Function current_backend_kind 

pub fn current_backend_kind() -> ConPtyBackendKind

Reports whether the process-wide ConPTY API table resolved to the system kernel32.dll or to a sidecar conpty.dll. See #443.

Integration tests gate Win10-with-sidecar coverage on this — the byte-exact passthrough assertions can only hold when a sidecar is loaded on Win10, since the system kernel32!CreatePseudoConsole on Win10 < build 22000 silently ignores PSEUDOCONSOLE_PASSTHROUGH_MODE.