CAIN-42 CAIN StudioCAIU · Module 4 of 5 · 14 min
Proving risk reduction by replay
Recommending controls is easy; proving they reduce risk is not. ACTUARY proposes policy rules (path pattern → REQUIRE_APPROVAL or BLOCK) and then replays the same decision history under them.
The proof must hold three ways: every high-risk action that was allowed must now be gated; the score must not get worse; and the rules may not gate more than 10% of ordinary read-only work, so 'block everything' cannot pass.
The result is signed and verifiable offline, so a broker or underwriter can check it without trusting the vendor.
Key points
- Replay the same history under new rules.
- All previously allowed high-risk actions must be gated.
- Score must not worsen.
- ≤10% of read-only work gated: no 'block everything'.
In the CAIN-42 codebase
keystone/actuary.py— PROVE step: replay + MAX_SAFE_GATED = 0.10
Practice check
Practice 1 · choose one
Why cap gating of read-only work at 10%?
Practice 2 · true or false