--concurrency
A Claude Code CLI flag, read out of the shipped bundle. It has been in the build since v2.1.269, including the newest one read.
claude plugin eval gains a --concurrency flag to run up to 8 test cases at once
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.269.
In the changelogs
3Releases whose published page names --concurrency.
-
v2.1.269
claude plugin evalgains a--concurrencyflagclaude plugin evalgains a--concurrencyflag to run up to 8 test cases at oncefound in this entry's text, named in this entry
-
v2.1.269
'claude plugin eval' gains --allow-real-servers and concurrency options, plus harness-failure tracking
'claude plugin eval' adds --allow-real-servers and concurrency options, plus separate harness-failure tracking
named in this entry
-
v2.1.269
CLI eval tool's --max-cost-usd help text clarifies overrun bound
Help text for --max-cost-usd now explains its cost ceiling is checked before each run, not per single run
found in this entry's text
First cited
2The earliest release whose published evidence quoted --concurrency was v2.1.269, 11 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 below.
Presence across releases
1Build by build
47One 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 CLI flag does. All CLI flags.