CI setup

Network clone and fetch requests with --depth (any value), --single-branch, --filter=blob:none, or --filter=tree:0 use full history from the shared store. The first request fills a cold store; later requests reuse its objects and still contact the remote for updates. There is no shallow-upgrade opt-out: use native Git when true shallow semantics matter. --shallow-since and --shallow-exclude pass through unchanged. Sparse checkout still controls which files appear in the working tree. Existing shallow repositories become full on supported fetches; --deepen and --unshallow impose no restriction on full repositories.

Use checkout-git-dedup, our fork of actions/checkout, to call the installed wrapper directly:

steps:
  - uses: bhouston/checkout-git-dedup@main

Install git-dedup on the runner once, alongside native Git and Node.js. The action inherits the runner's settings, including GIT_DEDUP_STORE and git-dedup.gitPath, with no action-specific configuration or git PATH shim. It keeps HOME intact during credential setup, so the default store remains ~/.git-dedup. Keep the store between jobs and make it readable and writable by the runner account. Inputs, outputs, authentication, and post-job cleanup follow upstream checkout.

Use a git-dedup build containing pool-backed fetch support (PR #144, available on main); npm 2.1.0 predates this feature. The action requires git-dedup on PATH for checkout and post-job cleanup.

If you keep the standard actions/checkout, it invokes git directly. A git PATH shim installed before checkout remains an alternative; set git-dedup.gitPath to the absolute native Git executable to avoid recursion.

For a cache check, run git-dedup --stats fetch --depth=1 origin in each of two fresh initialized checkouts of the same remote. The second report should say reused object pool; git rev-parse --is-shallow-repository should print false. This reports pool reuse, not an offline checkout: remote updates still require network access. Linked checkouts depend on the store, so keep it in place.