Merge pull request '失效图片保持容器宽度和下载入口' (#34) from codex/image-preview-error-width-20261104 into main

同步生图超过边缘等待期限时，生成仍可能在源站继续执行。实际记录中，Cloudflare 在 125.006 秒断开，原请求在约 172 秒完成；应用已经显示 524，成功图片没有送达。原结果 GET 和原图片只读验证均返回 200。

同步图片生成／编辑收到 502、504、524 或提交响应丢失后，现在使用原 Key 和原 Idempotency-Key 查询既有请求。处理中继续查询，成功后 GET 同一请求的保留结果，进入原有图片归档与展示流程。查询复用已有轮询间隔和期限；缺失、失败、未确认、过期或未保留结果不会变成新的生成提交。普通成功响应保持直接返回，原生任务沿用现有协议。ProviderTaskUncertainError 也不触发自动模型切换。

验证：645 项辅助测试通过、1 项原有跳过，包含 524 后处理中到成功取回并进入展示流程、提交响应丢失、查询暂时失败、结果 GET 暂时失败、过期／缺失结果、轮询期限及一次 POST。TypeScript、改动文件 lint、日志脱敏、凭据、测试与制品检查通过。生产构建与上线验收另行记录。

已知问题：全量 lint 有 1004 项历史诊断。Cloudflare 本身的读取期限保持；本次通过取回已受理请求的原结果完成交付，不提高边缘期限。

app/(chat)/api/chat/route.ts

@@ -1,10 +1,11 @@
 import { isExplicitDestructiveIntent } from "@/lib/ai/canvas-agent-runtime/capability-access";
 import { inferVideoTaskRequirements } from "@/lib/ai/canvas-agent-runtime/video-protocol";
 import { createLogger } from "@/lib/observability/logger";
+import { trackRuntimeWork } from "@/lib/observability/active-work";
 import { geolocation } from "@vercel/functions";
 import {
   convertToModelMessages,
-  createUIMessageStream,
+  createUIMessageStream as createAiUIMessageStream,
   generateText,
   smoothStream,
   stepCountIs,
@@ -426,6 +427,8 @@ import {
 } from "./_lib/video-models";
 
 const chatApiLogger = createLogger("chat.route");
+const createUIMessageStream: typeof createAiUIMessageStream = (options) =>
+  createAiUIMessageStream({ ...options, execute: (writer) => trackRuntimeWork(() => options.execute(writer)) });
 
 const INTERNAL_IMAGE_GENERATION_FAILURE_PATTERN =
   /生成图片失败|图片生成失败|未找到图片数据|未解析到图片|模型未返回生成图片|图片数据不可用|未返回可用图片/i;
@@ -443,13 +446,13 @@ function assertGeneratedImageMarkdownHasImage(markdown: string, modelLabel: stri
   throw new Error(`${modelLabel} 未返回可用图片：${reason.slice(0, 160)}`);
 }
 
-function getPublicImageGenerationErrorText(error: unknown) {
+function getPublicImageGenerationErrorText(error: unknown, requestId: string) {
   const message = error instanceof Error ? error.message : String(error || "");
   const publicMessage = getUserFacingImageGenerationErrorMessage(error);
   if (!message || (publicMessage === message && INTERNAL_IMAGE_GENERATION_FAILURE_PATTERN.test(message))) {
-    return "图片生成失败，请稍后重试";
+    return `图片生成失败，请稍后重试。若连续失败，请联系管理员。\n\n请求编号：${requestId}`;
   }
-  return publicMessage;
+  return `${publicMessage}\n\n请求编号：${requestId}`;
 }
 
 
@@ -9630,9 +9633,10 @@ export async function POST(request: Request) {
             
             // 如果故障转移也失败，返回错误消息
             const errorMessageId = generateUUID();
+            const errorText = getPublicImageGenerationErrorText(error, errorMessageId);
             writeAssistantTextChunk(
               writer,
-              "图片生成失败，请稍后重试",
+              errorText,
               "gemini:error",
               errorMessageId,
             );
@@ -9652,7 +9656,7 @@ export async function POST(request: Request) {
                     id: errorMessageId,
                     chatId: id,
                     role: "assistant",
-                    parts: [{ type: "text", text: "图片生成失败，请稍后重试" }],
+                    parts: [{ type: "text", text: errorText }],
                     attachments: [],
                     createdAt: new Date(),
                     videoStorageStatus: null,
@@ -10332,7 +10336,7 @@ export async function POST(request: Request) {
             
             // 返回错误消息
             const errorMessageId = generateUUID();
-            const errorText = getPublicImageGenerationErrorText(error);
+            const errorText = getPublicImageGenerationErrorText(error, errorMessageId);
             writeAssistantTextChunk(
               writer,
               errorText,
@@ -10772,9 +10776,10 @@ export async function POST(request: Request) {
           } catch (error) {
             chatApiLogger.error("[Chat API] Volcano Vision generation error:", error);
             const errorMessageId = generateUUID();
+            const errorText = getPublicImageGenerationErrorText(error, errorMessageId);
             writeAssistantTextChunk(
               writer,
-              "图片生成失败，请稍后重试",
+              errorText,
               "volcano:error",
               errorMessageId,
             );
@@ -10794,7 +10799,7 @@ export async function POST(request: Request) {
                     id: errorMessageId,
                     chatId: id,
                     role: "assistant",
-                    parts: [{ type: "text", text: "图片生成失败，请稍后重试" }],
+                    parts: [{ type: "text", text: errorText }],
                     attachments: [], // 必须提供 attachments 字段
                     createdAt: new Date(),
                     videoStorageStatus: null,
@@ -11702,7 +11707,7 @@ export async function POST(request: Request) {
             chatApiLogger.error("[Chat API] OpenAI-compatible image model generation error:", error);
 
             const errorMessageId = generateUUID();
-            const errorText = getPublicImageGenerationErrorText(error);
+            const errorText = getPublicImageGenerationErrorText(error, errorMessageId);
 
             dataStream.write({
               type: "data-appendMessage",

app/(chat)/featured/page.tsx

@@ -8,6 +8,8 @@ import { ArrowLeft, Download, ChevronLeft, ChevronRight, ChevronsLeft, ChevronsR
 import { Input } from "@/components/ui/input";
 import Image from "next/image";
 import { formatBeijingTime } from "@/lib/utils";
+import { toast } from "sonner";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 type FeaturedImage = {
   id: string;
@@ -74,18 +76,11 @@ export default function FeaturedPage() {
 
   const handleDownload = async (url: string, prompt: string) => {
     try {
-      const response = await fetch(url);
+      await downloadOriginalImage({ url, name: "featured-image" });
-      const blob = await response.blob();
+      toast.success("原图已开始下载");
-      const blobUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = `featured-${Date.now()}.png`;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.URL.revokeObjectURL(blobUrl);
     } catch (error) {
       console.error("Download failed:", error);
+      toast.error(getCanvasImageDownloadErrorMessage(error));
     }
   };
 

app/(chat)/gallery/page.tsx

@@ -13,6 +13,7 @@ import { requestLongTaskResult } from "@/lib/client/long-task";
 import { buildImageProxyUrl, getImageDownloadExtension } from "@/lib/image-delivery";
 import { inferOriginalImageUrl } from "@/lib/image-url";
 import { formatBeijingTime } from "@/lib/utils";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 type GalleryImage = {
   id: string;
@@ -59,7 +60,7 @@ function buildGalleryDownloadFilename(url: string, alt: string, contentType: str
     }
   }
 
-  return `${safeBase}-${Date.now()}.${getImageDownloadExtension(contentType) || extension}`;
+  return `${safeBase}.${getImageDownloadExtension(contentType) || extension}`;
 }
 
 export default function GalleryPage() {
@@ -119,25 +120,11 @@ export default function GalleryPage() {
       const parsed = new URL(originalUrl, window.location.origin);
       const source = parsed.pathname === "/api/image-proxy" ? originalUrl : inferOriginalImageUrl(originalUrl);
 
-      const response = await fetch(
+      await downloadOriginalImage({ url: source, name: buildGalleryDownloadFilename(originalUrl, alt, "") });
-        buildImageProxyUrl(source, { delivery: "original" })
-      );
-      if (!response.ok) {
-        throw new Error(`download failed: ${response.status}`);
-      }
-      const blob = await response.blob();
-      const blobUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = buildGalleryDownloadFilename(originalUrl, alt, blob.type);
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.setTimeout(() => window.URL.revokeObjectURL(blobUrl), 1000);
       toast.success("图片已开始下载");
     } catch (error) {
       console.error("Download failed:", error);
-      toast.error(error instanceof Error && error.message.includes("无法确认原图") ? error.message : "原图下载失败，请重试");
+      toast.error(getCanvasImageDownloadErrorMessage(error));
     }
   };
 

app/api/canvas/[id]/capabilities/route.ts

@@ -8,6 +8,7 @@ import { getCanvasCapabilityManifest } from "@/lib/canvas/capabilities/registry"
 import { executeCanvasCapabilityRuntime } from "@/lib/canvas/capabilities/runtime";
 import { getCanvasCapabilityTask } from "@/lib/canvas/capabilities/task-store";
 import { CanvasAgentMutationError } from "@/lib/canvas/agent-mutations";
+import { formatRequestFailure, getRequestFailureDetails } from "@/lib/request-error";
 
 export const dynamic = "force-dynamic";
 export const maxDuration = 600;
@@ -39,7 +40,8 @@ export async function GET(
       { status: 404 }
     );
   }
-  return NextResponse.json({ success: true, task });
+  const failure = task.status === "failed" ? getRequestFailureDetails(task.error) : undefined;
+  return NextResponse.json({ success: true, task: { ...task, failure, error: failure ? formatRequestFailure(failure, task.id) : task.error } });
 }
 
 export async function POST(
@@ -51,9 +53,11 @@ export async function POST(
     return NextResponse.json({ success: false, error: "未登录" }, { status: 401 });
   }
 
+  let requestId: string | undefined;
   try {
     const { id } = await params;
     const command = canvasCapabilityClientCommandSchema.parse(await request.json());
+    requestId = command.requestId;
     const result = await executeCanvasCapabilityRuntime({
       command,
       projectId: id,
@@ -67,8 +71,9 @@ export async function POST(
       error instanceof CanvasCapabilityRuntimeError ||
       error instanceof CanvasAgentMutationError
     ) {
+      const failure = getRequestFailureDetails(error);
       return NextResponse.json(
-        { success: false, error: error.message, code: error.code },
+        { success: false, error: formatRequestFailure(failure, requestId), code: error.code, failure, requestId },
         { status: error.status }
       );
     }
@@ -82,9 +87,9 @@ export async function POST(
         { status: 400 }
       );
     }
-    const message = error instanceof Error ? error.message : "执行画布能力失败";
+    const failure = getRequestFailureDetails(error, "执行画布能力失败");
     return NextResponse.json(
-      { success: false, error: message },
+      { success: false, error: formatRequestFailure(failure, requestId), failure, requestId },
       { status: 500 }
     );
   }

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

@@ -1,6 +1,9 @@
 import { resolveCanvasCdnDownload } from "@/lib/storage/canvas-cdn-download";
 import { isRetiredStorageUrl, RETIRED_STORAGE_MESSAGE } from "@/lib/storage/retired-storage";
-import { prepareImageArchiveDownload } from "@/lib/storage/image-download-preparation";
+import { scheduleImageDownloadPreparation } from "@/lib/storage/image-download-preparation";
+import { randomUUID } from "node:crypto";
+import { formatDownloadFailure, getDownloadFailure, type DownloadFailure } from "@/lib/canvas/download-error";
+import { createLogger } from "@/lib/observability/logger";
 import { after, NextRequest, NextResponse } from "next/server";
 import { auth } from "@/app/(auth)/auth";
 import { getDownloadPreparationQueue, type DownloadPreparationInput } from "@/lib/canvas/download-preparation";
@@ -13,6 +16,22 @@ import {
 
 export const runtime = "nodejs";
 export const maxDuration = 120;
+const logger = createLogger("canvas.download");
+
+function failed(failure: DownloadFailure, requestId: string) {
+  logger.warn("request_failed", { requestId, code: failure.code, status: failure.status });
+  return NextResponse.json({ success: false, error: formatDownloadFailure(failure, requestId), failure, requestId }, {
+    status: failure.status,
+    headers: { "Cache-Control": "no-store", ...(failure.status === 429 ? { "Retry-After": "3" } : {}) },
+  });
+}
+
+function preparing(requestId: string) {
+  return NextResponse.json({ delivery: "preparing", retryAfter: 2, requestId,
+    message: "正在准备原图，完成后将自动开始下载" }, {
+    status: 202, headers: { "Retry-After": "2", "Cache-Control": "no-store" },
+  });
+}
 
 async function prepareDownload(input: DownloadPreparationInput, signal: AbortSignal) {
   // A proxy candidate for the same original must not repeat the same slow
@@ -21,22 +40,25 @@ async function prepareDownload(input: DownloadPreparationInput, signal: AbortSig
     const source = extractImageProxySourceUrl(url) || url;
     return inferOriginalImageUrl(source) || source;
   }))];
-  for (let attempt = 0; attempt < 3; attempt++) {
+  let lastError: unknown;
+  for (let attempt = 0; attempt < 2; attempt++) {
     signal.throwIfAborted();
     for (const url of sources) {
       signal.throwIfAborted();
       const result = await fetchCanvasDownloadAsset({
         file: { url, name: "original" }, index: 0,
         requestOrigin: input.requestOrigin, cookie: input.cookie,
-        includeSequencePrefix: false, timeoutMs: 12_000, retryCount: 1, signal,
+        includeSequencePrefix: false, timeoutMs: 60_000, retryCount: 1, signal,
       });
       if (result.ok) return { buffer: result.bytes, contentType: result.contentType };
+      lastError = result.error;
     }
     // Each pass resolves the latest archive URL inside fetchCanvasDownloadAsset.
     // No AI/model request is involved and a completed source fetch is shared.
-    if (attempt < 2) await new Promise(resolve => setTimeout(resolve, 1_000));
+    if (attempt < 1 && getDownloadFailure(lastError).retryable) await new Promise(resolve => setTimeout(resolve, 1_000));
+    else break;
   }
-  throw new Error("Original image sources unavailable");
+  throw new Error(String(lastError || "Original image sources unavailable"));
 }
 
 function getRequestOrigin(request: NextRequest): string {
@@ -76,31 +98,43 @@ function resolveDownloadUrls(body: Record<string, unknown>, origin: string): str
 }
 
 export async function POST(request: NextRequest) {
+  const requestId = randomUUID();
   try {
     const session = await auth();
     if (!session?.user?.id) {
-      return NextResponse.json({ success: false, error: "未登录" }, { status: 401 });
+      return failed(getDownloadFailure("未登录"), requestId);
     }
 
     const body = (await request.json().catch(() => ({}))) as Record<string, unknown>;
     const requestOrigin = getRequestOrigin(request);
     const candidates = resolveDownloadUrls(body, requestOrigin);
     if (candidates.length && candidates.every(isRetiredStorageUrl)) {
-      return NextResponse.json({ success: false, error: RETIRED_STORAGE_MESSAGE, code: "storage_retired" }, { status: 410 });
+      return failed(getDownloadFailure(RETIRED_STORAGE_MESSAGE), requestId);
     }
     const urls = candidates.filter(url => !isRetiredStorageUrl(url));
     const requestedUrls = [...urls];
     if (urls.length === 0) {
-      return NextResponse.json({ success: false, error: "图片地址无效" }, { status: 400 });
+      return failed(getDownloadFailure("图片地址无效"), requestId);
     }
 
     const name = sanitizeCanvasDownloadFileName(String(body.name || ""), "canvas-image");
     if (body.preferDirect === true) {
-      const { task, direct } = await resolveCanvasCdnDownload(urls, `${name}.png`).catch(() => ({ task: null, direct: null }));
+      const { task, direct, canPrepareDirect } = await resolveCanvasCdnDownload(urls, `${name}.png`).catch((error) => {
+        logger.warn("cdn_lookup_failed", error, { requestId });
+        return { task: null, direct: null, canPrepareDirect: false };
+      });
       if (direct) return NextResponse.json(direct, { headers: { "Cache-Control": "no-store" } });
+      if (task && canPrepareDirect && body.preparation === "async") {
+        const asset = (task.metadata as { downloadAsset?: { status?: string; failure?: DownloadFailure; retryAt?: string } } | null)?.downloadAsset;
+        if (asset?.status === "abandoned" || (asset?.status === "failed" && Date.parse(asset.retryAt || "") > Date.now())) {
+          return failed(asset.failure || getDownloadFailure(null), task.id);
+        }
+        scheduleImageDownloadPreparation(task.id);
+        return preparing(task.id);
+      }
       if (task?.targetUrl) {
         if (!urls.includes(task.targetUrl)) urls.unshift(task.targetUrl);
-        after(() => prepareImageArchiveDownload(task.id));
+        scheduleImageDownloadPreparation(task.id);
       }
     }
     const cookie = request.headers.get("cookie") || "";
@@ -109,13 +143,10 @@ export async function POST(request: NextRequest) {
         userId: session.user.id, urls: requestedUrls, requestOrigin, cookie,
       });
       if (result.status === "preparing") {
-        return NextResponse.json({ delivery: "preparing", retryAfter: 3,
+        return preparing(result.requestId);
-          message: "正在准备原图，完成后将自动下载" }, {
-          status: 202, headers: { "Retry-After": "3", "Cache-Control": "no-store" },
-        });
       }
       if (result.status === "failed") {
-        return NextResponse.json({ success: false, error: result.error }, { status: 502 });
+        return failed(result.failure, result.requestId);
       }
       return new NextResponse(new Uint8Array(result.asset.buffer), { headers: {
         "Content-Type": result.asset.contentType,
@@ -136,17 +167,14 @@ export async function POST(request: NextRequest) {
         includeSequencePrefix: false,
       });
       if (result.ok) break;
-      failures.push(`${url}: ${result.error}`);
+      failures.push(result.error);
     }
 
     if (!result?.ok) {
       if (failures.length > 0) {
-        console.warn("[CanvasDownloadImage] All candidates failed:", failures);
+        logger.warn("all_sources_failed", { requestId, failures });
       }
-      return NextResponse.json(
+      return failed(getDownloadFailure(result?.error), requestId);
-        { success: false, error: result?.error || "图片源文件暂时不可访问" },
-        { status: 502 }
-      );
     }
 
     return new NextResponse(result.bytes, {
@@ -159,7 +187,7 @@ export async function POST(request: NextRequest) {
       },
     });
   } catch (error) {
-    console.error("[CanvasDownloadImage] Failed:", error);
+    logger.error("download_failed", error, { requestId });
-    return NextResponse.json({ success: false, error: "图片下载失败" }, { status: 500 });
+    return failed(getDownloadFailure(error), requestId);
   }
 }

app/api/canvas/generate/image/route.ts

@@ -2,6 +2,7 @@ import { executeCanvasImageResponse } from "@/lib/canvas/generate-image-response
 import { NextResponse } from "next/server";
 import { auth } from "@/app/(auth)/auth";
 import { getCanvasImageTaskForUser } from "@/lib/canvas/image-task-queue";
+import { formatRequestFailure, getRequestFailureDetails } from "@/lib/request-error";
 
 export const maxDuration = 1200;
 
