Guide · checked November 2026
Choosing CI when agents write the code
When coding agents write most of the code, more changes reach CI, each one waits for a verdict, and that verdict is what decides whether the change is safe. The criteria that matter most are queue time under bursts, test cost per change, and a verdict that never turns a failure into a pass.
What changes when agents push
- More pushes. An agent iterates by pushing and reading CI. Several agents working in parallel push in bursts, and each push starts the full workflow.
- Queue time becomes the wait. When pushes arrive faster than runners free up, jobs wait before they start. A long suite multiplies that.
- Test cost scales with change count. On per-minute pricing, every extra push runs every test again. The bill tracks change volume, not team size.
- The verdict carries more weight. A person reviews less of each change, so the pass or fail is doing more of the reviewing. A CI that skips tests to go faster weakens the one check you rely on.
The criteria that matter most
- Push-to-verdict time under load, measured at the 90th percentile on a busy day, not the median on a quiet one.
- Tests per change, and the rule that decides them. Running only the tests a change can reach cuts time and cost; it is only safe if, when the tool cannot tell, it runs the test.
- Same verdict. Run the candidate beside your current CI and check that every pass and fail matches.
- Elastic parallelism, so a burst of pushes is spread across runners instead of queued.
- Agent access. Whether an agent can read results, rerun and set the tool up without a person clicking through.
How the options compare on this
| Option | Under agent volume |
|---|---|
| Graphide CI | Built for it: each change runs the tests it can reach (more when unsure), split across runners with warm caches; agent signals warm machines before a push lands; agents switch repositories through its MCP server. x64 Linux GitHub Actions jobs. |
| Depot, Blacksmith | Faster machines and caches for every push; every push still runs the full workflow. |
| GitHub Actions, GitLab CI/CD, CircleCI | Every push runs the full pipeline; concurrency and minutes per plan set how bursts are absorbed. CircleCI's timing-based splitting shortens each run. |
| Buildkite, Jenkins | As elastic as the fleet you run; bursts are a capacity question you own. |
What to do this week
- Pull two weeks of run data and split it by author: agent or person. Compare push counts and queue times.
- Find the job that most often holds up a merge.
- Try a runner layer on that job on one branch, and run the benchmark, checking verdicts first.
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