A gate runs after the steps that produce what it judges

The coordinator’s decision of LAND-OC-FIX round 9 (the web suite’s regression gate judged a profile report no step of the run had produced).

requires names a gate’s producers. A VALIDATE or MERGE command of workspaceIsolation.commands may declare requires: the commands that produce what it judges (the perf profile step makes the report the web suite’s regression gate reads).
One sequencer runs them. runDeclaredCommands (engine/src/workflow/checkout-setup.ts) runs each producer before the first gate that requires it, once per sequence however many gates require it; a gate whose producer failed is not run, and the phase fails: a gate never judges an artifact no step of its sequence produced. The workspace phases, promotion and the landing all run through it, and commandsRun is what a ceiling, a plan digest or a toolchain census of a sequence counts.
The schema refuses what would make it ambiguous. A producer is declared, is not the gate itself, requires nothing itself (one level), is never a judged (ledger) gate, and is named by no phase — a phase naming it would run it a second time, and a setup command is the checkout’s, never a gate’s input (round 12, correctness B-L11). A command with requires runs only in the validate and merge phases.