Decision API engine

decide.fyi is the Decision API engine.

Binding production verdicts use Rulebook v1: declarative rules, optional trusted adapter facts, and replayable Decision Record material. Legacy LLM-assisted modes are advisory only.

Production boundary

Use Decide before governed software acts: the rulebook selects the verdict, adapter facts stay facts-only, and the response carries the record material.

API
POST /api/decide with mode: "rulebook"
Core
hybrid_declarative_rulebook_with_trusted_adapters
Output
rulebook_contract, runtime_binding, attestation, and replayable evidence
Role
Infrastructure layer, not the human-facing workflow product.
Engine stays here

Application proof

Reference applications show the same contract powering workflow apps, policy MCPs, decision memo packets, and execution gates.

Advisory
single, multi, and runtime return decision_contract.authority = "advisory_only"
Binding
Production handoffs require Rulebook v1 response material.
Applications prove the primitive

Stable notary remotes

Refund Notary

Stable runtime endpoint for policy-check reference applications.

MCP
refund.decide.fyi/api/mcp
REST
POST /api/v1/refund/eligibility

Cancel Notary

Stable runtime endpoint for policy-check reference applications.

MCP
cancel.decide.fyi/api/mcp
REST
POST /api/v1/cancel/penalty

Return Notary

Stable runtime endpoint for policy-check reference applications.

MCP
return.decide.fyi/api/mcp
REST
POST /api/v1/return/eligibility

Trial Notary

Stable runtime endpoint for policy-check reference applications.

MCP
trial.decide.fyi/api/mcp
REST
POST /api/v1/trial/terms
Compatibility promise

Existing MCP registry links, GitHub notary lists, and client configs can keep using Decide URLs. Applications can build policy MCPs, workflow apps, memo packets, and execution gates on the same Rulebook-backed contract.

MCP server card Runtime GitHub Agent card