Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Model SwitchingArea: what it touches
Internal ChangesKind: in v2.1.290,
Internal ChangesSection of the release
Unclear It is not clear which 400 errors count as a mode-based refusal.
What
Before Claude Code switches you to a different model, it checks with the server that the switch is allowed. If the server answers with an HTTP 400 error (a response meaning the request was not accepted) of a particular kind, Claude Code now marks the result as a refusal caused by the session's mode, rather than treating it as an ordinary failure.
Why
This lets Claude Code tell a refusal that comes from the mode your session is in apart from other errors that can happen while changing models.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtIt is not clear which 400 errors count as a mode-based refusal.
