running-process-platform-internal

Internal, published host-mechanics boundary for running-process. Its public surface is intentionally small; product policy remains in the caller crates.

Deprecated 4.x PTY trait accessors remain source-compatible until 5.0, but platform mechanics never consume their primitive values. Native PTY control state must stay captured inside concrete operations; the neutral facade may not introduce descriptor/HANDLE payload structs or tokens.

The established 4.x broker post-Hello callback, client stream returns, and pre-bound async SESSION listener entry points likewise remain source-compatible until 5.0. A hidden crate-root adapter may convert an opaque IPC stream only at those public return/callback boundaries, and the facade conversion trait may accept the legacy listener on entry. The neutral platform::ipc facade never returns the concrete transport type, and new callers must use the opaque transport.

src/lib.rs is the only host selector. Neutral capability indexes live in src/platform/; their private Windows, Linux, and macOS implementations are selected behind that boundary.