diff --git a/app/api/canvas/text-edit/route.ts b/app/api/canvas/text-edit/route.ts
index c08192485..05052e178 100644
--- a/app/api/canvas/text-edit/route.ts
+++ b/app/api/canvas/text-edit/route.ts
@@ -16,11 +16,14 @@ import { createKrea } from "@/lib/ai/providers/krea";
 import { createVolcanoVision } from "@/lib/ai/providers/volcano-vision";
 import { isImageGenerationModelDescriptor } from "@/lib/ai/model-classification";
 import { createLogger } from "@/lib/observability/logger";
+import { uploadFile } from "@/lib/storage/service";
 
 export const runtime = "nodejs";
 export const maxDuration = 120;
 
 const logger = createLogger("canvas-text-edit");
+const TEXT_EDIT_SOURCE_ARCHIVE_TIMEOUT_MS = 20_000;
+const TEXT_EDIT_MODEL_FALLBACK_LIMIT = 3;
 
 const textItemSchema = z.object({
   id: z.string().min(1),
@@ -50,8 +53,12 @@ const SUPPORTED_TEXT_EDIT_PROVIDER_TYPES = new Set([
   "volcano-vision",
 ]);
 
-function pickTextEditModel(models: Awaited<ReturnType<typeof getEnabledAiModelsWithProvider>>) {
-  const candidates = models
+type TextEditModelCandidate = Awaited<ReturnType<typeof getEnabledAiModelsWithProvider>>[number];
+
+function getTextEditModelCandidates(
+  models: Awaited<ReturnType<typeof getEnabledAiModelsWithProvider>>
+) {
+  return models
     .filter(
       (item) =>
         isImageGenerationModelDescriptor({
@@ -77,8 +84,6 @@ function pickTextEditModel(models: Awaited<ReturnType<typeof getEnabledAiModelsW
         (b.model.displayName?.includes("火山") ? 3 : 0);
       return bScore - aScore;
     });
-
-  return candidates[0];
 }
 
 function createTextEditProvider(
@@ -118,6 +123,85 @@ function createTextEditProvider(
   }
 }
 
+function bufferToArrayBuffer(buffer: Buffer): ArrayBuffer {
+  return buffer.buffer.slice(
+    buffer.byteOffset,
+    buffer.byteOffset + buffer.byteLength
+  ) as ArrayBuffer;
+}
+
+function inferImageExtension(contentType: string, imageUrl: string) {
+  const normalizedContentType = contentType.toLowerCase();
+  if (normalizedContentType.includes("image/jpeg")) return "jpg";
+  if (normalizedContentType.includes("image/png")) return "png";
+  if (normalizedContentType.includes("image/webp")) return "webp";
+  if (normalizedContentType.includes("image/gif")) return "gif";
+  const pathname = (() => {
+    try {
+      return new URL(imageUrl).pathname;
+    } catch {
+      return "";
+    }
+  })();
+  const match = pathname.match(/\.([a-z0-9]{2,5})$/i);
+  const ext = String(match?.[1] || "").toLowerCase();
+  return ["jpg", "jpeg", "png", "webp", "gif"].includes(ext) ? ext : "png";
+}
+
+async function archiveTextEditSourceImage(imageUrl: string) {
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), TEXT_EDIT_SOURCE_ARCHIVE_TIMEOUT_MS);
+
+  try {
+    const response = await fetch(imageUrl, {
+      cache: "no-store",
+      signal: controller.signal,
+    });
+    if (!response.ok) {
+      throw new Error(`源图下载失败：${response.status} ${response.statusText}`);
+    }
+
+    const contentType = response.headers.get("content-type") || "";
+    if (contentType && !contentType.toLowerCase().startsWith("image/")) {
+      throw new Error(`源图类型异常：${contentType}`);
+    }
+
+    const buffer = Buffer.from(await response.arrayBuffer());
+    if (buffer.length === 0) {
+      throw new Error("源图为空文件");
+    }
+
+    const ext = inferImageExtension(contentType, imageUrl);
+    const uploaded = await uploadFile(
+      `canvas-text-edit-source-${Date.now()}-${Math.random().toString(36).slice(2, 8)}.${ext}`,
+      bufferToArrayBuffer(buffer)
+    );
+    return {
+      bytes: buffer.length,
+      url: uploaded.url,
+    };
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}
+
+async function resolveTextEditSourceImageUrl(imageUrl: string) {
+  try {
+    const archived = await archiveTextEditSourceImage(imageUrl);
+    logger.info("source_image_archived", {
+      bytes: archived.bytes,
+      sourceHost: new URL(imageUrl).host,
+      targetHost: new URL(archived.url).host,
+    });
+    return archived.url;
+  } catch (error) {
+    logger.warn("source_image_archive_failed", {
+      error: error instanceof Error ? error.message : String(error),
+    });
+    return imageUrl;
+  }
+}
+
 function normalizeGeneratedImageUrl(value: unknown) {
   const raw = String(value || "").trim();
   if (!raw) return "";
@@ -271,6 +355,70 @@ function buildTextEditPrompt(
   return sections.join("\n");
 }
 
