lib/ai/extend/service.ts

@@ -22,8 +22,7 @@ type ExtendConfig = {
   routeOptionId?: string;
 };
 
-const VIP98K_EXPANSION_FALLBACK_MODEL = "google/nano-banana-pro/edit";
-const VIP98K_SOURCE_DOWNLOAD_TIMEOUT_MS = 120_000;
+const SOURCE_DOWNLOAD_TIMEOUT_MS = 120_000;
 const DASHSCOPE_MIN_IMAGE_EDGE = 512;
 const DASHSCOPE_MAX_IMAGE_EDGE = 4096;
 const DASHSCOPE_MAX_IMAGE_BYTES = 10 * 1024 * 1024;
@@ -146,7 +145,7 @@ async function normalizeDashscopeExpansionInput(imageUrl: string): Promise<strin
   const response = await fetch(imageUrl, {
     cache: "no-store",
     redirect: "follow",
-    signal: AbortSignal.timeout(VIP98K_SOURCE_DOWNLOAD_TIMEOUT_MS),
+    signal: AbortSignal.timeout(SOURCE_DOWNLOAD_TIMEOUT_MS),
   });
   if (!response.ok) {
     throw new ExtendServiceError(
@@ -241,97 +240,6 @@ async function normalizeDashscopeExpansionInput(imageUrl: string): Promise<strin
   return uploaded.url;
 }
 
-function isTemporaryVip98kExpansionError(error: unknown) {
-  const message = error instanceof Error ? error.message : String(error || "");
-  return /HTTP\s+(?:429|5\d\d)|temporar(?:y|ily)|timeout|timed out|unavailable/i.test(
-    message,
-  );
-}
-
-async function createVip98kExpansionCanvas(
-  imageUrl: string,
-  xScale: number,
-  yScale: number,
-) {
-  const response = await fetch(imageUrl, {
-    cache: "no-store",
-    redirect: "follow",
-    signal: AbortSignal.timeout(VIP98K_SOURCE_DOWNLOAD_TIMEOUT_MS),
-  });
-  if (!response.ok) {
-    throw new ExtendServiceError(
-      "下载待拓展图片失败",
-      502,
-      `${response.status} ${response.statusText}`,
-    );
-  }
-
-  const sourceBuffer = Buffer.from(await response.arrayBuffer());
-  const sharp = await import("sharp");
-  const image = sharp.default(sourceBuffer, { failOn: "none" });
-  const metadata = await image.metadata();
-  const width = Number(metadata.width || 0);
-  const height = Number(metadata.height || 0);
-  if (!width || !height) {
-    throw new ExtendServiceError("无法识别待拓展图片尺寸", 422);
-  }
-
-  const targetWidth = Math.max(width, Math.round(width * xScale));
-  const targetHeight = Math.max(height, Math.round(height * yScale));
-  const left = Math.floor((targetWidth - width) / 2);
-  const top = Math.floor((targetHeight - height) / 2);
-  const canvas = await image
-    .ensureAlpha()
-    .extend({
-      left,
-      right: targetWidth - width - left,
-      top,
-      bottom: targetHeight - height - top,
-      background: { r: 0, g: 0, b: 0, alpha: 0 },
-    })
-    .png()
-    .toBuffer();
-  const arrayBuffer = canvas.buffer.slice(
-    canvas.byteOffset,
-    canvas.byteOffset + canvas.byteLength,
-  ) as ArrayBuffer;
-  const uploaded = await uploadFile(
-    `extend-vip98k-canvas-${Date.now()}-${Math.random().toString(36).slice(2, 8)}.png`,
-    arrayBuffer,
-  );
-  return {
-    imageUrl: uploaded.url,
-    width,
-    height,
-    targetWidth,
-    targetHeight,
-  };
-}
-
-async function extendImageWithVip98kEditFallback(
-  imageUrl: string,
-  xScale: number,
-  yScale: number,
-) {
-  const canvas = await createVip98kExpansionCanvas(imageUrl, xScale, yScale);
-  const result = await executeConfiguredVip98kTask({
-    modelId: VIP98K_EXPANSION_FALLBACK_MODEL,
-    kind: "image",
-    prompt: [
-      "Outpaint only the transparent regions of this image.",
-      "Keep every original pixel, subject, scale, position, perspective, lighting and style unchanged.",
-      `Complete the ${canvas.targetWidth}x${canvas.targetHeight} canvas naturally from the centered ${canvas.width}x${canvas.height} source.`,
-      "Do not crop, zoom, move, replace or redraw the original content.",
-    ].join(" "),
-    imageUrls: [canvas.imageUrl],
-  });
-  const outputUrl = result.outputUrls[0];
-  if (!outputUrl) {
-    throw new ExtendServiceError("VIP98K 生成式扩图未返回图片", 502);
-  }
-  return outputUrl;
-}
-
 async function extendImage(
   imageUrl: string,
   config: ExtendConfig,
@@ -340,27 +248,17 @@ async function extendImage(
   requestId?: string | null,
 ): Promise<string> {
   if (config.provider === "vip98k") {
-    try {
-      const result = await executeConfiguredVip98kTask({
-        modelId: "image-expansion",
-        kind: "image-tool",
-        prompt: `Expand the image canvas naturally to ${xScale}x width and ${yScale}x height. Preserve the original subject, perspective, lighting and style.`,
-        imageUrls: [imageUrl],
-        imageParams: { xScale, yScale },
-      });
-      const outputUrl = result.outputUrls[0];
-      if (!outputUrl) {
-        throw new ExtendServiceError("VIP98K 图像拓展未返回图片", 502);
-      }
-      return outputUrl;
-    } catch (error) {
-      if (!isTemporaryVip98kExpansionError(error)) throw error;
-      console.warn(
-        "[Extend Service] VIP98K expansion tool is temporarily unavailable; using VIP98K generative outpainting fallback",
-        error instanceof Error ? error.message : String(error),
-      );
-      return extendImageWithVip98kEditFallback(imageUrl, xScale, yScale);
+    const result = await executeConfiguredVip98kTask({
+      modelId: "image-expansion",
+      kind: "image-tool",
+      imageUrls: [imageUrl],
+      imageParams: { xScale, yScale },
+    });
+    const outputUrl = result.outputUrls[0];
+    if (!outputUrl) {
+      throw new ExtendServiceError("VIP98K 图像拓展未返回图片", 502);
     }
+    return outputUrl;
   }
 
