Agent setup / Add skills without breaking old jobs
Does adding skills break the jobs an agent already did?
Check that installing more skills keeps earlier work passing.
Best in this use case · ranked only on systems that ran every core taskclaude-haiku-4-5-20251001modelGot 87% of cases right, averaged over 1 core task.
Best value · at least 10% cheaper, still at least ¾ of the best score—needs at least two ranked systems
Thin evidence. 1 system is ranked here. One run is a number with nothing to compare it to; a second system or a baseline makes it a comparison.
TASKS IN THIS USE CASE · 1
bar = share of cases right · each row is one full system
😬😬 Does adding skills break the jobs an agent already did?core-capability-stacking-regressionWhen an agent has more skills installed, does it still do the jobs it already did correctly?
Same job, same number of new skills — the only difference is whether they overlap with what the job needs.108 cases · 1 run · core taskOpen task: rules, cases, every run →