
+        $videoId = $_POST['videoId'] ?? null;
+        $prompt = $_POST['prompt'] ?? '';
+        $cfgScale = $_POST['cfgScale'] ?? '0.5';
+        $negativePrompt = $_POST['negativePrompt'] ?? '';
+
+        if (!$videoId) {
+            throw new Exception('Video ID is required for video extension');
+        }
+
+        $opts = [
+            'prompt' => trim($prompt),
+            'negative_prompt' => trim($negativePrompt),
+            'cfg_scale' => $cfgScale
+        ];
+
+        $result = $api->extendVideo($videoId, $opts);
+
+        echo json_encode([
+            'success' => true,
+            'status' => 'pending',
+            'taskId' => $result['taskId'],
+            'taskType' => 'video-extend',
+            'message' => 'Video extension started. Polling for status.'
+        ]);
+        exit;
+    }
+
+    // =========================================================================
+    // Action: lipsync (Lip Sync Generation)
+    // =========================================================================
+    if ($action === 'lipsync') {
+        $imageData = $_POST['image'] ?? null;
+        $audioData = $_POST['audioFile'] ?? null;
+        $prompt = $_POST['prompt'] ?? '';
+        $mode = $_POST['mode'] ?? 'std';
+
+        if (!$imageData) {
+            throw new Exception('Face image is required for lip sync');
+        }
+
+        if (!$audioData) {
+            throw new Exception('Audio file is required for lip sync');
+        }
+
+        if (!in_array($mode, ['std', 'pro'])) {
+            $mode = 'std';
+        }
+
+        $opts = [
+            'prompt' => trim($prompt),
+            'mode' => $mode
+        ];
+
+        $result = $api->lipSync($imageData, $audioData, $opts);
+
+        echo json_encode([
+            'success' => true,
+            'status' => 'pending',
+            'taskId' => $result['taskId'],
+            'taskType' => 'avatar',
+            'message' => 'Lip sync generation started. Polling for status.'
+        ]);
+        exit;
+    }
+
+    // =========================================================================
+    // Action: check_status (Poll task status for any workflow)
+    // =========================================================================
+    if ($action === 'check_status') {
+        $taskId = $_POST['taskId'] ?? null;
+        $taskType = $_POST['taskType'] ?? 'text2video';
+
+        if (!$taskId) {
+            throw new Exception('Task ID is required');
+        }
+
+        $response = $api->checkStatus($taskId, $taskType);
+
+        // Extract status from response
+        $taskStatus = $response['data']['task_status'] ?? 'processing';
+        $taskStatusMsg = $response['data']['task_status_msg'] ?? '';
+
+        if ($taskStatus === 'succeed') {
+            // Task completed - extract video URL
+            $videos = $response['data']['task_result']['videos'] ?? [];
+
+            if (empty($videos)) {
+                throw new Exception('Kling generation completed but no video was returned');
+            }
+
+            $videoUrl = $videos[0]['url'] ?? null;
+            $videoDuration = $videos[0]['duration'] ?? null;
+
+            if (!$videoUrl) {
+                throw new Exception('Kling generation completed but video URL is missing');
+            }
+
+            // Download from Kling CDN and save locally (CDN URLs are temporary)
+            $filename = $api->downloadAndSaveVideo($videoUrl);
+
+            echo json_encode([
+                'success' => true,
+                'status' => 'complete',
+                'video' => [
+                    'url' => '/generated_videos/' . $filename,
+                    'filename' => $filename,
+                    'mime_type' => 'video/mp4',
+                    'duration' => $videoDuration
+                ],
+                'taskId' => $taskId
+            ]);
+        } elseif ($taskStatus === 'failed') {
+            throw new Exception('Kling video generation failed: ' . ($taskStatusMsg ?: 'Unknown error'));
+        } else {
+            // Still processing (submitted, processing)
+            echo json_encode([
+                'success' => true,
+                'status' => 'pending',
+                'taskStatus' => $taskStatus,
+                'message' => 'Kling video generation in progress...'
+            ]);
+        }
+        exit;
+    }
+
+    // =========================================================================
+    // Action: download_video (Proxy download from Kling CDN)
+    // =========================================================================
+    if ($action === 'download_video') {
+        $videoUrl = $_POST['videoUrl'] ?? null;
+
+        if (!$videoUrl) {
+            throw new Exception('Video URL is required');
+        }
+
+        $filename = $api->downloadAndSaveVideo($videoUrl);
+
+        echo json_encode([
+            'success' => true,
+            'video' => [
+                'url' => '/generated_videos/' . $filename,
+                'filename' => $filename,
+                'mime_type' => 'video/mp4'
+            ]
+        ]);
+        exit;
+    }
+
+    throw new Exception('Invalid action: ' . $action);
+
+} catch (Exception $e) {
+    http_response_code(500);
+
+    error_log("Exception in kling_api.php: " . $e->getMessage());
+    error_log("Stack trace: " . $e->getTraceAsString());
+
+    echo json_encode([
+        'success' => false,
+        'error' => $e->getMessage(),
+        'debug' => [
+            'file' => basename($e->getFile()),
+            'line' => $e->getLine(),
+            'timestamp' => date('Y-m-d H:i:s')
+        ]
+    ]);
+    exit;
+}

