You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
ModelsArea: what it touches
ImprovementsKind: in v2.1.283,
ImprovementsSection of the release
What
When you switch models, Claude Code checks whether your account can use Sonnet with a 1 million token context window. The context window is how much text the model can hold at once. If your account cannot, you see "Sonnet with 1M context is not available for your account". This check used to catch only a few short names. It now applies to any model name containing both "sonnet" and "[1m]", and still to opusplan[1m]. These models are exempt:
There is also a new way to label a refused model switch as either "denied_by_managed_settings" or "not_allowed".
Why
Full Sonnet model names with [1m] used to get past this check. Accounts without 1M access now get the clear refusal up front instead.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhere the new "denied_by_managed_settings" and "not_allowed" labels are shown is not known.
Anthropic's release notes agreeFixed /model accepting Sonnet 4.6 or Sonnet 5 with [1m] when the id carried a date or -v1:0 suffix, in the cases where the plain id was…
