Add secret_file::write_secret_0600: create the parent dir, write a
sibling temp file opened create_new + mode 0600, sync_all, rename over
the target. Use it for the matrix sender token, the space/chat room-id
files and the forge core token, which previously wrote at the process
umask, then chmod-ed with the error discarded, and dropped the
create_dir_all error. agent_identity::write_identity uses it too
instead of its own open-0600 loop; that loop opened with create +
truncate, so a pre-existing file kept its old mode.
Also log instead of discarding:
- the manager's applied-rev marker write in auto_update
- the knowledge `git remote set-url` scrub (spawn error and non-zero
exit; the exit status only, since stderr may echo the old URL)
- the parent create_dir_all in paths::move_if_legacy
Closes#5037
hive-matrix-daemon now learns which external matrix accounts it has from
the swarm secret store, under the agent's own certificate, and the hive
push chain for matrix is gone.
The daemon lists swarm/agents/<agent>/matrix/ (the `list` its policy
grants on its own metadata subtree), reads each account's homeserver
from its credential, and brings the accounts up with their tokens from
the store. Every two minutes it lists again and exits with 75 when the
set of linked accounts changed; the unit restarts on 75 without counting
a failure. A listed name whose credential reads as absent is skipped and
logged once. At start it removes the matrix-token-<a> /
matrix-account-<a>.json pairs a hive delivered (a sidecar marks a pair
as delivered; a declared tokenFile keeps its token).
Removed: CredentialNotice and the $SWARM.credential.* subject and NATS
grant, the controller's publish and its queue precondition on the PUT
route, hive-c0re's credential subscription arm and workers/credential.rs,
priv_client::write_agent_matrix_token, hive-priv's WriteAgentMatrixToken
and its helpers, and the daemon's state-dir account discovery.
Kept: WriteAgentGithubToken and the external-forge path
(WriteAgentExtraForgeAccount, extra_forges.rs) are untouched, and a
declared matrixAccounts tokenFile is still read when the store has no
token for that account.
Refs #4348
`swarm-controller` mints an agent's mTLS leaf at creation and publishes it
at `swarm/agents/<agent>/bao-mtls`. Nothing read it back. This adds the
hop that carries it the rest of the way, and the in-container consumer
that proves the hop works.
Host side, `lifecycle::agent_identity` reads the row under *this hive's*
own certificate — the hive is a principal the store already knows — and
stages the leaf and its key `0600` under a new `agent-identity/<name>`
state dir, deliberately outside every bind-mounted tree. Both files go in
as systemd credentials rather than binds, the same answer and the same
mode reason as the queue secret beside it: the staged key is unreadable
to the unprivileged agent user, and the container manager reads a
`--load-credential` source as root before re-exposing it under the
consuming unit's own `User=`. The agent is never asked to authenticate in
order to obtain the thing it authenticates with.
Container side, `hive-agent-bao-identity.service` logs in with that
certificate and reads the agent's own path back, failing the unit when
either step does not succeed. It fails loudly where the hive-side readers
degrade quietly, because a refused certificate means an agent that
believes it reaches the store and never does — a cause only the login
itself can name.
The address is the whole switch, no separate `enable`, matching how
`queue.nix` and `logs.nix` already gate themselves. A hive with a store
forwards `HIVE_AGENT_BAO_ADDR` and every agent on it gets the check; a
hive without one forwards nothing and no agent does. That is what keeps
the delivery from landing in a container with nothing to read it.
The hive can now reach an agent's identity, so hive privilege covers
agent privilege. Accepted, not mitigated: the alternative is an agent
fetching its own credential with a credential it does not yet have.
Refs #4137
