Preserve image ratio settings through NewApiWG generation

Image generation settings arrive at /api/generate as top-level aspectRatio and resolution fields, but the NewApiWG provider path only forwarded model-specific parameters. Native NewApiWG Gemini image generation therefore fell back to default imageConfig values and ignored composer/control-panel ratio choices. The route now merges top-level image settings into provider parameters while preserving explicit model parameter overrides.

Constraint: NewApiWG provider implementations read aspect ratio and image size from GenerationInput.parameters.
Rejected: Parse aspect ratio from prompt text | UI settings should be authoritative and prompts are ambiguous.
Confidence: high
Scope-risk: narrow
Directive: Keep top-level GenerateRequest image settings and provider parameters in sync for image providers.
Tested: npm test -- --run src/app/api/generate/__tests__/route.test.ts src/store/execution/__tests__/nanoBananaExecutor.test.ts src/components/__tests__/GenerationComposer.test.tsx
Tested: npx tsc --noEmit --pretty false filtered to generate route files
Not-tested: Full tsc due existing test mock overload errors in route.test.ts

src/app/api/generate/__tests__/route.test.ts

@@ -1020,6 +1020,60 @@ describe("/api/generate route", () => {
       expect(data.image).toMatch(/^data:image\/png;base64,/);
       expect(data.contentType).toBe("image");
     });
+
+    it("should pass top-level aspect ratio and resolution to native NewApiWG image models", async () => {
+      mockFetch.mockResolvedValueOnce({
+        ok: true,
+        json: () => Promise.resolve({
+          candidates: [
+            {
+              content: {
+                parts: [
+                  {
+                    inlineData: {
+                      mimeType: "image/png",
+                      data: "nativeImageData",
+                    },
+                  },
+                ],
+              },
+            },
+          ],
+        }),
+      });
+
+      const request = createMockPostRequest(
+        {
+          prompt: "A tall poster",
+          aspectRatio: "9:16",
+          resolution: "2K",
+          selectedModel: {
+            provider: "newapiwg",
+            modelId: "apiyi_nano_banana_2",
+            displayName: "PopiArt Nano Pro",
+            capabilities: ["text-to-image", "image-to-image"],
+          },
+        },
+        { "X-NewApiWG-Key": "test-newapiwg-key" }
+      );
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(200);
+      expect(data.success).toBe(true);
+      expect(mockFetch).toHaveBeenCalledWith(
+        expect.stringContaining("/models/gemini-3.1-flash-image-preview:generateContent"),
+        expect.objectContaining({
+          body: expect.stringContaining('"aspectRatio":"9:16"'),
+        })
+      );
+      const body = JSON.parse(mockFetch.mock.calls[0][1].body as string);
+      expect(body.generationConfig.imageConfig).toMatchObject({
+        aspectRatio: "9:16",
+        imageSize: "2K",
+      });
+    });
   });
 
   describe("Replicate provider", () => {

src/app/api/generate/route.ts

@@ -83,6 +83,23 @@ function capabilitiesForMediaType(mediaType?: string): ModelCapability[] {
   return map[mediaType ?? ""] ?? ["text-to-image"];
 }
 
+function mergeImageGenerationParameters(
+  parameters: Record<string, unknown> | undefined,
+  aspectRatio: string | undefined,
+  resolution: string | undefined
+): Record<string, unknown> | undefined {
+  const merged = { ...(parameters || {}) };
+  if (aspectRatio && merged.aspectRatio === undefined && merged.aspect_ratio === undefined) {
+    merged.aspectRatio = aspectRatio;
+    merged.aspect_ratio = aspectRatio;
+  }
+  if (resolution && merged.resolution === undefined && merged.imageSize === undefined) {
+    merged.resolution = resolution;
+    merged.imageSize = resolution;
+  }
+  return Object.keys(merged).length > 0 ? merged : undefined;
+}
+
 export async function POST(request: NextRequest) {
   const requestId = Math.random().toString(36).substring(7);
   console.log(`\n[API:${requestId}] ========== NEW GENERATE REQUEST ==========`);
@@ -162,7 +179,7 @@ export async function POST(request: NextRequest) {
         },
         prompt: prompt || "",
         images: images ? [...images] : [],
-        parameters,
+        parameters: mergeImageGenerationParameters(parameters, aspectRatio, resolution),
         dynamicInputs,
       };