[tgockel]

A subclass of outrig.Agent declares a long-lived child agent. Its docstring is the first part of the child's instructions, and each async def it marks @outrig.agent is a request channel of that name: the method's docstring describes it, its parameters make the request -- none carries None, one its value, several a frozen dataclass Message the class holds -- and its return annotation is the reply's type. The body is never run or read. Every rule is checked as the class is made, in a module or a submission alike, and a broken one raises TypeError naming the member; @outrig.agent in the body of a class that is not an agent class is refused the same way.

FooAgent(**inputs, model=...) checks its inputs and returns at once, launching a request child in the background. The child's first round opens as it launches, for getting ready, and await foo.ready() waits for it. A method call checks its arguments, sends the request and returns its handle at once. A request made before the child exists is held on the child's record, made with the instance and taken by the child's kernel when it opens, so it counts against requests-max, cancels and ends like any other, and is sent as the spawn answers. What the launch meets -- an unknown model, a limit, the session closing -- raises at ready() and at each request, never in the constructor. release(), async with, the session's close, and a finalizer for an instance collected unreleased each end the child and what it launched; a request in flight holds its instance.

The host tells the interpreter requests-max in a new limits line, and an instance's readiness in an oriented line. Five events record each instance under its child's subject: agent.instance.started, .ready, .released, .collected and .handle.collected. Payload gains their variants, with AgentInstanceId and InstanceRelease.

Summary

What does this change, and why?

Checklist

• cargo fmt --all -- --check passes
• cargo clippy --workspace --all-targets -- -D warnings is clean
• cargo test --workspace passes
• Docs in doc/ updated if behavior changed (mdbook build still clean)
• CHANGELOG updated for user-visible changes

Notes for reviewers

Anything worth calling out -- tricky bits, follow-ups, or intentionally out-of-scope items.