@@ -23,13 +24,15 @@ export async function GET(request: Request) {
       return NextResponse.json({ success: false, error: "任务不存在" }, { status: 404 });
     }
 
+    const failure = task.status === "failed" ? getRequestFailureDetails(task.error) : undefined;
     return NextResponse.json({
       success: true,
       task: {
         id: task.id,
         status: task.status,
         attempts: task.attempts,
-        error: task.error || null,
+        error: failure ? formatRequestFailure(failure, task.id) : null,
+        failure,
         result: task.result || null,
         createdAt: task.createdAt,
         startedAt: task.startedAt,

app/api/image-proxy/route.ts

@@ -1,8 +1,11 @@
 import crypto from "node:crypto";
 import { isRetiredStorageUrl, RETIRED_STORAGE_MESSAGE } from "@/lib/storage/retired-storage";
 import { NextRequest, NextResponse } from "next/server";
+import { formatDownloadFailure, getDownloadFailure } from "@/lib/canvas/download-error";
+import { createLogger } from "@/lib/observability/logger";
 
 export const runtime = "nodejs";
+const logger = createLogger("image.download");
 
 const DEFAULT_QUALITY = 82;
 const MAX_WIDTH = 4096;
@@ -267,8 +270,17 @@ function redirectToDirectImage(target: URL): NextResponse {
 
 export async function GET(request: NextRequest) {
   const { searchParams } = request.nextUrl;
+  const requestId = crypto.randomUUID();
+  const downloadFailure = (error: unknown) => {
+    const failure = getDownloadFailure(error);
+    logger.warn("original_download_failed", error, { requestId, code: failure.code, status: failure.status });
+    return NextResponse.json({ error: formatDownloadFailure(failure, requestId), failure, requestId }, {
+      status: failure.status, headers: { "Cache-Control": "no-store" },
+    });
+  };
   const rawUrl = (searchParams.get("url") || "").trim();
   if (isRetiredStorageUrl(rawUrl)) {
+    if (searchParams.get("original") === "1") return downloadFailure(RETIRED_STORAGE_MESSAGE);
     return NextResponse.json({ error: RETIRED_STORAGE_MESSAGE, code: "storage_retired" }, { status: 410 });
   }
   if (!rawUrl) {
@@ -306,6 +318,18 @@ export async function GET(request: NextRequest) {
     );
   }
 
+  if (original && searchParams.get("download") === "resolve") {
+    try {
+      const { buildImageProxyUrl } = await import("@/lib/image-delivery");
+      buildImageProxyUrl(target.toString(), { delivery: "original" });
+      const { resolveOriginalCdnDownload } = await import("@/lib/storage/original-image-download");
+      const direct = await resolveOriginalCdnDownload(target.toString(), searchParams.get("name") || "", request.signal);
+      return NextResponse.json(direct || { delivery: "proxy" }, { headers: { "Cache-Control": "no-store" } });
+    } catch (error) {
+      return downloadFailure(error);
+    }
+  }
+
   if (!forceProxy && !original) {
     const directImageTarget = resolveDirectImageTarget(
       request,
@@ -346,10 +370,11 @@ export async function GET(request: NextRequest) {
 
   const fetchSignal = AbortSignal.any([
     request.signal,
-    AbortSignal.timeout(width && width <= 256 ? SMALL_PREVIEW_FETCH_TIMEOUT_MS : FETCH_TIMEOUT_MS),
+    AbortSignal.timeout(original ? 60_000 : width && width <= 256 ? SMALL_PREVIEW_FETCH_TIMEOUT_MS : FETCH_TIMEOUT_MS),
   ]);
   const upstreamFailure = (error: unknown) => {
     if (request.signal.aborted) return new NextResponse(null, { status: 499 });
+    if (original) return downloadFailure(error);
     const timedOut = (error instanceof Error && error.name === "TimeoutError") || fetchSignal.reason?.name === "TimeoutError";
     return NextResponse.json(
       { error: timedOut ? "读取源图片超时，请重试" : "源图片传输中断，请重试" },
@@ -369,6 +394,7 @@ export async function GET(request: NextRequest) {
   }
 
   if (!upstreamResponse.ok) {
+    if (original) return downloadFailure(`HTTP ${upstreamResponse.status}`);
     return NextResponse.json(
       { error: `Upstream responded with ${upstreamResponse.status}` },
       { status: 502 }
@@ -377,6 +403,7 @@ export async function GET(request: NextRequest) {
 
   const contentType = upstreamResponse.headers.get("content-type") || "application/octet-stream";
   if (!contentType.toLowerCase().startsWith("image/")) {
+    if (original) return downloadFailure("Source is not an image");
     return NextResponse.json({ error: "Upstream is not an image" }, { status: 400 });
   }
 

components/agents/AgentGenerationWorkspace.tsx

@@ -1,4 +1,5 @@
 "use client";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 import { useChat } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
@@ -575,31 +576,11 @@ export function AgentGenerationWorkspace({
       toast.error("图片地址无效");
       return;
     }
-
-    const filename = buildDownloadFilename(raw);
     try {
-      const response = await fetch(raw);
+      await downloadOriginalImage({ url: raw, name: buildDownloadFilename(raw) });
-      if (!response.ok) {
+      toast.success("原图已开始下载");
-        throw new Error(`download failed: ${response.status}`);
+    } catch (error) {
-      }
+      toast.error(getCanvasImageDownloadErrorMessage(error));
-      const blob = await response.blob();
-      const blobUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = filename;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.URL.revokeObjectURL(blobUrl);
-    } catch {
-      const link = document.createElement("a");
-      link.href = raw;
-      link.target = "_blank";
-      link.rel = "noopener noreferrer";
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      toast.message("已打开原图，可右键另存为");
     }
   }, []);
 

components/agents/AgentGenerationWorkspaceDarkV2.tsx

@@ -1,4 +1,5 @@
 "use client";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 import { useChat } from "@ai-sdk/react";
 import { appendGenerationMessage, mergeGenerationHistory, parseAppendedGenerationMessage, recoverReplacementRun } from "@/lib/agents/replacement-run-recovery";
@@ -6793,31 +6794,11 @@ export function AgentGenerationWorkspaceDarkV2({
       toast.error("图片地址无效");
       return;
     }
-
-    const filename = buildDownloadFilename(raw);
     try {
-      const response = await fetch(raw);
+      await downloadOriginalImage({ url: raw, name: buildDownloadFilename(raw) });
-      if (!response.ok) {
+      toast.success("原图已开始下载");
-        throw new Error(`download failed: ${response.status}`);
+    } catch (error) {
-      }
+      toast.error(getCanvasImageDownloadErrorMessage(error));
-      const blob = await response.blob();
-      const blobUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = filename;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.URL.revokeObjectURL(blobUrl);
-    } catch {
-      const link = document.createElement("a");
-      link.href = raw;
-      link.target = "_blank";
-      link.rel = "noopener noreferrer";
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      toast.message("已打开原图，可右键另存为");
     }
   }, []);
   const uploadBase64ResultToStorage = useCallback(async (base64Url: string) => {

components/agents/AgentGenerationWorkspaceNew.tsx

@@ -1,4 +1,5 @@
 "use client";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 import { useChat } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
@@ -725,30 +726,11 @@ export function AgentGenerationWorkspaceNew({
       toast.error("图片地址无效");
       return;
     }
-    const filename = buildDownloadFilename(raw);
     try {
-      const response = await fetch(raw);
+      await downloadOriginalImage({ url: raw, name: buildDownloadFilename(raw) });
-      if (!response.ok) {
+      toast.success("原图已开始下载");
-        throw new Error(`download failed: ${response.status}`);
+    } catch (error) {
-      }
+      toast.error(getCanvasImageDownloadErrorMessage(error));
-      const blob = await response.blob();
-      const blobUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = filename;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.URL.revokeObjectURL(blobUrl);
-    } catch {
-      const link = document.createElement("a");
-      link.href = raw;
-      link.target = "_blank";
-      link.rel = "noopener noreferrer";
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      toast.message("已打开原图，可右键另存为");
     }
   }, []);
 

components/image-preview.tsx

@@ -5,7 +5,8 @@ import dynamic from "next/dynamic";
 import React, { useState, useEffect } from "react";
 import { X, Download, Edit, Target, Paintbrush, Sparkles, Scissors, Expand, Maximize2, Move3D, Droplet } from "lucide-react";
 import { toast } from "sonner";
-import { buildImageProxyUrl, getImageDownloadExtension } from "@/lib/image-delivery";
+import { buildImageProxyUrl } from "@/lib/image-delivery";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 const ImageAnnotator = dynamic(
   () => import("./image-annotator").then((module) => module.ImageAnnotator),
@@ -23,25 +24,6 @@ const AngleEditDialog = dynamic(
   }
 );
 
-function triggerBrowserDownload(
-  url: string,
-  filename?: string,
-  options?: { openInNewTab?: boolean }
-) {
-  const link = document.createElement("a");
-  link.href = url;
-  if (filename) {
-    link.download = filename;
-  }
-  if (options?.openInNewTab) {
-    link.target = "_blank";
-  }
-  link.rel = "noopener noreferrer";
-  document.body.appendChild(link);
-  link.click();
-  document.body.removeChild(link);
-}
-
 export function ImagePreview({ 
   src, 
   alt,
@@ -238,24 +220,12 @@ export function ImagePreview({
       toast.error("下载失败，请重试");
       return;
     }
-    const filenameBase = `generated-image-${Date.now()}`;
     try {
-      const response = await fetch(
+      await downloadOriginalImage({ url: safeOriginalUrl });
-        buildImageProxyUrl(safeOriginalUrl, { delivery: "original" })
+      toast.success("原图已开始下载");
-      );
-      if (!response.ok) {
-        throw new Error(`下载失败（${response.status}）`);
-      }
-      const blob = await response.blob();
-      const extension = getImageDownloadExtension(blob.type);
-      const filename = extension ? `${filenameBase}.${extension}` : filenameBase;
-      const url = window.URL.createObjectURL(blob);
-      triggerBrowserDownload(url, filename);
-      window.URL.revokeObjectURL(url);
-      toast.success("下载成功");
     } catch (error) {
       console.error("下载失败:", error);
-      toast.error(error instanceof Error && error.message.includes("无法确认原图") ? error.message : "原图下载失败，请重试");
+      toast.error(getCanvasImageDownloadErrorMessage(error));
     }
   };
 
@@ -337,9 +307,18 @@ export function ImagePreview({
           }}
           loading="lazy"
           decoding="async"
+          onLoad={(event) => {
+            event.currentTarget.style.aspectRatio = "";
+            event.currentTarget.parentElement?.style.removeProperty("width");
+            event.currentTarget.alt = "Generated Image";
+          }}
           onError={(event) => {
             if (event.currentTarget.src !== (thumbnail || original)) {
               event.currentTarget.src = thumbnail || original;
+            } else if (!compactGrid) {
+              event.currentTarget.style.aspectRatio = "1";
+              event.currentTarget.parentElement?.style.setProperty("width", "100%");
+              event.currentTarget.alt = "预览暂不可用，可尝试下载原图";
             }
           }}
           onClick={() => setIsOpen(true)}

components/preview-attachment.tsx

@@ -9,6 +9,7 @@ import { Button } from "./ui/button";
 import { X, Download, Target, Paintbrush } from "lucide-react";
 import { toast } from "sonner";
 import { ImageAnnotator } from "./image-annotator";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 export const PreviewAttachment = ({
   attachment,
@@ -73,18 +74,11 @@ export const PreviewAttachment = ({
   // 下载图片函数
   const handleDownload = async () => {
     try {
-      const response = await fetch(url);
+      await downloadOriginalImage({ url, name: name ?? "image" });
-      const blob = await response.blob();
+      toast.success("原图已开始下载");
-      const downloadUrl = window.URL.createObjectURL(blob);
-      const link = document.createElement("a");
-      link.href = downloadUrl;
-      link.download = name ?? `image-${Date.now()}.jpg`;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      window.URL.revokeObjectURL(downloadUrl);
     } catch (error) {
       console.error("下载失败:", error);
+      toast.error(getCanvasImageDownloadErrorMessage(error));
     }
   };
 

components/scene-fusion-view.tsx

@@ -1,4 +1,5 @@
 "use client";
+import { downloadOriginalImage, getCanvasImageDownloadErrorMessage } from "@/lib/client/canvas-image-download";
 
 import {
   ArrowLeft,
@@ -2073,18 +2074,9 @@ export function SceneFusionView({
 
   const downloadImage = async (url: string, filename: string) => {
     try {
-      const response = await fetch(url);
+      await downloadOriginalImage({ url, name: filename });
-      const blob = await response.blob();
+    } catch (error) {
-      const blobUrl = URL.createObjectURL(blob);
+      toast.error(getCanvasImageDownloadErrorMessage(error));
-      const link = document.createElement("a");
-      link.href = blobUrl;
-      link.download = filename;
-      document.body.appendChild(link);
-      link.click();
-      document.body.removeChild(link);
-      setTimeout(() => URL.revokeObjectURL(blobUrl), 100);
-    } catch {
-      window.open(url, "_blank");
     }
   };
 

lib/ai/providers/alibaba-image.ts

@@ -5,7 +5,7 @@
  * - qwen-image-edit-plus 系列：支持 1-6 张输出，自定义分辨率，提示词优化
  * - qwen-image-edit：仅支持 1 张输出
  * 
- * API 文档：https://help.aliyun.com/zh/model-studio/developer-reference/qwen-vl-plus
+ * API 文档：https://help.aliyun.com/en/model-studio/qwen-image-generation-and-editing-api-reference
  */
 
 import sharp from "sharp";
@@ -46,6 +46,8 @@ interface AlibabaImageResponse {
   output?: {
     task_id?: string;
     task_status?: string;
+    code?: string;
+    message?: string;
     choices?: Array<{
       finish_reason: string;
       message: {
@@ -122,6 +124,11 @@ async function fetchImageBufferWithRetry(
   timeoutMs = ALIBABA_IMAGE_FETCH_TIMEOUT_MS,
   attempts = 2
 ): Promise<{ buffer: Buffer; contentType: string | null }> {
+  if (imageUrl.startsWith("data:image/")) {
+    const match = imageUrl.match(/^data:(image\/[a-z0-9.+-]+);base64,(.+)$/i);
+    if (!match) throw new Error("输入图片数据格式无效");
+    return { buffer: Buffer.from(match[2], "base64"), contentType: match[1] };
+  }
   let lastError: unknown = null;
   for (let attempt = 1; attempt <= attempts; attempt += 1) {
     const ctx = createAbortSignal(timeoutMs);
@@ -168,7 +175,7 @@ function calculateAlibabaSizeByAspect(aspectValue: number, baseSize: number): st
 }
 
 async function inferAspectRatioFromImageUrl(imageUrl: string): Promise<number | null> {
-  if (!/^https?:\/\//i.test(imageUrl)) return null;
+  if (!/^(?:https?:\/\/|data:image\/)/i.test(imageUrl)) return null;
 
   try {
     const { buffer } = await fetchImageBufferWithRetry(imageUrl);
@@ -186,7 +193,7 @@ async function inferAspectRatioFromImageUrl(imageUrl: string): Promise<number |
 async function inferImageDimensionsFromImageUrl(
   imageUrl: string,
 ): Promise<{ width: number; height: number; aspectRatio: number } | null> {
-  if (!/^https?:\/\//i.test(imageUrl)) return null;
+  if (!/^(?:https?:\/\/|data:image\/)/i.test(imageUrl)) return null;
 
   try {
     const { buffer } = await fetchImageBufferWithRetry(imageUrl);
@@ -302,6 +309,14 @@ async function prepareAlibabaInputImageUrl(
     maxSide: ALIBABA_MAX_INPUT_SIDE,
     modelId,
   });
+  if (isAlibabaQwenImage3ModelId(modelId)) {
+    if (prepared.buffer.length > maxInputBytes) {
+      throw new Error("输入图片超过模型大小限制，请先压缩图片后重试");
+    }
+    const format = prepared.transformed ? prepared.extension : metadata.format;
+    const mime = format === "jpg" || format === "jpeg" ? "image/jpeg" : `image/${format}`;
+    return `data:${mime};base64,${prepared.buffer.toString("base64")}`;
+  }
   if (!prepared.transformed) {
     return normalizedUrl;
   }
@@ -565,8 +580,10 @@ async function sendAlibabaImageAsyncRequest(params: {
         return task;
       }
       if (["FAILED", "CANCELED", "UNKNOWN"].includes(taskStatus)) {
+        const reason = task.output?.message || task.message || `阿里图片任务${taskStatus || "失败"}`;
+        const code = task.output?.code || task.code;
         throw new AlibabaImageTerminalTaskError(
-          task.message || `阿里图片任务${taskStatus || "失败"}（task_id: ${taskId}）`,
+          `${reason}${code ? `（${code}）` : ""}（task_id: ${taskId}）`,
         );
       }
       lastPollError = null;

lib/ai/providers/vip98k.ts

@@ -1024,6 +1024,77 @@ function getConfiguredPollSeconds(config: Vip98kModelRuntimeConfig, key: string,
   return Math.min(Math.max(value, 1), 3600);
 }
 
