Function derive_step_name 

fn derive_step_name(cmd: &Command, target: PipeTarget) -> String

LSD-2 — short, greppable name for a Command dispatched as part of a saga step. Mirrors srv’s command_discriminant_name in spirit (snake_case strings rather than Debug formatting) but prefixes with issue_cmd_<target>_<discriminant> so --diag sagas output makes the dispatch target obvious without a separate column lookup.

Falls back to issue_cmd_<target>_unknown for variants serde can’t stringify (shouldn’t happen for the snake_case-tagged Command enum; defensive default).