The APR ratchet — how sharing only ever lowers your rate

The ratchet is the load-bearing promise of the Credit module. Three numbers define every loan:

- **Baseline APR** — the rate with zero signals shared. Locked at origination. This is your ceiling. It never rises for the life of the loan.
- **Floor APR** — the lowest the rate can go no matter how much you share. Set by the product.
- **Current APR** — what you actually pay this period. Always between the floor and the baseline.

When you share a financial signal that matches one of the product's reductions (e.g. "Bank cash-flow → −3%"), your current APR drops by that amount. Share more, drop more — down to the floor. Revoke a signal and the current APR rises back toward baseline by exactly that amount — never past baseline, and with no penalty: no surcharge, no acceleration, no re-underwriting, no clawback.

You can do this any time from the My Loans tab — toggle a reduction on or off and watch the APR move. The lender sees the new rate and which reductions are active on their next read; they never see the underlying data.

This is the same architecture as the Insurance rate ratchet, applied to credit. The five rails: immutable baseline, one-way ratchet, aggregated views, per-grant revoke, and a user-side read log.