Previously, serveConfig was a pkgs.writeText store path embedded in
ExecStart. Any repo edit (gateway.nix, frontend, unrelated nix modules)
changes hyperhiveFlakeSource → serveConfig hash → ExecStart → systemd
restarts hive-c0re → StartupSweep → every agent rebuilt unnecessarily.
Fix: write the JSON to /etc/hyperhive/serve.json via environment.etc
(a managed /etc symlink to the store-path content). ExecStart now
references the stable /etc path, changing only when cfg.package (the
hive-c0re binary) changes. Unrelated module edits no longer bounce c0re
or trigger a cascade agent rebuild.
hive-c0re still restarts — and triggers the sweep — when its binary
changes, which is the correct invariant: a new release legitimately
needs to resync all agents with updated harness modules.
ef4dd67e9a