Which evaluation surface ran the pipeline a gate.result event came from
(KRZ-312). The same gate id is evaluated more than once per mission —
once at plan approval and once at the final gate — so a gate id plus
ladder position alone cannot name ONE evaluation; the surface does. It is
recorded on the event itself rather than inferred from neighbouring
events: a replay that reconstructs the ladder from the log alone must not
depend on emission-order conventions that a later refactor could move.
Final-gate contract gates (orchestrator::final_gate): the static
floor re-checked against the active tree, plus any configured pack’s
deterministic gates registered after it.