diff --git a/components/canvas/CanvasChatPanel.tsx b/components/canvas/CanvasChatPanel.tsx
index cc384e868..512952ac9 100644
--- a/components/canvas/CanvasChatPanel.tsx
+++ b/components/canvas/CanvasChatPanel.tsx
@@ -120,6 +120,7 @@ import {
   shouldBypassCanvasImagePointsPrecheckForAgentControl,
   shouldPreserveCanvasAgentSlotOnlyContext,
 } from "@/lib/canvas/agent-client-intent";
+import { orderItemsBySelectionIds } from "@/lib/canvas/selection-order";
 import { getCanvasSkillIconComponent } from "@/components/canvas/canvas-skill-icons";
 import { ImageParamsBar, type ImageGenerationParams } from "@/components/image-params-bar";
 import { VideoParamsBar, type VideoGenerationParams } from "@/components/video-params-bar";
@@ -2190,13 +2191,16 @@ export function CanvasChatPanel({
   );
   
   // 获取选中的图片节点
-  const selectedImageNodes = useMemo(
-    () =>
+  const selectedImageNodes = useMemo(() => {
+    const selectedNodeIdSet = new Set(selectedNodeIds);
+    return orderItemsBySelectionIds(
       nodes.filter(
-        (node) => selectedNodeIds.includes(node.id) && isCanvasImageReadyForAi(node)
+        (node) => selectedNodeIdSet.has(node.id) && isCanvasImageReadyForAi(node)
       ),
-    [nodes, selectedNodeIds]
-  );
+      selectedNodeIds,
+      (node) => node.id,
+    );
+  }, [nodes, selectedNodeIds]);
   const selectedImageNodesRef = useRef<CanvasNode[]>([]);
   const generationAnchorNodesRef = useRef<CanvasNode[]>([]);
 
@@ -6410,9 +6414,11 @@ export function CanvasChatPanel({
 
     const MAX_CONTEXT_IMAGES = 12;
     const MAX_AGENT_CANDIDATE_NODES = 30;
-    const selectedCanvasNodes = nodes
-      .filter((node) => selectedNodeIdSet.has(node.id))
-      .slice(0, 20);
+    const selectedCanvasNodes = orderItemsBySelectionIds(
+      nodes.filter((node) => selectedNodeIdSet.has(node.id)),
+      effectiveSelectedNodeIds,
+      (node) => node.id,
+    ).slice(0, 20);
     const selectedContextNodes = selectedImageNodesForContext.slice(0, 20);
     generationAnchorNodesRef.current = selectedContextNodes.slice(0, 4);
     const selectedIds = new Set(selectedContextNodes.map((node) => node.id));
diff --git a/lib/ai/context-memory/media-input.ts b/lib/ai/context-memory/media-input.ts
index 955d16aa1..6d06e1697 100644
--- a/lib/ai/context-memory/media-input.ts
+++ b/lib/ai/context-memory/media-input.ts
@@ -1,6 +1,7 @@
 import "server-only";
 
 import { extractImageUrlsFromText, inferOriginalImageUrl } from "@/lib/image-url";
+import { orderItemsBySelectionIds } from "@/lib/canvas/selection-order";
 import type { DBMessage } from "@/lib/db/schema";
 import type {
   CanvasImageNodeContext,
@@ -228,9 +229,16 @@ export function resolveChatMediaInput(
   );
 
   const canvasImageRefs = toCanvasImageRefs(params.contextPayload?.canvasImageNodes, maxImages);
-  const selectedNodeIds = new Set(params.contextPayload?.selectedNodeIds || []);
+  const selectedNodeIds = (params.contextPayload?.selectedNodeIds || [])
+    .map((id) => String(id || "").trim())
+    .filter(Boolean);
+  const selectedNodeIdSet = new Set(selectedNodeIds);
   const selectedImageRefs = dedupeRefs(
-    canvasImageRefs.filter((ref) => ref.isSelected || (ref.nodeId && selectedNodeIds.has(ref.nodeId))),
+    orderItemsBySelectionIds(
+      canvasImageRefs.filter((ref) => ref.isSelected || (ref.nodeId && selectedNodeIdSet.has(ref.nodeId))),
+      selectedNodeIds,
+      (ref) => ref.nodeId,
+    ),
     maxImages,
   );
   const history = extractHistoryImageRefs({
diff --git a/lib/ai/providers/snapgen-image.ts b/lib/ai/providers/snapgen-image.ts
index 15d104cab..f1d91c6b5 100644
--- a/lib/ai/providers/snapgen-image.ts
+++ b/lib/ai/providers/snapgen-image.ts
@@ -2,6 +2,7 @@ import "server-only";
 
