Run shared validation once

Remove overlapping task or matrix invocations that perform the same check on the same inputs.

Prompt

Evaluate and apply this CI technique to my repository: Run shared validation once.

Remove overlapping task or matrix invocations that perform the same check on the same inputs.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/avoid-duplicate-validation.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.

View all playbooks

How companies used this technique

Read what each company changed and follow the original sources.

Run platform-independent checks on one matrix leg

The desktop job ran on macOS, Linux x64 and Linux arm64, and each leg repeated typecheck, lint, format, API drift, unit, component and security suites. The PR runs those steps on the ubuntu-latest leg; every leg still packages the app, with ubuntu-latest x64 running the full journey suite and macOS and ubuntu arm64 running a 5-journey smoke subset.

Use it when: A matrix over operating systems repeats checks whose result is the same on every OS.
Before applying it: Keep any check that reads platform-specific code paths, native modules or line endings on every leg it can differ on.

Avoid repeating CI checks in a version bot’s commit hook

The versioning action disabled Husky because separate workflows already handled its precommit checks. This adapts the duplicate-command recipe and depends on required CI running the same checks.

Use it when: An automated version PR repeats hooks already enforced by required CI.
Before applying it: Never bypass a check merely because it is expensive. Prove equivalent file scope and failure propagation in required workflows; retain checks that only the hook performs.

Run snapshot checks once in a dedicated lane

Stripe iOS re-records snapshots in a dedicated job and skips those snapshot classes in the main unit-test jobs only when that dedicated job is part of the pipeline. Standalone framework jobs keep every test.

Use it when: Snapshot or generated-output checks run both on their own and inside a broad suite.
Before applying it: Skip a class in one lane only while a required lane runs it, and keep runtime variants and aggregate results unchanged.

Stop invoking tests twice through overlapping tasks

Stripe Android’s screenshot verification already ran the unit tests. A new dispatcher task runs screenshot verification for modules that have it and unit tests for the rest, so each module runs its tests once. Stripe .NET removed a Debug build and test pass that repeated the Release pass for an SDK with no configuration-specific code.

Use it when: A test wrapper invokes another test task that CI also calls directly, or two configurations run the same code.
Before applying it: Compare the test and screenshot inventories before and after, and keep a configuration that has its own code paths or its own published build.

How companies used this technique

Run platform-independent checks on one matrix leg

Avoid repeating CI checks in a version bot’s commit hook

Run snapshot checks once in a dedicated lane

Stop invoking tests twice through overlapping tasks

Related techniques

Package once, and build full installers after merge

Remove repeated build steps

Build once and share the output with test shards

Company Playbooks

Related guides

Filter workflows by changed files

Cancel superseded CI runs

Bound runner jobs with timeouts

Right-size GitHub Actions runners