Evidence graph

An audit log says events happened. An evidence graph explains why one event caused another and which exact inputs supported it.

Causal model

source signal ─► case ─► task ─► proposed action
                   │                 │
                   ├─► fact set ─────┤
                   ├─► rule versions ┤
                   └─► evidence ─────┤
                                     ▼
                             compliance decision
                                     │
                         approval ────┤
                                     ▼
                         execution / blocked attempt
                                     │
                     acknowledgement + authoritative result
                                     │
                              reconciliation outcome

IDs and hashes make each edge explicit; temporal proximity is never treated as causation.

Decision record

{
  "decisionId": "dec_CONTACT_81",
  "caseId": "case_HBR_COL_51",
  "action": "send_interaction",
  "outcome": "allowed",
  "facts": [
    {
      "name": "loan.daysPastDue",
      "value": 22,
      "source": "authoritative_core",
      "asOf": "2027-05-01T10:11:56-07:00",
      "freshness": "fresh"
    }
  ],
  "rules": [
    {
      "ruleId": "contact-time-CA-v4",
      "jurisdiction": "US-CA",
      "outcome": "pass",
      "effectiveVersion": "2027-01-01"
    }
  ],
  "requestedBy": "worker_ANA_4",
  "recordedAt": "2027-05-01T10:11:58-07:00"
}

Sensitive values are referenced or masked according to export permission; evidence does not become broadly readable merely because it is linked.

Tamper evidence

Durable records are append-only and carry canonical content digests. Evidence packages include a manifest of record IDs, versions, artifact SHA-256 values, generation time, and package digest. Any changed or missing item breaks verification. Corrections and supersessions add records rather than editing the original.

Approvals and overrides

An approval links actor, role, decision, reason, request hash, evidence, time, and separation-of-duties result. If policy permits an exception, the graph preserves both the original outcome and the approved exception scope; it never replaces “blocked” with “allowed” and loses the path.

Export

POST /v1/servicing/cases/{caseId}/evidence-export creates an access-filtered package asynchronously. A useful export contains:

• case and workflow versions;
• tasks, reservations, outcomes, and service-level times;
• interactions and provider delivery evidence;
• compliance decisions, fact provenance, and rule versions;
• promises, action requests, approvals, and acknowledgements;
• document metadata and permitted artifacts;
• reconciliation items and resolution evidence;
• a manifest and integrity digests.

Exports are point-in-time snapshots with expiry and audit. They do not silently include restricted documents the requesting actor cannot read.