+function isSynchronousImagePath(path: string) {
+  return /^\/v1\/images\/(?:generations|edits)\/?$/.test(path);
+}
+
+async function recoverImageSubmission(params: {
+  apiKey: string;
+  baseURL: string;
+  modelId: string;
+  path: string;
+  idempotencyKey: string;
+  pollIntervalMs: number;
+  maxPollMs: number;
+}) {
+  if (!isSynchronousImagePath(params.path)) return null;
+  const startedAt = Date.now();
+  const deadline = startedAt + params.maxPollMs;
+  logger.info("recovering original image request", { modelId: params.modelId });
+
+  while (Date.now() < deadline) {
+    try {
+      const lookup = await fetch(`${params.baseURL}/api/external/requests/by-idempotency-key`, {
+        cache: "no-store",
+        headers: {
+          Authorization: `Bearer ${params.apiKey}`,
+          "Idempotency-Key": params.idempotencyKey,
+        },
+        signal: AbortSignal.timeout(Math.min(60_000, deadline - Date.now())),
+      });
+      if ([401, 403, 404, 410].includes(lookup.status)) return null;
+      if (lookup.ok) {
+        const state = toRecord(await parseJsonResponse(lookup));
+        if (!state || !["processing", "succeeded"].includes(String(state.status))) return null;
+        if (state.status === "succeeded") {
+          if (state.result_available !== true || !state.request_id) return null;
+          const result = await fetch(
+            `${params.baseURL}/api/external/requests/${encodeURIComponent(String(state.request_id))}/result`,
+            {
+              cache: "no-store",
+              headers: { Authorization: `Bearer ${params.apiKey}` },
+              signal: AbortSignal.timeout(Math.max(1, Math.min(60_000, deadline - Date.now()))),
+            },
+          );
+          if ([401, 403, 404, 410].includes(result.status)) return null;
+          if (result.ok) {
+            const payload = await parseJsonResponse(result);
+            const outputs = collectOutputUrls(payload);
+            if (!outputs.length) {
+              throw new ProviderTaskUncertainError("原生图请求已完成，但未取回图片结果，请勿重复生成");
+            }
+            logger.info("original image request recovered", {
+              modelId: params.modelId,
+              providerRequestId: state.request_id,
+              outputCount: outputs.length,
+              durationMs: Date.now() - startedAt,
+            });
+            return { payload, taskId: extractTaskId(payload), resultPath: extractResultPath(payload), outputs };
+          }
+        }
+      }
+    } catch (error) {
+      if (error instanceof ProviderTaskUncertainError) throw error;
+    }
+    await delay(Math.max(0, Math.min(params.pollIntervalMs, deadline - Date.now())));
+  }
+  logger.warn("original image request recovery timed out", {
+    modelId: params.modelId,
+    durationMs: Date.now() - startedAt,
+  });
+  return null;
+}
+
 async function submitTask(params: {
   apiKey: string;
   baseURL?: string | null;
@@ -1036,6 +1107,8 @@ async function submitTask(params: {
   submissionTimeoutMs: number;
   maxSubmissionAttempts: number;
   submissionRetryBaseDelayMs: number;
+  pollIntervalMs: number;
+  maxPollMs: number;
 }) {
   const baseURL = normalizeVip98kBaseUrl(params.baseURL);
   const path = String(params.path || "/api/external/task/generate").trim();
@@ -1099,7 +1172,9 @@ async function submitTask(params: {
         signal: AbortSignal.timeout(params.submissionTimeoutMs),
       });
     } catch (error) {
-      if (attempt >= maxAttempts) {
+      const recovered = await recoverImageSubmission({ ...params, baseURL, path, idempotencyKey });
+      if (recovered) return recovered;
+      if (isSynchronousImagePath(path) || attempt >= maxAttempts) {
         logger.error("provider submission transport failed", {
           modelId: params.modelId,
           path,
@@ -1145,6 +1220,14 @@ async function submitTask(params: {
       };
     }
 
+    if ([502, 504, 524].includes(response.status)) {
+      const recovered = await recoverImageSubmission({ ...params, baseURL, path, idempotencyKey });
+      if (recovered) return recovered;
+      if (isSynchronousImagePath(path)) {
+        throw new ProviderTaskUncertainError(`供应商提交结果未确认，可能仍在处理，请勿重复生成：${getUserFacingImageGenerationErrorMessage({ message: extractErrorMessage(payload), status: response.status })} (HTTP ${response.status})`);
+      }
+    }
+
     const errorMessage = extractErrorMessage(payload);
     const stagedMediaRetryDelayMs = getVip98kStagedMediaRetryDelay({
       status: response.status,
@@ -1311,6 +1394,12 @@ export async function submitVip98kExternalTask(params: {
     ),
     maxSubmissionAttempts: params.durable ? 1 : runtimeConfig.maxSubmissionAttempts,
     submissionRetryBaseDelayMs: runtimeConfig.submissionRetryBaseDelayMs,
+    pollIntervalMs: getConfiguredPollSeconds(
+      taskParams.modelConfig, "pollIntervalSeconds", DEFAULT_POLL_INTERVAL_SECONDS,
+    ) * 1000,
+    maxPollMs: getConfiguredPollSeconds(
+      taskParams.modelConfig, "maxPollSeconds", DEFAULT_MAX_POLL_SECONDS,
+    ) * 1000,
   });
   const resultPath = submitted.resultPath || invocation?.resultPath || "";
   return {

lib/ai/runtime/model-health.ts

@@ -1,4 +1,5 @@
 import "server-only";
+import { ProviderTaskUncertainError } from "@/lib/video-canvas/video-task-lifecycle";
 import { isProviderAuthenticationFailure, isCredentialFailureBan } from "./authentication-failover";
 
 import { and, desc, eq, inArray, sql } from "drizzle-orm";
@@ -343,7 +344,7 @@ export function classifyAiModelHealthFailure(error: unknown): {
 }
 
 export function shouldFailoverAiModelError(error: unknown) {
-  if (isGatewayResponseTimeout(error)) return false;
+  if (error instanceof ProviderTaskUncertainError || isGatewayResponseTimeout(error)) return false;
   const classification = classifyAiModelHealthFailure(error);
   const normalized = getErrorMessage(error).toLowerCase();
   const imageProviderTaskFailed =

lib/canvas/capabilities/runtime.ts

@@ -14,13 +14,16 @@ import { getCanvasCapability } from "@/lib/canvas/capabilities/registry";
 import { enqueueCanvasCapabilityExecution } from "@/lib/canvas/capabilities/task-queue";
 import {
   createOrRecoverCanvasCapabilityTask,
-  MAX_CANVAS_CAPABILITY_TASK_ATTEMPTS,
+  getCanvasCapabilityTask,
+  heartbeatCanvasCapabilityTask,
   markCanvasCapabilityTaskFailed,
   markCanvasCapabilityTaskRunning,
   markCanvasCapabilityTaskSucceeded,
 } from "@/lib/canvas/capabilities/task-store";
 import { applyCanvasOperationPlan } from "@/lib/canvas/agent-mutations";
 import type { CanvasOperationPlan } from "@/types/canvas/agent-protocol";
+import { formatRequestFailure, getRequestFailureDetails } from "@/lib/request-error";
+import { trackRuntimeWork } from "@/lib/observability/active-work";
 
 export type CanvasCapabilityRuntimeResult = {
   clientCommand?: CanvasCapabilityClientCommand;
@@ -58,9 +61,11 @@ function serializeTask(task: {
   status: string;
   version: number;
 }) {
+  const failure = task.status === "failed" ? getRequestFailureDetails(task.error) : undefined;
   return {
     attempts: task.attempts,
-    error: task.error,
+    error: failure ? formatRequestFailure(failure, task.id) : task.error,
+    failure,
     id: task.id,
     requestId: task.requestId,
     result: task.result,
@@ -69,6 +74,13 @@ function serializeTask(task: {
   };
 }
 
+function storedTaskResult(task: Parameters<typeof serializeTask>[0], mode: "headless" | "interactive"): CanvasCapabilityRuntimeResult {
+  const result = task.status === "succeeded" && task.result && typeof task.result === "object"
+    ? task.result as Omit<CanvasCapabilityRuntimeResult, "task">
+    : { mode };
+  return { ...result, task: serializeTask(task) };
+}
+
 function buildMediaOperationPlan(params: {
   command: CanvasCapabilityClientCommand;
   mediaResults: CanvasCapabilityMediaResult[];
@@ -211,11 +223,7 @@ export async function executeCanvasCapabilityRuntime(params: {
   });
 
   if (task.status === "succeeded") {
-    const storedResult =
+    return storedTaskResult(task, "headless");
-      task.result && typeof task.result === "object"
-        ? (task.result as Omit<CanvasCapabilityRuntimeResult, "task">)
-        : ({ mode: "headless" } as const);
-    return { ...storedResult, task: serializeTask(task) };
   }
   if (task.status === "running") {
     return {
@@ -225,15 +233,8 @@ export async function executeCanvasCapabilityRuntime(params: {
       task: serializeTask(task),
     };
   }
-  if (
+  if (task.status === "failed") {
-    task.status === "failed" &&
+    return { mode: "headless", task: serializeTask(task) };
-    task.attempts >= MAX_CANVAS_CAPABILITY_TASK_ATTEMPTS
-  ) {
-    throw new CanvasCapabilityRuntimeError(
-      task.error || "画布能力任务超过最大重试次数",
-      409,
-      "CANVAS_CAPABILITY_RETRY_EXHAUSTED"
-    );
   }
 
   const shouldRunHeadlessly = shouldExecuteCanvasCapabilityHeadlessly({
@@ -241,7 +242,9 @@ export async function executeCanvasCapabilityRuntime(params: {
     command,
   });
   if (!shouldRunHeadlessly) {
-    task = await markCanvasCapabilityTaskRunning(task.id);
+    const claimed = await markCanvasCapabilityTaskRunning(task.id);
+    if (!claimed) return storedTaskResult((await getCanvasCapabilityTask({ requestId: command.requestId, userId: params.userId, projectId: params.projectId })) || task, "interactive");
+    task = claimed;
     const result = {
       mode: "interactive" as const,
       clientCommand: command,
@@ -250,10 +253,18 @@ export async function executeCanvasCapabilityRuntime(params: {
     return { ...result, task: serializeTask(task) };
   }
 
-  return enqueueCanvasCapabilityExecution({
+  const heartbeat = setInterval(() => {
+    void heartbeatCanvasCapabilityTask(task.id).catch((error) => {
+      console.warn("[Canvas Capability] Task heartbeat failed:", error);
+    });
+  }, 30_000);
+  try {
+    return await trackRuntimeWork(() => enqueueCanvasCapabilityExecution({
     projectId: params.projectId,
     execute: async () => {
-      task = await markCanvasCapabilityTaskRunning(task.id);
+      const claimed = await markCanvasCapabilityTaskRunning(task.id);
+      if (!claimed) return storedTaskResult((await getCanvasCapabilityTask({ requestId: command.requestId, userId: params.userId, projectId: params.projectId })) || task, "headless");
+      task = claimed;
       try {
         const projectRevision = context.project.updatedAt.toISOString();
         const mutationPlan = buildMutationOperationPlan({
@@ -299,5 +310,8 @@ export async function executeCanvasCapabilityRuntime(params: {
         throw error;
       }
     },
-  });
+    }));
+  } finally {
+    clearInterval(heartbeat);
+  }
 }

lib/canvas/capabilities/task-store.ts

@@ -1,11 +1,11 @@
-import { and, eq, lt, sql } from "drizzle-orm";
+import { and, eq, inArray, lt, sql } from "drizzle-orm";
 
 import type { CanvasCapabilityClientCommand } from "@/lib/canvas/capabilities/client-command";
 import { db } from "@/lib/db";
 import { canvasCapabilityTask } from "@/lib/db/schema";
 
 const STALE_RUNNING_TASK_MS = 15 * 60 * 1000;
-export const MAX_CANVAS_CAPABILITY_TASK_ATTEMPTS = 3;
+const INTERRUPTED_TASK_MESSAGE = "任务执行中断，结果尚未确认。请先查看画布和历史记录，或联系管理员核对原任务，避免重复处理。";
 
 export type CanvasCapabilityTaskResult = Record<string, unknown>;
 
@@ -25,7 +25,25 @@ export async function getCanvasCapabilityTask(params: {
       )
     )
     .limit(1);
-  return task || null;
+  if (!task) return null;
+  const staleBefore = new Date(Date.now() - STALE_RUNNING_TASK_MS);
+  if (["pending", "running"].includes(task.status) && task.updatedAt < staleBefore) {
+    const [interrupted] = await db.update(canvasCapabilityTask).set({
+      status: "failed",
+      error: INTERRUPTED_TASK_MESSAGE,
+      completedAt: new Date(),
+      updatedAt: new Date(),
+    }).where(and(
+      eq(canvasCapabilityTask.id, task.id),
+      inArray(canvasCapabilityTask.status, ["pending", "running"]),
+      lt(canvasCapabilityTask.updatedAt, staleBefore),
+    )).returning();
+    if (interrupted) return interrupted;
+    const [latest] = await db.select().from(canvasCapabilityTask)
+      .where(eq(canvasCapabilityTask.id, task.id)).limit(1);
+    return latest || task;
+  }
+  return task;
 }
 
 export async function createOrRecoverCanvasCapabilityTask(params: {
@@ -42,6 +60,7 @@ export async function createOrRecoverCanvasCapabilityTask(params: {
       capabilityId: params.command.capabilityId,
       source: params.command.source,
       request: params.command,
+      updatedAt: new Date(),
     })
     .onConflictDoNothing({ target: canvasCapabilityTask.requestId });
 
@@ -50,57 +69,17 @@ export async function createOrRecoverCanvasCapabilityTask(params: {
     userId: params.userId,
     projectId: params.projectId,
   };
-  let task = await getCanvasCapabilityTask(taskLookup);
+  const task = await getCanvasCapabilityTask(taskLookup);
   if (!task) {
     throw new Error("无法创建画布能力任务");
   }
 
-  const staleBefore = new Date(Date.now() - STALE_RUNNING_TASK_MS);
+  return task;
-  if (
-    task.status === "failed" &&
-    task.attempts < MAX_CANVAS_CAPABILITY_TASK_ATTEMPTS
-  ) {
-    await db
-      .update(canvasCapabilityTask)
-      .set({
-        status: "pending",
-        error: null,
-        completedAt: null,
-        updatedAt: new Date(),
-      })
-      .where(eq(canvasCapabilityTask.id, task.id));
-  } else if (
-    task.status === "running" &&
-    task.updatedAt < staleBefore &&
-    task.attempts < MAX_CANVAS_CAPABILITY_TASK_ATTEMPTS
-  ) {
-    await db
-      .update(canvasCapabilityTask)
-      .set({
-        status: "pending",
-        error: "恢复超时的执行中任务",
-        updatedAt: new Date(),
-      })
-      .where(
-        and(
-          eq(canvasCapabilityTask.id, task.id),
-          lt(canvasCapabilityTask.updatedAt, staleBefore)
-        )
-      );
-  } else if (task.status === "running" && task.updatedAt < staleBefore) {
-    await db
-      .update(canvasCapabilityTask)
-      .set({
-        status: "failed",
-        error: "画布能力任务超过最大重试次数",
-        completedAt: new Date(),
-        updatedAt: new Date(),
-      })
-      .where(eq(canvasCapabilityTask.id, task.id));
 }
 
-  task = (await getCanvasCapabilityTask(taskLookup)) || task;
+export async function heartbeatCanvasCapabilityTask(taskId: string) {
-  return task;
+  await db.update(canvasCapabilityTask).set({ updatedAt: new Date() })
+    .where(and(eq(canvasCapabilityTask.id, taskId), inArray(canvasCapabilityTask.status, ["pending", "running"])));
 }
 
 export async function markCanvasCapabilityTaskRunning(taskId: string) {
@@ -115,11 +94,10 @@ export async function markCanvasCapabilityTaskRunning(taskId: string) {
       error: null,
       updatedAt: now,
     })
-    .where(eq(canvasCapabilityTask.id, taskId))
+    .where(and(eq(canvasCapabilityTask.id, taskId), eq(canvasCapabilityTask.status, "pending")))
     .returning();
 
-  if (!task) throw new Error("画布能力任务不存在");
+  return task || null;
-  return task;
 }
 
 export async function markCanvasCapabilityTaskSucceeded(

lib/canvas/download-error.ts

@@ -0,0 +1,31 @@
+export type DownloadFailure = {
+  code: string;
+  message: string;
+  recommendation: string;
+  status: number;
+  retryable: boolean;
+};
+
+export function getDownloadFailure(error: unknown): DownloadFailure {
+  const text = error && typeof error === "object" && "message" in error
+    ? `${"name" in error ? error.name : "Error"}: ${error.message}` : String(error || "");
+  const failure = (code: string, message: string, recommendation: string, status: number, retryable = false) =>
+    ({ code, message, recommendation, status, retryable });
+  if (/旧存储已停用|storage_retired/.test(text)) return failure("STORAGE_RETIRED", "原图所在的旧存储已停用。", "请重新上传原图；重试下载无法恢复该文件。", 410);
+  if (/HTTP (?:404|410)|SOURCE_NOT_FOUND/i.test(text)) return failure("SOURCE_NOT_FOUND", "原图链接已失效或源文件已被删除。", "请重新上传原图，或联系管理员核对归档副本；无需重新生成图片。", 404);
+  if (/HTTP (?:401|403)|SOURCE_FORBIDDEN/i.test(text)) return failure("SOURCE_FORBIDDEN", "图片源站拒绝访问原图。", "请联系管理员检查原图访问权限或链接有效期，并提供下载编号。", 403);
+  if (/queue.*busy|正在准备的原图较多|DOWNLOAD_BUSY/i.test(text)) return failure("DOWNLOAD_BUSY", "正在准备的下载较多。", "请等待当前下载完成后再试，避免同时重复点击。", 429, true);
+  if (/TimeoutError|AbortError|timeout|timed out|deadline|超时|HTTP (?:408|504|524)/i.test(text)) return failure("SOURCE_TIMEOUT", "读取原图或准备下载文件超时。", "请稍后再次下载；持续失败时联系管理员并提供下载编号，已归档的原图无需重新生成。", 504, true);
+  if (/fetch failed|failed to fetch|ECONN|ENOTFOUND|EAI_AGAIN|network|HTTP (?:429|5\d\d)/i.test(text)) return failure("SOURCE_UNAVAILABLE", "暂时无法连接图片源站。", "请稍后重试下载；持续失败时联系管理员检查取图线路，并提供下载编号。", 503, true);
+  if (/not.*image|error document|不是图片|无法识别图片|empty response|image is empty|Invalid prepared original/i.test(text)) return failure("INVALID_IMAGE", "源地址没有返回可用的图片文件。", "请重新上传可打开的原图；若原图正常，请联系管理员并提供下载编号。", 422);
+  if (/sharp|pngload|jpegload|unsupported image|无法解析图片|convert|转换/i.test(text)) return failure("IMAGE_CONVERSION_FAILED", "原图无法转换为下载所需的 PNG 文件。", "请保留原图并联系管理员提供下载编号，或重新上传 PNG/JPEG 图片。", 422);
+  if (/upload|存储桶|保存下载|STORAGE_WRITE_FAILED/i.test(text)) return failure("DOWNLOAD_STORAGE_FAILED", "下载文件保存失败，已归档的原图仍然保留。", "请稍后重试；持续失败时联系管理员检查存储，并提供下载编号。", 503, true);
+  if (/未登录/.test(text)) return failure("LOGIN_REQUIRED", "登录状态已失效。", "请重新登录后下载，当前图片不会因此删除。", 401);
+  if (/无法确认原图/.test(text)) return failure("ORIGINAL_IMAGE_UNCONFIRMED", "图片链接包含处理参数，无法确认原图。", "请选择未裁剪、未缩放的原图链接，或重新上传原图。", 400);
+  if (/图片地址无效/.test(text)) return failure("INVALID_IMAGE_URL", "图片地址无效。", "请刷新画布后重新选择图片；仍然失败时请重新上传原图。", 400);
+  return failure("DOWNLOAD_FAILED", "下载准备未能完成。", "请联系管理员并提供下载编号，以便核对原图、转换和存储的具体错误；无需重新生成。", 500, true);
+}
+
+export function formatDownloadFailure(failure: DownloadFailure, requestId?: string) {
+  return `${failure.message}${failure.recommendation}${requestId ? `\n下载编号：${requestId}` : ""}`;
+}

lib/canvas/download-preparation.ts

@@ -1,6 +1,10 @@
 import "server-only";
-import { createHash } from "node:crypto";
+import { createHash, randomUUID } from "node:crypto";
 import { cacheImageBytes, readImageBytes, type ImageBytes } from "@/lib/storage/image-byte-cache";
+import { formatDownloadFailure, getDownloadFailure, type DownloadFailure } from "./download-error";
+import { createLogger } from "@/lib/observability/logger";
+
+const logger = createLogger("canvas.download");
 
 export type DownloadPreparationInput = {
   userId: string;
@@ -9,17 +13,18 @@ export type DownloadPreparationInput = {
   cookie: string;
 };
 type Result =
-  | { status: "preparing" }
+  | { status: "preparing"; requestId: string }
   | { status: "ready"; asset: ImageBytes }
-  | { status: "failed"; error: string };
+  | { status: "failed"; error: string; failure: DownloadFailure; requestId: string };
 type Job = {
+  requestId: string;
   userId: string;
   input: DownloadPreparationInput;
   status: "queued" | "running" | "ready" | "failed";
   updatedAt: number;
   asset?: ImageBytes;
+  failure?: DownloadFailure;
 };
-const FAILURE_MESSAGE = "原图暂时无法读取，图片仍保留在画布中，请稍后重试";
 const MAX_MEMORY_BYTES = 128 * 1024 * 1024;
 
