GUI cache layers (main-only save)

How the vox-gui UI CI job uses GitHub Actions caches without writing pull-request-scoped entries. Rust and Node package-manager caches save only from main; pull-request and merge-queue jobs restore but never save, because the repository’s Actions cache budget is capped and PR-scoped keys cannot be read by any other ref. The page shows the ui job pattern (package-manager-cache: false, main-scoped pnpm and Vite keys), names the jobs that write the caches, and gives agents the setup-node snippet to copy. vox ci cache-key-lint enforces it.

Policy

Rust caches (Swatinem/rust-cache) and Node package-manager caches save only from main. PR and merge_group jobs may restore but must not save — enforced by vox ci cache-key-lint. The Actions cache budget is hard-capped (~10 GB); PR-scoped keys are write-only garbage.

ui job pattern (ci.yml)

• actions/setup-node uses package-manager-cache: false on PRs.
• pnpm store / Vite cache: restore from a main-scoped key when present; never actions/cache with save on pull_request.
• Nightly / cache-seed (or push-to-main) jobs are the writers for layered pnpm + Vite artifact keys.

Local agents

Do not add cache: pnpm / cache: npm to PR workflows. Prefer:

- uses: actions/setup-node@v4
  with:
    node-version-file: crates/vox-gui/ui/package.json
    package-manager-cache: false

See runner-contract.md and AGENTS.md §CI Contract.