What it is
A new environment variable lets you inject per-content-hash skill and plugin attribution into command and skill telemetry.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.259.
Presence across releases
1Build by build
19One 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.
First cited
3The earliest release whose published evidence quoted CLAUDE_CODE_SKILL_ATTRIBUTION was v2.1.259, 2 Sep 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 above.
Names beside it
Every environment variable in the inventory starting claude_code_skill, up to twelve of them.
CLAUDE_CODE_SKILL_DESC_REFRAMENo description from anybody. v2.1.196
CLAUDE_CODE_SKILL_PROPOSALSAn env var turns on the tool that proposes new skills; otherwise it stays off in this build. v2.1.233
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.