# Data Model: Stat Block Panel Fold/Unfold and Pin

**Feature**: 035-statblock-fold-pin
**Date**: 2026-03-11

## Entities

### Panel State

This feature introduces UI-only ephemeral state — no persistence changes, no domain model changes.

| Field | Type | Description |
|-------|------|-------------|
| `selectedCreatureId` | `CreatureId \| null` | Currently browsed creature (right panel). **Exists already.** |
| `pinnedCreatureId` | `CreatureId \| null` | Creature locked to left panel. **New.** |
| `isRightPanelFolded` | `boolean` | Whether the right (browse) panel is collapsed to a tab. **New.** |

### State Transitions

```
No panel → Open panel
  Trigger: Click combatant row / auto-show on turn change
  Effect: selectedCreatureId = creatureId, isRightPanelFolded = false

Open panel → Folded tab
  Trigger: Click fold button
  Effect: isRightPanelFolded = true (selectedCreatureId preserved)

Folded tab → Open panel
  Trigger: Click folded tab
  Effect: isRightPanelFolded = false

Open panel → Open panel + Pinned panel
  Trigger: Click pin button (xl+ viewport only)
  Effect: pinnedCreatureId = selectedCreatureId

Pinned panel → No pinned panel
  Trigger: Click unpin button
  Effect: pinnedCreatureId = null

Open panel (mobile) → Dismissed
  Trigger: Click backdrop
  Effect: selectedCreatureId = null
```

### Viewport Breakpoints

| Breakpoint | Panels Available | Pin Button |
|------------|-----------------|------------|
| < 1024px (mobile) | Mobile drawer only | Hidden |
| 1024px–1279px (lg) | Right panel only | Hidden |
| >= 1280px (xl) | Right + optional left pinned | Visible |

## Existing Entities (Unchanged)

- **Creature** (`CreatureId`, `name`, stats…) — read-only, no changes
- **Encounter state** — no changes
- **Bestiary cache** — no changes

## Persistence

No persistence changes. All new state (pinnedCreatureId, isRightPanelFolded) is ephemeral React component state that resets on page reload. This aligns with the existing pattern where selectedCreatureId is also ephemeral.