 // A download is independent of node autosave and of the archive worker's batch.
@@ -69,7 +74,7 @@ export function createDownloadPreparationQueue(deps: {
               timer = setTimeout(() => {
                 controller.abort();
                 reject(new Error("Download preparation deadline"));
-              }, deps.timeoutMs || 90_000);
+              }, deps.timeoutMs || 150_000);
             }),
           ]);
           if (asset.contentType !== "image/png" || !asset.buffer.length || asset.buffer.length > MAX_MEMORY_BYTES) {
@@ -81,8 +86,10 @@ export function createDownloadPreparationQueue(deps: {
           const stored = await deps.read(key).catch(() => null);
           if (stored?.contentType === "image/png" && stored.buffer.length) job.asset = undefined;
           job.status = "ready";
-        } catch {
+        } catch (error) {
           job.status = "failed";
+          job.failure = getDownloadFailure(error);
+          logger.warn("preparation_failed", error, { requestId: job.requestId, code: job.failure.code });
         } finally {
           if (timer) clearTimeout(timer);
           // Do not retain authentication data after a preparation finishes.
@@ -105,8 +112,11 @@ export function createDownloadPreparationQueue(deps: {
       prune();
       const current = jobs.get(key);
       if (current?.status === "ready" && current.asset) return { status: "ready", asset: current.asset };
-      if (current?.status === "failed") return { status: "failed", error: FAILURE_MESSAGE };
+      if (current?.status === "failed") {
-      if (current && current.status !== "ready") return { status: "preparing" };
+        const failure = current.failure || getDownloadFailure(null);
+        return { status: "failed", error: formatDownloadFailure(failure, current.requestId), failure, requestId: current.requestId };
+      }
+      if (current && current.status !== "ready") return { status: "preparing", requestId: current.requestId };
       if (jobs.size >= 64) {
         for (const [oldKey, job] of jobs) {
           if (job.status === "ready" || job.status === "failed") jobs.delete(oldKey);
@@ -115,11 +125,14 @@ export function createDownloadPreparationQueue(deps: {
       }
       if (jobs.size >= 64 || [...jobs.values()].filter(job => job.userId === input.userId &&
           (job.status === "queued" || job.status === "running")).length >= 4) {
-        return { status: "failed", error: "正在准备的原图较多，请等待当前下载完成后再试" };
+        const requestId = randomUUID();
+        const failure = getDownloadFailure("DOWNLOAD_BUSY");
+        return { status: "failed", error: formatDownloadFailure(failure, requestId), failure, requestId };
       }
-      jobs.set(key, { userId: input.userId, input, status: "queued", updatedAt: now() });
+      const requestId = randomUUID();
+      jobs.set(key, { requestId, userId: input.userId, input, status: "queued", updatedAt: now() });
       deps.schedule(drain);
-      return { status: "preparing" };
+      return { status: "preparing", requestId };
     },
   };
 }

lib/canvas/generate-image-response.ts

@@ -10,7 +10,7 @@ import { generateCanvasImage, type CanvasGenerateImageRequest } from "@/lib/canv
 import { getPointsSystemConfig } from "@/lib/db/queries";
 import { prepareFeaturePointsCharge } from "@/lib/points/feature-charge";
 import { getImageToolCreditCost, type ImageToolCreditFeature } from "@/lib/points/config";
-import { getUserFacingImageGenerationErrorMessage } from "@/lib/request-error";
+import { getUserFacingImageGenerationErrorMessage, getRequestFailureDetails } from "@/lib/request-error";
 
 interface GenerateImageRequest extends CanvasGenerateImageRequest {
   async?: boolean;
@@ -121,7 +121,7 @@ export async function executeCanvasImageResponse(body: GenerateImageRequest, use
   } catch (error) {
     console.error("[Canvas Generate Image] Error:", error);
     return NextResponse.json(
-      { success: false, error: getUserFacingImageGenerationErrorMessage(error),
+      { success: false, error: getUserFacingImageGenerationErrorMessage(error), failure: getRequestFailureDetails(error),
         ...(error instanceof ProviderTaskUncertainError ? { code: "PROVIDER_TASK_UNCERTAIN" } : {}) },
       { status: error instanceof ProviderTaskUncertainError ? 503 : 500 },
     );

lib/canvas/image-task-queue.ts

@@ -38,6 +38,7 @@ import {
 } from "@/lib/agents/detail-replacement-batch";
 import { executeDetailReplacementBatch } from "@/lib/agents/detail-replacement-batch-runner";
 import { getUserFacingImageGenerationErrorMessage } from "@/lib/request-error";
+import { trackRuntimeWork } from "@/lib/observability/active-work";
 
 type CanvasImageTaskStatus =
   | "waiting"
@@ -328,7 +329,7 @@ async function markStaleDatabaseRunningTasksFailed() {
     .update(canvasImageTask)
     .set({
       status: "failed",
-      error: "图片生成任务已超时，请重新发起生成",
+      error: "图片任务执行中断或等待超时，结果尚未确认。请先查看原任务和历史记录，联系管理员核对，避免重复生成。",
       completedAt,
       updatedAt: completedAt,
     })
@@ -383,7 +384,7 @@ async function runSingleTask(entry: PendingTaskEntry) {
       }
     }
     const runningTimeoutMs = getCanvasImageRunningTimeoutMs(request);
-    const execution: Promise<CanvasImageTaskResult> = isStyleProTaskRequest(request)
+    const execution: Promise<CanvasImageTaskResult> = trackRuntimeWork<CanvasImageTaskResult>(() => isStyleProTaskRequest(request)
       ? executeStyleProTask({
           request,
           userId: String(task.userId || entry.userId),
@@ -412,7 +413,7 @@ async function runSingleTask(entry: PendingTaskEntry) {
               ownerKey,
               request: imageRequest,
             });
-          })();
+          })());
     const heartbeat = isDetailReplacementBatchRequest(request)
       ? setInterval(() => {
           void db.update(canvasImageTask).set({ updatedAt: new Date() })
@@ -426,7 +427,7 @@ async function runSingleTask(entry: PendingTaskEntry) {
     try {
       result = await withCanvasImageTaskExecutionTimeout(
         execution,
-        runningTimeoutMs,
+        Math.max(runningTimeoutMs, LOCAL_ACTIVE_RUNNING_HARD_TIMEOUT_MS),
         entry.taskId
       );
     } finally {
@@ -751,7 +752,7 @@ export async function getCanvasImageTaskForUser(params: {
 
     if (shouldMarkStale) {
       const staleBefore = new Date(now - runningTimeoutMs);
-      const timeoutMessage = "图片生成任务已超时，请重新发起生成";
+      const timeoutMessage = "图片任务执行中断或等待超时，结果尚未确认。请先查看原任务和历史记录，联系管理员核对，避免重复生成。";
       const completedAt = new Date();
       const [timedOutTask] = await db
         .update(canvasImageTask)

lib/canvas/photoshop-safe-download.ts

@@ -2,6 +2,7 @@ import { createHash } from "node:crypto";
 import { isRetiredStorageUrl, RETIRED_STORAGE_MESSAGE } from "@/lib/storage/retired-storage";
 import { fetchImageBytes, onceImageBytes } from "@/lib/storage/image-byte-cache";
 import { extractImageProxySourceUrl, inferOriginalImageUrl } from "@/lib/image-url";
+import { getDownloadFailure } from "./download-error";
 
 type DownloadFileItem = {
   url: string;
@@ -31,6 +32,7 @@ function sleep(ms: number) {
 
 function normalizeDownloadError(error: unknown): string {
   if (error instanceof Error) return error.message || "download failed";
+  if (error && typeof error === "object" && "message" in error && typeof error.message === "string") return error.message;
   if (typeof error === "string") return error;
   return "download failed";
 }
@@ -330,6 +332,7 @@ export async function fetchCanvasDownloadAsset(params: {
       try {
         const data = await fetchImageBytes(candidateUrl, {
           timeoutMs,
+          signal: params.signal,
           headers: buildRemoteFetchHeaders(candidateUrl, params.requestOrigin, params.cookie),
           // Authenticated local assets must never share a cache across users.
           scope: new URL(candidateUrl).origin === params.requestOrigin && params.cookie
@@ -344,11 +347,13 @@ export async function fetchCanvasDownloadAsset(params: {
         });
       } catch (error) {
         params.signal?.throwIfAborted();
-        lastError = normalizeDownloadError(error);
+        const message = normalizeDownloadError(error);
+        if (!lastError || getDownloadFailure(message).retryable || !getDownloadFailure(lastError).retryable) lastError = message;
       }
     }
     // Archiving may have completed during the failed fetch. Resolve aliases
     // again before retrying, rather than spending every attempt on the old URL.
+    if (!getDownloadFailure(lastError).retryable) break;
     if (attempt < retryCount) await sleep(350 * attempt);
   }
 

lib/client/canvas-image-download.ts

@@ -1,5 +1,6 @@
-import { buildImageProxyUrl } from "@/lib/image-delivery";
+import { buildImageProxyUrl, getImageDownloadExtension } from "@/lib/image-delivery";
 import { inferOriginalImageUrl } from "@/lib/image-url";
+import { formatDownloadFailure, getDownloadFailure, type DownloadFailure } from "@/lib/canvas/download-error";
 
 export type CanvasImageDownloadPhase = "preparing" | "downloading" | "saving";
 
@@ -26,6 +27,8 @@ export class CanvasImageDownloadError extends Error {
   code: CanvasImageDownloadErrorCode;
   retryAfterSeconds?: number;
   status?: number;
+  failure?: DownloadFailure;
+  requestId?: string;
 
   constructor(
     message: string,
@@ -33,6 +36,8 @@ export class CanvasImageDownloadError extends Error {
       code: CanvasImageDownloadErrorCode;
       retryAfterSeconds?: number;
       status?: number;
+      failure?: DownloadFailure;
+      requestId?: string;
     }
   ) {
     super(message);
@@ -40,11 +45,14 @@ export class CanvasImageDownloadError extends Error {
     this.code = options.code;
     this.retryAfterSeconds = options.retryAfterSeconds;
     this.status = options.status;
+    this.failure = options.failure;
+    this.requestId = options.requestId;
   }
 }
 
 export function getCanvasImageDownloadErrorMessage(error: unknown) {
   if (error instanceof CanvasImageDownloadError) {
+    if (error.failure) return formatDownloadFailure(error.failure, error.requestId);
     if (error.code === "rate_limited") {
       return error.retryAfterSeconds
         ? `图片下载请求过于频繁，请 ${error.retryAfterSeconds} 秒后重试`
@@ -54,10 +62,10 @@ export function getCanvasImageDownloadErrorMessage(error: unknown) {
       return "原图暂时无法读取，图片仍保留在画布中，请稍后重试";
     }
     if (error.code === "preparation_timeout") {
-      return "原图仍在后台准备中，请稍后再次点击下载";
+      return `原图仍在后台准备中，请稍后再次点击下载${error.requestId ? `\n下载编号：${error.requestId}` : ""}`;
     }
   }
-  return error instanceof Error ? error.message : "图片下载失败，请稍后重试";
+  return formatDownloadFailure(getDownloadFailure(error));
 }
 
 type DownloadCanvasImageParams = {
@@ -71,6 +79,8 @@ type DownloadCanvasImageParams = {
 type DownloadErrorPayload = {
   error?: string;
   retryAfter?: number;
+  failure?: DownloadFailure;
+  requestId?: string;
 };
 
 const MAX_RATE_LIMIT_RETRIES = 1;
@@ -166,6 +176,63 @@ function triggerBlobDownload(blob: Blob, filename: string) {
   window.setTimeout(() => URL.revokeObjectURL(blobUrl), 1000);
 }
 
+function triggerCdnDownload(result: { downloadUrl: string; filename: string; bytes?: number }, signal?: AbortSignal) {
+  if (typeof result.downloadUrl !== "string" || new URL(result.downloadUrl).protocol !== "https:") {
+    throw new Error("下载链接无效");
+  }
+  signal?.throwIfAborted();
+  const frame = document.createElement("iframe");
+  frame.hidden = true;
+  frame.src = result.downloadUrl;
+  document.body.appendChild(frame);
+  window.setTimeout(() => frame.remove(), 10 * 60_000);
+  return { filename: result.filename, bytes: result.bytes || 0 };
+}
+
+/** Keep the source format and bytes for chat, gallery and reference downloads. */
+export async function downloadOriginalImage({ url, name, signal, onProgress }: DownloadCanvasImageParams): Promise<CanvasImageDownloadResult> {
+  const source = String(url || "").trim();
+  if (!source) throw new Error("图片地址无效");
+  const proxy = buildImageProxyUrl(source, { delivery: "original" });
+  const filenameBase = sanitizeDownloadName(name || inferDownloadNameFromUrl(source), "image");
+  const target = new URL(proxy, window.location.origin);
+  onProgress?.({ phase: "preparing", message: "正在准备原图..." });
+  const checkedFetch = async (input: string) => {
+    let response: Response;
+    try { response = await fetch(input, { signal }); }
+    catch (error) {
+      if (signal?.aborted) throw error;
+      const failure = getDownloadFailure(error);
+      throw new CanvasImageDownloadError(failure.message, { code: "request_failed", failure });
+    }
+    if (!response.ok) {
+      const payload = await response.json().catch(() => null) as DownloadErrorPayload | null;
+      throw new CanvasImageDownloadError(payload?.error || "原图下载失败", { code: "request_failed",
+        status: response.status, failure: payload?.failure || getDownloadFailure(`HTTP ${response.status}`), requestId: payload?.requestId });
+    }
+    return response;
+  };
+  if (target.origin === window.location.origin && target.pathname === "/api/image-proxy") {
+    target.searchParams.set("download", "resolve");
+    target.searchParams.set("name", filenameBase);
+    const metadata = await checkedFetch(target.pathname + target.search);
+    const delivery = await metadata.json();
+    if (delivery.delivery === "cdn") {
+      const result = triggerCdnDownload(delivery, signal);
+      onProgress?.({ phase: "downloading", message: "已开始下载，可在浏览器下载列表查看进度" });
+      return result;
+    }
+    if (delivery.delivery !== "proxy") throw new Error("下载链接无效");
+  }
+  const response = await checkedFetch(proxy);
+  const blob = await readResponseBlobWithProgress(response, onProgress);
+  if (!blob.type.toLowerCase().startsWith("image/")) throw new Error("Source is not an image");
+  const extension = getImageDownloadExtension(blob.type);
+  const filename = extension ? `${filenameBase}.${extension}` : filenameBase;
+  triggerBlobDownload(blob, filename);
+  return { filename, bytes: blob.size };
+}
+
 function toDownloadCandidates(url: string, candidates: string[] = []) {
   const raw = String(url || "").trim();
   const originalUrl = String(inferOriginalImageUrl(raw) || raw).trim();
@@ -257,6 +324,7 @@ export async function downloadCanvasImageAsPng({
   let preparationPolls = 0;
   for (;;) {
     signal?.throwIfAborted();
+    try {
       response = await fetch("/api/canvas/download-image", {
       method: "POST",
       headers: { "Content-Type": "application/json" },
@@ -269,6 +337,11 @@ export async function downloadCanvasImageAsPng({
       }),
       signal,
       });
+    } catch (error) {
+      if (signal?.aborted) throw error;
+      const failure = getDownloadFailure(error);
+      throw new CanvasImageDownloadError(failure.message, { code: "request_failed", failure });
+    }
 
     if (response.status === 202) {
       rateLimitRetries = 0;
@@ -278,7 +351,7 @@ export async function downloadCanvasImageAsPng({
         throw new CanvasImageDownloadError("下载准备状态无效", { code: "request_failed", status: 202 });
       }
       if (Date.now() >= preparationDeadline || preparationPolls >= 60) {
-        throw new CanvasImageDownloadError("原图仍在准备中", { code: "preparation_timeout", status: 202 });
+        throw new CanvasImageDownloadError("原图仍在准备中", { code: "preparation_timeout", status: 202, requestId: preparing.requestId });
       }
       onProgress?.({ phase: "preparing", message: preparing.message || "正在准备原图，完成后将自动下载" });
       const delaySeconds = Math.max(preparationPolls > 5 ? 5 : 1, Math.min(5, Number(preparing.retryAfter) || 3));
@@ -299,6 +372,8 @@ export async function downloadCanvasImageAsPng({
           code: "rate_limited",
           retryAfterSeconds,
           status: response.status,
+          failure: errorPayload?.failure,
+          requestId: errorPayload?.requestId,
         }
       );
     }
@@ -321,22 +396,18 @@ export async function downloadCanvasImageAsPng({
       {
         code: status === 502 ? "source_unavailable" : "request_failed",
         status,
+        failure: errorPayload?.failure,
+        requestId: errorPayload?.requestId,
       }
     );
   }
 
   if (response.headers.get("content-type")?.includes("application/json")) {
     const result = await response.json();
-    if (result.delivery !== "cdn" || typeof result.downloadUrl !== "string"
+    if (result.delivery !== "cdn") throw new Error("下载链接无效");
-        || new URL(result.downloadUrl).protocol !== "https:") throw new Error("下载链接无效");
+    const downloaded = triggerCdnDownload(result, signal);
-    if (signal?.aborted) throw signal.reason || new DOMException("已取消下载", "AbortError");
-    const frame = document.createElement("iframe");
-    frame.hidden = true;
-    frame.src = result.downloadUrl;
-    document.body.appendChild(frame);
-    window.setTimeout(() => frame.remove(), 10 * 60_000);
     onProgress?.({ phase: "downloading", message: "已开始下载，可在浏览器下载列表查看进度" });
-    return { filename: result.filename, bytes: result.bytes || 0 };
+    return downloaded;
   }
 
   const filename =

lib/client/canvas-toolbar-capability.ts

@@ -1,6 +1,40 @@
 import type { CanvasCapabilityClientCommand } from "@/lib/canvas/capabilities/client-command";
 import { mergeCanvasSnapshots } from "@/lib/video-canvas/merge-snapshot";
 import { useCanvasStore } from "@/store/canvas";
+import { formatRequestFailure, getRequestFailureDetails } from "@/lib/request-error";
+
+async function requestCapabilityResult(command: CanvasCapabilityClientCommand) {
+  const endpoint = `/api/canvas/${command.projectId}/capabilities`;
+  let payload: any = null;
+  try {
+    const response = await fetch(endpoint, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify(command),
+    });
+    payload = await response.json().catch(() => null);
+    if (payload?.success === false || (!response.ok && ![502, 503, 504, 524].includes(response.status))) {
+      throw Object.assign(new Error(payload?.error || "图片处理请求未通过"), { confirmedRejection: true });
+    }
+    if (!response.ok) payload = null;
+  } catch (error) {
+    if ((error as { confirmedRejection?: boolean })?.confirmedRejection) throw error;
+  }
+  const deadline = Date.now() + 20 * 60 * 1000;
+  while (Date.now() < deadline) {
+    const task = payload?.task;
+    if (task?.status === "succeeded") return payload;
+    if (task?.status === "failed") throw new Error(task.error || "图片处理失败，请联系管理员核对任务结果");
+    await new Promise(resolve => setTimeout(resolve, 1500));
+    try {
+      const response = await fetch(`${endpoint}?requestId=${encodeURIComponent(command.requestId)}`, { cache: "no-store", signal: AbortSignal.timeout(12_000) });
+      payload = response.ok ? await response.json() : null;
+    } catch {
+      payload = null;
+    }
+  }
+  throw new Error(formatRequestFailure(getRequestFailureDetails({ providerOutcomeUnknown: true }), command.requestId));
+}
 
