An agent's capabilities move from the hive's meta repo
(`meta/capabilities.json`, injected as `HIVE_CAPABILITIES`) into the
`capabilities` field of its key in a new `agent-permissions` KV bucket,
which swarm-controller alone writes.
- swarm-queue-client: `agent_permissions` (bucket, key, `AgentPermissions`,
direct-get read, the import subject and its wire types).
- swarm-controller: creates the bucket at start; `GET|PUT|DELETE
/api/agents/{name}/permissions` (deny_unknown_fields and unknown
capability ⇒ 422, duplicate ⇒ 400, agent must be declared by a hive);
answers each hive's one-shot import, writing a key only where there is
none and only for agents that hive's wanted state declares.
- swarmctl: `agent permissions get|set|clear`.
- swarm-nats-auth: a hive reads every key of the bucket and sends its
import on its own subject; the controller subscribes to the imports and
may answer them (`responses`).
- hive-c0re: reads each of its agents' keys every 30s into
/var/lib/hyperhive/swarm-agent-permissions.json and restarts an agent,
gracefully, when its capabilities change. Unset is the compiled-in
default (ruth: manage_root_agent; everyone else: none). A failed read
keeps the stored value. On first boot it seeds that file from
meta/capabilities.json, sends the grants to the controller, and deletes
the file once the controller answers.
Deleted: the capabilities.json reader/writer, `HIVE_CAPABILITIES` in the
rendered meta flake, ruth's capability seed, the capabilities half of the
permissions rebuild job (`PermPayload::Capabilities`/`Combined`), the
dashboard's capabilities table and `capabilities_changed` event, and the
now-unused `Capability::description`.
Part of #5170.
f862354e43