   if (!config.apiKey) {
@@ -560,7 +458,7 @@ export async function executeExtendJob(
     modelId = config.provider === "vip98k" ? "image-expansion" : "extend-1.0";
   }
   const imageBase64Result = includeBase64 ? buffer.toString("base64") : undefined;
-  const uploadResult = await uploadBufferPairToS3(buffer, config.provider === "fal" || modelId === VIP98K_OUTPAINT_MODEL ? "png" : "jpg");
+  const uploadResult = await uploadBufferPairToS3(buffer, config.provider === "fal" || config.provider === "vip98k" ? "png" : "jpg");
   console.log("[Extend Service] Result uploaded:", {
     requestId,
     includeBase64,

lib/ai/providers/vip98k.ts

@@ -1666,6 +1666,7 @@ export function buildTaskBody(params: Vip98kTaskParams, invocation: Vip98kInvoca
   }
   if (params.modelId.toLowerCase() === "image-expansion") {
     bindVip98kExpansionParams(body, imageParams);
+    body.output_format = "png";
   }
   if (params.kind === "image-tool" && params.modelId.toLowerCase() === "ocr") {
     // Old synced examples include generic image fields and both language aliases.

tests/routes/extend-provider-config.test.ts

@@ -3,6 +3,24 @@ import sharp from "sharp";
 import { resolveAlibabaExtendApiKey, resolveFalExtendApiKey } from "@/lib/ai/extend/config";
 import { composeOutpaint, getOutpaintGeometry } from "@/lib/ai/extend/fal-outpaint";
 import { expandWithVip98kOutpaint, getVip98kOutpaintGeometry } from "@/lib/ai/extend/vip98k-outpaint";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+
+test("native expansion sends the original image and never switches models after an upstream failure", async () => {
+  for (const message of ["HTTP 503 unavailable", "request timed out"]) {
+    const calls: any[] = [];
+    const service = serverLoader({
+      "@/lib/db/queries": { getSystemSetting: async () => ({ value: { provider: "vip98k", modelId: "image-expansion" } }) },
+      "@/lib/db": {},
+      "@/lib/db/schema": {},
+      "@/lib/storage/service": {},
+      "@/lib/ai/vip98k-runtime": {
+        executeConfiguredVip98kTask: async (params: unknown) => { calls.push(params); throw new Error(message); },
+      },
+    })("lib/ai/extend/service.ts");
+    await expect(service.executeExtendJob({ userId: "test", imageUrl: "https://source.test/original.jpg", xScale: 1.5, yScale: 2 })).rejects.toThrow(message);
+    expect(calls).toEqual([{ modelId: "image-expansion", kind: "image-tool", imageUrls: ["https://source.test/original.jpg"], imageParams: { xScale: 1.5, yScale: 2 } }]);
+  }
+});
 
 test.describe("image extension provider configuration", () => {
   test("uses the most recently updated Alibaba image provider key", () => {

tests/routes/vip98k-reference-routing.test.ts

@@ -54,6 +54,20 @@ const textToImageInvocation: Vip98kTaskInvocation = {
     "/api/external/tools/result?tool_id=google%2Fnano-banana-2%2Ftext-to-image&taskId={task_id}",
 };
 
+test("native expansion maps final canvas scales to per-side ratios and requests PNG", () => {
+  const invocation: Vip98kTaskInvocation = {
+    kind: "task", method: "POST", path: "/extensions/v1/tasks", contentType: "application/json",
+    resultMethod: "GET", resultPath: "/extensions/v1/tasks/{task_id}/result",
+    requestExample: { model: "image-expansion", metadata: { top: 0.1, bottom: 0.1, left: 0.1, right: 0.1 }, output_format: "" },
+    inputSchema: { properties: { model: { type: "string" }, file_urls: { type: "array" }, metadata: { type: "object" }, output_format: { type: "string" } } },
+  };
+  const { body } = buildTaskBody({ apiKey: "test", modelId: "image-expansion", kind: "image-tool", prompt: "", imageUrls: ["https://source.test/original.jpg"], videoUrls: [], modelConfig: {}, imageParams: { xScale: 1.5, yScale: 2 } }, invocation);
+  expect(body).toMatchObject({ model: "image-expansion", file_urls: ["https://source.test/original.jpg"], metadata: { left: 0.25, right: 0.25, top: 0.5, bottom: 0.5 }, output_format: "png" });
+  expect(body).not.toHaveProperty("mask");
+  expect(body).not.toHaveProperty("prompt");
+  expect(body).not.toHaveProperty("x_scale");
+});
+
 test("text-to-image uses the advertised task contract with native size and ratio, without example reference images", () => {
   const configured: Vip98kTaskInvocation = { ...textToImageInvocation, path: "/v1/images/generations", requestExample: { model: "nano-banana-pro", prompt: "sample" } };
   const task: Vip98kTaskInvocation = { ...configured, kind: "task", path: "/extensions/v1/tasks",