diff --git a/components/canvas/CanvasChatPanel.tsx b/components/canvas/CanvasChatPanel.tsx
index a4e9e0018..22f897b2f 100644
--- a/components/canvas/CanvasChatPanel.tsx
+++ b/components/canvas/CanvasChatPanel.tsx
@@ -5175,6 +5175,12 @@ export function CanvasChatPanel({
   
   useEffect(() => {
     if (!hasHydratedHistoryRef.current) return;
+    const activeStreamState = streamImageGenerationStateByChatId[activeChatId];
+    const shouldDeferAssistantMediaAutosync =
+      activeStreamState?.phase === "queued" ||
+      activeStreamState?.phase === "processing" ||
+      activeStreamState?.phase === "finalizing";
+    if (shouldDeferAssistantMediaAutosync) return;
 
     let cancelled = false;
 
@@ -5515,6 +5521,7 @@ export function CanvasChatPanel({
       cancelled = true;
     };
   }, [
+    activeChatId,
     messages,
     addNode,
     nodes,
@@ -5522,6 +5529,7 @@ export function CanvasChatPanel({
     clearStreamImageGenerationStateForChat,
     focusCanvasOnNode,
     selectNodes,
+    streamImageGenerationStateByChatId,
     updateNode,
   ]);
 
diff --git a/lib/canvas/agent-mutations.ts b/lib/canvas/agent-mutations.ts
index b72362333..adfc93700 100644
--- a/lib/canvas/agent-mutations.ts
+++ b/lib/canvas/agent-mutations.ts
@@ -115,15 +115,32 @@ function buildMediaNode(params: {
 }) {
   const now = new Date().toISOString();
   const type = mediaNodeType(params.item);
+  const itemMetadata =
+    params.item.metadata &&
+    typeof params.item.metadata === "object" &&
+    !Array.isArray(params.item.metadata)
+      ? params.item.metadata
+      : {};
+  const planMetadata =
+    params.plan.metadata &&
+    typeof params.plan.metadata === "object" &&
+    !Array.isArray(params.plan.metadata)
+      ? params.plan.metadata
+      : {};
+  const sourceMessageId = String(
+    itemMetadata.messageId || planMetadata.messageId || ""
+  ).trim();
   const metadata = {
-    ...(params.plan.metadata || {}),
-    ...(params.item.metadata || {}),
+    ...planMetadata,
+    ...itemMetadata,
     generatedByAgent: true,
     canvasAgentOperationId: params.plan.operationId,
     canvasAgentOperation: params.plan.operation,
     canvasAgentMediaItemId: params.item.mediaItemId,
     canvasAgentPlacement: params.plan.placement,
     canvasAgentPlacementStrategy: params.plan.placementStrategy,
+    sourceMessageId: sourceMessageId || undefined,
+    sourceImageKey: type === "image" && sourceMessageId ? params.item.url : undefined,
     sourceNodeIds: params.sourceNodeIds,
     revisionOf:
       params.plan.operation === "append_revision"
diff --git a/tests/routes/canvas-chat-helpers.test.ts b/tests/routes/canvas-chat-helpers.test.ts
index d27b46300..ac4f2c910 100644
--- a/tests/routes/canvas-chat-helpers.test.ts
+++ b/tests/routes/canvas-chat-helpers.test.ts
@@ -1095,6 +1095,9 @@ test.describe("canvas chat pure helpers", () => {
             url: "https://cdn.example.com/revision.png",
             title: "白底版本",
             prompt: "换成白底",
+            metadata: {
+              messageId: "assistant-append-1",
+            },
           },
         ],
       },
@@ -1118,6 +1121,8 @@ test.describe("canvas chat pure helpers", () => {
           canvasAgentOperationId: "op-append-1",
           canvasAgentMediaItemId: "media-append-1",
           revisionOf: "image-1",
+          sourceMessageId: "assistant-append-1",
+          sourceImageKey: "https://cdn.example.com/revision.png",
         },
       },
     });