Add weekly cache warmer to keep SPM caches alive past 7-day TTL#149
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Add weekly cache warmer to keep SPM caches alive past 7-day TTL#149
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GitHub evicts cache entries 7 days after their last access. For branches that go quiet over a long weekend or holiday, the SPM build cache that ci.yml relies on can expire between PR pushes, forcing a cold rebuild that has been observed pushing the `MCP integration tests` step past its 30-min cap (PR #141). `cache-warm.yml` runs weekly Sunday 05:00 UTC and on `workflow_dispatch`, mirroring ci.yml's two cache keys — `spm-macOS-build-{hash}` and `spm-macOS-ios-{hash}` — by running the same `swift build` + `swift build --package-path examples/spm` sequence each job uses. Each job restores its key, builds, and the actions/cache post-step refreshes the cache content under the same key, resetting the eviction clock. Weekly + 7-day TTL is tight margin; the dispatch button on the Actions page is the safety valve for cases where a holiday delay or runner queue pushes the next scheduled fire past the eviction deadline. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
.github/workflows/cache-warm.yml, a small workflow that runs weekly (Sunday 05:00 UTC) plus on-demand viaworkflow_dispatch.ci.yml's two SPM cache keys —spm-macOS-build-{hash}andspm-macOS-ios-{hash}— by running each job's relevantswift buildsequence, refreshing the cache content under the same key.Why
GitHub evicts cache entries 7 days after their last access. For branches that go quiet over a long weekend or holiday, the cache can expire between PR pushes, forcing a cold rebuild that has been observed pushing the
MCP integration testsstep past its 30-min cap on slow GHA runners (see PR #141, where commite7449f9's build-and-test took 2315s vs. the same workflow taking 470s a week earlier — empirically the cache hit cleanly that day, so the issue was runner variance, but cache expiry would have stacked badly on top).Weekly + 7-day TTL is tight margin; the
workflow_dispatchbutton on the Actions page is the manual safety valve if a holiday delay or runner queue pushes the next scheduled fire past the eviction deadline.Cost
~16 macos-15 GHA minutes per week (two parallel jobs, ~8 min each warm). Single-digit-percent of the project's CI budget.
Test plan
Cache SPM buildsteps inci.ymlreportCache hit for: spm-macOS-build-…/spm-macOS-ios-….🤖 Generated with Claude Code