Cairn
NousResearch/hermes-agent

Fix misplaced system/marker messages causing HTTP 400 errors

Cluster 20866 · agent. Data as of

Nothing open on GitHub. Fix attempted, not merged.

The short answer

0open issues
0open PRs
3items grouped
Known?
Yes. 3 related items grouped here, 1 issue already closed.
Fix event
No fix has been merged to main. 2 PRs closed without merging; see the attempts below.
Tracker
The maintainers' tracker marks this unresolved. That is separate from the fix event.
Still open
Nothing open on GitHub.

These issues and fixes address two related problems: system messages appearing mid-conversation instead of at the start, and model-switch markers using role='system' mid-conversation, both causing HTTP 400 errors on strict providers like vLLM and Qwen.

Open issues0

No open issues.

Open PRs0

No open pull requests.

2 PRs closed without merging

From the close comments: closed without comment 1 · other 1

  • #20913 fix(auxiliary): ensure system messages precede other roles before LLM call · other → #20866
  • #22624 fix(auxiliary-client): hoist misplaced system messages to front before dispatch (#20866) · closed without comment
Closed issues · 1
  • Closed#20866[Bug]: 400 format_error on Qwen3.6-27B — "System message must be at the beginning" in auxiliary tasks
How this cluster was grouped
  • Link evidence (structural links throughout): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.
  • Pairwise link density 0.67: the share of item 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.

Pick up a Lab task

Check whether a fix covers the open issues here, with your own agent. Bring back evidence for maintainers.

Open the Lab

At a glance

Subsystem
agent
Closed issues
1
Attempts
2 PRs closed without merging

For your agent

The same facts, typed.

cluster/20866.json
cluster/20866.md