add backend proxy to minio (upload)

backend/src/app/api/v1/uploads.py

@@ -1,6 +1,6 @@
 """Upload API routes."""
 
-from fastapi import APIRouter, status
+from fastapi import APIRouter, File, UploadFile, status
 
 from app.api.dependencies import CurrentUser, DatabaseSession, S3ClientDep
 from app.api.schemas import (
@@ -49,6 +49,36 @@ async def create_upload(
     )
 
 
+@router.post("/{asset_id}/file")
+async def upload_file(
+    asset_id: str,
+    file: UploadFile,
+    current_user: CurrentUser,
+    session: DatabaseSession,
+    s3_client: S3ClientDep,
+):
+    """
+    Upload file content through backend proxy to S3.
+
+    Args:
+        asset_id: Asset ID from create_upload
+        file: File to upload
+        current_user: Current authenticated user
+        session: Database session
+        s3_client: S3 client
+
+    Returns:
+        Success status
+    """
+    asset_service = AssetService(session, s3_client)
+    await asset_service.upload_file_to_s3(
+        user_id=current_user.id,
+        asset_id=asset_id,
+        file=file,
+    )
+    return {"status": "success"}
+
+
 @router.post("/{asset_id}/finalize", response_model=AssetResponse)
 async def finalize_upload(
     asset_id: str,

backend/src/app/infra/s3_client.py

@@ -114,6 +114,22 @@ class S3Client:
             ExtraArgs={"ContentType": content_type},
         )
 
+    def put_object(self, storage_key: str, file_data: bytes, content_type: str) -> None:
+        """
+        Upload file data (bytes) to S3.
+
+        Args:
+            storage_key: S3 object key
+            file_data: File content as bytes
+            content_type: File content type
+        """
+        self.client.put_object(
+            Bucket=self.bucket,
+            Key=storage_key,
+            Body=file_data,
+            ContentType=content_type,
+        )
+
     def delete_object(self, storage_key: str) -> None:
         """
         Delete an object from S3.

backend/src/app/services/asset_service.py

@@ -3,7 +3,8 @@
 import os
 from typing import AsyncIterator, Optional, Tuple
 
-from fastapi import HTTPException, status
+from botocore.exceptions import ClientError
+from fastapi import HTTPException, UploadFile, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.domain.models import Asset, AssetStatus, AssetType
@@ -90,6 +91,51 @@ class AssetService:
 
         return asset, presigned_post
 
+    async def upload_file_to_s3(
+        self,
+        user_id: str,
+        asset_id: str,
+        file: UploadFile,
+    ) -> None:
+        """
+        Upload file content to S3 through backend.
+
+        Args:
+            user_id: User ID
+            asset_id: Asset ID
+            file: File to upload
+
+        Raises:
+            HTTPException: If asset not found or not authorized
+        """
+        # Get asset and verify ownership
+        asset = await self.asset_repo.get_by_id(asset_id)
+        if not asset or asset.user_id != user_id:
+            raise HTTPException(
+                status_code=status.HTTP_404_NOT_FOUND,
+                detail="Asset not found",
+            )
+
+        if not asset.storage_key_original:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="Asset has no storage key",
+            )
+
+        # Upload file to S3
+        try:
+            content = await file.read()
+            self.s3_client.put_object(
+                storage_key=asset.storage_key_original,
+                file_data=content,
+                content_type=asset.content_type,
+            )
+        except Exception as e:
+            raise HTTPException(
+                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+                detail=f"Failed to upload file: {str(e)}",
+            )
+
     async def finalize_upload(
         self,
         user_id: str,
@@ -251,7 +297,19 @@ class AssetService:
             content_type = asset.content_type
 
         # Stream file from S3
-        file_stream, content_length = await self.s3_client.stream_object(storage_key)
+        try:
+            file_stream, content_length = await self.s3_client.stream_object(storage_key)
+        except ClientError as e:
+            error_code = e.response.get("Error", {}).get("Code", "")
+            if error_code == "NoSuchKey":
+                raise HTTPException(
+                    status_code=status.HTTP_404_NOT_FOUND,
+                    detail="Media file not found in storage",
+                )
+            raise HTTPException(
+                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+                detail=f"Failed to retrieve media from storage: {error_code}",
+            )
 
         return file_stream, content_type, content_length
 

frontend/src/components/UploadDialog.tsx

@@ -79,8 +79,8 @@ export default function UploadDialog({ open, onClose, onComplete }: UploadDialog
 
       updateFileProgress(index, 33, 'uploading', undefined, uploadData.asset_id);
 
-      // Step 2: Upload to S3
-      await api.uploadToS3(uploadData.upload_url, file, uploadData.fields);
+      // Step 2: Upload file to backend
+      await api.uploadFileToBackend(uploadData.asset_id, file);
 
       updateFileProgress(index, 66, 'uploading', undefined, uploadData.asset_id);
 

frontend/src/services/api.ts

@@ -142,6 +142,17 @@ class ApiClient {
     });
   }
 
+  async uploadFileToBackend(assetId: string, file: File): Promise<void> {
+    const formData = new FormData();
+    formData.append('file', file);
+
+    await this.client.post(`/uploads/${assetId}/file`, formData, {
+      headers: {
+        'Content-Type': 'multipart/form-data',
+      },
+    });
+  }
+
   async finalizeUpload(assetId: string, etag?: string, sha256?: string): Promise<Asset> {
     const { data } = await this.client.post(`/uploads/${assetId}/finalize`, { etag, sha256 });
     return data;