ANTHROPIC_DEFAULT_MODEL
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.236, including the newest one read.
Model that new sessions start on by default. Requires Claude Code v2.1.236 or later. See Set a default model for new sessions
Anthropic's own wording. Read off Environment variables, captured 2026-09-28.
In the changelogs
5Releases whose published page names ANTHROPIC_DEFAULT_MODEL.
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v2.1.284
Gateway config checks warn about model lists that would reject every request
Gateway checks now warn when availableModels is empty or leaves out the default model, both of which get requests refused
found in this entry's text
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v2.1.275
New 'settings_env_default' model-source classification when ANTHROPIC_DEFAULT_MODEL is set via managed settings
Model-source tracking adds a 'settings_env_default' label for ANTHROPIC_DEFAULT_MODEL set via managed settings
found in this entry's text, named in this entry
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v2.1.259
Settings can now supply a default model, ahead of ANTHROPIC_DEFAULT_MODEL
A model set in settings.json now takes precedence over the ANTHROPIC_DEFAULT_MODEL environment variable at startup.
found in this entry's text, named in this entry
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v2.1.236
ANTHROPIC_DEFAULT_MODELsets the model when nothing else doesSet ANTHROPIC_DEFAULT_MODEL and it becomes your model whenever no flag or ANTHROPIC_MODEL applies.
named in this entry, found in this entry's text
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v2.1.236
Startup records whether
ANTHROPIC_DEFAULT_MODELactually took effectStartup now records whether your default-model environment variable actually won or was overridden.
named in this entry, found in this entry's text
First cited
4The earliest release whose published evidence quoted ANTHROPIC_DEFAULT_MODEL was v2.1.236, 19 Aug 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
1Build by build
62One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.