StateMirror — Examples

StateMirror stores immutable snapshots of computed evidence payloads at decision time. It does not decide outcomes, interpret payloads, or prove that the submitted state was correct.

// Application-owned evidence example.
// StateMirror preserves the submitted snapshot.
// Your application computes facts and enforces outcomes.

const deny = await denySignal.state({ subject, scope: "global" });
const exp  = await expirySignal.state({ subject, scope: "plan" });
const plan = await planSignal.state({ subject, scope: "account" });

const eligible =
  deny.signal !== "denial_present" &&
  exp.signal !== "expired" &&
  plan.status === "active";

// Application-owned evidence payload.
const decisionState = {
  subject,
  evidence_type: "api_access_gate",
  inputs: {
    deny,
    exp,
    plan,
  },
  computed: {
    eligible,
    plan: plan.plan ?? null,
  },
  policy_version: "2025-12-REV-A",
  correlation_id: req.headers["x-correlation-id"] ?? null,
};

// Snapshot the evidence around the decision moment.
const snapshot = await stateMirror.capture({
  evidence_ref: `access:${subject}:${Date.now()}`,
  evidence_type: "api_access_gate",
  captured_at: new Date().toISOString(),
  state_payload: decisionState,
});

// Application-owned outcome.
if (eligible) {
  return grantApiAccess();
}

return rejectApiAccess("Not eligible");

// Store snapshot_id in an audit record, support ticket, or dispute record.
log.info({
  snapshot_id: snapshot.snapshot_id,
  evidence_ref: snapshot.evidence_ref,
});

// Support or Tier-3 workflow.
// Retrieval is reference-driven. No dashboard required.

GET /v1/snapshots/{snapshot_id}
→ returns the exact payload stored at decision time.

GET /v1/snapshots?evidence_ref=access:user_123:1734460000000
→ returns snapshots for that evidence_ref.

// The question is:
// "What did the system believe was true when it decided?"

// The question is not:
// "Can StateMirror reconstruct the past?"
// "Can StateMirror prove the outcome was correct?"
// "Can StateMirror search every event?"

// Network failures happen.
// Retries should not create duplicate evidence snapshots.

POST /v1/snapshots
Idempotency-Key: 3b5c2b2a-3d31-4f2b-9f1b-8b1dd4b0f1ad

{
  "evidence_ref": "access:user_123:1734460000000",
  "evidence_type": "api_access_gate",
  "captured_at": "2025-12-01T18:44:22.000Z",
  "state_payload": {
    "subject": "user_123",
    "eligible": true
  }
}

// Replay behavior:
//
// same idempotency key + same payload
// → returns original snapshot response
//
// same idempotency key + different payload
// → explicit conflict response

• StateMirror does not validate the business meaning of your payload.
• StateMirror does not decide whether your application outcome was correct.
• StateMirror does not provide analytics, dashboards, or payload-wide search.
• Retrieval is reference-driven, not exploratory event reconstruction.
• Snapshot volume should normally be decision-level, not event-level.

Facts are computed.
Evidence is captured.
Decisions are made.
Actions are executed.

StateMirror preserves submitted evidence.
SimpleStates stops at state.