Lowest channel ID the adapter assigns to pw_rpc2 connections. Must be larger than a project's own channel IDs and must not be 0. Defaults to 100.

New IDs are assigned sequentially upward from first_channel_id. IDs already open on the server are skipped. Closed connections' channels remain open, but are reused before allocating new IDs.

ID assignments never wrap past UINT32_MAX, so set first_channel_id above your project's largest channel ID, but leave room below UINT32_MAX for peak concurrent pw_rpc2 connections.

Maximum number of channels the adapter keeps open on the server at once, or 0 for no limit other than the server's free channel slots.

Maximum outgoing stream messages to buffer per call before writes fail (must not be 0). Defaults to 8 so handlers can write a short burst without waiting while bounding the memory a stalled call can hold.