Source Intelligence
Follow Discord

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.222 Home All releases ←olderv2.1.221 v2.1.223newer→
Claude Code v2.1.222

Subagent model fallback says why it fell back

You'll notice
Useful3 Signal0
Subagents

When a subagent can't use its requested model, you now see why it fell back.

What

When a subagent cannot get the model it asked for, the notify callback now carries a reason distinguishing a same-family step-down from inheriting the parent's model, and the message shown downstream differs accordingly.

Details
  • Reason is either family_step_down, meaning a fallback within the same model family was picked, or parent_inherit, meaning the subagent fell back to the parent session's model.
Evidence

family_step_down

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.222 →