One system per file
The code here is written by agents. The audit is done by a person. That only works if the code is auditable by construction, so it became rule: one system per file, no cross imports, and a mandatory header in every file stating which section of the document it implements and what it must never do. An unreadable monolith is indefensible even when it runs.
Zero magic numbers
Every balance value is read from a calibration file, never hardcoded. That rule came out of a real loss: a C = 1.0 hardcoded in a generator left an entire batch of creatures 11% weaker. Nobody noticed for weeks.
Proof, not a stamp
Beyond per-system tests there are invariant tests, which prove the ceilings and the idempotency. The build itself generates an audit report, system by system, with the tests that passed. The final rule is short: without reproducible evidence, it did not pass.