CLIClaude Code, interactive mode, seeded with flags-account. 0 added and 1 removed, of 214 lines, in the prompt 17 of 27 arms receive. 3 other prompts also changed. 3 of 30 tool descriptions changed. 1 of 28 tool schemas changed. The appended system-reminder blocks moved: 1 line added, 1 line removed. Compared against v2.1.270.
The two arm counts on this page measure different things: 17 arms receive the prompt the headline is about, and the widest edit below reached 23, because the same changed lines sit in more than one prompt.
This arm was captured with the sandbox seeded from flags-account, this account's own GrowthBook payload, seeded into the sandbox .claude.json. 635 flags from data/flags/snapshots/flags-20260914T192504Z.json. What a seeded capture does and does not tell you.
Releasedcaptured
Compared withv2.1.270the previous capture on this arm
Prompt214 ln4 families, 27,022 characters
Model strings27every capture asks all of them
Tool descriptions303 moved this release, 28 with a parameter schema
6 capture arms for this release, one page each, never diffed against each other
What changed since the previous capture
5One line per document that moved, the system prompt and the tool descriptions in the same table.
PromptReachMovedThe first line that changed
System prompt 214 ln, and 1 other copy of it moved the same way23 of 27 arms+0−2<total_tokens>15000000 tokens left</total_tokens>
System prompt, Opus 4.8 52 ln, and 2 other copies of it moved the same way4 of 27 arms+1−3For actions that are hard to reverse or outward-facing, confirm first unless durably authorized or explicitly told to proceed without asking; approval...
Monitor 71 lnall 27 arms+2−2- **One per occurrence, indefinitely** ("tell me every time an ERROR line appears") → Monitor with an unbounded command (`tail -f`, `inotifywait -m`,...
SendMessage 33 lnall 27 arms+1−1A listed peer is alive and will process your message; messages enqueue and drain at the receiver's next tool round (its `ListAgents` row says whether...
Workflow 35 lnall 27 arms+1−1This session has the default workflow size guideline: medium — keep workflows under 15 agents. This is a guideline, not a hard limit — follow it unles...
The families in this capture
4A family is one prompt and every model-interpolated copy of it, ranked by the model strings it reaches.
#FamilyHeadReachCopiesOpens with
1Haiku family, 12 model strings214 ln · 27k17 of 273 copiesYou are an interactive agent that helps users with software engineering tasks.
2claude-fable-575 ln · 9.9k2 of 272 copiesYou are an interactive agent that helps users with software engineering tasks.
3Opus family, 6 model strings66 ln · 9k6 of 271 copyYou are an interactive agent that helps users with software engineering tasks.
4default52 ln · 5.6k2 of 272 copiesYou are an interactive agent that helps users with software engineering tasks.
Tool descriptions
30The text the model is given for each tool, on this arm.