What probably matters to youSection of the release
What
The [1m] long-context model variants were hidden from subscription accounts whose credit state disallowed extra usage. That credit check now applies only when you are talking to Anthropic's own endpoints or a local socket, so subscription users pointed at a custom ANTHROPIC_BASE_URL see the 1M variants offered. Setting CLAUDE_CODE_DISABLE_1M_CONTEXT still hides them everywhere.
Details
The first-party test is satisfied by ANTHROPIC_UNIX_SOCKET being set, or by the base URL being an Anthropic one.
On first-party endpoints behaviour is unchanged: cached extra-usage state still decides.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed sinceAnthropic's documentation has since written up ANTHROPIC_BASE_URL, on Claude Code changelog.* Fixed every turn failing with HTTP 400 on third-party Anthropic-compatible endpoints (`ANTHROPIC_BASE_URL`) since 2.1.265: a regex in the Artifact tool's input schema that those endpoints rejectchangelogsee the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up ANTHROPIC_BASE_URL, on Claude Code changelog.
Anthropic's release notes agreeFixed /model rejecting Sonnet/Opus 1M for claude.ai subscribers using a custom ANTHROPIC_BASE_URL gateway
