CLAUDE_CODE_ATTRIBUTION_PROJECT
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.304, including the newest one read.
Claude Code now recognises CLAUDE_CODE_ATTRIBUTION_PROJECT and drops a value that is not a valid claude.ai Project ID from saved jobs
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.304.
In the changelogs
4Releases whose published page names CLAUDE_CODE_ATTRIBUTION_PROJECT.
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v2.1.305
How Claude Code picks the claude.ai Project for usage reports
The claude.ai Project used for usage reports now comes from an environment variable, a setting or a managed default, and bad IDs are flagged
found in this entry's text
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v2.1.304
New
CLAUDE_CODE_ATTRIBUTION_PROJECTsetting checked against claude.ai Project IDsClaude Code now recognises
CLAUDE_CODE_ATTRIBUTION_PROJECTand drops a value that is not a valid claude.ai Project ID from saved jobsfound in this entry's text, named in this entry
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v2.1.304
New environment variables can stop plugins from starting local MCP servers
Setting CLAUDE_CODE_SKIP_PLUGIN_LOCAL_MCP_SERVERS keeps only remote MCP servers from plugins, and several other environment variables are new
found in this entry's text
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v2.1.304
New CLAUDE_CODE_ATTRIBUTION_PROJECT environment variable passed to spawned sessions
Claude Code now always passes a CLAUDE_CODE_ATTRIBUTION_PROJECT environment variable along, empty when it is not set
found in this entry's text, named in this entry
First cited
1The earliest release whose published evidence quoted CLAUDE_CODE_ATTRIBUTION_PROJECT was v2.1.304, 19 Oct 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
1Build by build
5One 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.