feat: create generate3d executor

Extracted from nanoBananaExecutor's 3D handling code. Handles 3D model
generation via /api/generate with mediaType: "3d", cost tracking, and
auto-save to generations folder.

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

src/store/execution/generate3dExecutor.ts

@@ -0,0 +1,168 @@
+/**
+ * Generate3D Executor
+ *
+ * Executor for generate3d (3D model generation) nodes.
+ * Extracted from nanoBananaExecutor's 3D handling code.
+ */
+
+import type { Generate3DNodeData } from "@/types";
+import { buildGenerateHeaders } from "@/store/utils/buildApiHeaders";
+import type { NodeExecutionContext } from "./types";
+
+export interface Generate3DOptions {
+  /** When true, falls back to stored inputImages/inputPrompt if no connections provide them. */
+  useStoredFallback?: boolean;
+}
+
+export async function executeGenerate3D(
+  ctx: NodeExecutionContext,
+  options: Generate3DOptions = {}
+): Promise<void> {
+  const {
+    node,
+    getConnectedInputs,
+    updateNodeData,
+    getFreshNode,
+    signal,
+    providerSettings,
+    addIncurredCost,
+    generationsPath,
+    trackSaveGeneration,
+  } = ctx;
+
+  const { useStoredFallback = false } = options;
+
+  const { images: connectedImages, text: connectedText, dynamicInputs } = getConnectedInputs(node.id);
+
+  // Get fresh node data from store
+  const freshNode = getFreshNode(node.id);
+  const nodeData = (freshNode?.data || node.data) as Generate3DNodeData;
+
+  // Determine images and text (with optional fallback to stored values)
+  let images: string[];
+  let promptText: string | null;
+
+  if (useStoredFallback) {
+    images = connectedImages.length > 0 ? connectedImages : nodeData.inputImages;
+    promptText = connectedText ?? nodeData.inputPrompt;
+  } else {
+    images = connectedImages;
+    const promptFromDynamic = Array.isArray(dynamicInputs.prompt)
+      ? dynamicInputs.prompt[0]
+      : dynamicInputs.prompt;
+    promptText = connectedText || promptFromDynamic || null;
+  }
+
+  // 3D models may work with just images (image-to-3d) or just text (text-to-3d)
+  if (!promptText && images.length === 0) {
+    updateNodeData(node.id, {
+      status: "error",
+      error: "Missing text or image input",
+    });
+    throw new Error("Missing text or image input");
+  }
+
+  updateNodeData(node.id, {
+    inputImages: images,
+    inputPrompt: promptText,
+    status: "loading",
+    error: null,
+  });
+
+  const provider = nodeData.selectedModel?.provider || "fal";
+  const headers = buildGenerateHeaders(provider, providerSettings);
+
+  const requestPayload = {
+    images,
+    prompt: promptText || "",
+    selectedModel: nodeData.selectedModel,
+    parameters: nodeData.parameters,
+    dynamicInputs,
+    mediaType: "3d" as const,
+  };
+
+  try {
+    const response = await fetch("/api/generate", {
+      method: "POST",
+      headers,
+      body: JSON.stringify(requestPayload),
+      ...(signal ? { signal } : {}),
+    });
+
+    if (!response.ok) {
+      const errorText = await response.text();
+      let errorMessage = `HTTP ${response.status}`;
+      try {
+        const errorJson = JSON.parse(errorText);
+        errorMessage = errorJson.error || errorMessage;
+      } catch {
+        if (errorText) errorMessage += ` - ${errorText.substring(0, 200)}`;
+      }
+
+      updateNodeData(node.id, {
+        status: "error",
+        error: errorMessage,
+      });
+      throw new Error(errorMessage);
+    }
+
+    const result = await response.json();
+
+    if (result.success && result.model3dUrl) {
+      updateNodeData(node.id, {
+        output3dUrl: result.model3dUrl,
+        status: "complete",
+        error: null,
+      });
+
+      // Track cost if applicable
+      if (nodeData.selectedModel?.pricing) {
+        addIncurredCost(nodeData.selectedModel.pricing.amount);
+      }
+
+      // Auto-save 3D model to generations folder if configured
+      if (generationsPath) {
+        const savePromise = fetch("/api/save-generation", {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({
+            directoryPath: generationsPath,
+            model3d: result.model3dUrl,
+            prompt: promptText,
+          }),
+        })
+          .then((res) => res.json())
+          .catch((err) => {
+            console.error("Failed to save 3D model:", err);
+          });
+
+        trackSaveGeneration(`3d-${Date.now()}`, savePromise);
+      }
+    } else {
+      updateNodeData(node.id, {
+        status: "error",
+        error: result.error || "3D generation failed",
+      });
+      throw new Error(result.error || "3D generation failed");
+    }
+  } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") {
+      throw error;
+    }
+
+    let errorMessage = "3D generation failed";
+    if (error instanceof TypeError && error.message.includes("NetworkError")) {
+      errorMessage = "Network error. Check your connection and try again.";
+    } else if (error instanceof TypeError) {
+      errorMessage = `Network error: ${error.message}`;
+    } else if (error instanceof Error) {
+      errorMessage = error.message;
+    }
+
+    updateNodeData(node.id, {
+      status: "error",
+      error: errorMessage,
+    });
+    throw new Error(errorMessage);
+  }
+}