 import sharp from "sharp";
 import { uploadFile } from "@/lib/storage/service";
+import { buildSnapgenReferenceOrderPrompt } from "@/lib/ai/providers/snapgen-reference-order";
 import {
   SNAPGEN_GPT_IMAGE_2_REQUEST_ASPECT_RATIOS,
   SNAPGEN_STANDARD_REQUEST_ASPECT_RATIOS,
@@ -876,9 +877,10 @@ export function createSnapgenImage({ apiKey, baseURL }: SnapgenImageConfig) {
         const outputFormat = normalizeOutputFormat(options.imageParams?.outputFormat);
         const maxImages = options.imageGenConfig?.maxImages || (apiFormat === "snapgen-grok-image" ? 8 : apiFormat === "snapgen-meta-ai-image" ? 4 : 1);
         const imageCount = clampImageCount(options.imageParams?.imageCount, maxImages);
+        const promptForRequest = buildSnapgenReferenceOrderPrompt(prompt, imageUrls);
         const formData = await buildRequestForm({
           apiFormat,
-          prompt,
+          prompt: promptForRequest,
           runtimeModelId,
           imageUrls,
           aspectRatio,
@@ -908,6 +910,7 @@ export function createSnapgenImage({ apiKey, baseURL }: SnapgenImageConfig) {
               : apiFormat === "snapgen-generic-image"
                 ? "file_urls"
                 : "files",
+          referenceOrderPrompt: promptForRequest !== prompt,
         });
 
         const createPayload = await requestSnapgenMultipart({
diff --git a/lib/ai/providers/snapgen-reference-order.ts b/lib/ai/providers/snapgen-reference-order.ts
new file mode 100644
index 000000000..8d7b8e1d3
--- /dev/null
+++ b/lib/ai/providers/snapgen-reference-order.ts
@@ -0,0 +1,14 @@
+export function buildSnapgenReferenceOrderPrompt(prompt: string, imageUrls: string[]) {
+  const normalizedPrompt = String(prompt || "").trim();
+  const referenceCount = imageUrls.filter((url) => String(url || "").trim()).length;
+  if (referenceCount < 2) return normalizedPrompt;
+
+  return [
+    `参考图顺序说明：本次请求包含 ${referenceCount} 张参考图，顺序与上传/选中顺序一致。`,
+    "第 1 张参考图优先作为主参考；如果用户提到“第一张图/图1/主图/原图”，对应第 1 张参考图，除非用户明确另行指定。",
+    "第 2 张及后续参考图仅作为辅助参考，按用户提示使用。",
+    normalizedPrompt,
+  ]
+    .filter(Boolean)
+    .join("\n");
+}
diff --git a/lib/canvas/selection-order.ts b/lib/canvas/selection-order.ts
new file mode 100644
index 000000000..e260343fe
--- /dev/null
+++ b/lib/canvas/selection-order.ts
@@ -0,0 +1,40 @@
+export function orderItemsBySelectionIds<T>(
+  items: T[],
+  selectedIds: string[],
+  getItemId: (item: T) => string | null | undefined,
+) {
+  const normalizedSelectedIds = Array.from(
+    new Set(
+      selectedIds
+        .map((id) => String(id || "").trim())
+        .filter(Boolean),
+    ),
+  );
+  if (normalizedSelectedIds.length === 0) return items;
+
+  const itemById = new Map<string, T>();
+  for (const item of items) {
+    const id = String(getItemId(item) || "").trim();
+    if (id && !itemById.has(id)) {
+      itemById.set(id, item);
+    }
+  }
+
+  const orderedItems: T[] = [];
+  const orderedItemSet = new Set<T>();
+  for (const id of normalizedSelectedIds) {
+    const item = itemById.get(id);
+    if (item && !orderedItemSet.has(item)) {
+      orderedItems.push(item);
+      orderedItemSet.add(item);
+    }
+  }
+
+  for (const item of items) {
+    if (!orderedItemSet.has(item)) {
+      orderedItems.push(item);
+    }
+  }
+
+  return orderedItems;
+}