+async function generateTextEditImageWithFailover(params: {
+  candidates: TextEditModelCandidate[];
+  imageUrl: string;
+  prompt: string;
+}) {
+  let lastError: unknown = null;
+  const candidates = params.candidates.slice(0, TEXT_EDIT_MODEL_FALLBACK_LIMIT);
+
+  for (const selected of candidates) {
+    try {
+      logger.info("selected_model", {
+        providerType: selected.provider.type,
+        providerName: selected.provider.name,
+        modelId: selected.model.modelId,
+        displayName: selected.model.displayName,
+        isDefault: selected.model.isDefault,
+        isDefaultTextEditModel: selected.model.isDefaultTextEditModel,
+      });
+
+      const provider = createTextEditProvider(selected.provider);
+      const result = await provider.chat(selected.model.modelId).doGenerate({
+        messages: [
+          {
+            role: "user",
+            content: [
+              { type: "image_url", image_url: { url: params.imageUrl } },
+              { type: "text", text: params.prompt },
+            ],
+          },
+        ],
+        imageParams: {
+          imageCount: 1,
+        },
+      });
+
+      const resultText = String(result?.text || "").trim();
+      const finishReason = String(result?.finishReason || "").toLowerCase();
+      if (!resultText) {
+        throw new Error("模型未返回结果");
+      }
+      if (finishReason === "error" || resultText.startsWith("图片生成失败")) {
+        throw new Error(resultText);
+      }
+
+      const parsed = parseImageFromGenerationText(resultText);
+      return {
+        ...parsed,
+        model: selected.model.displayName,
+      };
+    } catch (error) {
+      lastError = error;
+      logger.warn("candidate_failed", {
+        providerType: selected.provider.type,
+        providerName: selected.provider.name,
+        modelId: selected.model.modelId,
+        displayName: selected.model.displayName,
+        error: error instanceof Error ? error.message : String(error),
+      });
+    }
+  }
+
+  throw lastError instanceof Error ? lastError : new Error("文字替换失败");
+}
+
 export async function POST(request: Request) {
   try {
     const session = await auth();
@@ -327,9 +475,9 @@ export async function POST(request: Request) {
     }
 
     const models = await getEnabledAiModelsWithProvider();
-    const selected = pickTextEditModel(models);
+    const candidates = getTextEditModelCandidates(models);
 
-    if (!selected) {
+    if (candidates.length === 0) {
       return NextResponse.json(
         {
           success: false,
@@ -339,46 +487,20 @@ export async function POST(request: Request) {
       );
     }
 
-    logger.info("selected_model", {
-      providerType: selected.provider.type,
-      providerName: selected.provider.name,
-      modelId: selected.model.modelId,
-      displayName: selected.model.displayName,
-      isDefault: selected.model.isDefault,
-      isDefaultTextEditModel: selected.model.isDefaultTextEditModel,
-    });
-
-    const provider = createTextEditProvider(selected.provider);
-
     const prompt = buildTextEditPrompt(replacements, deletions);
-
-    const result = await provider.chat(selected.model.modelId).doGenerate({
-      messages: [
-        {
-          role: "user",
-          content: [
-            { type: "image_url", image_url: { url: imageUrl } },
-            { type: "text", text: prompt },
-          ],
-        },
-      ],
-      imageParams: {
-        imageCount: 1,
-      },
+    const generationSourceImageUrl = await resolveTextEditSourceImageUrl(imageUrl);
+    const { originalUrl, thumbnailUrl, model } = await generateTextEditImageWithFailover({
+      candidates,
+      imageUrl: generationSourceImageUrl,
+      prompt,
     });
 
-    if (!result?.text) {
-      throw new Error("模型未返回结果");
-    }
-
-    const { originalUrl, thumbnailUrl } = parseImageFromGenerationText(result.text);
-
     return NextResponse.json({
       success: true,
       data: {
         originalUrl,
         thumbnailUrl,
-        model: selected.model.displayName,
+        model,
       },
     });
   } catch (error) {
diff --git a/components/agents/AgentDetailReferenceStitchDialog.tsx b/components/agents/AgentDetailReferenceStitchDialog.tsx
index dba96df1e..6de97f37b 100644
--- a/components/agents/AgentDetailReferenceStitchDialog.tsx
+++ b/components/agents/AgentDetailReferenceStitchDialog.tsx
@@ -894,7 +894,13 @@ export function AgentDetailReferenceStitchDialog({
                                   </div>
                                   <button
                                     type="button"
+                                    onPointerDown={(event) => {
+                                      event.preventDefault();
+                                      event.stopPropagation();
+                                      setDraggingLineIndex(null);
+                                    }}
                                     onClick={(event) => {
+                                      event.preventDefault();
                                       event.stopPropagation();
                                       handleRemoveCutLine(index);
                                     }}