Greenlight
CentennialHacks 2026
3rdplace
Greenlight turns a utility bill into verified savings opportunities and official next steps: grounded reasoning over reviewed evidence, with the money math done by deterministic code.
A bill goes in; a defensible list of programs and next steps comes out.
Rebate and efficiency programs are real money left on the table because eligibility is tedious to check. Greenlight reads the bill, retrieves reviewed program evidence, and produces steps a person can actually act on.
Route handlers, retrieval, and the line between model and calculator.
I worked the backend: OCR through Textract into S3, grounded reasoning routes through the Vercel AI SDK and OpenRouter, and reviewed program evidence retrieved from Postgres.
Eligibility and financial calculations are deterministic backend code: the model explains and researches, it does not decide the numbers. Live web sources come back marked unreviewed so the interface can label them as such.
Three surfaces, one weekend, strict ownership.
Frontend, OCR, and backend were split with an explicit ownership map and a no-cross-editing rule, so parallel work did not turn into merge archaeology. The API contract was the coordination point.
Third place, and a schema that survived the demo.
