fix: add Gemini prompt fallback from dynamicInputs, improve parallel batch error logging

- Resolve prompt from dynamicInputs.prompt in Gemini code path as fallback
- Return clear 400 error when prompt is provided but is not a string (corrupted data)
- Improve parallel batch error logging to include nodeId and nodeType for diagnosis
- Replace find() with for-loop to preserve index mapping between results and batch nodes

src/app/api/generate/route.ts

@@ -432,10 +432,27 @@ export async function POST(request: NextRequest) {
     // Use selectedModel.modelId if available (new format), fallback to legacy model field
     const geminiModel = (selectedModel?.modelId as ModelType) || model;
 
+    // Resolve prompt: use top-level prompt, fall back to dynamicInputs.prompt
+    // This handles cases where the prompt arrives via dynamicInputs instead of top-level
+    let resolvedPrompt = prompt;
+    if (!resolvedPrompt && dynamicInputs?.prompt) {
+      resolvedPrompt = Array.isArray(dynamicInputs.prompt)
+        ? dynamicInputs.prompt[0]
+        : dynamicInputs.prompt;
+    }
+    // Validate: if a prompt was provided but isn't a string (corrupted data), return clear error
+    // If no prompt provided but images exist, that's valid (image-to-image)
+    if (resolvedPrompt !== undefined && resolvedPrompt !== null && typeof resolvedPrompt !== 'string') {
+      return NextResponse.json<GenerateResponse>(
+        { success: false, error: "prompt must be a string" },
+        { status: 400 }
+      );
+    }
+
     return await generateWithGemini(
       requestId,
       geminiApiKey,
-      prompt,
+      resolvedPrompt,
       images || [],
       geminiModel,
       aspectRatio,

src/store/workflowStore.ts

@@ -962,21 +962,21 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
             batch.map((node) => executeSingleNode(node, abortController.signal))
           );
 
-          // Check for failures (fail-fast behavior)
+          // Check for failures with node context (fail-fast behavior)
-          const failed = results.find(
+          for (let i = 0; i < results.length; i++) {
-            (r): r is PromiseRejectedResult =>
+            const r = results[i];
-              r.status === 'rejected' &&
+            if (r.status === 'rejected' &&
-              !(r.reason instanceof DOMException && r.reason.name === 'AbortError')
+                !(r.reason instanceof DOMException && r.reason.name === 'AbortError')) {
-          );
+              const failedNode = batch[i];
-
-          if (failed) {
-            // Log the failure and abort remaining executions
               logger.error('workflow.error', 'Node execution failed in parallel batch', {
                 level: levelIdx,
-              error: failed.reason instanceof Error ? failed.reason.message : String(failed.reason),
+                nodeId: failedNode.id,
+                nodeType: failedNode.type,
+                error: r.reason instanceof Error ? r.reason.message : String(r.reason),
               });
               abortController.abort();
-            throw failed.reason;
+              throw r.reason;
+            }
           }
         }
       }