fix: display Gemini fallback model parameters in node panel

Gemini image models (nano-banana, nano-banana-pro, nano-banana-2) were
not showing parameters when set as fallback models. Three root causes:

1. Schema API returned empty for Gemini image models — added
   getGeminiImageSchema() with aspect ratio, resolution, and search
   grounding parameters per model
2. ModelParameters had an early-return guard skipping all non-Veo Gemini
   models — removed to make the component provider-agnostic
3. nanoBananaExecutor ignored parametersOverride for Gemini-specific
   fields (aspectRatio, resolution, useGoogleSearch, useImageSearch) —
   now reads from override when available

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/app/api/models/[modelId]/route.ts

@@ -1000,6 +1000,48 @@ function getGeminiVideoSchema(modelId: string): ExtractedSchema | null {
   return schemas[modelId] ?? null;
 }
 
+/**
+ * Get schema for Gemini image models (native image generation via Gemini API)
+ * Returns null if the model is not a Gemini image model.
+ */
+function getGeminiImageSchema(modelId: string): ExtractedSchema | null {
+  const baseAspectRatios = ["1:1", "2:3", "3:2", "3:4", "4:3", "4:5", "5:4", "9:16", "16:9", "21:9"];
+  const extendedAspectRatios = ["1:1", "1:4", "1:8", "2:3", "3:2", "3:4", "4:1", "4:3", "4:5", "5:4", "8:1", "9:16", "16:9", "21:9"];
+
+  const commonInputs: ModelInput[] = [
+    { name: "prompt", type: "text", required: true, label: "Prompt" },
+    { name: "image", type: "image", required: false, label: "Image", isArray: true },
+  ];
+
+  const schemas: Record<string, ExtractedSchema> = {
+    "nano-banana": {
+      parameters: [
+        { name: "aspectRatio", type: "string", description: "Output aspect ratio", enum: baseAspectRatios, default: "1:1" },
+      ],
+      inputs: commonInputs,
+    },
+    "nano-banana-pro": {
+      parameters: [
+        { name: "aspectRatio", type: "string", description: "Output aspect ratio", enum: baseAspectRatios, default: "1:1" },
+        { name: "resolution", type: "string", description: "Output resolution", enum: ["1K", "2K", "4K"], default: "2K" },
+        { name: "useGoogleSearch", type: "boolean", description: "Enable Google Search grounding", default: false },
+      ],
+      inputs: commonInputs,
+    },
+    "nano-banana-2": {
+      parameters: [
+        { name: "aspectRatio", type: "string", description: "Output aspect ratio", enum: extendedAspectRatios, default: "1:1" },
+        { name: "resolution", type: "string", description: "Output resolution", enum: ["512", "1K", "2K", "4K"], default: "2K" },
+        { name: "useGoogleSearch", type: "boolean", description: "Enable Google Search grounding", default: false },
+        { name: "useImageSearch", type: "boolean", description: "Enable Image Search grounding", default: false },
+      ],
+      inputs: commonInputs,
+    },
+  };
+
+  return schemas[modelId] ?? null;
+}
+
 /**
  * Get static schema for WaveSpeed models (fallback when dynamic schema not available)
  */
@@ -1260,12 +1302,14 @@ export async function GET(
     let result: ExtractedSchema;
 
     if (provider === "gemini") {
-      // Gemini video models use hardcoded schemas
+      // Gemini models use hardcoded schemas (video and image)
       const geminiVideoSchema = getGeminiVideoSchema(decodedModelId);
+      const geminiImageSchema = getGeminiImageSchema(decodedModelId);
       if (geminiVideoSchema) {
         result = geminiVideoSchema;
+      } else if (geminiImageSchema) {
+        result = geminiImageSchema;
       } else {
-        // Gemini image models don't use schema endpoint (params are built-in)
         result = { parameters: [], inputs: [] };
       }
     } else if (provider === "replicate") {

src/components/__tests__/ModelParameters.test.tsx

@@ -66,11 +66,14 @@ describe("ModelParameters", () => {
   });
 
   describe("Initial Rendering", () => {
-    it("should not render for Gemini provider", () => {
+    it("should fetch schema for Gemini provider", () => {
-      const { container } = render(
+      (global.fetch as ReturnType<typeof vi.fn>).mockImplementation(
+        () => new Promise(() => {})
+      );
+      render(
         <ModelParameters {...defaultProps} provider="gemini" />
       );
-      expect(container.firstChild).toBeNull();
+      expect(screen.getByText("Loading parameters...")).toBeInTheDocument();
     });
 
     it("should not render when modelId is empty", () => {
@@ -767,8 +770,17 @@ describe("ModelParameters", () => {
       });
     });
 
-    it("should call onInputsLoaded with empty array for Gemini", () => {
+    it("should fetch schema and call onInputsLoaded for Gemini", async () => {
       const onInputsLoaded = vi.fn();
+      (global.fetch as ReturnType<typeof vi.fn>).mockResolvedValueOnce({
+        ok: true,
+        json: () =>
+          Promise.resolve({
+            success: true,
+            parameters: [],
+            inputs: [{ name: "prompt", type: "text", required: true, label: "Prompt" }],
+          }),
+      });
 
       render(
         <ModelParameters
@@ -778,7 +790,11 @@ describe("ModelParameters", () => {
         />
       );
 
-      expect(onInputsLoaded).toHaveBeenCalledWith([]);
+      await waitFor(() => {
+        expect(onInputsLoaded).toHaveBeenCalledWith([
+          { name: "prompt", type: "text", required: true, label: "Prompt" },
+        ]);
+      });
     });
   });
 

src/components/nodes/ModelParameters.tsx

@@ -82,11 +82,9 @@ function ModelParametersInner({
   // Use stable selector for API keys to prevent unnecessary re-fetches
   const { replicateApiKey, falApiKey, kieApiKey, wavespeedApiKey } = useProviderApiKeys();
 
-  const isVeoModel = modelId?.startsWith("veo-");
-
   // Fetch schema when modelId changes
   useEffect(() => {
-    if (!modelId || (provider === "gemini" && !isVeoModel)) {
+    if (!modelId) {
       setSchema([]);
       onInputsLoaded?.([]);
       return;
@@ -219,8 +217,8 @@ function ModelParametersInner({
       : sortedSchema;
   }, [sortedSchema, useGrid, colCount]);
 
-  // Don't render anything for Gemini (except Veo) or if no model selected
+  // Don't render if no model selected
-  if ((provider === "gemini" && !isVeoModel) || !modelId) {
+  if (!modelId) {
     return null;
   }
 

src/store/execution/nanoBananaExecutor.ts

@@ -104,11 +104,11 @@ export async function executeNanoBanana(
     const requestPayload = {
       images,
       prompt: finalPrompt,
-      aspectRatio: nodeData.aspectRatio,
+      aspectRatio: (parametersOverride?.aspectRatio as string) ?? nodeData.aspectRatio,
-      resolution: nodeData.resolution,
+      resolution: (parametersOverride?.resolution as string) ?? nodeData.resolution,
       model: nodeData.model,
-      useGoogleSearch: nodeData.useGoogleSearch,
+      useGoogleSearch: (parametersOverride?.useGoogleSearch as boolean) ?? nodeData.useGoogleSearch,
-      useImageSearch: nodeData.useImageSearch,
+      useImageSearch: (parametersOverride?.useImageSearch as boolean) ?? nodeData.useImageSearch,
       selectedModel: modelToUse,
       parameters: parametersOverride ?? nodeData.parameters,
       dynamicInputs: sanitizedDynamicInputs,