# NousResearch/hermes-agent · Fallback chain lost on model switch bug

## Open now

- 1 issue, 2 PRs open on GitHub.
- #103788: \[Bug\]: switch_model() silently empties fallback_providers chain when entries use bare 'custom' provider
- PR #103804: fix(agent): keep custom fallbacks available after model switches
- PR #103817: fix(agent): preserve custom fallback chain entries during model switch (#103788)

These issues and PRs concern a bug where switching models causes custom fallback chain entries to be silently dropped or pruned. The work focuses on preserving user-defined fallback configurations across model switches.

## TL;DR

- 4 member(s): 1 open issue(s), 0 closed issue(s), 2 open PR(s), 0 merged PR(s), 1 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evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.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 `0.50`: 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

- #103788: \[Bug\]: switch_model() silently empties fallback_providers chain when entries use bare 'custom' provider

## Prior & competing PRs

- **#103804: fix(agent): keep custom fallbacks available after model switches**. open
  - maintainer direction: category `partial_fix`; implication `needs_llm`
  - files: `agent/agent_runtime_helpers.py`, `tests/run_agent/test_switch_model_fallback_prune.py`
- **#103817: fix(agent): preserve custom fallback chain entries during model switch (#103788)**. open
  - maintainer direction: category `implemented_elsewhere`; implication `superseded`
  - files: `agent/agent_runtime_helpers.py`, `tests/run_agent/test_switch_model_fallback_prune.py`
- **#103819: fix(switch_model): prune fallback chain by endpoint identity, not provider string**. closed without merge
  - maintainer direction: category `superseded_by_pr`; implication `superseded`; refs `#103788`, `#103804`, `#103817`, `#103804`, `#103819`, `#103817`

## Fix status

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