Proof API

Base URL: https://cronozen.com/api/v1

Authentication

The Proof API uses API Key authentication, not JWT tokens. Include your key in the Authorization header:

Authorization: Bearer czk_live_abc123...

API Key Scopes

Each API key has one or more scopes that control access:

Scope	Permissions
`proof:read`	Query events, get evidence, export reports
`proof:write`	Record events, add approvals

A key with proof:read cannot record or approve decisions. A key with proof:write can do everything.

# Read-only key — can query and export, but cannot record
curl https://cronozen.com/api/v1/decision-events \
  -H "Authorization: Bearer czk_live_readonly_..."

# Write key — full access
curl -X POST https://cronozen.com/api/v1/decision-events \
  -H "Authorization: Bearer czk_live_full_..." \
  -H "Content-Type: application/json" \
  -d '{ ... }'

API keys are hashed with SHA-256 before storage. The plaintext key is only shown once at creation time. Treat it like a password.

Proof API keys are separate from JWT tokens used for the rest of the Cronozen platform. A JWT token will not authenticate against the Proof API, and vice versa.

Endpoints

POST /v1/decision-events

Record a new decision event. Scope required: proof:write Request:

{
  "type": "agent_execution",
  "actor": {
    "id": "support_agent",
    "type": "ai_agent",
    "name": "Support Agent"
  },
  "action": {
    "type": "refund_approved",
    "description": "Auto-approved refund based on policy threshold",
    "input": {
      "orderId": "ORD-1234",
      "amount": 45000
    },
    "output": {
      "refundId": "REF-5678"
    }
  },
  "aiContext": {
    "model": "gpt-4",
    "provider": "openai",
    "confidence": 0.87,
    "reasoning": "Amount within auto-approval threshold"
  },
  "tags": ["refund", "support", "auto-approved"],
  "idempotencyKey": "refund-ORD-1234-20260312"
}

Field	Type	Required	Description
`type`	string	Yes	Event type: `agent_execution` \| `workflow_step` \| `human_approval` \| `ai_recommendation` \| `automated_action` \| `policy_decision` \| `escalation` \| `custom`
`actor`	object	Yes	Who/what made the decision
`actor.id`	string	Yes	Actor identifier
`actor.type`	string	Yes	`human` \| `ai_agent` \| `system` \| `service`
`actor.name`	string	No	Display name
`action`	object	Yes	What action was taken
`action.type`	string	Yes	Action type identifier
`action.description`	string	No	Human-readable description
`action.input`	object	No	Action input data (any JSON)
`action.output`	object	No	Action output data (any JSON)
`aiContext`	object	No	AI involvement details
`aiContext.model`	string	No	Model name (e.g., `gpt-4`, `claude-sonnet-4-5-20250514`)
`aiContext.provider`	string	No	AI provider (e.g., `openai`, `anthropic`)
`aiContext.confidence`	number	No	Confidence score (0–1)
`aiContext.reasoning`	string	No	Decision reasoning
`tags`	string[]	No	Filterable tags for categorization
`idempotencyKey`	string	No	Prevents duplicate recording (see below)

Response (201):

{
  "data": {
    "id": "cmmnhiobs0002bfi9mlu8eof4",
    "decisionId": "refund-ORD-1234-20260312",
    "type": "agent_execution",
    "status": "recorded",
    "actor": {
      "id": "support_agent",
      "type": "ai_agent",
      "name": "Support Agent"
    },
    "action": {
      "type": "refund_approved",
      "input": { "orderId": "ORD-1234", "amount": 45000 }
    },
    "occurredAt": "2026-03-12T13:00:00.000Z",
    "tags": ["refund", "support", "auto-approved"],
    "evidence": {
      "id": "evi_x1y2z3",
      "status": "pending",
      "chainHash": null,
      "chainIndex": null
    },
    "createdAt": "2026-03-12T13:00:00.000Z",
    "updatedAt": "2026-03-12T13:00:00.000Z"
  }
}

Idempotency

Pass an idempotencyKey to prevent duplicate events from retries or network issues. If the same key is sent again, the original event is returned (200) instead of creating a duplicate.

# First call — creates event
curl -X POST .../v1/decision-events \
  -d '{ "idempotencyKey": "settle-STL-001", ... }'
# → 201 Created

# Retry with same key — returns original
curl -X POST .../v1/decision-events \
  -d '{ "idempotencyKey": "settle-STL-001", ... }'
# → 200 OK (same event, no duplicate)

Use idempotency keys for any event that might be retried — settlement webhooks, queue consumers, or cron-triggered recordings.

