feat(05-02): convert large images to URLs with cleanup

- Import uploadImageForUrl, shouldUseImageUrl, deleteImages from @/lib/images
- Process images for Replicate/fal providers before generation
- Small images (<256KB) use data URIs directly
- Large images converted to temporary URLs via /api/images/[id]
- Cleanup uploaded images in finally block (success or failure)
- Gemini path unchanged (handles base64 directly)

src/app/api/generate/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { GoogleGenAI } from "@google/genai";
 import { GenerateRequest, GenerateResponse, ModelType, SelectedModel, ProviderType } from "@/types";
 import { GenerationInput, GenerationOutput, ProviderModel } from "@/lib/providers/types";
+import { uploadImageForUrl, shouldUseImageUrl, deleteImages } from "@/lib/images";
 
 export const maxDuration = 300; // 5 minute timeout for API calls
 export const dynamic = 'force-dynamic'; // Ensure this route is always dynamic
@@ -567,6 +568,26 @@ export async function POST(request: NextRequest) {
         );
       }
 
+      // Process images: convert large images to URLs for provider to fetch
+      const baseUrl = new URL(request.url).origin;
+      const uploadedImageIds: string[] = [];
+      const processedImages: string[] = [];
+
+      if (images && images.length > 0) {
+        for (const image of images) {
+          if (shouldUseImageUrl(image)) {
+            const { url, id } = uploadImageForUrl(image, baseUrl);
+            uploadedImageIds.push(id);
+            processedImages.push(url);
+            console.log(`[API:${requestId}] Converted large image to URL: ${url}`);
+          } else {
+            processedImages.push(image);
+            console.log(`[API:${requestId}] Using base64 directly (small image)`);
+          }
+        }
+      }
+
+      try {
         // Build generation input
         const genInput: GenerationInput = {
           model: {
@@ -577,7 +598,7 @@ export async function POST(request: NextRequest) {
             description: null,
           },
           prompt,
-        images,
+          images: processedImages,
           parameters,
         };
 
@@ -609,12 +630,39 @@ export async function POST(request: NextRequest) {
           success: true,
           image: outputImage,
         });
+      } finally {
+        // Clean up uploaded images
+        if (uploadedImageIds.length > 0) {
+          deleteImages(uploadedImageIds);
+          console.log(`[API:${requestId}] Cleaned up ${uploadedImageIds.length} uploaded images`);
+        }
+      }
     }
 
     if (provider === "fal") {
       // Get fal.ai API key from request headers (optional - fal.ai works without key but rate limited)
       const falApiKey = request.headers.get("X-Fal-API-Key");
 
+      // Process images: convert large images to URLs for provider to fetch
+      const baseUrl = new URL(request.url).origin;
+      const uploadedImageIds: string[] = [];
+      const processedImages: string[] = [];
+
+      if (images && images.length > 0) {
+        for (const image of images) {
+          if (shouldUseImageUrl(image)) {
+            const { url, id } = uploadImageForUrl(image, baseUrl);
+            uploadedImageIds.push(id);
+            processedImages.push(url);
+            console.log(`[API:${requestId}] Converted large image to URL: ${url}`);
+          } else {
+            processedImages.push(image);
+            console.log(`[API:${requestId}] Using base64 directly (small image)`);
+          }
+        }
+      }
+
+      try {
         // Build generation input
         const genInput: GenerationInput = {
           model: {
@@ -625,7 +673,7 @@ export async function POST(request: NextRequest) {
             description: null,
           },
           prompt,
-        images,
+          images: processedImages,
           parameters,
         };
 
@@ -657,6 +705,13 @@ export async function POST(request: NextRequest) {
           success: true,
           image: outputImage,
         });
+      } finally {
+        // Clean up uploaded images
+        if (uploadedImageIds.length > 0) {
+          deleteImages(uploadedImageIds);
+          console.log(`[API:${requestId}] Cleaned up ${uploadedImageIds.length} uploaded images`);
+        }
+      }
     }
 
     // Default: Use Gemini