## Summary
Use `DocumentService.RemoveDocumentKeepFile` when deleting files that
are linked to documents.
## Change
- inject `DocumentService` into `FileService`
- replace direct document deletion in `deleteSingleFile`
- remove the obsolete file-local engine deletion helper
## Result
Deleting a file now cleans up linked documents through the same service
path used elsewhere, keeping KB counters and document engine cleanup
consistent.
## Summary
Align the Go implementations of these APIs with the Python behavior:
- `POST /api/v1/datasets/:dataset_id/metadata/update`
- `PATCH /api/v1/datasets/:dataset_id/documents/metadatas`
- `POST /api/v1/documents/upload`
## What changed
- Added the Go routes and handlers for the 3 APIs.
- Aligned batch document metadata updates with Python semantics:
- support `match` in update items
- support list append / replace behavior
- support deleting specific list values
- remove metadata entirely when it becomes empty
- create metadata for documents that previously had none when updates
apply
- count `updated` only when a document actually changes
- Aligned `documents/upload` file uploads with Python-style
`upload_info` behavior:
- store upload-info blobs in the per-user downloads bucket
- return lightweight upload descriptors instead of normal
file-management responses
- Improved URL upload behavior:
- SSRF-guarded fetch with redirect validation
- redirect limit aligned to Python behavior
- normalize filename and MIME type
- add `.pdf` when the fetched content is PDF
- normalize HTML content into readable text instead of storing raw HTML
shells
## Validation
### Unit tests
Passed:
- `go test ./internal/service`
- `go test ./internal/handler`
Also verified targeted cases for:
- batch metadata update semantics
- upload_info URL handling
- upload_info download bucket behavior
### curl checks
Verified the new Go endpoints with `curl` and compared the response
shape and behavior with Python for:
- `POST /api/v1/datasets/{dataset_id}/metadata/update`
- `PATCH /api/v1/datasets/{dataset_id}/documents/metadatas`
- `POST /api/v1/documents/upload`
The Go responses were checked against Python for:
- argument validation
- success response shape
- metadata update results
- upload_info result structure
- file vs URL input handling
## What does this PR do?
This PR migrates the Agent Temporary File Download endpoint (`GET
/api/v1/agents/download`) from the Python backend to the Go backend,
optimizing the data retrieval flow and maintaining strict functional
parity. It also fixes a persistent parsing error in the Sandbox code
execution node.
## Checklist
- [x] Code logic matches Python implementation
- [x] All local unit tests passed
- [x] No breaking changes to existing router interfaces
Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
