# Data Model: Display Initiative

## Modified Entities

### Creature (domain)

**File**: `packages/domain/src/creature-types.ts`

Add one new field to the `Creature` interface:

| Field | Type | Description |
|-------|------|-------------|
| `initiativeProficiency` | `number` | Proficiency multiplier for initiative (0, 1, or 2). Defaults to 0 when absent from bestiary data. |

This field stores the raw multiplier from bestiary data. The actual initiative modifier is derived via the `calculateInitiative` function — not stored on the entity.

### Initiative (derived value)

**File**: `packages/domain/src/initiative.ts`

Not a persisted entity — a computed result from a pure function.

| Field | Type | Description |
|-------|------|-------------|
| `modifier` | `number` | The initiative modifier: DEX mod + (proficiency multiplier × proficiency bonus) |
| `passive` | `number` | The passive initiative: 10 + modifier |

## New Functions

### `calculateInitiative` (domain)

**File**: `packages/domain/src/initiative.ts`

```
Input:  { dexScore: number, cr: string, initiativeProficiency: number }
Output: { modifier: number, passive: number }
```

Pure function. No side effects. Uses existing `proficiencyBonus(cr)` helper.

### `formatInitiativeModifier` (domain)

**File**: `packages/domain/src/initiative.ts`

```
Input:  modifier: number
Output: string (e.g., "+7", "−1", "+0")
```

Formats the modifier with explicit sign. Uses U+2212 (−) for negative values.

## Modified Adapters

### Bestiary Adapter

**File**: `apps/web/src/adapters/bestiary-adapter.ts`

- Add `initiative?: { proficiency?: number }` to `RawMonster` interface
- Parse `m.initiative?.proficiency ?? 0` into `Creature.initiativeProficiency`

## State Transitions

None. This feature is purely derived/display. No state mutations, no events, no persistence changes.