VERTEX_REGION_CLAUDE_5_OPUS
A Claude Code environment variable, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
Opus 5 is now the default Opus, with a 1M-context option in the model picker.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.219.
In the changelogs
2Releases whose published page names VERTEX_REGION_CLAUDE_5_OPUS.
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v2.1.219
Opus 5 replaces Opus 4.8 as the default Opus model
Opus 5 is now the default Opus, with a 1M-context option in the model picker.
named in this entry, found in this entry's text
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v2.1.219
Opus 5 wired through region env vars, refusal fallbacks and pricing copy
An Opus 5 model is wired through region variables, fast mode, 1M context and pricing text.
named in this entry, found in this entry's text
First cited
1The earliest release whose published evidence quoted VERTEX_REGION_CLAUDE_5_OPUS was v2.1.219, 24 Jul 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
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
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.