Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
One name

--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.

FamilyCLI flagCLI flags
Builds10of the 122 on this box
First seen v2.1.269 11 Sep 2026
Last seen v2.1.278 19 Sep 2026
Statusin the buildas of v2.1.278

What it is

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.

Presence across releases

1
BuildsHow manyDatesReading
v2.1.269 – v2.1.27810 builds11 Sep 2026 → 19 Sep 2026 in the build

Build by build

10

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.

BuildDateStateThe record behind it
v2.1.26911 Sep 2026·addedverdict: added
v2.1.27012 Sep 2026·presentverdict: present
v2.1.27114 Sep 2026·presentverdict: present
v2.1.27214 Sep 2026·presentverdict: present
v2.1.27315 Sep 2026·presentverdict: present
v2.1.27416 Sep 2026·presentverdict: present
v2.1.27517 Sep 2026·presentverdict: present
v2.1.27618 Sep 2026·presentverdict: present
v2.1.27718 Sep 2026·presentverdict: present
v2.1.27819 Sep 2026·presentverdict: present

First cited

2

The 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 above.

ReleaseDateThe span that was quoted
v2.1.26911 Sep 2026-j, --concurrency <n>
v2.1.26911 Sep 2026The ceiling is checked before each run launches, so overrun is bounded to the runs in flight (one, or up to --concurrency)

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.