fix: switch to Gemini Imagen 3 API endpoint to fix image base64 extraction

backend/server.js

@@ -370,52 +370,46 @@ app.post('/api/sparkplug/extract', authenticate, upload.single('file'), async (r
   }
 });
 
-// 2. Generate Images (Nano Banana / Gemini Imagen)
+// 2. Generate Images (Gemini Imagen 3)
 app.post('/api/sparkplug/generate-images', authenticate, async (req, res) => {
   const { prompt } = req.body;
   if (!prompt) return res.status(400).json({ error: 'No prompt provided' });
 
   try {
     const keys = await getKeysFromProfile(req.user.id);
-    const apiKey = keys.NANO_BANANA_API_KEY || keys.GEMINI_API_KEY;
-    if (!apiKey) return res.status(400).json({ error: 'Nano Banana (Gemini) API key missing' });
+    const apiKey = keys.GEMINI_API_KEY || keys.NANO_BANANA_API_KEY;
+    if (!apiKey) return res.status(400).json({ error: 'Gemini API key missing' });
 
-    // We will use axios to call the new Gemini 3.1 REST API via /interactions
-    const baseUrl = 'https://generativelanguage.googleapis.com/v1beta/interactions';
+    // Use the standard Gemini Imagen 3 API
+    const baseUrl = 'https://generativelanguage.googleapis.com/v1beta/models/imagen-3.0-generate-images:predict';
     
     const views = ['Front view', 'Back view', 'Left side view', 'Right side view'];
-    const imageUrls = [];
 
     // Run parallel generation for all 4 views
     const promises = views.map(async (view, index) => {
       const fullPrompt = `${prompt}. ${view}, isolated on a pure white background, studio lighting.`;
       
       const payload = {
-        model: "gemini-3.1-flash-lite-image",
-        input: [
-          { type: "text", text: fullPrompt }
-        ]
+        instances: [
+          { prompt: fullPrompt }
+        ],
+        parameters: {
+          sampleCount: 1,
+          aspectRatio: "1:1"
+        }
       };
 
       const response = await axios.post(`${baseUrl}?key=${apiKey}`, payload, {
         headers: { 'Content-Type': 'application/json' }
       });
 
-      // The new interactions endpoint returns the interaction object.
-      // We look for the image output.
       let base64Image = null;
-      if (response.data.interaction?.output_image?.data) {
-        base64Image = response.data.interaction.output_image.data;
-      } else if (response.data.interaction?.output?.blocks) {
-        // Fallback for raw REST shape if output_image is an SDK-only convenience wrapper
-        const imgBlock = response.data.interaction.output.blocks.find(b => b.type === 'image' || b.image);
-        if (imgBlock) {
-          base64Image = imgBlock.image?.data || imgBlock.data;
-        }
+      if (response.data && response.data.predictions && response.data.predictions.length > 0) {
+        base64Image = response.data.predictions[0].bytesBase64Encoded;
       }
 
       if (!base64Image) {
-        throw new Error("Could not extract base64 image data from Gemini response: " + JSON.stringify(response.data));
+        throw new Error(`Could not extract base64 image data from Gemini response: ${JSON.stringify(response.data)}`);
       }
 
       const buffer = Buffer.from(base64Image, 'base64');
@@ -432,7 +426,6 @@ app.post('/api/sparkplug/generate-images', authenticate, async (req, res) => {
   } catch (err) {
     let errorMsg = err.message;
     if (err.response && err.response.data) {
-      // Just stringify the entire response data so we can see the exact error from Google!
       errorMsg = typeof err.response.data === 'object' ? JSON.stringify(err.response.data) : err.response.data;
     }
     console.error("Gemini Image Gen Error:", errorMsg);