AI BriefingClaude Code Subagent Model Behavior Changed
Key point
Claude Code's subagents have changed from using the existing Haiku model to inheriting the main session's model.
Details
Following the Claude Code v2.1.198 update, the model behavior of Subagents has changed.
Previously, subagents ran on the lower-cost Haiku model to reduce token consumption, but now, without a separate configuration, they inherit the main conversation session's model as-is (Inherit). For example, if a user is running a session with the Opus model, the subagent will also operate on the Opus model.
Key Changes and Solutions:
- Model Inheritance: The subagent's
modelfield is set toinheritby default. - Cost Management: To prevent subagents from using high-cost models, you need to set the
CLAUDE_CODE_SUBAGENT_MODEL=haikuenvironment variable, or specifymodel: haikuin the specific agent's frontmatter. - Resolution Order: Applied in the order of environment variable → model parameter at invocation → subagent frontmatter → main conversation model.
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