feat: support download file

aperag/api/openapi.yaml

@@ -67,6 +67,8 @@ paths:
     $ref: './paths/collections.yaml#/document_preview'
   /collections/{collection_id}/documents/{document_id}/object:
     $ref: './paths/collections.yaml#/document_object'
+  /collections/{collection_id}/documents/{document_id}/download:
+    $ref: './paths/collections.yaml#/document_download'
   /collections/{collection_id}/documents/upload:
     $ref: './paths/collections.yaml#/upload_document'
   /collections/{collection_id}/documents/confirm:

aperag/api/paths/collections.yaml

@@ -398,6 +398,94 @@ document_object:
             schema:
               $ref: '../components/schemas/common.yaml#/failResponse'
 
+document_download:
+  get:
+    summary: Download document file
+    description: |
+      Download the original document file.
+      Returns the file as a streaming response with appropriate Content-Type and Content-Disposition headers.
+      The file is streamed through the backend to support internal network deployments and maintain access control.
+
+      **Document Lifecycle and Download Availability:**
+      - UPLOADED: Downloadable (temporary status, auto-deleted after 24 hours if not confirmed)
+      - PENDING/RUNNING/COMPLETE/FAILED: Downloadable (permanent, not auto-deleted)
+      - EXPIRED: Not downloadable (file deleted by cleanup task)
+      - DELETED: Not downloadable (soft-deleted by user)
+
+      **Auto-Cleanup Mechanism:**
+      A scheduled task runs every 10 minutes to clean up documents in UPLOADED status that are older than 24 hours.
+      Once confirmed, documents will never be auto-deleted.
+    operationId: download_document
+    tags:
+      - documents
+    security:
+      - BearerAuth: []
+    parameters:
+      - name: collection_id
+        in: path
+        required: true
+        schema:
+          type: string
+        description: Collection ID
+      - name: document_id
+        in: path
+        required: true
+        schema:
+          type: string
+        description: Document ID
+    responses:
+      '200':
+        description: Document file stream
+        content:
+          application/octet-stream:
+            schema:
+              type: string
+              format: binary
+        headers:
+          Content-Type:
+            description: MIME type of the document (e.g., application/pdf, text/plain)
+            schema:
+              type: string
+          Content-Disposition:
+            description: Attachment header with original filename
+            schema:
+              type: string
+              example: 'attachment; filename="document.pdf"'
+          Content-Length:
+            description: Size of the file in bytes
+            schema:
+              type: integer
+      '400':
+        description: Bad request - document status does not allow download (EXPIRED or DELETED)
+        content:
+          application/json:
+            schema:
+              $ref: '../components/schemas/common.yaml#/failResponse'
+      '401':
+        description: Unauthorized
+        content:
+          application/json:
+            schema:
+              $ref: '../components/schemas/common.yaml#/failResponse'
+      '403':
+        description: Forbidden - user does not have access to this document
+        content:
+          application/json:
+            schema:
+              $ref: '../components/schemas/common.yaml#/failResponse'
+      '404':
+        description: Document not found or file not found in storage
+        content:
+          application/json:
+            schema:
+              $ref: '../components/schemas/common.yaml#/failResponse'
+      '500':
+        description: Internal server error - failed to download from storage
+        content:
+          application/json:
+            schema:
+              $ref: '../components/schemas/common.yaml#/failResponse'
+
 rebuild_indexes:
   post:
     summary: Rebuild document indexes

aperag/schema/view_models.py

@@ -14,7 +14,7 @@
 
 # generated by datamodel-codegen:
 #   filename:  openapi.merged.yaml
-#   timestamp: 2025-11-11T06:17:00+00:00
+#   timestamp: 2026-01-13T12:50:23+00:00
 
 from __future__ import annotations
 

aperag/service/document_service.py

@@ -1004,6 +1004,80 @@ async def _get_document_preview(session: AsyncSession):
         # Execute query with proper session management
         return await self.db_ops._execute_query(_get_document_preview)
 
