Lifecycle

Symbol	Direction	Purpose
`mc1_plugin_main()`	plugin → host	Returns the descriptor; called once at load.
`create()`	host → plugin	Allocate state for a sample rate / max block size.
`destroy()`	host → plugin	Free state on unload or hot-reload.

DSP interface

Callback	Thread	Notes
`process(state, in, out, frames)`	audio	Real-time; no allocations, no locks, no syscalls.
`set_param(state, id, value)`	audio/UI	Atomic parameter update; keep it wait-free.

Input interface

Callback	Returns	Notes
`open(url)`	`int`	Resolve/connect a source; 0 = success.
`read(buf, frames)`	`int`	Fill interleaved float PCM; returns frames produced.
`close()`	`void`	Tear down the source.

Output interface

Callback	Thread	Notes
`write(buf, frames)`	audio	Sink the playback bus to a device/encoder.
`flush()`	any	Drain buffers on stop.

Parameters

Each parameter has an id, name, min, max, and def. The host renders a control, persists the value with the project, and may automate it. Read incoming changes via set_param.

Host services

The host exposes a small services struct for logging, sample-rate queries, and (opt-in) access to the AI backends for metadata-aware behavior. Treat all host calls as non-real-time unless documented otherwise.

ABI beta — symbol names may evolve. Pin to MC1_ABI_VERSION and watch the changelog.