 /** Runs after the editor has saved and while its save queue is reserved. */
 export async function executeCanvasToolbarCapability(
@@ -10,15 +44,7 @@ export async function executeCanvasToolbarCapability(
   const before = useCanvasStore.getState();
   if (before.projectId !== projectId) throw new Error("画布已切换，请重新选择图片");
   const base = JSON.stringify({ canvasData: before.getCanvasState() });
-  const response = await fetch(`/api/canvas/${projectId}/capabilities`, {
+  await requestCapabilityResult(command);
-    method: "POST",
-    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify(command),
-  });
-  const payload = await response.json().catch(() => ({}));
-  if (!response.ok || payload?.success !== true) {
-    throw new Error(payload?.error || "图片处理失败");
-  }
 
   const projectResponse = await fetch(`/api/canvas/${projectId}`);
   const result = await projectResponse.json();

lib/image-delivery.ts

@@ -20,6 +20,8 @@ export function getImageDownloadExtension(contentType: string) {
     "image/avif": "avif",
     "image/gif": "gif",
     "image/svg+xml": "svg",
+    "image/bmp": "bmp",
+    "image/tiff": "tiff",
   };
   return extensions[mime] || "";
 }
@@ -183,8 +185,8 @@ export function buildImageProxyUrl(url: string, options: ImageProxyOptions = {})
     return source;
   }
 
-  // An original download must go through the same-origin byte-preserving
+  // The same-origin endpoint can resolve a native CDN download without relying
-  // proxy even for trusted storage hosts: a direct fetch may fail CORS.
+  // on cross-origin fetch, while retaining a byte-preserving proxy fallback.
   if (options.delivery === "original") {
     const params = new URLSearchParams({ url: source, original: "1" });
     return `${IMAGE_PROXY_PATH}?${params.toString()}`;

lib/jobs/image-archive-job.ts

@@ -1,5 +1,6 @@
-import { preparePendingImageDownloads } from "@/lib/storage/image-download-preparation";
+import { scheduleImageDownloadPreparation } from "@/lib/storage/image-download-preparation";
 import "server-only";
+import { trackRuntimeWork } from "@/lib/observability/active-work";
 
 import { archiveTemporaryImage } from "@/lib/storage/image-archive";
 import {
@@ -26,10 +27,12 @@ function getBatchSize() {
 }
 
 export async function runImageArchiveJob() {
+  return trackRuntimeWork(async () => {
   const batchSize = getBatchSize();
   console.log(`[ImageArchiveJob] Start image archive job (batchSize=${batchSize})`);
 
   await recoverStaleImageArchiveTasks();
+  scheduleImageDownloadPreparation();
   const storeTasks = await getImageArchiveTasksToStore({ limit: batchSize });
   let storeSucceeded = 0;
   let storeFailed = 0;
@@ -43,6 +46,7 @@ export async function runImageArchiveJob() {
         id: task.id,
         targetUrl: archived.url,
       });
+      scheduleImageDownloadPreparation(task.id);
       storeSucceeded += 1;
       console.log("[ImageArchiveJob] stored", {
         taskId: task.id,
@@ -106,7 +110,6 @@ export async function runImageArchiveJob() {
     }
   }
 
-  const downloadTasks = await preparePendingImageDownloads();
   const stats = await getImageArchiveTaskStats();
   return {
     success: true,
@@ -122,7 +125,8 @@ export async function runImageArchiveJob() {
       failed: replaceFailed,
     },
     stats,
-    downloadTasks,
+    downloadTasks: 0,
     pendingDownloads: await hasPendingImageDownloads(),
   };
+  }, { durable: true });
 }

lib/observability/active-work.ts

@@ -0,0 +1,24 @@
+import "server-only";
+import { unlinkSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+const state = globalThis as typeof globalThis & { __aiChatbotActiveWork?: number; __aiChatbotDurableWork?: number };
+const path = join(process.platform === "win32" ? tmpdir() : "/tmp", `ai-chatbot-active-work-${process.pid}.json`);
+
+function update(delta: number, durable: boolean) {
+  state.__aiChatbotActiveWork = (state.__aiChatbotActiveWork || 0) + delta;
+  if (durable) state.__aiChatbotDurableWork = (state.__aiChatbotDurableWork || 0) + delta;
+  try {
+    writeFileSync(path, JSON.stringify({ pid: process.pid, active: state.__aiChatbotActiveWork, durable: state.__aiChatbotDurableWork || 0 }), { mode: 0o600 });
+  } catch (error) {
+    try { unlinkSync(path); } catch {}
+    console.warn("[Active Work] Failed to record running work:", error);
+  }
+}
+
+/** Includes generation that continues after the client connection closes. */
+export async function trackRuntimeWork<T>(execute: () => T | Promise<T>, options: { durable?: boolean } = {}): Promise<T> {
+  update(1, options.durable === true);
+  try { return await execute(); } finally { update(-1, options.durable === true); }
+}

lib/request-error.ts

@@ -189,14 +189,6 @@ export function isGatewayResponseTimeout(error: unknown): boolean {
     /\bHTTP\s*524\b|\b524\s*:\s*A timeout occurred\b|Error code\s*524\b/i.test(getRequestErrorText(error));
 }
 
-function getPublicGatewayErrorMessage(error: unknown): string | null {
-  if (isGatewayResponseTimeout(error)) {
-    return "模型服务响应超时（HTTP 524），生成结果尚未确认。请先查看历史记录，避免重复提交。";
-  }
-  const message = getRequestErrorMessage(error);
-  return message ? getGatewayErrorPageMessage(message) : null;
-}
-
 export function isProviderBalanceError(error: unknown): boolean {
   const message = getRequestErrorText(error);
   return PROVIDER_BALANCE_PATTERNS.some((pattern) => pattern.test(message));
@@ -221,19 +213,80 @@ export function isRateLimitError(error: unknown): boolean {
     RATE_LIMIT_PATTERNS.some((pattern) => pattern.test(message));
 }
 
+export type RequestFailureDetails = {
+  code: string;
+  message: string;
+  recommendation: string;
+  outcome: "failed" | "unknown";
+};
+
+export function getRequestFailureDetails(
+  error: unknown,
+  fallbackMessage = "请求未能完成",
+): RequestFailureDetails {
+  const text = getRequestErrorText(error);
+  const status = getRequestErrorStatus(error);
+  const detail = (code: string, message: string, recommendation: string, outcome: "failed" | "unknown" = "failed") =>
+    ({ code, message, recommendation, outcome });
+  if (isGatewayResponseTimeout(error)) {
+    return detail("RESULT_UNCONFIRMED", "模型服务响应超时（HTTP 524），生成结果尚未确认。", "请先查看历史记录，避免重复提交。", "unknown");
+  }
+  if ((isRecord(error) && error.providerOutcomeUnknown === true) || /结果(?:尚)?未确认|结果暂未确认|request_outcome_unknown|任务执行中断|may still be running/i.test(text)) {
+    return detail("RESULT_UNCONFIRMED", "任务结果尚未确认，可能仍在处理。", "请先查看原任务或历史记录；持续没有结果时联系管理员，避免重复生成。", "unknown");
+  }
+  if (isProviderBalanceError(error)) {
+    return detail("PROVIDER_BALANCE_EXHAUSTED", "图片服务商线路余额或额度不足，与您的积分余额无关。", "请切换可用模型或联系管理员处理线路额度。");
+  }
+  if (isRateLimitError(error)) {
+    return detail("RATE_LIMITED", "当前请求过于频繁。", "请稍后重试，避免连续点击；模型线路限流时可切换其他可用模型。");
+  }
+  if (/content.?polic|moderation|safety|policy_rejected|内容(?:敏感|审核|限制)|不能生成像那样|不能生成那样|违规/i.test(text)) {
+    return detail("CONTENT_POLICY_REJECTED", "模型服务因内容审核限制拒绝了本次请求。", "请调整描述或参考图中的受限内容后再提交；重复提交相同内容通常无法解决。");
+  }
+  if (/上传到存储桶失败|存储.*失败|归档.*失败|archive.*failed|storage.*failed/i.test(text)) {
+    return detail("RESULT_STORAGE_FAILED", "处理结果保存失败，生成结果可能已经存在。", "请保留当前页面并联系管理员提供请求编号，先不要重复生成。", "unknown");
+  }
+  if (/failed to download (?:the )?image url|failed to download.*reference.*image/i.test(text)) {
+    return detail("PROVIDER_REFERENCE_FETCH_FAILED", "模型服务未能读取参考图。", "请重新上传参考图或切换模型后再提交；若原图仍可打开，请联系管理员检查模型取图线路，并提供请求编号。");
+  }
+  if (/参考图.*(?:下载失败|不可|失效)|无法获取图片|图片(?:源文件|链接).*不可|获取图片.*失败|get image url failed/i.test(text)) {
+    return detail("SOURCE_IMAGE_UNAVAILABLE", "请求中的图片无法读取，链接可能已失效或没有访问权限。", "请重新上传原图后再提交；若原图仍可打开，请联系管理员检查取图服务。");
+  }
+  if (/版本冲突|画布.*(?:更新|过期)|CANVAS_REVISION_CONFLICT|stale.canvas/i.test(text)) {
+    return detail("CANVAS_REVISION_CONFLICT", "画布已更新，本次保存与当前版本冲突。", "请先重新同步画布，再继续操作，避免覆盖较新的修改。");
+  }
+  if (/no_eligible_route|service_unavailable|service_rejected|channel.*unavailable|暂无可用服务|未配置.*模型|没有可用.*(?:模型|通道)|通道.*(?:不可用|未通过)|鉴权/i.test(text)) {
+    return detail("PROVIDER_UNAVAILABLE", "当前模型服务或通道暂不可用。", "请切换其他可用模型；若多个模型都失败，请联系管理员检查服务配置。");
+  }
+  if (/neither a task ID nor output URLs|已完成.*未取回|completed without.*output/i.test(text)) {
+    return detail("RESULT_UNCONFIRMED", "模型服务没有返回可读取的任务结果，生成状态尚未确认。", "请保留当前任务并联系管理员核对，避免重复生成。", "unknown");
+  }
+  if (/(?:抠图|去水印|图片增强|图片|扩图)处理失败/.test(text)) {
+    return detail("PROCESSING_FAILED", "图片处理服务执行失败，未返回具体原因。", "请联系管理员并提供请求编号，先核对原任务结果，避免重复处理。", "unknown");
+  }
+  if (/service_error|upstream_server_error|excessive system load|generate(?: image)? failed/i.test(text)) {
+    return detail("PROVIDER_EXECUTION_FAILED", "模型服务未能完成本次处理。", "请稍后重试；若连续失败，请切换模型或联系管理员，并提供请求编号。");
+  }
+  if (/timeout|timed out|超时|fetch failed|ECONNRESET|ECONNREFUSED|failed to fetch|networkerror|load failed|network request failed/i.test(text) || [502, 504].includes(status || 0)) {
+    return detail("RESULT_UNCONFIRMED", "请求连接中断或等待超时，任务结果尚未确认。", "请先查看原任务或历史记录，避免重复提交；持续没有结果时联系管理员。", "unknown");
+  }
+  if (/generate(?: image)? failed|generation failed|upstream_server_error|service_error|excessive system load|未返回可用图片|任务FAILED/i.test(text) || (status !== null && status >= 500)) {
+    return detail("PROVIDER_EXECUTION_FAILED", "模型服务未能完成本次处理。", "请稍后重试；若连续失败，请切换模型或联系管理员，并提供请求编号。");
+  }
+  const message = getRequestErrorMessage(error);
+  return detail("REQUEST_FAILED", message && !/^\s*</.test(message) ? message : fallbackMessage, "");
+}
+
+export function formatRequestFailure(details: RequestFailureDetails, requestId?: string) {
+  const text = [details.message, details.recommendation].filter(Boolean).join("");
+  return requestId ? `${text}\n\n请求编号：${requestId}` : text;
+}
+
 export function getUserFacingImageGenerationErrorMessage(
   error: unknown,
   fallbackMessage = "图片生成失败，请稍后重试",
 ) {
-  const gatewayMessage = getPublicGatewayErrorMessage(error);
+  return formatRequestFailure(getRequestFailureDetails(error, fallbackMessage));
-  if (gatewayMessage) return gatewayMessage;
-  if (isProviderBalanceError(error)) {
-    return "图片服务商线路余额或额度不足，请切换模型或联系管理员；与您的积分余额无关。";
-  }
-  if (isRateLimitError(error)) {
-    return "图片服务请求过于频繁，请稍后重试或切换模型。";
-  }
-  return getRequestErrorMessage(error) || fallbackMessage;
 }
 
 export function getFriendlyRateLimitMessage(
@@ -251,15 +304,12 @@ export function getUserFacingRequestErrorMessage(
     rateLimitMessage?: string;
   }
 ) {
-  const gatewayMessage = getPublicGatewayErrorMessage(error);
-  if (gatewayMessage) return gatewayMessage;
-  if (isProviderBalanceError(error)) {
-    return "模型服务商线路余额或额度不足，请切换模型或联系管理员。";
-  }
   if (isRateLimitError(error)) {
     return getFriendlyRateLimitMessage(options?.rateLimitMessage);
   }
 
+  const failure = getRequestFailureDetails(error, fallbackMessage);
+  if (failure.code !== "REQUEST_FAILED") return formatRequestFailure(failure);
   const message = getRequestErrorMessage(error);
   if (!message) {
     return fallbackMessage;

lib/storage/canvas-cdn-download.ts

@@ -10,17 +10,21 @@ export async function resolveCanvasCdnDownload(urls: string[], filename: string)
   })));
   const task = await findImageArchiveDownloadTask(sources, true);
   const asset = (task?.metadata as { downloadAsset?: { status?: string; url?: string; contentType?: string; bytes?: number } } | null)?.downloadAsset;
-  if (asset?.status !== "ready" || !asset.url || asset.contentType !== "image/png") return { task, direct: null };
+  if (!task) return { task, direct: null, canPrepareDirect: false };
   const config = await getDefaultStorageConfig();
-  if (config?.type !== "qiniu-kodo" || !config.publicUrl || !config.isEnabled) return { task, direct: null };
+  if (config?.type !== "qiniu-kodo" || !config.publicUrl || !config.isEnabled) return { task, direct: null, canPrepareDirect: false };
-  const url = new URL(asset.url);
+  const ready = asset?.status === "ready" && asset.url && asset.contentType === "image/png";
+  const source = ready ? asset.url : task.targetUrl;
+  if (!source) return { task, direct: null, canPrepareDirect: false };
+  const url = new URL(source);
   const base = new URL(config.publicUrl);
   const origin = process.env.CANVAS_QINIU_ORIGIN_URL;
   if (origin && url.origin === new URL(origin).origin) url.host = base.host;
   if (base.protocol !== "https:" || url.origin !== base.origin
-      || !(url.pathname.startsWith(base.pathname.replace(/\/$/, "") + "/"))) return { task, direct: null };
+      || !(url.pathname.startsWith(base.pathname.replace(/\/$/, "") + "/"))) return { task, direct: null, canPrepareDirect: false };
+  if (!ready) return { task, direct: null, canPrepareDirect: true };
   // attname is interpreted by Kodo/CDN as Content-Disposition, including Chinese
   // filenames. Keep all processing/auth parameters intact for correct cache keys.
   url.searchParams.set("attname", filename);
-  return { task, direct: { delivery: "cdn", downloadUrl: url.toString(), filename, bytes: asset.bytes || 0 } };
+  return { task, direct: { delivery: "cdn", downloadUrl: url.toString(), filename, bytes: asset?.bytes || 0 }, canPrepareDirect: true };
 }

