# NousResearch/hermes-agent · json_schema response_format causes 400 errors in title generation

## Open now

- 1 issue, 2 PRs open on GitHub.
- #121973: \[Bug\]: title generation always 400s on opencode-go deepseek-v4.1-flash (json_schema rejected, error body not recognized)
- PR #121975: fix(opencode-go): skip json_schema response_format so title generation stops 400ing
- PR #121980: fix(aux): hear OpenCode's bare model-echo 400 rejecting json_schema

These items concern a bug where title generation fails with 400 errors because the json_schema response_format is rejected by certain model backends (specifically opencode-go with deepseek). The fixes involve skipping or handling json_schema in affected contexts.

## TL;DR

- 3 member(s): 1 open issue(s), 0 closed issue(s), 2 open PR(s), 0 merged PR(s), 0 PR(s) closed without merging.
- No fix has been merged to main; one or more PRs were attempted (see below).
- **Recommended:** review the prior/competing PR(s) below. A fix was attempted but not merged; your case may extend or revive that work.

## Maintainer resolution verdict

- Internal-tracker verdict over this cluster's issue members: `unresolved`. This is distinct from the fix status above. Weigh it yourself.

## How this cluster was grouped

- Link evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.
- Pairwise link density `0.67`: the share of member pairs that carry a link, counting a structural link in full and a relevance-only link at 0.36. `1.00` means every pair is linked.

## Open related issues

- #121973: \[Bug\]: title generation always 400s on opencode-go deepseek-v4.1-flash (json_schema rejected, error body not recognized)

## Prior & competing PRs

- **#121975: fix(opencode-go): skip json_schema response_format so title generation stops 400ing**. open
  - maintainer direction: category `wontfix_bydesign`; implication `wontfix`; refs `#121980`
  - files: `plugins/model-providers/opencode-zen/__init__.py`, `tests/agent/test_auxiliary_structured_output.py`
- **#121980: fix(aux): hear OpenCode's bare model-echo 400 rejecting json_schema**. open
  - maintainer direction: category `merged_via`; implication `superseded`; refs `#121980`, `#121975`
  - files: `agent/auxiliary_client.py`, `agent/auxiliary_structured_output.py`, `tests/agent/test_auxiliary_structured_output.py`, `tests/agent/test_structured_output_rejection_retry.py`

## Fix status

- No merged fix on record.
- Subsystem: `agent`