The GitHub job's store is ~7.3 GiB but gc-max-store-size-linux is 6G, and
nothing roots the devshells, so cache-nix-action's pre-save `nix store gc`
deletes whichever paths cross the cap before every save. The snapshots land
missing the JDK and the Android SDK components, so both `nix develop` steps
re-download or rebuild them on every run.
Raise the cap to 10G, which clears the store, and bump the key to nix-v3-. The
first run after that downloads the full closure once and saves a complete
snapshot; the gutted nix-v2- snapshots are not restored, so there is one cold
run per ref and v3 is warm from then on.
Compressed at ~0.47x its store the snapshot is ~4.7 GiB at worst, inside the
10 GB per-repo budget. What pushes the repo over that budget today is the four
stale gradle- (v1) entries, which no restore-key can reach and which age out by
LRU.
Replace the reusable workflow with .github/actions/build plus a nested
nix setup action, invoked as a step. CI and the next build stay a single
job (no extra runner or Nix restore); the release keeps its build/publish
split for credential isolation.
austinried