When the primary model (e.g. DeepSeek during peak hours) returns an empty
choices response with HTTP 200, the error carries no status code or
structured error metadata. The existing _FALLBACK_ERROR_TOKENS had no
matching token, so _should_fallback() returned False and fallback models
were never tried.
Changes:
- Add 'empty' token to _FALLBACK_ERROR_TOKENS so 'Error: API returned
empty choices.' text matches the fallback path
- Set error_kind='empty' in openai_compat_provider when returning
the empty-choices error, making the classification explicit
- Add test coverage for both text-only and error_kind matching paths
Fixes: glebov reported primary never falls back when DeepSeek returns
empty responses
nanobot-contributorandXubin Ren
c2c47f7a03