diff --git a/src/game.ts b/src/game.ts
index 860556f..53fbfb1 100644
--- a/src/game.ts
+++ b/src/game.ts
@@ -1,7 +1,7 @@
 import { CFG, VW, VH, TAU, FONT_STACK, DIFFICULTIES, STARS } from './config';
 import type { Difficulty } from './config';
 import { clamp, easeOutBack, fmtTime } from './util';
-import { Store, getStats, getBest, getBestStars, getDailyBest, getDailyStars, getGhostEnabled, setGhostEnabled, getGhostTrack, saveGhostTrack, getFoundFossils, findFossil } from './store';
+import { Store, getStats, getBest, getBestStars, getDailyBest, getDailyStars, getGhostEnabled, setGhostEnabled, getGhostTrack, saveGhostTrack, getFoundFossils, findFossil, getSkinId, setSkinId } from './store';
 import type { GameStats } from './store';
 import { AudioManager } from './audio';
 import { Input } from './input';
@@ -17,7 +17,7 @@ import type { LevelInfo } from './level-data';
 import { generateDailyLevel, dailySeed, dailyLabel, rexCode } from './daily';
 import { GhostRecorder, GhostPlayer } from './ghost';
 import { drawDecor } from './decor';
-import { Sprite } from './sprite';
+import { Sprite, SKINS, skinUnlocked } from './sprite';
 import type { GameCtx } from './ctx';
 import type { Checkpoint } from './checkpoint';
 import type { Platform } from './platform';
@@ -120,6 +120,8 @@ export class Game implements GameCtx {
   godMode = false;
   /** Cheat: rainbow Rex skin (persists across runs). */
   rainbow = false;
+  /** Cosmetic skin id (see SKINS); Mint unlocks at 3 fossils. */
+  skin: string = getSkinId();
   /** Ghost race: replay the stored best run alongside the player. */
   ghostOn: boolean = getGhostEnabled();
   /** Fossil ids discovered so far (persistent meta-progress). */
@@ -251,6 +253,33 @@ export class Game implements GameCtx {
     this.audio.play('ui');
   }
 
+  /** Choose a cosmetic skin (Mint needs 3 fossils). */
+  selectSkin(id: string): void {
+    if (!skinUnlocked(id, this.fossilsFound)) {
+      this.audio.play('ui');
+      return;
+    }
+    if (id === this.skin) return;
+    this.skin = id;
+    setSkinId(id);
+    if (this.player) this.player.skin = id;
+    if (this.ghost) this.ghost.skin = id;
+    this.audio.play('ui');
+  }
+
+  /** Cycle skins with [ / ] on the menu; locked skins are skipped. */
+  cycleSkin(dir: 1 | -1): void {
+    let idx = SKINS.findIndex((s) => s.id === this.skin);
+    if (idx < 0) idx = 0;
+    for (let i = 1; i <= SKINS.length; i++) {
+      const cand = SKINS[(((idx + dir * i) % SKINS.length) + SKINS.length) % SKINS.length];
+      if (cand.id !== this.skin && skinUnlocked(cand.id, this.fossilsFound)) {
+        this.selectSkin(cand.id);
+        return;
+      }
+    }
+  }
+
   /** Advance to the next level and start a fresh run. */
   nextLevel(): void {
     this.levelIdx = (this.levelIdx + 1) % LEVELS.length;
@@ -278,6 +307,7 @@ export class Game implements GameCtx {
     this.player.maxHearts = this.maxHearts;
     this.player.hearts = this.maxHearts;
     this.player.rainbow = this.rainbow;
+    this.player.skin = this.skin;
     if (this.maxHeartsCheat) {
       this.maxHeartsCheat = false;
       this.player.maxHearts = Game.MAX_HEARTS_CAP;
@@ -306,7 +336,10 @@ export class Game implements GameCtx {
     this.ghost = null;
     if (this.ghostOn) {
       const track = getGhostTrack(this.daily ? -1 : this.levelIdx, this.daily ? dailySeed() : 0);
-      if (track) this.ghost = new GhostPlayer(track);
+      if (track) {
+        this.ghost = new GhostPlayer(track);
+        this.ghost.skin = this.skin;
+      }
     }
     this.camera.x = 0;
     this.camera.shake = 0;
@@ -387,6 +420,10 @@ export class Game implements GameCtx {
       this.toggleGhost();
       return;
     }
+    if ((k === 'skinPrev' || k === 'skinNext') && this.state === 'menu') {
+      this.cycleSkin(k === 'skinNext' ? 1 : -1);
+      return;
+    }
     if (k === 'debug') {
       this.debug = !this.debug;
       return;
@@ -546,6 +583,10 @@ export class Game implements GameCtx {
       this.addShake(2);
       this.burst(x, y, 22, ['#f4ecd9', '#e8dcc0', '#cbb98f', '#fff'], 'dot', 170);
       this.texts.push(new FloatingText(x, y - 34, 'NEW FOSSIL!', '#f4ecd9'));
+      if (this.fossilsFound.length === 3) {
+        this.addStatus('Mint Rex unlocked! Pick it on the menu', '#63e0a8');
+        this.audio.play('star');
+      }
     } else {