GET /v1/decision-events

List decision events with filters. Scope required: proof:read Query parameters:

Parameter	Type	Description
`type`	string	Filter by event type (e.g., `agent_execution`)
`status`	string	`recorded` \| `sealed` \| `approved` \| `rejected`
`tag`	string	Filter by a single tag
`limit`	number	Max results, 1–100 (default: 20)
`offset`	number	Pagination offset (default: 0)

Example:

# Events tagged with "settlement", sealed only
curl "https://cronozen.com/api/v1/decision-events?tag=settlement&status=sealed&limit=50" \
  -H "Authorization: Bearer czk_live_..."

Response (200):

{
  "data": [
    {
      "id": "cmmnhiobs0002bfi9mlu8eof4",
      "decisionId": "settle-STL-001",
      "type": "automated_action",
      "status": "sealed",
      "actor": { "id": "finance_bot", "type": "system" },
      "action": { "type": "settlement_created" },
      "tags": ["settlement", "finance"],
      "createdAt": "2026-03-12T13:00:00.000Z",
      "updatedAt": "2026-03-12T13:05:00.000Z"
    }
  ],
  "pagination": {
    "total": 142,
    "limit": 50,
    "offset": 0,
    "hasMore": true
  }
}

POST /v1/decision-events//approvals

Add human approval and seal the event with SHA-256. Scope required: proof:write Request:

{
  "approver": {
    "id": "team_lead",
    "type": "human",
    "name": "Kim"
  },
  "result": "approved",
  "reason": "Verified against refund policy v2.1"
}

Field	Type	Required	Description
`approver`	object	Yes	Who approved the decision
`approver.id`	string	Yes	Approver identifier
`approver.type`	string	Yes	`human` \| `system`
`approver.name`	string	No	Display name
`result`	string	Yes	`approved` \| `rejected`
`reason`	string	No	Reason for the decision

Response (200):

{
  "data": {
    "approvalId": "apr_m1n2o3",
    "decisionId": "refund-ORD-1234-20260312",
    "approver": {
      "id": "team_lead",
      "type": "human",
      "name": "Kim"
    },
    "result": "approved",
    "reason": "Verified against refund policy v2.1",
    "evidenceLevel": "AUDIT_READY",
    "sealedHash": "sha256:9943798c6313e9dd2cffa71686176d4125a65777...",
    "sealedAt": "2026-03-12T13:05:00.000Z",
    "createdAt": "2026-03-12T13:05:00.000Z"
  }
}

Error — Already sealed (409):

{
  "error": {
    "code": "CONFLICT",
    "message": "Event is already sealed. Sealed events cannot be modified."
  }
}

Once an event is sealed, it is immutable. Attempting to approve an already-sealed event returns 409 Conflict. This is by design — sealed events are part of the hash chain and cannot be altered without breaking chain integrity.

GET /v1/evidence/

Retrieve sealed evidence with full hash chain verification data. Scope required: proof:read Response (200):

{
  "data": {
    "id": "evi_x1y2z3",
    "decisionId": "refund-ORD-1234-20260312",
    "status": "sealed",
    "evidenceLevel": "AUDIT_READY",
    "event": {
      "type": "agent_execution",
      "actor": { "id": "support_agent", "type": "ai_agent" },
      "action": {
        "type": "refund_approved",
        "input": { "orderId": "ORD-1234", "amount": 45000 }
      },
      "occurredAt": "2026-03-12T13:00:00.000Z",
      "aiContext": {
        "model": "gpt-4",
        "confidence": 0.87
      }
    },
    "approval": {
      "approver": { "id": "team_lead", "type": "human", "name": "Kim" },
      "result": "approved",
      "reason": "Verified against refund policy v2.1",
      "approvedAt": "2026-03-12T13:05:00.000Z"
    },
    "chain": {
      "hash": "sha256:9943798c6313e9dd2cffa71686176d4125a65777...",
      "previousHash": "sha256:7f3a8b2c...",
      "index": 42,
      "domain": "proof"
    },
    "sealedAt": "2026-03-12T13:05:00.000Z",
    "createdAt": "2026-03-12T13:00:00.000Z"
  }
}

Field	Description
`chain.hash`	SHA-256 hash of this event (content + previousHash + timestamp)
`chain.previousHash`	Hash of the preceding event in the chain (null for genesis)
`chain.index`	Position in the sequential chain
`chain.domain`	Hash chain domain (e.g., `proof`)
`evidenceLevel`	`DRAFT` → `DOCUMENTED` → `AUDIT_READY`

The evidence.get() endpoint returns the full event payload including input data, AI context, and chain position. Use this for compliance checks and chain integrity verification. Use evidence.export() when you need a portable audit document.

