# S4/B Exchange

> Governed marketing intelligence from Search for Businesses, LLC for people and software. The first planned paid product is the S4/B Media Plan Stress Test.

## Canonical routes

- Human overview: https://search.for-businesses.com/exchange
- Machine-readable catalog: https://search.for-businesses.com/exchange/catalog.json
- OpenAPI 3.1 contract: https://search.for-businesses.com/openapi.json
- Free coverage check: https://search.for-businesses.com/api/exchange/v1/coverage
- Privacy policy: https://search.for-businesses.com/privacy

## Free coverage check

POST application/json to https://search.for-businesses.com/api/exchange/v1/coverage using only the enumerated fields in the OpenAPI contract. The endpoint does not accept free text, personal information, raw prompts or raw media plans.

The response distinguishes benchmark-supported requests, partial benchmark support and structural review only. A coverage result never discloses client-identifiable evidence or a numeric benchmark.

## Evidence and trust

- Public routes never receive direct access to S4/B's canonical evidence library.
- Thin, non-comparable, unpermissioned or reconstructable evidence is suppressed.
- Future paid outputs must state evidence grade, sample size or suppression reason, coverage period, confidence, method version, limitations, usage license and human-review status.
- The free checker stores only daily aggregate counts of bounded request categories, result class and self-declared caller type at the application layer.

## Current protocol status

- REST + OpenAPI: available
- Remote MCP: planned after product validation
- Stripe MPP: planned after fulfillment validation
- x402: testnet experiment planned
- A2A: deferred until S4/B supports delegated, asynchronous work

llms.txt is an orientation aid, not an authorization grant or a substitute for the OpenAPI contract, product terms or privacy policy.