1.0 — Reactor Physics
The fusion core cannot be cold-started. Once it shuts down, a restart takes 40 hours, during which the station has no main power and no life support beyond emergency cells, which last 6 hours. This is the central clock of the story and must never be contradicted.

2.0 — Communication
Messages to the Rim take 12 minutes each way. Real-time contact with the Corporation is impossible. Every decision is made locally, with no one to ask for permission.

3.0 — Artificial Gravity
Gravity comes from the station's rotation. If rotation control fails, the station goes weightless within 90 seconds. The reactor failure threatens rotation, so gravity is never guaranteed in late scenes.

4.0 — Airlocks
Every airlock requires two crew to operate from inside — a deliberate safeguard against anyone acting alone. No character can cycle an airlock by themselves.