pub type HandlerSignatureIr = (Vec<(String, TyId)>, Vec<String>, TyId, bool);Expand description
(params, given, ret, effectful) — lower_service_handler_signature_ir’s
return shape (#1187’s slice 5), a named alias rather than a bare tuple
because its consumer (emit_service, bynk-emit/src/emitter/emit.rs)
has to spell it out in a function signature. (The agent-handler
signature reader that shared it went with Slice D1 of #1542.)