The problem: CI is the bottleneck

Coding agents write pull requests faster than CI can test them. siftwise is a self-hosted service that picks the tests a change can affect, runs the full suite whenever it isn't sure, and tells people and agents whether each failure is a new regression, already broken on main, or flaky. Version 0.1.0 is out today on PyPI and GHCR. Here's how it works, how to try it, and what replays of four real repos' CI history do and don't show.

Coding agents made writing a change cheap. Verifying it didn't get any cheaper. Anthropic reports a 25x increase in CI jobs over six months as agents sped up writing code (Agentic coding is straining CI), and Linear found that as development accelerates, CI becomes a bottleneck, because every PR still has to pass through it (AI coding has made CI a bottleneck).

Most pipelines answer "which tests does this change need?" with "all of them". That is safe, and on a large suite it is slow: every push pays for tests the change can't reach. And when something fails, someone still has to work out whether the change broke it, main was already broken, or the test is flaky. An agent that can't tell those apart may spend its next turn "fixing" a failure it didn't cause.