+    async def download_document(self, user_id: str, collection_id: str, document_id: str):
+        """
+        Download the original document file.
+        Returns a StreamingResponse with the file content.
+        """
+
+        async def _download_document(session):
+            # 1. Verify user has access to the document
+            stmt = select(db_models.Document).filter(
+                db_models.Document.id == document_id,
+                db_models.Document.collection_id == collection_id,
+                db_models.Document.user == user_id,
+                db_models.Document.gmt_deleted.is_(None),  # Only allow downloading non-deleted documents
+            )
+            result = await session.execute(stmt)
+            document = result.scalars().first()
+            if not document:
+                raise DocumentNotFoundException(document_id)
+
+            # 2. Check document status - only disallow downloading expired/deleted documents
+            # UPLOADED documents can be downloaded (before confirmation, within 24 hours)
+            # Once expired or deleted, files may no longer exist in storage
+            if document.status in [db_models.DocumentStatus.EXPIRED, db_models.DocumentStatus.DELETED]:
+                raise HTTPException(
+                    status_code=400, detail=f"Document status is {document.status.value}, cannot download"
+                )
+
+            # 3. Get object path from doc_metadata
+            try:
+                metadata = json.loads(document.doc_metadata) if document.doc_metadata else {}
+                object_path = metadata.get("object_path")
+                if not object_path:
+                    raise HTTPException(status_code=404, detail="Document file not found in storage")
+            except json.JSONDecodeError:
+                logger.error(f"Invalid JSON in doc_metadata for document {document_id}")
+                raise HTTPException(status_code=500, detail="Document metadata is corrupted")
+
+            # 4. Stream file from object store
+            try:
+                async_obj_store = get_async_object_store()
+
+                # Get file stream and size
+                get_result = await async_obj_store.get(object_path)
+                if not get_result:
+                    raise HTTPException(status_code=404, detail="Document file not found in object store")
+
+                data_stream, file_size = get_result
+
+                # Determine content type from filename
+                content_type, _ = mimetypes.guess_type(document.name)
+                if content_type is None:
+                    content_type = "application/octet-stream"
+
+                # Set headers for file download
+                headers = {
+                    "Content-Type": content_type,
+                    "Content-Disposition": f'attachment; filename="{document.name}"',
+                    "Content-Length": str(file_size),
+                }
+
+                logger.info(
+                    f"User {user_id} downloading document {document_id} ({document.name}) "
+                    f"from collection {collection_id}, size: {file_size} bytes"
+                )
+
+                return StreamingResponse(data_stream, headers=headers)
+
+            except Exception as e:
+                logger.error(f"Failed to download document {document_id} from path {object_path}: {e}", exc_info=True)
+                raise HTTPException(status_code=500, detail="Failed to download document from storage")
+
+        # Execute query with proper session management
+        return await self.db_ops._execute_query(_download_document)
+
     async def get_document_object(
         self, user_id: str, collection_id: str, document_id: str, path: str, range_header: str = None
     ):

aperag/views/collections.py

@@ -269,6 +269,21 @@ async def get_document_view(
     return await document_service.get_document(str(user.id), collection_id, document_id)
 
 
+@router.get("/collections/{collection_id}/documents/{document_id}/download", tags=["documents"])
+@audit(resource_type="document", api_name="DownloadDocument")
+async def download_document_view(
+    request: Request,
+    collection_id: str,
+    document_id: str,
+    user: User = Depends(required_user),
+):
+    """
+    Download the original document file.
+    Returns the file as a streaming response with appropriate headers.
+    """
+    return await document_service.download_document(str(user.id), collection_id, document_id)
+
+
 @router.delete("/collections/{collection_id}/documents/{document_id}", tags=["documents"])
 @audit(resource_type="document", api_name="DeleteDocument")
 async def delete_document_view(

docs/design/document_export_design_zh.md

@@ -25,8 +25,8 @@
 │  └──────────────────┘         └──────────────────┘        │
 └─────────┬──────────────────────────┬────────────────────────┘
           │                          │
-          │ GET /documents/{id}/download        (同步，流式返回)
-          │ POST /collections/{id}/export       (异步，生成下载链接)
+          │ GET /collections/{id}/documents/{id}/download  (同步，流式返回)
+          │ POST /collections/{id}/export                  (异步，生成下载链接)
           ▼                          ▼
 ┌─────────────────────────────────────────────────────────────┐
 │                      View Layer                             │
@@ -111,7 +111,7 @@
 
 | 场景 | API | 模式 | 说明 |
 |------|-----|------|------|
-| **单个文档下载** | `GET /documents/{id}/download` | 同步流式 | 直接返回文件流 |
+| **单个文档下载** | `GET /collections/{collection_id}/documents/{id}/download` | 同步流式 | 直接返回文件流 |
 | **知识库导出** | `POST /collections/{id}/export` | 异步 | 生成后端下载 URL |
 
 ## 核心流程详解
@@ -124,26 +124,32 @@
 用户点击"下载"按钮
     │
     ▼
-GET /api/v1/documents/{document_id}/download
+GET /api/v1/collections/{collection_id}/documents/{document_id}/download
     │
     ▼
 后端处理：
     │
     ├─► 验证用户身份（JWT）
     │
-    ├─► 验证文档访问权限
+    ├─► 验证文档访问权限（user、collection_id 匹配）
     │
-    ├─► 查询 Document 记录
+    ├─► 查询 Document 记录（过滤软删除文档）
     │
-    ├─► 从 doc_metadata 获取 object_path
+    ├─► 检查文档状态（只禁止 EXPIRED/DELETED 状态）
+    │   ├─ UPLOADED: ✅ 允许下载（上传后 24 小时内）
+    │   ├─ PENDING/RUNNING/COMPLETE/FAILED: ✅ 允许下载（永久）
+    │   ├─ EXPIRED: ❌ 禁止（文件已被清理）
+    │   └─ DELETED: ❌ 禁止（用户已删除）
+    │
+    ├─► 从 doc_metadata JSON 获取 object_path
     │
     ├─► 从对象存储读取文件（流式）
-    │   └─ 路径：user-{user_id}/{collection_id}/{doc_id}/original.pdf
+    │   └─ 路径：user-{user_id}/{collection_id}/{doc_id}/original.xxx
     │
     └─► 返回 StreamingResponse
-        ├─ Content-Type: application/octet-stream
-        ├─ Content-Disposition: attachment; filename="xxx.pdf"
-        └─ Transfer-Encoding: chunked (流式传输)
+        ├─ Content-Type: 根据文件扩展名判断（默认 application/octet-stream）
+        ├─ Content-Disposition: attachment; filename="原始文件名"
+        └─ Content-Length: 文件大小（从对象存储获取）
     │
     ▼
 文件通过后端流式传输给客户端
@@ -156,7 +162,7 @@ GET /api/v1/documents/{document_id}/download
 
