CI timing analysis

Agent Skill metadata

name: ci-timing
description: Compare a Julia PR's Buildkite job durations against recent CI history (per-job mean/min/max over the last N days). Use when asked whether a PR slows down or speeds up CI, or to check a build's timings against the weekly baseline.

julia --startup-file=no --project=contrib/ci-timing contrib/ci-timing/ci_timing_compare.jl <PR-number>

Prints a markdown table, slowest job first, plus a TOTAL row: each job's duration in the PR's julia-pr build vs. the mean/min/max of the same job name over the last 7 days of julia-ci-timing history. ⚠️ = above the weekly max, ✅ = below the weekly min. No Buildkite token needed; gh is only needed to turn a PR number into a build.

Flags: --build julia-pr/853, --days N, --include-failed, --min-seconds N (hides short jobs).

Caveats when reading it:

One build vs. a week of samples — anything inside the min/max band is agent variance, and even ⚠️/✅ rows need a second build to mean anything.
juliasyntax/Launch * jobs are seconds long, so their percentages are noise; --min-seconds 120 drops them.
A fleet-wide shift in one direction skews TOTAL and is not a PR effect.
Broken (never run), running, and superseded retry jobs are excluded; a failed job's time is cut short or stretched by the failure.

For logs behind a slow or failed job, see the buildkite-logs skill.