You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
ModelsArea: what it touches
ImprovementsKind: in v2.1.283,
ImprovementsSection of the release
What
A "[1m]" suffix on a model name asks for a context window of about a million tokens. The context window is how much text the model can take in at once. Claude Code now treats any model name that contains both "sonnet" and "[1m]" as a Sonnet 1M-context name, apart from a set of excluded names. Before, it matched only sonnet[1m], sonnet-4-6[1m] and sonnet-5[1m].
Why
Other Sonnet names ending in [1m] now go through the same availability check as the ones matched before.
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 doubtIt is not clear what this check controls or which names are excluded.
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…
