The client, not the app, now drives the transport; events are delivered
asynchronously, per ADR 0001.
- ChatClient owns Arc<Mutex<Core>> + a worker thread.
- The worker select!s over the inbound and shutdown channels; Drop joins it.
Outbound runs on the caller's thread.
- A single Transport (DeliveryService + inbound()) owns both directions of the
boundary, so the client takes one transport rather than a (delivery, inbound)
pair. InProcessDelivery::new, CDelivery, and chat-cli's transports implement it.
- FFI replaces client_receive with client_push_inbound + client_poll_events.
- chat-cli drains Receiver<Event>; inbound and event channels are both crossbeam.
- Corrects ADR 0001's inbound sequence to push — the worker parks on select!,
it never polls.
Implement a `client` crate that wraps the `libchat` context behind a
simple `ChatClient<D>` API. The delivery strategy is pluggable via a
`DeliveryService` trait, with two implementations provided:
- `InProcessDelivery` — shared `MessageBus` for single-process tests
- `CDelivery` — C function-pointer callback for the FFI layer
Add a `client-ffi` crate that exposes the client as a C API via
`safer-ffi`. A `generate-headers` binary produces the companion C
header.
Include two runnable examples:
- `examples/in-process` — Alice/Bob exchange using in-process delivery
- `examples/c-ffi` — same exchange written entirely in C; smoketested
under valgrind (to catch memory leaks) in CI
iterates: #71
