Improve canvas image download fallback

app/api/canvas/download-image/route.ts

@@ -30,6 +30,21 @@ function resolveDownloadUrl(rawUrl: unknown, origin: string): string {
   }
 }
 
+function resolveDownloadUrls(body: Record<string, unknown>, origin: string): string[] {
+  const rawCandidates = Array.isArray(body.urls) ? body.urls : [body.url];
+  const urls: string[] = [];
+  const seen = new Set<string>();
+
+  for (const rawUrl of rawCandidates) {
+    const url = resolveDownloadUrl(rawUrl, origin);
+    if (!url || seen.has(url)) continue;
+    seen.add(url);
+    urls.push(url);
+  }
+
+  return urls.slice(0, 6);
+}
+
 export async function POST(request: NextRequest) {
   try {
     const session = await auth();
@@ -39,23 +54,34 @@ export async function POST(request: NextRequest) {
 
     const body = (await request.json().catch(() => ({}))) as Record<string, unknown>;
     const requestOrigin = getRequestOrigin(request);
-    const url = resolveDownloadUrl(body.url, requestOrigin);
-    if (!url) {
+    const urls = resolveDownloadUrls(body, requestOrigin);
+    if (urls.length === 0) {
       return NextResponse.json({ success: false, error: "图片地址无效" }, { status: 400 });
     }
 
     const name = sanitizeCanvasDownloadFileName(String(body.name || ""), "canvas-image");
-    const result = await fetchCanvasDownloadAsset({
-      file: { url, name },
-      index: 0,
-      requestOrigin,
-      cookie: request.headers.get("cookie") || "",
-      includeSequencePrefix: false,
-    });
+    const cookie = request.headers.get("cookie") || "";
+    let result: Awaited<ReturnType<typeof fetchCanvasDownloadAsset>> | null = null;
+    const failures: string[] = [];
 
-    if (!result.ok) {
+    for (const url of urls) {
+      result = await fetchCanvasDownloadAsset({
+        file: { url, name },
+        index: 0,
+        requestOrigin,
+        cookie,
+        includeSequencePrefix: false,
+      });
+      if (result.ok) break;
+      failures.push(`${url}: ${result.error}`);
+    }
+
+    if (!result?.ok) {
+      if (failures.length > 0) {
+        console.warn("[CanvasDownloadImage] All candidates failed:", failures);
+      }
       return NextResponse.json(
-        { success: false, error: result.error || "图片下载失败" },
+        { success: false, error: result?.error || "图片源文件暂时不可访问" },
         { status: 502 }
       );
     }

components/canvas/nodes/ImageNode.tsx

@@ -7383,6 +7383,21 @@ export function ImageNode({
   const handleDownload = async () => {
     if (!data.src) return;
     const originalUrl = String(resolveOriginalImageUrl(data.src) || data.src || "").trim();
+    const downloadCandidates = Array.from(
+      new Set(
+        [
+          originalUrl,
+          data.src,
+          displayImageSrc,
+          fullscreenPreviewSrc,
+          buildImageProxyUrl(originalUrl || data.src || "", {
+            delivery: "proxy",
+          }),
+        ]
+          .map((value) => String(value || "").trim())
+          .filter(Boolean)
+      )
+    );
     if (!originalUrl) {
       toast.error("下载失败，请重试");
       return;
@@ -7397,7 +7412,8 @@ export function ImageNode({
           "Content-Type": "application/json",
         },
         body: JSON.stringify({
-          url: originalUrl,
+          url: downloadCandidates[0],
+          urls: downloadCandidates,
           name: displayTitle,
         }),
       });
@@ -7434,17 +7450,11 @@ export function ImageNode({
       toast.success("下载成功");
     } catch (error) {
       console.error("下载失败:", error);
-      try {
-        triggerBrowserDownload(originalUrl, undefined, { openInNewTab: true });
-        toast.message(
-          error instanceof Error
-            ? `${error.message}，已打开原图，可稍后重试标准 PNG 下载`
-            : "标准 PNG 下载失败，已打开原图，可稍后重试"
-        );
-      } catch (openError) {
-        console.error("打开原图失败:", openError);
-        toast.error("下载失败，请重试");
-      }
+      toast.error(
+        error instanceof Error
+          ? `${error.message}，源图可能已失效，请稍后重试或重新生成图片`
+          : "图片源文件暂时不可访问，请稍后重试或重新生成图片"
+      );
     }
   };