* feat(server): add background agents
An agent can be created background in any workspace. It stays a durable,
addressable agent, but default discovery, workspace status and attention
leave it out. Effective background is agent.background ||
workspace.background.
- Protocol: `create_agent_request.background` now marks the agent itself
and stays the workspace intent for a workspace the request creates.
Snapshots carry `background`. The daemon advertises
`features.backgroundAgents`. Clients advertise the `background_agents`
capability.
- Daemon: the flag persists in the agent record, so restart and resume
keep it. AgentDirectory owns visibility. Inclusive reads and
subscriptions from sources without `background_agents` see only agents
in background workspaces, because older apps would otherwise open a tab
for each one.
- Inheritance: omitted on agent-scoped creation, children and new
workspaces take the caller agent's background.
- MCP: create_agent accepts `background`.
- SDK: placing a background agent in an existing workspace, or under a
caller, fails fast with "Update the host to use background agents." on
older hosts.
- CLI: `ls -a` and `ls --background` add a BACKGROUND column.
* feat(app): hide background agents from tabs, track and status
* docs(plugins): point hidden helpers at background agents
* fix: keep background agents hidden across cache reload and connected hosts
* fix: keep remote creation working on older hosts and inherit foreign parents' background
Mohamed Boudra
a880c9619d