### What problem does this PR solve?
Refs #15743
Some Go API handlers return raw `err.Error()` strings in
`CodeServerError` responses. Those errors can include internal backend
details such as database, storage, search engine, or host information.
This PR adds a small shared `jsonInternalError` helper for handler-level
internal failures. The helper logs the raw error server-side with
request method/path context, then returns the existing generic
`common.CodeServerError.Message()` to API clients.
This first slice migrates the existing `jsonError(c,
common.CodeServerError, err.Error())` production call sites in agent,
dataset graph, file, and system handlers. It intentionally does not
close the full issue because direct `c.JSON` error responses in other
handlers remain for follow-up PRs.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):
### Tests
- `/root/go/bin/go test ./internal/handler -count=1`
---------
Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
### What problem does this PR solve?
As title
```
/api/v1/datasets/<dataset_id>/documents/<document_id>/metadata/config PUT
```
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
### What problem does this PR solve?
implement /api/v1/datasets/<dataset_id>/metadata/config
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Part of the Python → Go API server rewrite tracked in #15240 (Dataset
ingestion section). This PR implements the three dataset ingestion
endpoints in the Go API server, mirroring the existing Python
`dataset_api_service` behaviour:
- `GET /api/v1/datasets/<dataset_id>/ingestions/summary`
- `GET /api/v1/datasets/<dataset_id>/ingestions`
- `GET /api/v1/datasets/<dataset_id>/ingestions/<log_id>`
### Type of change
- [x] Refactoring
- [x] New Feature (non-breaking change which adds functionality)
Co-authored-by: sxxtony <sxxtony@users.noreply.github.com>
### What problem does this PR solve?
```
+---------------------+----------------------------------+-------------+-----------------+---------+--------+------+
| created_at | id | meta_fields | name | size | status | type |
+---------------------+----------------------------------+-------------+-----------------+---------+--------+------+
| 2026-05-08 19:35:08 | f6aa38bb4ad111f1ba6338a74640adcc | map[] | abc.pdf | 3387987 | 1 | pdf |
+---------------------+----------------------------------+-------------+-----------------+---------+--------+------+
```
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
### What problem does this PR solve?
Feat: CREATE / DELETE / LIST dataset api in Go
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: Lynn <lynn_inf@hotmail.com>
Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
