The earliest release whose published evidence quoted CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE was v2.1.129, 5 May 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.
ReleaseDateThe span that was quoted
v2.1.1295 May 2026CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE
Presence across releases
4
BuildsHow manyDatesReading
v2.1.138 – v2.1.1414 builds9 May 2026 → 12 May 2026 ◆in the build
v2.1.212 – v2.1.30885 builds16 Jul 2026 → 22 Oct 2026 ○not in the build
Build by build
149
One 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.
