diff --git a/apps/web/src/api/assets.ts b/apps/web/src/api/assets.ts
index b95c736fb..d68bd13af 100644
--- a/apps/web/src/api/assets.ts
+++ b/apps/web/src/api/assets.ts
@@ -154,6 +154,7 @@ export const uploadAsset = async (
 
 /** 预签名直传准备 */
 export const prepareDirectUpload = async (data: {
+  project_id: string;
   library_id: string;
   filename: string;
   content_type: string;
@@ -172,6 +173,7 @@ export const prepareDirectUpload = async (data: {
 
 /** 直传完成确认 */
 export const completeDirectUpload = async (data: {
+  project_id: string;
   library_id: string;
   storage_key: string;
 }): Promise<{ storage_key: string; ingest_job_id: string }> => {
@@ -184,7 +186,11 @@ export const uploadAssetDirect = async (data: {
   file: File;
   library_id: string;
 }): Promise<{ storage_key: string; ingest_job_id: string }> => {
+  // 后端要求 project_id，前端自动获取默认项目
+  const project = await getOrCreateDefaultProject();
+
   const prepared = await prepareDirectUpload({
+    project_id: project.id,
     library_id: data.library_id,
     filename: data.file.name,
     content_type: data.file.type || 'application/octet-stream',
@@ -206,6 +212,7 @@ export const uploadAssetDirect = async (data: {
   }
 
   return completeDirectUpload({
+    project_id: project.id,
     library_id: data.library_id,
     storage_key: prepared.storage_key,
   });
diff --git a/apps/web/src/pages/assets/AssetLibrary.tsx b/apps/web/src/pages/assets/AssetLibrary.tsx
index a11472957..f764f3a1e 100644
--- a/apps/web/src/pages/assets/AssetLibrary.tsx
+++ b/apps/web/src/pages/assets/AssetLibrary.tsx
@@ -44,8 +44,8 @@ import { getOrCreateDefaultProject } from '@/api/projects';
 const { Title, Text } = Typography;
 const { Dragger } = Upload;
 
-/** 最大文件大小：2GB */
-const MAX_FILE_SIZE = 2 * 1024 * 1024 * 1024; // 2147483648 bytes
+/** 最大文件大小：2048MB（与后端 OSS_DIRECT_UPLOAD_MAX_MB=2000 对齐，留少量余量） */
+const MAX_FILE_SIZE = 2048 * 1024 * 1024; // 2147483648 bytes
 /** 大文件阈值：100MB，超过此值走 OSS 直传通道 */
 const LARGE_FILE_THRESHOLD = 100 * 1024 * 1024; // 104857600 bytes