backend/video_api.php

@@ -10,6 +10,12 @@ ini_set('display_errors', 0);
 ini_set('log_errors', 1);
 set_time_limit(300); // Veo 3.1 operations poll for up to 5 minutes
 
+// Increase execution time and memory/POST limits for video generation with large images
+set_time_limit(600);
+ini_set('memory_limit', '512M');
+ini_set('post_max_size', '100M');
+ini_set('upload_max_filesize', '100M');
+
 header('Content-Type: application/json');
 header('Access-Control-Allow-Origin: *');
 header('Access-Control-Allow-Methods: POST, GET, OPTIONS');
@@ -60,6 +66,14 @@ class VeoVideoAPI {
             'sampleCount' => 1
         ];
 
+        // Person generation: T2V supports 'allow_all', but I2V only supports 'allow_adult'
+        // Note: 'allow_adult' means children will still be blocked in I2V mode (Google restriction)
+        if (!empty($referenceImages)) {
+            $parameters['personGeneration'] = 'allow_adult';
+        } else {
+            $parameters['personGeneration'] = 'allow_all';
+        }
+
         // Frame mode: first image is starting frame, optional second image is last frame for interpolation
         if (!empty($referenceImages)) {
             if (isset($referenceImages[0])) {

frontend/src/components/CinePromptStudio.jsx

@@ -725,12 +725,19 @@ const CinePromptStudio = ({ activeProjectId, editData, onEditLoaded }) => {
   const [imageError, setImageError] = useState('');
   const [referenceImages, setReferenceImages] = useState([]);
   const [imageResolution, setImageResolution] = useState('2K');
+  const [imageModelType, setImageModelType] = useState('pro');
   const [imagePreviewExpanded, setImagePreviewExpanded] = useState(false);
 
   // Project images state (for "Add from Library" feature)
   const [projectImages, setProjectImages] = useState([]);
   const [showProjectPicker, setShowProjectPicker] = useState(false);
 
+  // Image Model Options
+  const imageModelOptions = [
+    { value: 'pro', label: 'Pro', description: 'Higher quality' },
+    { value: 'flash', label: 'Flash', description: 'Faster, lower cost' }
+  ];
+
   // Effect: Auto-select camera and lens based on application
   useEffect(() => {
     const selectedApp = allApplicationData.find(app => app.value === application);
@@ -1158,6 +1165,7 @@ Return ONLY the final prompt text. No markdown, no preamble, no "Here is your pr
       formData.append('prompt', finalPrompt);
       formData.append('aspectRatio', aspectRatio);
       formData.append('imageSize', imageResolution);
+      formData.append('modelType', imageModelType);
 