GET /v1/evidence//export

Export a sealed event as a JSON-LD v2 audit document. Scope required: proof:read Response (200):

{
  "@context": "https://schema.cronozen.com/decision-proof/v2",
  "@type": "DecisionProof",
  "version": "2.0",
  "exportedAt": "2026-03-12T14:00:00.000Z",
  "evidence": {
    "id": "evi_x1y2z3",
    "decisionId": "refund-ORD-1234-20260312",
    "status": "sealed",
    "evidenceLevel": "AUDIT_READY",
    "event": { "..." : "..." },
    "approval": { "..." : "..." },
    "chain": { "..." : "..." }
  },
  "verification": {
    "hashAlgorithm": "SHA-256",
    "chainDomain": "proof",
    "chainIndex": 42,
    "chainHash": "sha256:9943798c...",
    "previousHash": "sha256:7f3a8b2c...",
    "verifyUrl": "https://cronozen.com/verify/cmmnhiobs0002bfi9mlu8eof4"
  }
}

This document is self-contained and can be stored, shared, or submitted to auditors independently of the Cronozen platform.

Error Reference

Status	Code	Description	Common Cause
400	`BAD_REQUEST`	Malformed request	Invalid JSON body
401	`UNAUTHORIZED`	Invalid or missing API key	Wrong key, expired key, missing header
403	`FORBIDDEN`	Insufficient scope	`proof:read` key trying to write
404	`NOT_FOUND`	Event not found	Invalid event ID, evidence not yet sealed
409	`CONFLICT`	Event already sealed	Attempting to approve a sealed event
422	`VALIDATION_ERROR`	Invalid request body	Missing required fields, invalid types
429	`RATE_LIMIT`	Too many requests	Retry after a short delay
500	`INTERNAL_ERROR`	Internal error	Contact support

All error responses follow this format:

{
  "error": {
    "code": "CONFLICT",
    "message": "Event is already sealed. Sealed events cannot be modified.",
    "details": {}
  }
}

409 Conflict — Sealed Event

The most common non-trivial error. Occurs when calling POST /v1/decision-events/{id}/approvals on an event that has already been approved and sealed. Why this happens:

Concurrent approval attempts (two approvers clicking simultaneously)
Retry logic re-sending an already-successful approval
Webhook handler firing multiple times

How to handle:

import { ConflictError } from "cronozen"

try {
  await cz.decision.approve(eventId, payload)
} catch (e) {
  if (e instanceof ConflictError) {
    // Already sealed — this is fine, the approval succeeded previously
    const existing = await cz.evidence.get(eventId)
    console.log("Already sealed at:", existing.sealedAt)
  }
}

Use idempotencyKey on the original decision.record() call to prevent duplicate events upstream.

Proof SDK

TypeScript SDK reference with error handling and integration patterns

Proof Pipeline

How the 4-stage evidence pipeline works under the hood

Getting Started

Architecture

Authentication

Tenant System

AI Agents

Guides

Examples

API Reference

Proof API

Proof API

Authentication

API Key Scopes

Endpoints

POST /v1/decision-events

Idempotency

GET /v1/decision-events

POST /v1/decision-events//approvals

GET /v1/evidence/

GET /v1/evidence//export

Error Reference

409 Conflict — Sealed Event

Proof SDK

Proof Pipeline

Getting Started

Architecture

Authentication

Tenant System

AI Agents

Guides

Examples

API Reference

​Proof API

​Authentication

​API Key Scopes

​Endpoints

​POST /v1/decision-events

​Idempotency

​GET /v1/decision-events

​POST /v1/decision-events//approvals

​GET /v1/evidence/

​GET /v1/evidence//export

​Error Reference

​409 Conflict — Sealed Event

Proof SDK

Proof Pipeline

Proof API

Authentication

API Key Scopes

Endpoints

POST /v1/decision-events

Idempotency

GET /v1/decision-events

POST /v1/decision-events//approvals

GET /v1/evidence/

GET /v1/evidence//export

Error Reference

409 Conflict — Sealed Event