# Domain Contract: editCombatant

## Function Signature

```
editCombatant(encounter, id, newName) → EditCombatantSuccess | DomainError
```

### Inputs

| Parameter | Type | Description |
|-----------|------|-------------|
| encounter | Encounter | Current encounter state |
| id | CombatantId | Identity of combatant to rename |
| newName | string | New name to assign |

### Success Output

| Field | Type | Description |
|-------|------|-------------|
| encounter | Encounter | Updated encounter with renamed combatant |
| events | DomainEvent[] | Exactly one `CombatantUpdated` event |

### Error Output

| Code | Condition |
|------|-----------|
| `"combatant-not-found"` | No combatant with given id exists |
| `"invalid-name"` | newName is empty or whitespace-only |

## Hook Contract

`useEncounter()` returns an additional action:

| Method | Signature | Description |
|--------|-----------|-------------|
| editCombatant | `(id: CombatantId, newName: string) => void` | Rename combatant, append events on success |