lib/storage/image-byte-cache.ts

@@ -81,7 +81,7 @@ function isMediaResponse(data: ImageBytes) {
   if (/^<\?xml/i.test(prefix) && !/<svg[\s>]/i.test(prefix)) return false;
   return data.buffer.length > 0;
 }
-export async function fetchImageBytes(url: string, options: { headers?: HeadersInit; timeoutMs?: number; scope?: string } = {}) {
+export async function fetchImageBytes(url: string, options: { headers?: HeadersInit; timeoutMs?: number; scope?: string; signal?: AbortSignal } = {}) {
   if (isRetiredStorageUrl(url)) throw new Error(`HTTP 410: ${RETIRED_STORAGE_MESSAGE}`);
   return onceImageBytes(`source:${options.scope || ""}:${url}`, async () => {
     if (url.startsWith("data:")) {
@@ -92,7 +92,9 @@ export async function fetchImageBytes(url: string, options: { headers?: HeadersI
     const response = await fetch(url, {
       headers: options.headers, cache: "no-store", redirect: "follow",
       // The deadline covers the body as well as the response headers.
-      signal: AbortSignal.timeout(options.timeoutMs || 60_000),
+      signal: options.signal
+        ? AbortSignal.any([options.signal, AbortSignal.timeout(options.timeoutMs || 60_000)])
+        : AbortSignal.timeout(options.timeoutMs || 60_000),
     });
     if (!response.ok) { await response.body?.cancel(); throw new Error(`HTTP ${response.status}`); }
     const buffer = Buffer.from(await response.arrayBuffer());

lib/storage/image-download-preparation.ts

@@ -2,14 +2,21 @@ import "server-only";
 import { randomUUID } from "node:crypto";
 import { fetchImageBytes, cacheImageBytes } from "./image-byte-cache";
 import { normalizeCanvasDownloadAsset } from "@/lib/canvas/photoshop-safe-download";
-import { claimImageDownloadTask, saveImageDownloadAsset, getImageDownloadTasks } from "./image-archive-db";
+import { claimImageDownloadTask, saveImageDownloadAsset, getImageDownloadTasks, hasPendingImageDownloads } from "./image-archive-db";
 import { uploadFile } from "./service";
+import { getDownloadFailure } from "@/lib/canvas/download-error";
+import { createLogger } from "@/lib/observability/logger";
+import { trackRuntimeWork } from "@/lib/observability/active-work";
+
+const logger = createLogger("canvas.download");
 
 export async function prepareImageArchiveDownload(id: string) {
   const task = await claimImageDownloadTask(id);
   if (!task?.targetUrl) return;
+  let phase: "read" | "convert" | "store" = "read";
   try {
     const source = await fetchImageBytes(task.targetUrl);
+    phase = "convert";
     const asset = await normalizeCanvasDownloadAsset({
       item: { url: task.targetUrl }, index: 0, bytes: source.buffer,
       contentType: source.contentType, includeSequencePrefix: false,
@@ -17,15 +24,22 @@ export async function prepareImageArchiveDownload(id: string) {
     if (!asset.ok) throw new Error(asset.error);
     // An already compatible PNG shares the original object; other formats get
     // one prepared PNG, without changing the original dimensions or transparency.
+    phase = "store";
     const url = source.buffer.equals(asset.bytes) && asset.contentType === "image/png"
       ? task.targetUrl
       : (await uploadFile(`canvas-download-${randomUUID()}.${asset.filename.split(".").pop() || "png"}`, Uint8Array.from(asset.bytes).buffer)).url;
     await saveImageDownloadAsset(id, { status: "ready", url, bytes: asset.bytes.length,
       contentType: asset.contentType, preparedAt: new Date().toISOString() });
     await cacheImageBytes(`source::${url}`, { buffer: asset.bytes, contentType: asset.contentType });
-  } catch {
+  } catch (error) {
     const attempts = Number((task.metadata as { downloadAsset?: { attempts?: number } } | null)?.downloadAsset?.attempts || 1);
-    await saveImageDownloadAsset(id, { status: attempts >= 12 ? "abandoned" : "failed", attempts, retryAt: new Date(Date.now() + 10 * 60_000).toISOString() });
+    const failure = phase === "store"
+      ? getDownloadFailure("STORAGE_WRITE_FAILED")
+      : phase === "convert" && getDownloadFailure(error).code === "DOWNLOAD_FAILED"
+        ? getDownloadFailure("图片转换失败") : getDownloadFailure(error);
+    logger.warn("archive_download_preparation_failed", error, { requestId: id, code: failure.code });
+    await saveImageDownloadAsset(id, { status: !failure.retryable || attempts >= 12 ? "abandoned" : "failed", attempts,
+      failure, retryAt: new Date(Date.now() + 60_000).toISOString() });
   }
 }
 export async function preparePendingImageDownloads() {
@@ -36,3 +50,45 @@ export async function preparePendingImageDownloads() {
   }));
   return tasks.length;
 }
+
+const state = globalThis as typeof globalThis & {
+  __imageDownloadWorker?: { running: boolean; scanPending: boolean; priority: Set<string>; retry?: ReturnType<typeof setTimeout> };
+};
+
+/** Download preparation runs independently of the archive URL replacement batch. */
+export function scheduleImageDownloadPreparation(id?: string) {
+  const worker = state.__imageDownloadWorker ??= { running: false, scanPending: false, priority: new Set() };
+  if (id) worker.priority.add(id);
+  else worker.scanPending = true;
+  if (worker.running) return;
+  if (worker.retry) { clearTimeout(worker.retry); worker.retry = undefined; }
+  worker.running = true;
+  setImmediate(() => {
+    void trackRuntimeWork(async () => {
+      try {
+        for (;;) {
+          const priority = [...worker.priority].slice(0, 2);
+          for (const taskId of priority) worker.priority.delete(taskId);
+          if (priority.length) {
+            await Promise.all(priority.map(prepareImageArchiveDownload));
+          } else if (!worker.scanPending || await preparePendingImageDownloads() === 0) {
+            break;
+          }
+        }
+      } catch (error) {
+        logger.error("download_worker_failed", error);
+      } finally {
+        worker.running = false;
+        // Eligible retry times live in the database, including interrupted leases.
+        if (worker.priority.size) {
+          scheduleImageDownloadPreparation([...worker.priority][0]);
+        } else if (worker.scanPending && await hasPendingImageDownloads().catch(() => true)) {
+          worker.retry = setTimeout(() => scheduleImageDownloadPreparation(), 60_000);
+          worker.retry.unref?.();
+        } else {
+          worker.scanPending = false;
+        }
+      }
+    });
+  });
+}

lib/storage/original-image-download.ts

@@ -0,0 +1,45 @@
+import "server-only";
+import { getDefaultStorageConfig } from "@/lib/db/queries";
+import { findImageArchiveDownloadTask } from "./image-archive-db";
+import { inferOriginalImageUrl } from "@/lib/image-url";
+import { getImageDownloadExtension } from "@/lib/image-delivery";
+import { sanitizeCanvasDownloadFileName } from "@/lib/canvas/photoshop-safe-download";
+
+/** Resolve the archived original without waiting for a separate PNG conversion. */
+export async function resolveOriginalCdnDownload(source: string, name: string, signal: AbortSignal) {
+  const config = await getDefaultStorageConfig();
+  if (config?.type !== "qiniu-kodo" || !config.isEnabled || !config.publicUrl) return null;
+  const base = new URL(config.publicUrl);
+  const origin = process.env.CANVAS_QINIU_ORIGIN_URL;
+  let target = new URL(source);
+  if (target.origin !== base.origin && (!origin || target.origin !== new URL(origin).origin)) {
+    const task = await findImageArchiveDownloadTask([...new Set([source, inferOriginalImageUrl(source)])]);
+    target = new URL(task?.targetUrl || source);
+  }
+  if (origin && target.origin === new URL(origin).origin && !target.searchParams.has("token")) {
+    target.host = base.host;
+    target.protocol = base.protocol;
+  }
+  if (base.protocol !== "https:" || target.origin !== base.origin ||
+      !target.pathname.startsWith(base.pathname.replace(/\/$/, "") + "/")) return null;
+  // A Kodo download token signs the complete URL; adding attname would invalidate it.
+  if (target.searchParams.has("token")) return null;
+
+  // Only metadata crosses the application server. The browser receives the file
+  // from the CDN, including when cross-origin fetch is disabled by storage CORS.
+  const response = await fetch(target, {
+    method: "HEAD", cache: "no-store",
+    signal: AbortSignal.any([signal, AbortSignal.timeout(10_000)]),
+  });
+  if (!response.ok) throw new Error(`HTTP ${response.status}`);
+  const contentType = response.headers.get("content-type") || "";
+  if (!contentType.toLowerCase().startsWith("image/")) throw new Error("Source is not an image");
+  const extension = getImageDownloadExtension(contentType);
+  if (!extension) return null;
+  const basename = sanitizeCanvasDownloadFileName(name || target.pathname.split("/").pop() || "image", "image")
+    .replace(/\.(?:png|jpe?g|webp|avif|gif|svg|bmp|tiff?)$/i, "");
+  const filename = `${basename}.${extension}`;
+  target.searchParams.set("attname", filename);
+  return { delivery: "cdn" as const, downloadUrl: target.toString(), filename,
+    bytes: Number(response.headers.get("content-length")) || 0 };
+}

playwright.helpers.config.ts

@@ -3,6 +3,15 @@ import { defineConfig } from "@playwright/test";
 export default defineConfig({
   testDir: "./tests",
   testMatch: [
+    /routes\/original-image-download\.test\.ts/,
+    /routes\/canvas-download-speed\.test\.ts/,
+    /routes\/canvas-download-recovery\.test\.ts/,
+    /routes\/canvas-download-rate-limit\.test\.ts/,
+    /routes\/canvas-zip-download\.test\.ts/,
+    /routes\/image-archive-flow\.test\.ts/,
+    /routes\/runtime-active-work\.test\.ts/,
+    /routes\/canvas-capability-task-recovery\.test\.ts/,
+    /routes\/canvas-toolbar-capability\.test\.ts/,
     /routes\/agent-project-recovery\.test\.ts/,
     /routes\/admin-media-loading\.test\.ts/,
     /routes\/video-canvas-production\.test\.ts/,
@@ -42,6 +51,7 @@ export default defineConfig({
     /routes\/replacement-product-identity\.test\.ts/,
     /routes\/detail-replacement-batch\.test\.ts/,
     /routes\/alibaba-image-input\.test\.ts/,
+    /routes\/alibaba-task-errors\.test\.ts/,
     /routes\/model3d-style-pro-regressions\.test\.ts/,
     /routes\/clawd-request-lifecycle\.test\.ts/,
     /routes\/canvas-skill-tag-order\.test\.ts/,

proxy.ts

@@ -43,6 +43,7 @@ const manualIpBlockCache = new Map<
 >();
 
 function isHighFrequencyReadApi(pathname: string, method: string) {
+  if (method === "POST" && /^\/api\/canvas\/[^/]+\/image-archives$/.test(pathname)) return true;
   if (method === "GET" && pathname === "/api/canvas/download-zip-task") return true;
   if (method !== "GET") return false;
   if (/^\/api\/canvas\/[^/]+\/detail-archives$/.test(pathname)) return true;
@@ -668,6 +669,19 @@ export async function proxy(request: NextRequest, event: NextFetchEvent) {
         }
       );
     }
+    } else if (request.method === "POST" && /^\/api\/canvas\/[^/]+\/image-archives$/.test(pathname)) {
+      const token = await resolveToken();
+      const identifier = typeof token?.sub === "string" && token.sub
+        ? `user:${token.sub}:image-archives`
+        : `ip:${clientIP}:image-archives`;
+      const result = checkRateLimitByIdentifier(identifier, rateLimiters.uiPolling);
+      if (!result.allowed) {
+        const retryAfter = Math.max(1, Math.ceil((result.resetTime - Date.now()) / 1000));
+        return withAccessLog(NextResponse.json(
+          { error: "图片状态查询过于频繁，请稍后再查看", retryAfter },
+          { status: 429, headers: { "Retry-After": String(retryAfter) } },
+        ), { outcome: "rate_limited", severity: "watch", reasons: ["图片归档状态查询限流"] });
+      }
     } else if (isHighFrequencyReadApi(pathname, request.method)) {
     const pollingRateLimit = checkRateLimit(request, rateLimiters.uiPolling);
     if (!pollingRateLimit.allowed) {

tests/routes/alibaba-task-errors.test.ts

@@ -0,0 +1,59 @@
+import { expect, test } from "@playwright/test";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+import sharp from "sharp";
+
+test("Alibaba terminal task errors preserve the nested provider reason and do not resubmit", async () => {
+  const methods: string[] = [];
+  const loader = serverLoader({
+    "@/lib/storage/image-archive": {}, "@/lib/storage/service": {},
+    setTimeout: (callback: () => void, ms: number) => setTimeout(callback, ms === 5000 ? 0 : ms),
+    fetch: async (_url: string, init: RequestInit) => {
+      methods.push(init.method || "GET");
+      return Response.json(methods.length === 1
+        ? { output: { task_id: "original-task", task_status: "PENDING" } }
+        : { output: { task_id: "original-task", task_status: "FAILED", code: "InvalidParameter", message: "Failed to download image URL after retries." } });
+    },
+  });
+  const provider = loader("lib/ai/providers/alibaba-image.ts").createAlibabaImage({ apiKey: "fixture-key", baseURL: "https://dashscope.example/api/v1/services/aigc/multimodal-generation/generation" });
+  let error: unknown;
+  try { await provider.chat("qwen-image-3.0").doGenerate({ messages: [{ role: "user", content: "fixture" }], imageParams: { aspectRatio: "1:1" } }); } catch (caught) { error = caught; }
+  expect(String(error)).toContain("Failed to download image URL after retries.");
+  expect(String(error)).toContain("InvalidParameter");
+  expect(String(error)).toContain("original-task");
+  expect(methods).toEqual(["POST", "GET"]);
+  const failure = loader("lib/request-error.ts").getRequestFailureDetails(error);
+  expect(failure).toMatchObject({ code: "PROVIDER_REFERENCE_FETCH_FAILED", message: "模型服务未能读取参考图。" });
+  expect(failure.recommendation).toContain("模型取图线路");
+  expect(failure.recommendation).not.toContain("稍后重试");
+});
+
+test("Qwen 3 sends reference bytes directly with the right MIME and keeps auto resolution", async () => {
+  const png = await sharp({ create: { width: 32, height: 64, channels: 3, background: "blue" } }).png().toBuffer();
+  const jpeg = await sharp(png).jpeg().toBuffer();
+  const webp = await sharp(png).webp().toBuffer();
+  const originals = [png, jpeg, webp];
+  let submitted: any;
+  let posts = 0;
+  const loader = serverLoader({
+    "@/lib/storage/image-archive": {}, "@/lib/storage/service": { uploadFile() { throw new Error("Reference transport must not upload an intermediate file"); } },
+    setTimeout: (callback: () => void, ms: number) => setTimeout(callback, ms === 5000 ? 0 : ms),
+    fetch: async (url: string, init: RequestInit = {}) => {
+      if (init.method === "POST") { posts++; submitted = JSON.parse(String(init.body)); return Response.json({ output: { task_id: "inline-task", task_status: "PENDING" } }); }
+      if (url.includes("/tasks/")) return Response.json({ output: { task_status: "FAILED", message: "transport-inspection-complete" } });
+      const index = Number(new URL(url).pathname.slice(1));
+      return new Response(originals[index], { headers: { "content-type": ["image/png", "image/jpeg", "image/webp"][index] } });
+    },
+  });
+  const provider = loader("lib/ai/providers/alibaba-image.ts").createAlibabaImage({ apiKey: "fixture-key", baseURL: "https://dashscope.example" });
+  await expect(provider.chat("qwen-image-3.0").doGenerate({ messages: [{ role: "user", content: [
+    { type: "text", text: "fixture" }, ...originals.map((_bytes, index) => ({ type: "image", image: `https://source.example/${index}` })),
+  ] }], imageParams: { aspectRatio: "auto", imageSize: "2K" } })).rejects.toThrow("transport-inspection-complete");
+  expect(posts).toBe(1);
+  expect(submitted.parameters.size).toBe("1024*2048");
+  const images = submitted.input.messages[0].content.filter((part: any) => part.image).map((part: any) => part.image);
+  expect(images).toHaveLength(3);
+  images.forEach((value: string, index: number) => {
+    expect(value.split(";", 1)[0]).toBe(["data:image/png", "data:image/jpeg", "data:image/webp"][index]);
+    expect(Buffer.from(value.split(",")[1], "base64").equals(originals[index])).toBe(true);
+  });
+});

tests/routes/canvas-capability-task-recovery.test.ts

@@ -0,0 +1,65 @@
+import { expect, test } from "@playwright/test";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+
+function harness(status = "running") {
+  let now = 2_000_000;
+  const row: any = { id: "task-a", requestId: "request-a", userId: "user-a", projectId: "project-a", status, attempts: status === "pending" ? 0 : 1, updatedAt: new Date(now - 16 * 60_000), error: null };
+  const matches = (predicate: any): boolean => !predicate || (predicate[0] === "and" ? predicate.slice(1).every(matches)
+    : predicate[0] === "eq" ? row[predicate[1]] === predicate[2]
+    : predicate[0] === "lt" ? row[predicate[1]] < predicate[2]
+    : predicate[2].includes(row[predicate[1]]));
+  const db = {
+    select: () => ({ from: () => ({ where: (p: any) => ({ limit: async () => matches(p) ? [{ ...row }] : [] }) }) }),
+    insert: () => ({ values: () => ({ onConflictDoNothing: async () => undefined }) }),
+    update: () => ({ set: (values: any) => ({ where: (p: any) => {
+      const apply = () => {
+        if (!matches(p)) return [];
+        for (const [key, value] of Object.entries(values)) row[key] = key === "attempts" ? row.attempts + 1 : value;
+        return [{ ...row }];
+      };
+      const result = apply();
+      return Object.assign(Promise.resolve(result), { returning: async () => result });
+    } }) }),
+  };
+  const columns = Object.fromEntries(["id", "requestId", "userId", "projectId", "status", "updatedAt", "attempts"].map(k => [k, k]));
+  const store = serverLoader({
+    "@/lib/db": { db }, "@/lib/db/schema": { canvasCapabilityTask: columns },
+    "drizzle-orm": { eq: (...v: any[]) => ["eq", ...v], lt: (...v: any[]) => ["lt", ...v], inArray: (...v: any[]) => ["in", ...v], and: (...v: any[]) => ["and", ...v], sql: () => "increment" },
+    Date: class extends Date { constructor(value?: any) { super(value ?? now); } static now() { return now; } },
+  })("lib/canvas/capabilities/task-store.ts");
+  const lookup = { requestId: "request-a", userId: "user-a", projectId: "project-a" };
+  return { row, store, lookup, advance: (ms: number) => { now += ms; } };
+}
+
+test("a stale task stops reporting running without authorizing another execution", async () => {
+  const h = harness();
+  const task = await h.store.getCanvasCapabilityTask(h.lookup);
+  expect(task.status).toBe("failed");
+  expect(task.error).toContain("结果尚未确认");
+  const repeated = await h.store.createOrRecoverCanvasCapabilityTask({ ...h.lookup, command: { requestId: "request-a" } });
+  expect(repeated.status).toBe("failed");
+  expect(repeated.attempts).toBe(1);
+});
+
+test("heartbeats keep a legitimate long-running task active beyond fifteen minutes", async () => {
+  const h = harness();
+  await h.store.heartbeatCanvasCapabilityTask("task-a");
+  h.advance(14 * 60_000);
+  await h.store.heartbeatCanvasCapabilityTask("task-a");
+  h.advance(14 * 60_000);
+  expect((await h.store.getCanvasCapabilityTask(h.lookup)).status).toBe("running");
+  expect(h.row.attempts).toBe(1);
+});
+
+test("only the pending task can be claimed and a duplicate claim cannot run again", async () => {
+  const h = harness("pending");
+  expect(await h.store.markCanvasCapabilityTaskRunning("task-a")).toMatchObject({ status: "running", attempts: 1 });
+  expect(await h.store.markCanvasCapabilityTaskRunning("task-a")).toBeNull();
+  expect(h.row.attempts).toBe(1);
+});
+
+test("another user cannot inspect or change a stale task", async () => {
+  const h = harness();
+  expect(await h.store.getCanvasCapabilityTask({ ...h.lookup, userId: "user-b" })).toBeNull();
+  expect(h.row.status).toBe("running");
+});

