Signal Composition — Examples

// Application-owned outcome example.
// SimpleStates does not decide or enforce.

// Read-time fact queries.
const plan = await planSignal.state({ subject });
const deny = await denySignal.state({ subject });
const exp  = await expirySignal.state({ subject });

// Application-owned interpretation.
// Do not treat absence as permission without an explicit rule.
const eligible =
  plan.plan === "gold" &&
  plan.status === "active" &&
  deny.signal === "denial_absent" &&
  exp.signal === "not_expired";

// Optional evidence capture.
// StateMirror records what the system considered.
// It does not validate the decision.
await stateMirror.capture({
  evidence_ref: `eligibility:${subject}:${Date.now()}`,
  evidence_type: "eligibility_gate",
  captured_at: new Date().toISOString(),
  state_payload: {
    inputs: { plan, deny, exp },
    computed: { eligible },
    decision: eligible ? "approved" : "rejected",
  },
});

// Enforcement stays outside SimpleStates.
if (eligible) {
  return grantFeatureAccess();
}

return rejectFeatureAccess("Not eligible");

// Boundary reminder:
// Facts are queried.
// Decisions are made.
// Actions are executed.
// SimpleStates stops at signal.