ProtectSystem=full makes /usr, /etc, and /boot read-only. Safe for
hive-c0re because it never writes to those paths directly:
- /etc writes (e.g. /etc/nixos-containers) go through hive-priv
- /etc/hyperhive/serve.json reads are read-only
- All runtime writes go to StateDirectory (/var/lib/hyperhive) and
RuntimeDirectory (/run/hyperhive), which remain writable under full
ProtectSystem=strict (everything read-only) is still deferred — it
requires auditing ReadWritePaths for every nix path c0re touches.
RestrictAddressFamilies deferred pending a watched deploy.
Also tightens the comment block to not mention a numbered issue.
3e5ddbd2c0