Side queries retry without structured output when a model rejects it

What

Side queries are small extra requests Claude Code sends to the model alongside your main conversation. Structured output asks the model to reply in a fixed format, using the output_config.format field. Before this release, side queries decided whether to ask for structured output by checking the model's capabilities in advance. There was no retry if the request was rejected.

Now the side-query path no longer attaches the structured-outputs beta (a preview API feature) based on that capability check. Instead:

• If the API rejects output_config.format, Claude Code marks the model as not supporting it for the rest of the session.
• It writes a log line starting [structured-outputs] model and records the retry as a usage event.
• It sends the request again without the format and without the beta.
• New helpers recognise the error text output_config.format: extra inputs are not permitted.
• New helpers also recognise error text saying a model does not support PDF input.

Why

A side query sent to a model that does not accept structured output can now go through on a second try instead of failing. This matters most if you reach models through a gateway or proxy that does not pass the output_config.format field along.