[tire-fire]

While an rvb competition is not started and no scored round exists yet, the engine runs preflight rounds: the same checks a scored round would run (inactive teams, disabled team services and checks without seeded credentials are skipped alike), with results stored in new preflight_round_schemas / preflight_check_schemas tables. They are never scored and never touch round_schemas, so points, uptime, and SLAs start clean.

• Preflight rounds are a persisted entity numbered separately from scored rounds (the round row is written even when no results arrived, so a timed-out round is visible). Tasks and results carry round_id and preflight, and the result collector ignores results from the other kind of round.
• The engine decides between preflight and scoring per round, under the rvb case only, from the DB rather than the in-memory round counter (which advances on rounds that stored nothing and is reseeded on restart): preflight while the competition is not started (GetCompetitionStarted, the same reader the UI and API gate on) and no scored round has been stored (GetLastRound). On a read error that iteration runs a preflight round, delaying scoring by one round. Stopping a competition that has stored scored rounds does not bring preflight back.
• GET /api/engine/reset now also drops preflight rounds. Reset while stopped (or stopping before the first scored round is stored) re-enters preflight; competition state is kept, so injects keep their anchor.
• GET /api/engine/preflight (admin-only; stored error/debug text can contain credentials) returns the latest preflight round.
• Preflight rounds need an upgraded runner: results without the preflight flag are discarded; scored rounds are unaffected. The new tables are added by AutoMigrate.
• Custom checks: the ROUND placeholder is the preflight round number during preflight and the scored round number afterwards (both start at 1); documented in README and docs/custom-checks.md.
• Runner: the result's task identity and runner metadata are set once; only check-produced fields are taken from the check.
• Engine tests share one fake runner helper stopped at test cleanup; the preflight gate/reset tests reset the competition-state row in setup and cleanup (testutil.ResetCompetitionState). Integration tests cover preflight storage, empty rounds, isolation from scored rounds, the start/stop/legacy-row gate, stopping after an unstored empty round, and reset re-entering preflight while keeping the competition start.

Known limits: GET /api/engine/reset is a pre-existing cookie-only GET that changes state; it should become a POST in its own change.