Cancel superseded pull request runs

Free runner capacity by canceling validation that a newer commit has replaced. Keep required main-branch and release runs intact.

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Prompt

Evaluate and apply this CI technique to my repository: Cancel superseded pull request runs.

Free runner capacity by canceling validation that a newer commit has replaced. Keep required main-branch and release runs intact.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/cancel-superseded-runs.md

Inspect this repository’s CI workflows, build and test commands, dependencies, and recent run timings. Identify where this technique applies and explain the expected benefit using this repository’s evidence.
Measure a baseline from recent comparable runs: elapsed time, queue time, runner minutes and failures where available. If data is unavailable, say what cannot be measured.
Compare relevant company approaches, checking prerequisites, platform differences and tradeoffs. Rank applicable options by evidence, fit and measurable opportunity; do not present company results as predictions for this repo.
Recommend the smallest safe change, show what checks and fallback paths remain, and ASK ME WHICH CHANGE TO APPROVE BEFORE EDITING ANY FILES.
Only after approval, work on a new feature branch, make one reversible change, and open a reviewable pull request. Never merge or push to a default or protected branch.
Keep required checks, test coverage, deployment and release behavior intact. Validate the change and compare equivalent runs where possible; report limitations and what should be monitored after merge.

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How it works

Group validation runs by the pull request or branch they validate. When a newer commit starts another run in that group, cancel the older validation. Scope the cancellation rule to work that the new run replaces; deployment, release and migration workflows need their own completion rules.

How companies used this technique

Read what each company changed and follow the original sources.

Cancel superseded runs, never on main

Anthropic's Python and TypeScript SDKs added a workflow concurrency group keyed on the branch, so a newer push cancels the older run. On main the group is keyed on the commit, so main runs never cancel each other.

Use it when: Developers or agents push to the same branch several times while CI is still running.
Before applying it: Deploy, publish and migration workflows keep running to completion; only runs whose result a newer commit replaces are cancelled.

Cancel obsolete runs using the correct event identity

Mastra added workflow concurrency and cancellation to lint, docs and workspace workflows. Related changes handled workflow_run identity and separated comment-driven approval updates from PR updates.

Use it when: Repeated pushes leave obsolete verification jobs occupying runners.
Before applying it: Key the group on workflow plus the logical PR or ref, with safe fallbacks, so a new commit cancels the old run. Keep release and destructive side-effect jobs out of indiscriminate cancellation.