#region DataModel [C:3] [TYPE ADR] [SEMANTICS data-model,agent-chat,schema]
@defgroup DataModel Data structures for 035-agent-chat-context — frontend TypeScript DTOs and backend Python counterparts.
@RATIONALE Updated for Path B (/agent page), Gradio payload safety, two-layer RBAC, and permission_denied event type.

## 1. UIContext — Navigation Context Payload

### Source
Derived from URL query parameters on `/agent` page entry. Static for visit duration. EnvId syncable via `updateActiveEnv`.

### TypeScript (`frontend/src/lib/models/AgentChatTypes.ts`)

```typescript
export interface UIContext {
  objectType: "dashboard" | "dataset" | "migration" | null;
  objectId: string | null;
  objectName: string | null;       // max 256 chars
  envId: string | null;           // synced with EnvSelector via updateActiveEnv
  route: string;                   // source page route (e.g. "/dashboards/42")
  contextVersion: number;          // currently 1
}
```

### Python validation (`backend/src/agent/_context.py` — NEW)

```python
# UIContext validation rules:
# objectType: must be one of ("dashboard","dataset","migration",None)
# objectId: must be numeric string or None
# objectName: max 256 chars
# envId: string or None
# route: string, max 512 chars
# contextVersion: positive integer ≤ 1
# Max payload size: 4 KB (413 Payload Too Large if exceeded)
```

---

## 2. ConfirmMetadataV2 — SSE confirm_required Event

```json
{
  "metadata": {
    "type": "confirm_required",
    "thread_id": "uuid",
    "tool_name": "deploy_dashboard",
    "tool_args": {"env_id": "prod", "dashboard_id": 42},
    "risk": "write",
    "risk_level": "guarded",
    "dangerous": false,
    "env_context": "prod",
    "prompt": "⚠️ Изменение данных в production",
    "requires_confirmation": true
  }
}
```

**Env resolution rule** (canonical):
1. `tool_args.env_id` (tool-targeted environment)
2. Submit-time `envId` parameter (position 5 in Gradio args)
3. `UIContext.envId` (from URL params)
4. `null` (no environment)

**Env normalization**: `env_id` containing "prod"/"production" → `"prod"`; "stag"/"test" → `"staging"`; "dev"/"local" → `"dev"`. Unknown values → `null`.

---

## 3. PermissionDeniedMetadata — SSE permission_denied Event (NEW)

```json
{
  "metadata": {
    "type": "permission_denied",
    "tool_name": "deploy_dashboard",
    "required_role": "admin",
    "user_role": "analyst",
    "alternatives": [
      {"action": "get_health_summary", "prompt": "Запросить отчёт о состоянии дашборда"}
    ]
  }
}
```

**Distinct from confirm_required**: This event BYPASSES HITL checkpoint. Frontend renders permission-denied card with «Закрыть» button — no confirm. Emitted at invocation-time guard (AgentChat.ToolFilter.InvocationGuard).

---

## 4. New SSE Event Types

| Event | When | Fields |
|-------|------|--------|
| `permission_denied` | Tool invocation rejected by RBAC guard | tool_name, required_role, user_role, alternatives |
| `tool_retry` | Read-only tool auto-retrying | tool, attempt, max_attempts |
| `tool_timeout` | Tool exceeded 30s timeout | tool, timeout_seconds, is_write_tool, retryable |

### `tool_timeout` (extended)

```json
{"metadata":{"type":"tool_timeout","tool":"superset_explore_database","timeout_seconds":30,"is_write_tool":false,"retryable":true}}
```

For write tools (`is_write_tool=true`): `retryable=false`, frontend shows "Operation status unknown — check Superset" (no retry button).

---

## 5. AgentChatModel — New Atoms (v2)

```typescript
// ADD to AgentChatModel class:
uiContext: UIContext | null = $state(null);
dangerousCountdown: number = $state(0);
dangerousCountdownActive: boolean = $state(false);
_activeEnvId: string | null = $state(null);
permissionAlternatives: Array<{ action: string; prompt: string }> | null = $state(null);

// ADD derived:
isProdContext: boolean = $derived(...);
showProdWarning: boolean = $derived(...);
contextPillLabel: string = $derived(...);

// updateActiveEnv now syncs BOTH atoms:
updateActiveEnv(envId: string | null): void {
  this._activeEnvId = envId;
  if (this.uiContext) this.uiContext.envId = envId;
}
```

**REMOVED**: `toolAffinity` atom (debug data must come from backend SSE, not frontend reconstruction).

---

## 6. Existing DB Models — No Changes

No new tables, no schema migrations. Context not persisted in conversations.

#endregion DataModel