# Pack Approvals Notification Contract

> **Status:** Implemented (NOTIFY-SVC-37-001)
> **Last Updated:** 2025-11-27
> **OpenAPI Spec:** `src/Notifier/StellaOps.Notifier/StellaOps.Notifier.WebService/openapi/pack-approvals.yaml`

## Overview

This document defines the canonical contract for pack approval notifications between Task Runner and the Notifier service. It covers event payloads, resume token mechanics, error handling, and security requirements.

## Event Kinds

| Kind | Description | Trigger |
|------|-------------|---------|
| `pack.approval.requested` | Approval required for pack deployment | Task Runner initiates deployment requiring approval |
| `pack.approval.updated` | Approval state changed | Decision recorded or timeout |
| `pack.policy.hold` | Policy gate blocked deployment | Policy Engine rejects deployment |
| `pack.policy.released` | Policy hold lifted | Policy conditions satisfied |

## Canonical Event Schema

```json
{
  "eventId": "550e8400-e29b-41d4-a716-446655440000",
  "issuedAt": "2025-11-27T10:30:00Z",
  "kind": "pack.approval.requested",
  "packId": "pkg:oci/stellaops/scanner@v2.1.0",
  "policy": {
    "id": "policy-prod-deploy",
    "version": "1.2.3"
  },
  "decision": "pending",
  "actor": "ci-pipeline@stellaops.example.com",
  "resumeToken": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9...",
  "summary": "Deployment approval required for production scanner update",
  "labels": {
    "environment": "production",
    "team": "security"
  }
}
```

### Required Fields

| Field | Type | Description |
|-------|------|-------------|
| `eventId` | UUID | Unique event identifier; used for deduplication |
| `issuedAt` | ISO 8601 | Event timestamp in UTC |
| `kind` | string | Event type (see Event Kinds table) |
| `packId` | string | Package identifier in PURL format |
| `decision` | string | Current state: `pending`, `approved`, `rejected`, `hold`, `expired` |
| `actor` | string | Identity that triggered the event |

### Optional Fields

| Field | Type | Description |
|-------|------|-------------|
| `policy` | object | Policy metadata (`id`, `version`) |
| `resumeToken` | string | Opaque token for Task Runner resume flow |
| `summary` | string | Human-readable summary for notifications |
| `labels` | object | Custom key-value metadata |

## Resume Token Mechanics

### Token Flow

```
┌─────────────┐     POST /pack-approvals      ┌──────────────┐
│ Task Runner │ ──────────────────────────────►│   Notifier   │
│             │   { resumeToken: "abc123" }   │              │
│             │◄──────────────────────────────│              │
│             │   X-Resume-After: "abc123"    │              │
└─────────────┘                               └──────────────┘
       │                                              │
       │                                              │
       │  User acknowledges approval                  │
       │                                              ▼
       │                              ┌──────────────────────────────┐
       │                              │  POST /pack-approvals/{id}/ack
       │                              │  { ackToken: "..." }         │
       │                              └──────────────────────────────┘
       │                                              │
       │◄─────────────────────────────────────────────┤
       │  Resume callback (webhook or message bus)    │
```

### Token Properties

- **Format:** Opaque string; clients must not parse or modify
- **TTL:** 24 hours from `issuedAt`
- **Uniqueness:** Scoped to tenant + packId + eventId
- **Expiry Handling:** Expired tokens return `410 Gone`

### X-Resume-After Header

When `resumeToken` is present in the request, the server echoes it in the `X-Resume-After` response header. This enables cursor-based processing for Task Runner polling.

## Error Handling

### HTTP Status Codes

| Code | Meaning | Client Action |
|------|---------|---------------|
| `200` | Duplicate request (idempotent) | Treat as success |
| `202` | Accepted for processing | Continue normal flow |
| `204` | Acknowledgement recorded | Continue normal flow |
| `400` | Validation error | Fix request and retry |
| `401` | Authentication required | Refresh token and retry |
| `403` | Insufficient permissions | Check scope; contact admin |
| `404` | Resource not found | Verify packId; may have expired |
| `410` | Token expired | Re-initiate approval flow |
| `429` | Rate limited | Retry after `Retry-After` seconds |
| `5xx` | Server error | Retry with exponential backoff |

