fix: make Veo negative prompt a connectable text handle

Instead of an inline text field, negative prompt is now a proper text
handle on the node that can receive connections from prompt/LLM nodes.
Updates the API route to merge dynamicInputs.negative_prompt into the
Veo parameters, and aligns the model schema definition accordingly.

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

src/app/api/generate/route.ts

@@ -480,13 +480,21 @@ export async function POST(request: NextRequest) {
 
     // Check if this is a Veo video model request
     if (selectedModel?.modelId?.startsWith("veo-")) {
+      // Merge negative prompt from dynamic inputs (connected handle) into parameters
+      const veoParams = { ...(parameters || {}) };
+      if (dynamicInputs?.negative_prompt) {
+        const neg = Array.isArray(dynamicInputs.negative_prompt)
+          ? dynamicInputs.negative_prompt[0]
+          : dynamicInputs.negative_prompt;
+        if (neg) veoParams.negativePrompt = neg;
+      }
       const result = await generateWithGeminiVideo(
         requestId,
         geminiApiKey,
         selectedModel.modelId,
         resolvedPrompt || "",
         images || [],
-        parameters || {},
+        veoParams,
       );
 
       if (!result.success) {

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

@@ -900,30 +900,34 @@ function getGeminiVideoSchema(modelId: string): ExtractedSchema | null {
     { name: "aspectRatio", type: "string", description: "Output aspect ratio", enum: ["16:9", "9:16"], default: "16:9" },
     { name: "durationSeconds", type: "string", description: "Video duration in seconds", enum: ["4", "6", "8"], default: "8" },
     { name: "resolution", type: "string", description: "Output resolution", enum: ["720p", "1080p", "4k"], default: "720p" },
-    { name: "negativePrompt", type: "string", description: "What to avoid in the generated video" },
     { name: "seed", type: "integer", description: "Random seed for reproducibility", minimum: 0 },
   ];
 
+  const textInputs: ModelInput[] = [
+    { name: "prompt", type: "text", required: true, label: "Prompt" },
+    { name: "negative_prompt", type: "text", required: false, label: "Neg. Prompt" },
+  ];
+
   const schemas: Record<string, ExtractedSchema> = {
     "veo-3.1/text-to-video": {
       parameters: commonParams,
-      inputs: [{ name: "prompt", type: "text", required: true, label: "Prompt" }],
+      inputs: textInputs,
     },
     "veo-3.1/image-to-video": {
       parameters: commonParams,
       inputs: [
-        { name: "prompt", type: "text", required: true, label: "Prompt" },
+        ...textInputs,
         { name: "image", type: "image", required: true, label: "Image" },
       ],
     },
     "veo-3.1-fast/text-to-video": {
       parameters: commonParams,
-      inputs: [{ name: "prompt", type: "text", required: true, label: "Prompt" }],
+      inputs: textInputs,
     },
     "veo-3.1-fast/image-to-video": {
       parameters: commonParams,
       inputs: [
-        { name: "prompt", type: "text", required: true, label: "Prompt" },
+        ...textInputs,
         { name: "image", type: "image", required: true, label: "Image" },
       ],
     },

src/components/nodes/GenerateVideoNode.tsx

@@ -114,6 +114,21 @@ export function GenerateVideoNode({ id, data, selected }: NodeProps<GenerateVide
     fetchModels();
   }, [fetchModels]);
 
+  // Set inputSchema for Veo models (hardcoded, not fetched via ModelParameters)
+  const selectedModelId = nodeData.selectedModel?.modelId;
+  useEffect(() => {
+    if (!isVeoModel(selectedModelId)) return;
+    const isI2V = selectedModelId!.includes("image-to-video");
+    const inputs: ModelInputDef[] = [
+      { name: "prompt", type: "text", required: true, label: "Prompt" },
+      { name: "negative_prompt", type: "text", required: false, label: "Neg. Prompt" },
+    ];
+    if (isI2V) {
+      inputs.unshift({ name: "image", type: "image", required: true, label: "Image" });
+    }
+    updateNodeData(id, { inputSchema: inputs });
+  }, [id, selectedModelId, updateNodeData]);
+
   // Handle provider change
   const handleProviderChange = useCallback(
     (e: React.ChangeEvent<HTMLSelectElement>) => {
@@ -776,14 +791,6 @@ export function GenerateVideoNode({ id, data, selected }: NodeProps<GenerateVide
                 ))}
               </select>
             </div>
-            {/* Negative prompt */}
-            <input
-              type="text"
-              placeholder="Negative prompt..."
-              value={(nodeData.parameters?.negativePrompt as string) || ""}
-              onChange={(e) => updateVeoParam("negativePrompt", e.target.value)}
-              className="w-full text-[10px] py-1 px-1.5 border border-neutral-700 rounded bg-neutral-900/50 focus:outline-none focus:ring-1 focus:ring-neutral-600 text-neutral-300 placeholder:text-neutral-600"
-            />
             {/* Seed */}
             <input
               type="number"