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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.

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Claude Code v2.1.236

ANTHROPIC_DEFAULT_MODEL sets the model when nothing else does

Use it now
Useful5 Signal3
Models Notable

Set ANTHROPIC_DEFAULT_MODEL and it becomes your model whenever no flag or ANTHROPIC_MODEL applies.

ANTHROPIC_DEFAULT_MODELANTHROPIC_MODEL--model
What

The model for a session now resolves from the --model flag, then the ANTHROPIC_MODEL environment variable, then ANTHROPIC_DEFAULT_MODEL, and only then the model Claude Code ships with. An organisation or a shell profile that exports the variable will see it take effect in sessions that previously fell through to the built-in default, and the model list marks the choice so you can tell where it came from.

Details
  • The model list shows the footnote "Set by ANTHROPIC_DEFAULT_MODEL" against the model the variable selected.
  • The literal values default and inherit are treated as unset, so resolution continues past them to the shipped default.
  • Startup telemetry records ANTHROPIC_DEFAULT_MODEL in its own field, separate from the existing ANTHROPIC_MODEL field.
  • On Amazon Bedrock and Google Vertex, the check for whether Opus is available to the account is skipped whenever the variable is set.
  • Sandboxed child processes spawned for bring-your-own-cloud setups have ANTHROPIC_DEFAULT_MODEL stripped from their environment, matching the existing handling of ANTHROPIC_MODEL.
  • Invoke it inline for a single session, for example ANTHROPIC_DEFAULT_MODEL=claude-sonnet-4-5 claude.
Evidence

Set by ANTHROPIC_DEFAULT_MODEL, t.model || process.env.ANTHROPIC_MODEL || V.ANTHROPIC_DEFAULT_MODEL

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 v2.1.236 →