From verified module to rated pool in one API call.

The eligibility rule

KeyScore ≥65 on the source module = eligible to enter a pool. Below that, the module stays in the registry but gets routed elsewhere (rehab, supplemental QA, scrap).

The rating function

keystone_pool_rating() is a Postgres function that takes the weighted KeyScore across the pool's eligible modules and emits a letter rating:

• AAA — weighted KeyScore ≥90
• AA — 85–89
• A — 80–84
• BBB — 72–79
• NR (not rated) — <72

A pool of 2 × KeyScore-92 modules = AAA, $85,968 collateral, securitization-ready.

The pool-summary API

POST /functions/v1/pool-summary returns:

• rating — AAA / AA / A / BBB / NR
• eligible_collateral — total dollar value
• weighted_keyscore — the weighted-by-value KeyScore
• securitization_ready — boolean
• tranches — senior 70% / mezz 20% / equity 10%

Revenue flow

Capital Rail revenue is gain-on-sale + servicing: 1.5% gain-on-sale + 0.35% servicing on pools rated BBB or better (KeyScore ≥72). Below that, fee-for-rating only.

Who pays for it

GSEs (Fannie, Freddie), LIHTC syndicators (Boston Capital, RBC, Raymond James AH, Enterprise CHP), debt funds, community development financial institutions, and private credit funds — anyone underwriting a pool of modular collateral and needing a defensible rating.

The pool is rated by the same KeyScore the lender already trusts. No spreadsheet, no manual underwriting, no inconsistency between deals.