#ci
Continuous integration, runners and build speed.
2026
The ten pound rule
Decision recordIn October our GitHub Actions use ran to nearly five times the minutes our plan includes, and a spending cap we kept raising turned two dozen alerts red. On 5 November we set one rule for every metered vendor: free tier or £10 a month.
Load average 14, and the CPU was mostly idle
PostmortemOne of our Macs crawled, with load readings up to 30 and eight agent sessions open. We blamed the cores. Measured at a load of 8 to 14, they were 68 to 80% idle. The memory had run out, and our first fix watched the wrong number.
24 files we are not allowed to edit
Deep diveEd proved his scheduling engine against ten thousand simulated worlds. TyreStack imports it unchanged, locks 24 files to his exact bytes with a hash, and the gate fails the moment one of them differs.
20.5 hours of agent time spent watching CI
By the numbersWe read two weeks of our AI coding-agent sessions by hand: 129 sessions, 496 prompts. The agents were rarely slow at the work. They were slow at finishing it: they kept stopping to ask, and 20.5 hours went on watching CI.