Agents keep git worktrees and cargo target dirs under /home/<agent>,
which lives in the container rootfs and is deleted on destroy. They
can't move them under state/, because a claude started there walks up
into state/CLAUDE.md and takes on the agent's identity.
Add a per-agent work/ dir next to state/ on the host
(/var/lib/hyperhive/agents/<n>/work), bind-mounted RW at
/agents/<n>/work. hive-c0re creates it in ensure_state_dir and in
set_nspawn_flags (the rebuild path reaches only the latter), the
agent's activation chowns it to the agent user like state/ and
harness/, and measure_agent_disk counts it. destroy never touches the
agent root, so work/ survives it; purge removes the whole root, so
work/ goes with it.
Closes#4977
/etc/tmpfiles.d/hyperhive-agents.conf was a boot-time backstop (#2290)
that pre-created every agent's bind sources. The start preamble already
creates them for every c0re-driven start, and on this host only hive-c0re
starts agent containers. The file was also the reason the socket dir's
owner had to be declared there, which is how it spent its life at
`0777 root root` whenever the uid could not be resolved (#4742).
- hive-priv gains `EnsureAgentSocketDir { name }`, called from
`set_nspawn_flags` in every start path. It creates
`/run/hive-agent/<name>` `0751 root:root` with mkdirat relative to an
O_DIRECTORY|O_NOFOLLOW fd for the parent. An existing entry has to be a
directory (fstatat AT_SYMLINK_NOFOLLOW); anything else is refused, and a
directory is left alone. hive-c0re's own create_dir_all went: its /run
is read-only under ProtectSystem=strict.
- The container's `hive-agent-user-migrate` activation chowns that dir to
the agent user and sets 0751, the same way it already handles state/ and
harness/. It refuses a symlink or non-directory there, since `test -d`
and chmod follow links. No host-side passwd parse, and no window where
the dir is world-writable.
- `/run/hyperhive/agents/<name>` stays created by hive-c0re itself
(`ensure_agent_runtime_dir`). It holds the `mcp.sock` that hive-c0re
binds as hive-core, so it must not become root- or agent-owned.
- The `/run/hive-agent` parent is declared in hive-priv.nix, `0755
root:root`, instead of hive-gateway's hive-core rule. hive-priv is its
only writer now, and hive-priv's ReadWritePaths needs it to exist.
- The manager start in `ensure_root_agent` now goes through
`converge_start_preamble` + `start_with_fallback`. It was a bare start,
so after a reboot the manager's bind sources existed only because of the
tmpfiles file, and its limits drop-in did not exist at all.
- Removed: `sync_tmpfiles`, `agent_uid_gid` / `parse_passwd_uid_gid`,
`priv_client::sync_agent_tmpfiles`, `AgentTmpfilesEntry`, the tmpfiles
body builder and their tests, plus the three call sites.
- Legacy: hive-priv unlinks the file at every start, ignoring ENOENT.
`SyncAgentTmpfiles` stays one release as a payload-ignoring variant that
does the same unlink and returns Ok, for an older hive-c0re.
Salvaged from #4752: the boundary.md correction that nginx only dials,
because ProtectSystem=strict makes its /run read-only.
Behaviour change: a manual `nixos-container start h-<name>` right after a
reboot, before hive-c0re has started that agent, now fails on a missing
bind source instead of starting.
Closes#4742
