# Data Model: Agent Ticket Queue

## Modified: `Agent`

No new column — `userId`/`user` already exist (010-identity-auth). This feature is the first to
actually write `userId` through an endpoint, and adds the supporting index below.

```prisma
model Assignment {
  // ...existing fields unchanged...

  @@index([ticketId, isCurrent])
  @@index([agentId, isCurrent])   // NEW — supports "current assignments for agent X"
  @@map("assignments")
}
```

## New (response-shape only, no new table): `AssignedTicketSummary`

A read projection, not a persisted entity — assembled per-request from `Ticket` joined to its
current `Assignment`, `Product`, `CustomerReference`, and (if present) `SLARun`.

| Field | Source | Notes |
|---|---|---|
| `id` | `Ticket.id` | |
| `code` | `Ticket.code` | e.g. `ACME-2026-0042` |
| `status` | `Ticket.status` | One of the 12 lifecycle states (003's own state machine) |
| `priority` | `Ticket.priority` | Opaque string, as already modeled |
| `severity` | `Ticket.severity` | Opaque string, as already modeled |
| `product` | `Ticket.product` | `{ id, externalProductId, name }` |
| `customer` | `Ticket.customer` | `{ externalUserId, externalTenantId }` — no PII beyond what 002's own `CustomerReference` already stores |
| `assignedAt` | `Assignment.assignedAt` | The current assignment's start time |
| `sla` | `SLARun` (nullable) | `{ status, firstResponseDueAt, resolutionDueAt, breachedAt }` or `null` if no `SLARun` exists yet for this ticket |

## Validation / Business Rules

- **Linking** (`PATCH /admin/agents/:agentId`'s new `userId` field):
  - The target `User` must exist and have role `AGENT` (FR-001).
  - No other `Agent` row may already have that `userId` (FR-001) — checked proactively before
    the write (research.md), not left to the database's own `@unique` constraint to reject.
  - `userId: null` explicitly unlinks (distinct from omitting the field, which leaves it
    unchanged — the existing `updateAgentSchema` pattern for optional fields).
- **Listing** (`GET /agents/me/tickets`, `GET /admin/agents/:agentId/tickets`):
  - Only `Assignment.isCurrent: true` rows are considered (FR-003).
  - The agent-self route resolves `agentId` exclusively from `request.user.id` → `Agent.userId`
    lookup — never from any request input (FR-004).
  - A session with no linked `Agent` row throws a specific `NotFoundError`
    ("No agent profile is linked to this account."), never an empty array (FR-006).