 **请求**：
 ```http
-GET /api/v1/documents/{document_id}/download
+GET /api/v1/collections/{collection_id}/documents/{document_id}/download
 Authorization: Bearer {token}
 ```
 
@@ -166,11 +172,14 @@ HTTP/1.1 200 OK
 Content-Type: application/octet-stream
 Content-Disposition: attachment; filename="user_manual.pdf"
 Content-Length: 5242880
-Transfer-Encoding: chunked
 
 [文件二进制流]
 ```
 
+**说明**：
+- 实际实现中不使用 `Transfer-Encoding: chunked` 响应头，而是通过 FastAPI 的 `StreamingResponse` 自动处理流式传输
+- `Content-Length` 会从对象存储获取文件大小后设置
+
 #### 1.3 关键特性
 
 - **流式读取**：从对象存储按块读取（chunk size = 64KB）
@@ -179,6 +188,58 @@ Transfer-Encoding: chunked
 - **超时控制**：设置合理的读取超时（如 30 分钟）
 - **权限控制**：每次下载都验证用户权限
 - **审计日志**：记录下载操作（用户、时间、文档）
+- **状态检查**：只禁止下载 EXPIRED/DELETED 状态的文档
+
+#### 1.4 文档生命周期与下载可用性
+
+**文档状态说明**：
+
+| 状态 | 说明 | 可下载 | 自动清理 | 触发条件 |
+|------|------|--------|----------|----------|
+| `UPLOADED` | 已上传，未确认 | ✅ | 是（24小时后） | 用户上传文件 |
+| `PENDING` | 已确认，等待处理 | ✅ | 否 | 用户确认文档 |
+| `RUNNING` | 正在处理索引 | ✅ | 否 | 后台任务开始处理 |
+| `COMPLETE` | 处理完成 | ✅ | 否 | 索引创建成功 |
+| `FAILED` | 处理失败 | ✅ | 否 | 索引创建失败 |
+| `EXPIRED` | 已过期 | ❌ | - | 自动清理任务 |
+| `DELETED` | 已删除 | ❌ | - | 用户删除操作 |
+
+**自动清理机制**：
+
+```
+定时任务：每 10 分钟运行一次
+清理目标：UPLOADED 状态 且 创建时间 > 24 小时 的文档
+清理操作：
+  1. 删除对象存储中的文件（包括所有相关文件）
+  2. 将文档状态更新为 EXPIRED
+  3. 记录清理日志
+
+配置位置：config/celery.py
+任务名称：cleanup_expired_documents_task
+执行频率：600 秒（10 分钟）
+```
+
+**设计理念**：
+- ✅ **用户友好**：上传后即可下载预览，无需等待确认
+- ✅ **资源优化**：未确认的临时文件自动清理，节省存储空间
+- ✅ **数据安全**：确认后的文档永久保留，不会被自动删除
+- ✅ **清晰提示**：EXPIRED 状态的文档返回明确错误信息
+
+**典型使用流程**：
+
+```
+1. 用户上传文档
+   └─► 状态：UPLOADED（可下载，24小时有效期）
+
+2. 场景 A：用户及时确认（< 24 小时）
+   └─► 状态：PENDING → RUNNING → COMPLETE
+       └─► 可永久下载，不会被清理 ✅
+
+3. 场景 B：用户未及时确认（> 24 小时）
+   └─► 自动清理任务执行
+       └─► 状态：EXPIRED（无法下载） ❌
+           └─► 用户需要重新上传
+```
 
 ### 场景 2: 知识库导出（异步打包）
 
@@ -617,7 +678,7 @@ Celery 任务超时：
 
 | 方法 | 路径 | 说明 | 模式 |
 |------|------|------|------|
-| GET | `/documents/{id}/download` | 下载单个文档 | 同步流式 |
+| GET | `/collections/{collection_id}/documents/{id}/download` | 下载单个文档 | 同步流式 |
 | POST | `/collections/{id}/export` | 知识库导出 | 异步 |
 | GET | `/export-tasks/{id}` | 查询导出任务状态 | - |
 | GET | `/export-tasks/{id}/download` | 下载导出结果 | 同步流式 |