       // If we have a generatedImage (from library edit or previous generation),
       // send it to the backend so it uses the correct image for editing
@@ -1197,7 +1205,7 @@ Return ONLY the final prompt text. No markdown, no preamble, no "Here is your pr
               await addItemToProject(activeProjectId, {
                 type: 'image',
                 prompt: generatedPrompt,
-                settings: { camera, lens, application, aspectRatio, imageResolution },
+                settings: { camera, lens, application, aspectRatio, imageResolution, imageModelType },
                 thumbnail: null,
                 data: imageData.data,
                 mimeType: imageData.mime_type
@@ -1840,6 +1848,27 @@ Return ONLY the final prompt text. No markdown, no preamble, no "Here is your pr
                 </p>
               </div>
 
+              {/* Model Selector */}
+              <div className="space-y-2">
+                <label className="text-xs font-bold text-slate-400 uppercase tracking-wider">Model</label>
+                <div className="flex gap-2">
+                  {imageModelOptions.map((opt) => (
+                    <button
+                      key={opt.value}
+                      onClick={() => setImageModelType(opt.value)}
+                      className={`flex-1 px-3 py-2 rounded-lg font-medium transition-all text-sm ${
+                        imageModelType === opt.value
+                          ? 'bg-cinema-gold text-slate-950'
+                          : 'bg-slate-800 text-slate-400 hover:bg-slate-700'
+                      }`}
+                    >
+                      <div>{opt.label}</div>
+                      <div className="text-xs opacity-70">{opt.description}</div>
+                    </button>
+                  ))}
+                </div>
+              </div>
+
               {/* Resolution Selector */}
               <div className="space-y-2">
                 <label className="text-xs font-bold text-slate-400 uppercase tracking-wider">Output Resolution</label>

frontend/src/components/ProjectsTab.jsx

@@ -1164,9 +1164,11 @@ const ProjectsTab = ({ onProjectSelect, activeProjectId, onRerunVideo, onEditInI
                             <div className={`absolute top-2 left-2 px-2 py-1 rounded text-xs font-medium ${
                               item.type === 'image'
                                 ? 'bg-blue-900/80 text-blue-300'
+                                : item.settings?.engine === 'kling'
+                                ? 'bg-indigo-900/80 text-indigo-300'
                                 : 'bg-purple-900/80 text-purple-300'
                             }`}>
-                              {item.type === 'image' ? 'IMG' : 'VID'}
+                              {item.type === 'image' ? 'IMG' : item.settings?.engine === 'kling' ? 'KLING' : 'VID'}
                             </div>
 
                             {/* Hover Overlay (hide when selecting) */}
@@ -1492,6 +1494,24 @@ const ProjectsTab = ({ onProjectSelect, activeProjectId, onRerunVideo, onEditInI
                     </span>
                   </div>
                 )}
+                {previewItem.type === 'video' && (
+                  <div className="mt-2 flex gap-1.5">
+                    <span className={`text-xs px-2 py-0.5 rounded-full font-medium ${
+                      previewItem.settings?.engine === 'kling'
+                        ? 'bg-indigo-900/50 text-indigo-300 border border-indigo-700'
+                        : 'bg-emerald-900/50 text-emerald-300 border border-emerald-700'
+                    }`}>
+                      {previewItem.settings?.engine === 'kling'
+                        ? `Kling ${previewItem.settings?.klingModel?.replace('kling-', '').toUpperCase() || 'AI'}`
+                        : `Veo ${previewItem.settings?.modelType === 'fast' ? 'Fast' : 'Std'}`}
+                    </span>
+                    {previewItem.settings?.engine === 'kling' && previewItem.settings?.klingTaskId && (
+                      <span className="text-xs px-2 py-0.5 bg-slate-800 rounded-full text-slate-500 border border-slate-700 font-mono">
+                        ID: {previewItem.settings.klingTaskId.substring(0, 8)}...
+                      </span>
+                    )}
+                  </div>
+                )}
                 <div className="flex items-center justify-between mt-3">
                   <span className="text-xs text-slate-500">{formatDate(previewItem.createdAt)}</span>
                   <div className="flex gap-2">