tests/routes/canvas-download-recovery.test.ts

@@ -0,0 +1,159 @@
+import { expect, test } from "@playwright/test";
+import { randomUUID } from "node:crypto";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+
+const auth = { auth: async () => ({ user: { id: "owner" } }) };
+const request = () => ({
+  url: "https://app.example/api/canvas/download-image", headers: new Headers(),
+  json: async () => ({ url: "https://provider.example/original.jpg", preferDirect: true, preparation: "async" }),
+});
+
+test("download failures distinguish permanent sources, transport, conversion and storage with actionable advice", () => {
+  const { getDownloadFailure, formatDownloadFailure } = serverLoader({})("lib/canvas/download-error.ts");
+  for (const [error, code, status] of [
+    ["HTTP 404", "SOURCE_NOT_FOUND", 404], ["HTTP 403", "SOURCE_FORBIDDEN", 403],
+    ["TimeoutError: slow body", "SOURCE_TIMEOUT", 504], ["fetch failed", "SOURCE_UNAVAILABLE", 503],
+    ["source returned an error document", "INVALID_IMAGE", 422], ["unsupported image format", "IMAGE_CONVERSION_FAILED", 422],
+    ["STORAGE_WRITE_FAILED", "DOWNLOAD_STORAGE_FAILED", 503], ["DOWNLOAD_BUSY", "DOWNLOAD_BUSY", 429],
+  ]) {
+    const failure = getDownloadFailure(new Error(error as string));
+    expect(failure).toMatchObject({ code, status });
+    expect(failure.recommendation).toBeTruthy();
+    expect(formatDownloadFailure(failure, "feedback-id")).toContain("下载编号：feedback-id");
+    if (status === 404) expect(failure.recommendation).not.toContain("稍后重试");
+  }
+});
+
+test("failed preparation polls retain the same cause and feedback ID without rerunning the load", async () => {
+  const { createDownloadPreparationQueue } = serverLoader({})("lib/canvas/download-preparation.ts");
+  const runs: Array<() => Promise<void>> = [];
+  let loads = 0;
+  const queue = createDownloadPreparationQueue({
+    load: async () => { loads++; throw new Error("HTTP 404 https://source.example/private?token=private"); },
+    read: async () => null, write: async () => {}, schedule: (run: () => Promise<void>) => runs.push(run),
+  });
+  const input = { userId: "owner", urls: ["https://source.example/original"], requestOrigin: "https://app.example", cookie: "session=private" };
+  const accepted = await queue.request(input);
+  await runs[0]();
+  for (let i = 0; i < 3; i++) {
+    const failed = await queue.request(input);
+    expect(failed).toMatchObject({ status: "failed", requestId: accepted.requestId, failure: { code: "SOURCE_NOT_FOUND", status: 404 } });
+    expect(failed.error).not.toContain("token=private");
+  }
+  expect(loads).toBe(1);
+});
+
+test("download queue saturation returns a retryable 429 instead of a source 502", async () => {
+  const { createDownloadPreparationQueue } = serverLoader({})("lib/canvas/download-preparation.ts");
+  const queue = createDownloadPreparationQueue({ load: async () => { throw new Error("not started"); }, read: async () => null, write: async () => {}, schedule() {} });
+  for (let i = 0; i < 4; i++) await queue.request({ userId: "owner", urls: [`https://source.example/${i}`], requestOrigin: "https://app.example", cookie: "" });
+  expect(await queue.request({ userId: "owner", urls: ["https://source.example/fifth"], requestOrigin: "https://app.example", cookie: "" }))
+    .toMatchObject({ status: "failed", failure: { code: "DOWNLOAD_BUSY", status: 429, retryable: true } });
+});
+
+test("cold archived downloads wait for CDN preparation and never buffer the file through the app", async () => {
+  const queued: string[] = [];
+  let ready = false;
+  const route = serverLoader({
+    "@/app/(auth)/auth": auth,
+    "next/server": { NextResponse: Response, after() {} },
+    "@/lib/storage/canvas-cdn-download": { resolveCanvasCdnDownload: async () => ({
+      task: { id: "archive-task", targetUrl: "https://cdn.example/original.jpg", metadata: { downloadAsset: { status: "pending" } } },
+      canPrepareDirect: true,
+      direct: ready ? { delivery: "cdn", downloadUrl: "https://cdn.example/prepared.png", filename: "original.png", bytes: 4000000 } : null,
+    }) },
+    "@/lib/storage/image-download-preparation": { scheduleImageDownloadPreparation: (id: string) => queued.push(id) },
+    "@/lib/canvas/photoshop-safe-download": { sanitizeCanvasDownloadFileName: () => "original", fetchCanvasDownloadAsset: () => { throw new Error("Must use CDN delivery"); } },
+  })("app/api/canvas/download-image/route.ts");
+  const first = await route.POST(request());
+  expect(first.status).toBe(202);
+  expect(await first.json()).toMatchObject({ delivery: "preparing", requestId: "archive-task" });
+  ready = true;
+  const second = await route.POST(request());
+  expect(second.status).toBe(200);
+  expect(await second.json()).toMatchObject({ delivery: "cdn", bytes: 4000000 });
+  expect(queued).toEqual(["archive-task"]);
+});
+
+test("an expired archived source returns its permanent cause and download task ID", async () => {
+  const errors = serverLoader({})("lib/canvas/download-error.ts");
+  const route = serverLoader({
+    "@/app/(auth)/auth": auth, "next/server": { NextResponse: Response, after() {} },
+    "@/lib/storage/canvas-cdn-download": { resolveCanvasCdnDownload: async () => ({ task: {
+      id: "failed-archive", targetUrl: "https://cdn.example/missing.png",
+      metadata: { downloadAsset: { status: "abandoned", failure: errors.getDownloadFailure("HTTP 404") } },
+    }, canPrepareDirect: true, direct: null }) },
+    "@/lib/storage/image-download-preparation": { scheduleImageDownloadPreparation() { throw new Error("Do not retry a permanent failure"); } },
+  })("app/api/canvas/download-image/route.ts");
+  const response = await route.POST(request());
+  expect(response.status).toBe(404);
+  expect(await response.json()).toMatchObject({ requestId: "failed-archive", failure: { code: "SOURCE_NOT_FOUND" } });
+});
+
+test("the download browser keeps the structured cause, advice and feedback ID", async () => {
+  const failure = { code: "SOURCE_FORBIDDEN", message: "图片源站拒绝访问原图。", recommendation: "请联系管理员检查访问权限。", status: 403, retryable: false };
+  const client = serverLoader({ fetch: async () => Response.json({ failure, requestId: "real-feedback" }, { status: 403 }) })("lib/client/canvas-image-download.ts");
+  let caught: unknown;
+  try { await client.downloadCanvasImageAsPng({ url: "https://source.example/original" }); } catch (error) { caught = error; }
+  expect(client.getCanvasImageDownloadErrorMessage(caught)).toBe("图片源站拒绝访问原图。请联系管理员检查访问权限。\n下载编号：real-feedback");
+});
+
+test("the preparation deadline cancels the source body as well as its headers", async () => {
+  const cache = serverLoader({ fetch: async (_url: string, options: { signal: AbortSignal }) => ({
+    ok: true, headers: new Headers({ "content-type": "image/png" }),
+    arrayBuffer: () => new Promise((_resolve, reject) => options.signal.addEventListener("abort", () => reject(options.signal.reason), { once: true })),
+  }) })("lib/storage/image-byte-cache.ts");
+  const controller = new AbortController();
+  const fetching = cache.fetchImageBytes(`https://source.example/${randomUUID()}`, { timeoutMs: 10000, signal: controller.signal });
+  setTimeout(() => controller.abort(new Error("Preparation canceled")), 20);
+  await expect(fetching).rejects.toThrow("Preparation canceled");
+});
+
+test("requested downloads are prioritized with two workers before scanning background assets", async () => {
+  let active = 0; let maximum = 0; let scans = 0;
+  const releases: Array<() => void> = [];
+  const workRecords: Array<{ active: number; durable: number }> = [];
+  const claimed: string[] = []; const saved: string[] = [];
+  const bytes = Buffer.from("compatible PNG fixture");
+  const worker = serverLoader({
+    "node:fs": { writeFileSync: (_path: string, value: string) => workRecords.push(JSON.parse(value)), unlinkSync() {} },
+    "./image-archive-db": {
+      claimImageDownloadTask: async (id: string) => { claimed.push(id); return { id, targetUrl: `https://cdn.example/${id}.png`, metadata: {} }; },
+      saveImageDownloadAsset: async (id: string) => saved.push(id),
+      getImageDownloadTasks: async () => { scans++; return []; }, hasPendingImageDownloads: async () => false,
+    },
+    "./image-byte-cache": { fetchImageBytes: async () => { active++; maximum = Math.max(maximum, active); await new Promise<void>(resolve => releases.push(resolve)); active--; return { buffer: bytes, contentType: "image/png" }; }, cacheImageBytes: async () => {} },
+    "@/lib/canvas/photoshop-safe-download": { normalizeCanvasDownloadAsset: async () => ({ ok: true, bytes, contentType: "image/png" }) },
+    "./service": { uploadFile() { throw new Error("Compatible PNG must retain its object"); } },
+  })("lib/storage/image-download-preparation.ts");
+  worker.scheduleImageDownloadPreparation("one"); worker.scheduleImageDownloadPreparation("two"); worker.scheduleImageDownloadPreparation("three");
+  await expect.poll(() => active).toBe(2);
+  expect(workRecords.at(-1)).toMatchObject({ active: 1, durable: 0 });
+  expect(scans).toBe(0);
+  releases.splice(0).forEach(release => release());
+  await expect.poll(() => claimed.length).toBe(3);
+  releases.splice(0).forEach(release => release());
+  await expect.poll(() => saved.length).toBe(3);
+  expect(maximum).toBe(2); expect(scans).toBe(0);
+});
+
+test("archive URL replacement cannot block the download worker wakeup", async () => {
+  let scheduled = false; let finish!: () => void; let replacing = false;
+  const gate = new Promise<void>(resolve => { finish = resolve; });
+  const job = serverLoader({
+    "@/lib/observability/active-work": { trackRuntimeWork: (execute: () => Promise<unknown>) => execute() },
+    "@/lib/storage/image-download-preparation": { scheduleImageDownloadPreparation() { scheduled = true; } },
+    "@/lib/storage/image-archive-db": { recoverStaleImageArchiveTasks: async () => {}, getImageArchiveTasksToStore: async () => [],
+      getImageArchiveTasksToReplace: async () => [{ id: "archive", sourceUrl: "https://source.example/a", targetUrl: "https://cdn.example/a" }],
+      markImageArchiveTaskReplacing: async () => true, markImageArchiveTaskCompleted: async () => {}, hasPendingImageDownloads: async () => false,
+      getImageArchiveTaskStats: async () => ({ pendingStore: 0, pendingReplace: 0 }),
+    },
+    "@/lib/storage/image-url-replacement": { replaceImageUrlInDatabase: async () => { replacing = true; await gate; return { changed: 1 }; } },
+    "@/lib/storage/image-archive": {},
+  })("lib/jobs/image-archive-job.ts");
+  const running = job.runImageArchiveJob();
+  await expect.poll(() => replacing).toBe(true);
+  expect(scheduled).toBe(true);
+  finish();
+  expect((await running).replace.succeeded).toBe(1);
+});

tests/routes/canvas-toolbar-capability.test.ts

@@ -47,7 +47,7 @@ test("merges the result with edits made while processing and advances the save r
   globalThis.fetch = (async (url) => {
     if (String(url).endsWith("/capabilities")) {
       useCanvasStore.getState().moveNode("source", { x: 50, y: 80 });
-      return Response.json({ success: true });
+      return Response.json({ success: true, task: { status: "succeeded" } });
     }
     return Response.json({ success: true, data: {
       updatedAt: "r2", canvasData: { nodes: [node("source"), node("result")], edges: [] },
@@ -67,12 +67,31 @@ test("a provider failure is shown without reloading or changing the canvas", asy
   expect(useCanvasStore.getState().canvasRevision).toBe("r1");
 });
 
+test("a lost submission response polls the original task and never resubmits", async () => {
+  const requests: { method: string; url: string }[] = [];
+  const originalSetTimeout = globalThis.setTimeout;
+  let polls = 0;
+  globalThis.setTimeout = ((fn: () => void) => originalSetTimeout(fn, 0)) as typeof setTimeout;
+  globalThis.fetch = (async (url, init) => {
+    requests.push({ method: init?.method || "GET", url: String(url) });
+    if (init?.method === "POST") throw new TypeError("fetch failed");
+    if (String(url).includes("/capabilities?")) return Response.json({ success: true, task: { status: ++polls === 1 ? "running" : "succeeded" } });
+    return Response.json({ success: true, data: { updatedAt: "r2", canvasData: { nodes: [node("source"), node("result")], edges: [] } } });
+  }) as typeof fetch;
+  const submitted = command();
+  try { await executeCanvasToolbarCapability(submitted); } finally { globalThis.setTimeout = originalSetTimeout; }
+  expect(requests.filter(r => r.method === "POST")).toHaveLength(1);
+  expect(requests.filter(r => r.url.includes("/capabilities?"))).toHaveLength(2);
+  expect(requests.filter(r => r.url.includes("/capabilities?")).every(r => r.url.includes(encodeURIComponent(submitted.requestId)))).toBe(true);
+  expect(useCanvasStore.getState().nodes.map(n => n.id)).toEqual(["source", "result"]);
+});
+
 test("switching projects during processing does not load the old result into the new project", async () => {
   globalThis.fetch = (async (url) => {
     if (String(url).endsWith("/capabilities")) {
       useCanvasStore.getState().setProject("project-b");
       useCanvasStore.getState().loadCanvas({ nodes: [node("other") as any], edges: [] });
-      return Response.json({ success: true });
+      return Response.json({ success: true, task: { status: "succeeded" } });
     }
     return Response.json({ success: true, data: { updatedAt: "r2", canvasData: { nodes: [node("result")], edges: [] } } });
   }) as typeof fetch;
@@ -104,7 +123,7 @@ test("a result merge conflict retains both the local edit and its original revis
   globalThis.fetch = (async (url) => {
     if (String(url).endsWith("/capabilities")) {
       useCanvasStore.getState().moveNode("source", { x: 50, y: 80 });
-      return Response.json({ success: true });
+      return Response.json({ success: true, task: { status: "succeeded" } });
     }
     return Response.json({ success: true, data: { updatedAt: "r2", canvasData: {
       nodes: [{ ...node("source"), position: { x: 200, y: 80 } }, node("result")], edges: [],

tests/routes/image-archive-flow.test.ts

@@ -224,7 +224,7 @@ test("bucket failure retains the provider URL and retry task", async () => {
   let stored = 0;
   let replaced = 0;
   const module = serverLoader({
-    "@/lib/storage/image-download-preparation": { preparePendingImageDownloads: async () => 0 },
+    "@/lib/storage/image-download-preparation": { scheduleImageDownloadPreparation() {} },
     "@/lib/storage/image-archive": {
       archiveTemporaryImage: async () => {
         throw new Error("Bucket unavailable");
@@ -414,7 +414,7 @@ test("successful background archive replaces saved references immediately", asyn
   let completed = false;
   const calls: string[][] = [];
   const module = serverLoader({
-    "@/lib/storage/image-download-preparation": { preparePendingImageDownloads: async () => 0 },
+    "@/lib/storage/image-download-preparation": { scheduleImageDownloadPreparation() {} },
     "@/lib/storage/image-archive": {
       archiveTemporaryImage: async () => ({ url: permanent, bytes: png.length }),
     },

tests/routes/image-delivery-qiniu.test.ts

@@ -154,7 +154,7 @@ test.describe("Qiniu image delivery", () => {
       expect((await GET(new NextRequest("http://localhost/api/image-proxy?url=http%3A%2F%2F192.168.1.1%2Fsecret&original=1"))).status).toBe(403);
       expect((await GET(new NextRequest("http://localhost/api/image-proxy?url=https%3A%2F%2Fpublic.example%2Fa.jpg&original=1&w=200"))).status).toBe(400);
       expect(fetchCount).toBe(0);
-      expect((await GET(new NextRequest("http://localhost/api/image-proxy?url=https%3A%2F%2Fpublic.example%2Fa.jpg&original=1"))).status).toBe(400);
+      expect((await GET(new NextRequest("http://localhost/api/image-proxy?url=https%3A%2F%2Fpublic.example%2Fa.jpg&original=1"))).status).toBe(422);
     } finally {
       globalThis.fetch = previousFetch;
     }

tests/routes/image-provider-error-classification.test.ts

@@ -2,11 +2,34 @@ import { expect, test } from "@playwright/test";
 import {
   getUserFacingImageGenerationErrorMessage,
   getUserFacingRequestErrorMessage,
+  getRequestFailureDetails,
+  formatRequestFailure,
   getGatewayErrorPageMessage,
   isGatewayResponseTimeout,
   isProviderBalanceError,
   isRateLimitError,
 } from "@/lib/request-error";
+
+test("known provider and platform failures explain their cause and next action", () => {
+  for (const [message, code, next] of [
+    ["We are sorry, this prompt may violate our content policies", "CONTENT_POLICY_REJECTED", "调整描述"],
+    ["The channel is temporarily unavailable", "PROVIDER_UNAVAILABLE", "切换其他"],
+    ["generate image failed", "PROVIDER_EXECUTION_FAILED", "稍后重试"],
+    ["excessive system load", "PROVIDER_EXECUTION_FAILED", "稍后重试"],
+    ["get image url failed", "SOURCE_IMAGE_UNAVAILABLE", "重新上传"],
+    ["抠图处理失败", "PROCESSING_FAILED", "核对原任务"],
+    ["去水印处理失败", "PROCESSING_FAILED", "核对原任务"],
+    ["图片上传到存储桶失败", "RESULT_STORAGE_FAILED", "不要重复生成"],
+    ["任务执行中断，结果尚未确认", "RESULT_UNCONFIRMED", "避免重复生成"],
+  ]) {
+    const failure = getRequestFailureDetails(new Error(message));
+    expect(failure.code).toBe(code);
+    expect(failure.recommendation).toContain(next);
+    expect(formatRequestFailure(failure, "request-123")).toContain("请求编号：request-123");
+  }
+  expect(getRequestFailureDetails({ providerOutcomeUnknown: true, message: "content policy" }).outcome).toBe("unknown");
+  expect(getRequestFailureDetails(new Error("图片上传到存储桶失败")).outcome).toBe("unknown");
+});
 import { isImageModelBalanceBlocked, resolveConfiguredImageBalanceFallback } from "@/lib/ai/runtime/image-balance";
 import { serverLoader } from "../helpers/canvas-download-server-loader";
 
