ConstLethal floor: dwell at/below this spo2 accrues toward death.
Dwell at/below the floor before the death seam fires (game-seconds).
Cause-of-death string by cause (the death seam's causeOfDeath).
spo2 drain rate per game-second by cause. Vacuum-vs-water tuning
(a per-medium split) would live here later; v1 keys by cause.
Game-ms per drain/recovery emission tick (→ WorldClockApi.every).
Voluntary breath-hold extension set by inhale (game-seconds).
Far-past guard (reuse metabolism's 4h) — a gap this long = absence.
spo2 recovery rate per game-second on return to breathable air.
W2: litres of air a worn tank yields per game-second under supply.
Automatic breath-hold grace on first submersion (game-seconds).
Every respiration dial as a module const-object (the
METABOLIC_DEFAULTSprecedent). All magnitudes are defensible playtest defaults — the structure is the deliverable, the rates are tuned. Times are GAME-seconds;*_PER_SECare%-points per game-second. Rates are playtest-tuned, not plan decisions.