What
Picking a subagent's model now tracks the source of the request separately from the model name, distinguishing tool overrides, the agent's own frontmatter, the CLAUDE_CODE_SUBAGENT_MODEL environment variable, and defaults.
Details
- The existing model-resolution telemetry gained outcomes for a model family alias being stepped down, an override being dropped, and a family mismatch.
- Aimed at correctness of which model a subagent ends up on; nothing new is surfaced in the UI.
Evidence
subagent_model_resolve
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Names in the bundleCLAUDE_CODE_SUBAGENT_MODEL
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up CLAUDE_CODE_SUBAGENT_MODEL, on Create custom subagents.
An alias in `CLAUDE_CODE_SUBAGENT_MODEL` always resolves to the version the alias points to, even when it names the main conversation's family.sub-agents see the edit
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up CLAUDE_CODE_SUBAGENT_MODEL, on Create custom subagents.
Anthropic's release notes agree
Changed CLAUDE_CODE_SUBAGENT_MODEL to set the default subagent model rather than override everything: an agent definition's model: and an…