@@ -45,13 +68,14 @@ test("HTTP 524 does not start another model while the original result is unconfi
   expect(health.shouldFailoverAiModelError(new Error("Service unavailable (HTTP 503)"))).toBe(true);
 });
 
-test("the provider submits once and keeps an HTTP 524 response unconfirmed", async () => {
+test("the provider submits once when an HTTP 524 request cannot be located", async () => {
   let submissions = 0;
   const provider = serverLoader({
     "@/lib/db/queries": { getSystemSetting: async () => null },
     "@/lib/storage/image-archive": {},
     "@/lib/storage/service": {},
-    fetch: async () => {
+    fetch: async (_url: string, init: RequestInit) => {
+      if (init?.method !== "POST") return Response.json({}, { status: 404 });
       submissions++;
       return new Response(gatewayHtml, { status: 524, headers: { "content-type": "text/html" } });
     },
@@ -61,6 +85,136 @@ test("the provider submits once and keeps an HTTP 524 response unconfirmed", asy
   expect(submissions).toBe(1);
 });
 
+function imageRecoveryHarness(
+  handler: (path: string, method: string, call: number) => Response | Promise<Response>,
+  maxPollSeconds = 3,
+) {
+  let now = 1_000;
+  const calls: { path: string; method: string; headers: Headers }[] = [];
+  const archived: string[] = [];
+  const load = serverLoader({
+    "@/lib/db": { db: {} },
+    "@/lib/db/queries": { getSystemSetting: async () => null },
+    "@/lib/storage/image-archive": { createDeferredUploadedImage: async (url: string) => {
+      archived.push(url);
+      return { thumbnail: url, original: url };
+    } },
+    "@/lib/storage/service": {},
+    Date: class extends Date { static now() { return now; } },
+    setTimeout: (fn: () => void, ms: number) => { now += ms; return setTimeout(fn, 0); },
+    fetch: async (url: string, init: RequestInit) => {
+      const path = new URL(url).pathname;
+      const method = init?.method || "GET";
+      calls.push({ path, method, headers: new Headers(init?.headers) });
+      return handler(path, method, calls.length);
+    },
+  });
+  const provider = load("lib/ai/providers/vip98k.ts");
+  return {
+    calls, load, archived,
+    generate: () => provider.createVip98k({ apiKey: "test-only-key", baseURL: "https://provider.test" })
+      .chat("gpt-image-2.5", { capabilities: { vip98k: { pollIntervalSeconds: 1, maxPollSeconds } } })
+      .doGenerate({ messages: [{ role: "user", content: "A desk" }] }),
+    run: () => provider.executeVip98kExternalTask({
+      apiKey: "test-only-key", baseURL: "https://provider.test", modelId: "gpt-image-2.5",
+      kind: "image", prompt: "A desk", imageUrls: [],
+      modelConfig: { capabilities: { vip98k: { pollIntervalSeconds: 1, maxPollSeconds } } },
+    }),
+  };
+}
+
+const recoveredImage = { created: 1, data: [{ url: "https://image.example/original.png" }] };
+const originalCompleted = { request_id: "original-request", status: "succeeded", result_available: true };
+
+test("an edge timeout waits for and delivers the original image without another POST", async () => {
+  let lookups = 0;
+  const h = imageRecoveryHarness((path, method) => {
+    if (method === "POST") return new Response(gatewayHtml, { status: 524 });
+    if (path.endsWith("by-idempotency-key")) {
+      return Response.json(++lookups === 1 ? { status: "processing" } : originalCompleted);
+    }
+    return Response.json(recoveredImage);
+  });
+  expect((await h.generate()).text).toContain(recoveredImage.data[0].url);
+  expect(h.archived).toEqual([recoveredImage.data[0].url]);
+  expect(h.calls.filter(c => c.method === "POST")).toHaveLength(1);
+  expect(lookups).toBe(2);
+  const originalKey = h.calls[0].headers.get("Idempotency-Key");
+  expect(originalKey).toBeTruthy();
+  for (const call of h.calls.filter(c => c.path.endsWith("by-idempotency-key"))) {
+    expect(call.headers.get("Idempotency-Key")).toBe(originalKey);
+    expect(call.headers.get("Authorization")).toBe("Bearer test-only-key");
+  }
+  expect(h.calls.at(-1)?.path).toBe("/api/external/requests/original-request/result");
+});
+
+test("a lost POST response recovers by its original key without resubmitting", async () => {
+  const h = imageRecoveryHarness((path, method) => {
+    if (method === "POST") throw new TypeError("fetch failed");
+    return Response.json(path.endsWith("by-idempotency-key") ? originalCompleted : recoveredImage);
+  });
+  expect((await h.run()).outputUrls).toHaveLength(1);
+  expect(h.calls.filter(c => c.method === "POST")).toHaveLength(1);
+});
+
+test("temporary lookup and result-read failures retry only GET requests", async () => {
+  let lookups = 0;
+  let reads = 0;
+  const h = imageRecoveryHarness((path, method) => {
+    if (method === "POST") return new Response("Gateway timeout", { status: 504 });
+    if (path.endsWith("by-idempotency-key")) {
+      return ++lookups === 1 ? new Response("Unavailable", { status: 503 }) : Response.json(originalCompleted);
+    }
+    return ++reads === 1 ? Response.json({}, { status: 409 }) : Response.json(recoveredImage);
+  }, 5);
+  expect((await h.run()).outputUrls).toHaveLength(1);
+  expect(h.calls.filter(c => c.method === "POST")).toHaveLength(1);
+  expect(reads).toBe(2);
+});
+
+test("missing, unconfirmed and unretained originals never create a replacement", async () => {
+  for (const state of [null, { status: "failed" }, { status: "unresolved" }, { ...originalCompleted, result_available: false }]) {
+    const h = imageRecoveryHarness((_path, method) => method === "POST"
+      ? new Response(gatewayHtml, { status: 524 })
+      : Response.json(state || {}, { status: state ? 200 : 404 }));
+    await expect(h.run()).rejects.toThrow(/结果未确认.*HTTP 524/);
+    expect(h.calls.map(c => c.method)).toEqual(["POST", "GET"]);
+  }
+});
+
+test("a still-processing original stops at the polling deadline without another POST", async () => {
+  const h = imageRecoveryHarness((_path, method) => method === "POST"
+    ? new Response(gatewayHtml, { status: 524 }) : Response.json({ status: "processing" }), 2);
+  await expect(h.run()).rejects.toThrow(/结果未确认.*HTTP 524/);
+  expect(h.calls.map(c => c.method)).toEqual(["POST", "GET", "GET"]);
+});
+
+test("HTTP 502 and 504 without a recoverable original do not repeat the POST", async () => {
+  for (const status of [502, 504]) {
+    const h = imageRecoveryHarness((_path, method) => method === "POST"
+      ? new Response("Gateway timeout", { status }) : Response.json({}, { status: 404 }));
+    await expect(h.run()).rejects.toThrow(/结果未确认/);
+    expect(h.calls.map(c => c.method)).toEqual(["POST", "GET"]);
+  }
+});
+
+test("a completed original with no image stays unconfirmed and cannot fail over", async () => {
+  const h = imageRecoveryHarness((path, method) => {
+    if (method === "POST") return new Response(gatewayHtml, { status: 524 });
+    return Response.json(path.endsWith("by-idempotency-key") ? originalCompleted : { data: [] });
+  });
+  const error = await h.run().then(() => null, (e: Error) => e);
+  expect(error).toBeTruthy();
+  expect(h.load("lib/ai/runtime/model-health.ts").shouldFailoverAiModelError(error)).toBe(false);
+  expect(h.calls.filter(c => c.method === "POST")).toHaveLength(1);
+});
+
+test("ordinary image success uses the original response directly", async () => {
+  const h = imageRecoveryHarness(() => Response.json(recoveredImage));
+  expect((await h.run()).outputUrls).toHaveLength(1);
+  expect(h.calls.map(c => c.method)).toEqual(["POST"]);
+});
+
 test("an explicit provider balance error takes precedence over HTTP 429", () => {
   const error = Object.assign(new Error("余额不足，请点击充值页面续费（HTTP 429）"), { status: 429 });
   expect(isProviderBalanceError(error)).toBe(true);

tests/routes/original-image-download.test.ts

@@ -0,0 +1,114 @@
+import { test, expect } from "@playwright/test";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+
+const config = { type: "qiniu-kodo", isEnabled: true, publicUrl: "https://cdn.example" };
+
+test("original downloads use the archived JPEG rather than the prepared PNG and transfer only HEAD metadata", async () => {
+  const calls: Array<{ url: string; method: string }> = [];
+  const loader = serverLoader({
+    "@/lib/db/queries": { getDefaultStorageConfig: async () => config },
+    "./image-archive-db": { findImageArchiveDownloadTask: async () => ({ targetUrl: "https://cdn.example/original.jpg", metadata: {
+      downloadAsset: { status: "ready", url: "https://cdn.example/converted.png", contentType: "image/png" },
+    } }) },
+    fetch: async (url: URL, options: { method: string }) => {
+      calls.push({ url: url.toString(), method: options.method });
+      return { ok: true, headers: new Headers({ "content-type": "image/jpeg", "content-length": "12345" }),
+        arrayBuffer() { throw new Error("Image bytes must bypass the application"); } };
+    },
+  });
+  const result = await loader("lib/storage/original-image-download.ts").resolveOriginalCdnDownload("https://upstream.example/temporary.png", "产品.png", new AbortController().signal);
+  expect(calls).toEqual([{ url: "https://cdn.example/original.jpg", method: "HEAD" }]);
+  expect(result).toMatchObject({ delivery: "cdn", filename: "产品.jpg", bytes: 12345 });
+  expect(new URL(result.downloadUrl).pathname).toBe("/original.jpg");
+});
+
+test("signed original URLs retain the byte-preserving proxy without changing their signature", async () => {
+  const module = serverLoader({
+    "@/lib/db/queries": { getDefaultStorageConfig: async () => config },
+    "./image-archive-db": { findImageArchiveDownloadTask: async () => null },
+    fetch() { throw new Error("Do not add filename parameters to a signed URL"); },
+  })("lib/storage/original-image-download.ts");
+  const result = await module.resolveOriginalCdnDownload("https://cdn.example/source.jpg?token=signature%2Fvalue&e=123", "image.jpg", new AbortController().signal);
+  expect(result).toBeNull();
+});
+
+test("existing CDN objects bypass the archive scan and retain the MIME-derived format", async () => {
+  const module = serverLoader({
+    "@/lib/db/queries": { getDefaultStorageConfig: async () => config },
+    "./image-archive-db": { findImageArchiveDownloadTask() { throw new Error("An existing CDN object needs no archive scan"); } },
+    fetch: async () => ({ ok: true, headers: new Headers({ "content-type": "image/webp" }) }),
+  })("lib/storage/original-image-download.ts");
+  const result = await module.resolveOriginalCdnDownload("https://cdn.example/source.png", "source.png", new AbortController().signal);
+  expect(result.filename).toBe("source.webp");
+  expect(new URL(result.downloadUrl).pathname).toBe("/source.png");
+});
+
+test("temporary third-party URLs are never checked with HEAD when no archive is ready", async () => {
+  const module = serverLoader({
+    "@/lib/db/queries": { getDefaultStorageConfig: async () => config },
+    "./image-archive-db": { findImageArchiveDownloadTask: async () => null },
+    fetch() { throw new Error("The upstream file service does not support HEAD"); },
+  })("lib/storage/original-image-download.ts");
+  expect(await module.resolveOriginalCdnDownload("https://upstream.example/image.png", "image", new AbortController().signal)).toBeNull();
+});
+
+test("original download metadata reports missing sources with cause, advice and a feedback ID", async () => {
+  const route = serverLoader({
+    "next/server": { NextResponse: Response },
+    "@/lib/storage/original-image-download": { resolveOriginalCdnDownload: async () => { throw new Error("HTTP 404"); } },
+  })("app/api/image-proxy/route.ts");
+  const request = { nextUrl: new URL("https://app.example/api/image-proxy?url=https%3A%2F%2Fcdn.example%2Fmissing.jpg&original=1&download=resolve"), signal: new AbortController().signal, headers: new Headers() };
+  const response = await route.GET(request);
+  const data = await response.json();
+  expect(response.status).toBe(404);
+  expect(data.failure).toMatchObject({ code: "SOURCE_NOT_FOUND", retryable: false });
+  expect(data.failure.recommendation).toBeTruthy();
+  expect(data.error).toContain(data.requestId);
+});
+
+function browserMocks() {
+  const frames: any[] = []; const links: any[] = [];
+  return { frames, links,
+    window: { location: { origin: "https://app.example" }, setTimeout() {} },
+    document: { createElement: (tag: string) => ({ tag, click() { links.push(this); }, remove() {} }),
+      body: { appendChild: (el: any) => { if (el.tag === "iframe") frames.push(el); }, removeChild() {} } },
+  };
+}
+
+test("chat original downloads use a native CDN download without fetching the image through CORS", async () => {
+  const dom = browserMocks(); const calls: string[] = [];
+  const client = serverLoader({ ...dom, fetch: async (url: string) => {
+    calls.push(url);
+    return Response.json({ delivery: "cdn", downloadUrl: "https://cdn.example/image.jpg?attname=original.jpg", filename: "original.jpg", bytes: 5000000 });
+  } })("lib/client/canvas-image-download.ts");
+  const result = await client.downloadOriginalImage({ url: "https://cdn.example/image.jpg" });
+  expect(result).toEqual({ filename: "original.jpg", bytes: 5000000 });
+  expect(calls).toHaveLength(1);
+  expect(new URL(calls[0], "https://app.example").searchParams.get("download")).toBe("resolve");
+  expect(dom.frames[0].src).toBe("https://cdn.example/image.jpg?attname=original.jpg");
+  expect(dom.links).toHaveLength(0);
+});
+
+test("original fallback preserves JPEG bytes and the MIME-derived filename", async () => {
+  const dom = browserMocks(); const bytes = Buffer.from([255, 216, 255, 224, 0, 16, 74, 70, 73, 70, 255, 217]); let calls = 0;
+  const client = serverLoader({ ...dom, fetch: async () => ++calls === 1 ? Response.json({ delivery: "proxy" }) : new Response(bytes, { headers: { "content-type": "image/jpeg" } }) })("lib/client/canvas-image-download.ts");
+  expect(await client.downloadOriginalImage({ url: "https://external.example/image.png", name: "original.png" })).toEqual({ filename: "original.jpg", bytes: bytes.length });
+  expect(calls).toBe(2);
+  const actual = await fetch(dom.links[0].href).then(r=>r.arrayBuffer());
+  expect(Buffer.from(actual).equals(bytes)).toBe(true);
+  URL.revokeObjectURL(dom.links[0].href);
+});
+
+test("original downloads reject processed references before network access", async () => {
+  const client = serverLoader({ ...browserMocks(), fetch() { throw new Error("Must not fetch a processed image as an original"); } })("lib/client/canvas-image-download.ts");
+  await expect(client.downloadOriginalImage({ url: "https://cdn.example/image.jpg?imageView2/2/w/320&token=signed" })).rejects.toThrow("无法确认原图");
+});
+
+test("chat downloads display the server cause and advice without losing its feedback ID", async () => {
+  const failure = { code: "SOURCE_FORBIDDEN", message: "图片源站拒绝访问原图。", recommendation: "请联系管理员检查访问权限。", status: 403, retryable: false };
+  const client = serverLoader({ ...browserMocks(), fetch: async () => Response.json({ failure, requestId: "original-feedback" }, { status: 403 }) })("lib/client/canvas-image-download.ts");
+  let error: unknown;
+  try { await client.downloadOriginalImage({ url: "https://cdn.example/image.jpg" }); } catch(e) { error=e; }
+  expect(client.getCanvasImageDownloadErrorMessage(error)).toContain("下载编号：original-feedback");
+  expect(client.getCanvasImageDownloadErrorMessage(error)).toContain(failure.recommendation);
+});

tests/routes/runtime-active-work.test.ts

@@ -0,0 +1,30 @@
+import { expect, test } from "@playwright/test";
+import { serverLoader } from "../helpers/canvas-download-server-loader";
+
+test("release draining includes background work until its original promise settles", async () => {
+  const counts: number[] = [];
+  const work = serverLoader({
+    "node:fs": { writeFileSync: (_path: string, text: string) => counts.push(JSON.parse(text).active), unlinkSync() {} },
+  })("lib/observability/active-work.ts");
+  let finish!: () => void;
+  const original = new Promise<void>(resolve => { finish = resolve; });
+  const pending = work.trackRuntimeWork(() => original);
+  await work.trackRuntimeWork(async () => "another request");
+  expect(counts).toEqual([1, 2, 1]);
+  finish();
+  await pending;
+  expect(counts).toEqual([1, 2, 1, 0]);
+  await expect(work.trackRuntimeWork(async () => { throw new Error("expected failure"); })).rejects.toThrow("expected failure");
+  expect(counts.at(-1)).toBe(0);
+});
+
+test("durable archive handoff is separate from unfinished original generation", async () => {
+  const records: Array<{ active: number; durable: number }> = [];
+  const work = serverLoader({ "node:fs": { writeFileSync: (_path: string, value: string) => records.push(JSON.parse(value)), unlinkSync() {} } })("lib/observability/active-work.ts");
+  let complete!: () => void;
+  const original = work.trackRuntimeWork(() => new Promise<void>(resolve => { complete = resolve; }));
+  await work.trackRuntimeWork(async () => "archive", { durable: true });
+  expect(records.map(x => [x.active, x.durable])).toEqual([[1, 0], [2, 1], [1, 0]]);
+  complete(); await original;
+  expect(records.at(-1)).toMatchObject({ active: 0, durable: 0 });
+});