### Error Response Format

```json
{
  "error": {
    "code": "invalid_request",
    "message": "eventId, packId, kind, decision, actor are required.",
    "traceId": "00-abc123-def456-00"
  }
}
```

### Retry Strategy

- **Transient errors (5xx, 429):** Exponential backoff starting at 1s, max 60s, max 5 retries
- **Validation errors (4xx except 429):** Do not retry; fix request
- **Idempotency:** Safe to retry any request with the same `Idempotency-Key`

## Security Requirements

### Authentication

All endpoints require a valid OAuth2 bearer token with one of these scopes:
- `packs.approve` — Full approval flow access
- `Notifier.Events:Write` — Event ingestion only

### Tenant Isolation

- `X-StellaOps-Tenant` header is **required** on all requests
- Server validates token tenant claim matches header
- Cross-tenant access returns `403 Forbidden`

### Idempotency

- `Idempotency-Key` header is **required** for POST endpoints
- Keys are scoped to tenant and expire after 15 minutes
- Duplicate requests within the window return `200 OK`

### HMAC Signature (Webhooks)

For webhook callbacks from Notifier to Task Runner:

```
X-StellaOps-Signature: sha256=<hex-encoded-signature>
X-StellaOps-Timestamp: <unix-timestamp>
```

Signature computed as:
```
HMAC-SHA256(secret, timestamp + "." + body)
```

Verification requirements:
- Reject if timestamp is >5 minutes old
- Reject if signature does not match
- Reject if body has been modified

### IP Allowlist

Configurable per environment in `notifier:security:ipAllowlist`:
```yaml
notifier:
  security:
    ipAllowlist:
      - "10.0.0.0/8"
      - "192.168.1.100"
```

### Sensitive Data Handling

- **Resume tokens:** Encrypted at rest; never logged in full
- **Ack tokens:** Signed with KMS; validated on acknowledgement
- **Labels:** Redacted if keys match `secret`, `password`, `token`, `key` patterns

## Audit Trail

All operations emit structured audit events:

| Event | Fields | Retention |
|-------|--------|-----------|
| `pack.approval.ingested` | packId, kind, decision, actor, eventId | 90 days |
| `pack.approval.acknowledged` | packId, ackToken, decision, actor | 90 days |
| `pack.policy.hold` | packId, policyId, reason | 90 days |

## Observability

### Metrics

| Metric | Type | Labels |
|--------|------|--------|
| `notifier_pack_approvals_total` | Counter | `kind`, `decision`, `tenant` |
| `notifier_pack_approvals_outstanding` | Gauge | `tenant` |
| `notifier_pack_approval_ack_latency_seconds` | Histogram | `decision` |
| `notifier_pack_approval_errors_total` | Counter | `code`, `tenant` |

### Structured Logs

All operations include:
- `traceId` — Distributed trace correlation
- `tenantId` — Tenant identifier
- `packId` — Package identifier
- `eventId` — Event identifier

## Integration Examples

### Task Runner → Notifier (Ingestion)

```bash
curl -X POST https://notifier.stellaops.example.com/api/v1/notify/pack-approvals \
  -H "Authorization: Bearer $TOKEN" \
  -H "X-StellaOps-Tenant: tenant-acme-corp" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "eventId": "550e8400-e29b-41d4-a716-446655440000",
    "issuedAt": "2025-11-27T10:30:00Z",
    "kind": "pack.approval.requested",
    "packId": "pkg:oci/stellaops/scanner@v2.1.0",
    "decision": "pending",
    "actor": "ci-pipeline@stellaops.example.com",
    "resumeToken": "abc123",
    "summary": "Approval required for production deployment"
  }'
```

### Console → Notifier (Acknowledgement)

```bash
curl -X POST https://notifier.stellaops.example.com/api/v1/notify/pack-approvals/pkg%3Aoci%2Fstellaops%2Fscanner%40v2.1.0/ack \
  -H "Authorization: Bearer $TOKEN" \
  -H "X-StellaOps-Tenant: tenant-acme-corp" \
  -H "Content-Type: application/json" \
  -d '{
    "ackToken": "ack-token-xyz789",
    "decision": "approved",
    "comment": "Reviewed and approved"
  }'
```

## Related Documents

- [Pack Approvals Integration Requirements](pack-approvals-integration.md)
- [Notifications Architecture](architecture.md)
- [Notifications API Reference](api.md)
- [Notification Templates](templates.md)