       this.burst(x, y, 10, ['#f4ecd9', '#e8dcc0'], 'dot', 130);
     }
@@ -1498,6 +1539,7 @@ export class Game implements GameCtx {
       dead: false,
       rot: 0,
       rainbow: this.rainbow,
+      skin: this.skin,
     };
     Sprite.drawRex(ctx, fakeP, this.time);
     // Title block (gently floating, theme-aware)
@@ -1547,7 +1589,7 @@ export class Game implements GameCtx {
       205,
     );
     // Controls panel (left)
-    const cpx = 34, cpy = 232, cpw = 240, cph = 232;
+    const cpx = 34, cpy = 232, cpw = 240, cph = 238;
     this.drawInfoPanel(ctx, cpx, cpy, cpw, cph, 'CONTROLS');
     const rows: Array<[string, string]> = [
       ['Move', 'A / D · ← →'],
@@ -1558,6 +1600,7 @@ export class Game implements GameCtx {
       ['Difficulty', '↑ / ↓'],
       ['Mute · Calm · Ghost', 'M · V · G'],
       ['Gamepad', 'A jump · B go'],
+      ['Skin', '[ / ]'],
       ['Debug', 'F2'],
     ];
     ctx.font = '600 13px ' + FONT_STACK;
@@ -1571,7 +1614,7 @@ export class Game implements GameCtx {
       ctx.fillText(keys, cpx + cpw - 20, y);
     });
     // Quest panel (right), rows vertically centred against the controls list
-    const qx = VW - 274, qy = 232, qw = 240, qh = 232;
+    const qx = VW - 274, qy = 232, qw = 240, qh = 238;
     this.drawInfoPanel(ctx, qx, qy, qw, qh, 'YOUR QUEST');
     const quest = [
       'Reach the glowing nest',
@@ -1685,6 +1728,60 @@ export class Game implements GameCtx {
       ctx.font = '800 12px ' + FONT_STACK;
       this.drawTracked(ctx, p.label, p.x + 45, 413, 2, false);
     });
+    // Skin picker (right of the difficulty pills)
+    ctx.font = '700 11px ' + FONT_STACK;
+    ctx.fillStyle = '#cfe0f2';
+    this.drawTracked(ctx, 'REX SKIN', 686, 413, 2, false);
+    SKINS.forEach((s, i) => {
+      const sx = 746 + i * 48;
+      const unlocked = skinUnlocked(s.id, this.fossilsFound);
+      ctx.save();
+      if (!unlocked) ctx.globalAlpha = 0.35;
+      this.roundRect(ctx, sx, 394, 40, 30, 8);
+      ctx.fillStyle = s.body;
+      ctx.fill();
+      // mini Rex head: spikes + eye
+      ctx.fillStyle = s.dark;
+      for (let k = 0; k < 3; k++) {
+        ctx.beginPath();
+        ctx.moveTo(sx + 11 + k * 5, 402);
+        ctx.lineTo(sx + 13.5 + k * 5, 397 + k * 1.2);
+        ctx.lineTo(sx + 16 + k * 5, 402);
+        ctx.closePath();
+        ctx.fill();
+      }
+      ctx.fillStyle = '#fff';
+      ctx.beginPath();
+      ctx.arc(sx + 26, 407, 3.6, 0, TAU);
+      ctx.fill();
+      ctx.fillStyle = s.line;
+      ctx.beginPath();
+      ctx.arc(sx + 27, 407, 1.6, 0, TAU);
+      ctx.fill();
+      ctx.restore();
+      if (!unlocked) {
+        // padlock over locked skins
+        ctx.strokeStyle = 'rgba(255,255,255,0.85)';
+        ctx.lineWidth = 1.6;
+        ctx.beginPath();
+        ctx.arc(sx + 20, 406, 3.6, Math.PI, 0);
+        ctx.stroke();
+        ctx.fillStyle = 'rgba(255,255,255,0.85)';
+        this.roundRect(ctx, sx + 15, 406, 10, 8, 2);
+        ctx.fill();
+      } else if (this.skin === s.id) {
+        ctx.strokeStyle = '#ffd257';
+        ctx.lineWidth = 2;
+        this.roundRect(ctx, sx + 1, 395, 38, 28, 7);
+        ctx.stroke();
+      }
+    });
+    if (!skinUnlocked('mint', this.fossilsFound)) {
+      ctx.font = '600 10px ' + FONT_STACK;
+      ctx.fillStyle = 'rgba(255,255,255,0.45)';
+      ctx.textAlign = 'center';
+      ctx.fillText('3 fossils to unlock Mint', 842, 436);
+    }
     // Bottom bar: Start + toggles (sitting on the ground strip for contrast)
     this.uiButtons = [
       // Tappable level cards (drawn above, hit-tested here)
@@ -1709,6 +1806,8 @@ export class Game implements GameCtx {
       },
       // Tappable difficulty pills (drawn above)
       ...pills.map((p) => ({ x: p.x, y: 394, w: 90, h: 30, label: p.label, card: true, action: () => this.selectDifficulty(p.d) })),
+      // Tappable skin swatches (drawn above)
+      ...SKINS.map((s, i) => ({ x: 746 + i * 48, y: 394, w: 40, h: 30, label: s.name, card: true, action: () => this.selectSkin(s.id) })),
       {
         x: 38, y: 474, w: 150, h: 40, label: 'Ghost: ' + (this.ghostOn ? 'On' : 'Off') + ' · G',
         color: '#8fa8ba',
diff --git a/src/ghost.ts b/src/ghost.ts
index 877a663..7fa253c 100644
--- a/src/ghost.ts
+++ b/src/ghost.ts
@@ -97,6 +97,9 @@ export class GhostPlayer {
     return !this.finished;
   }
 
+  /** Cosmetic skin to replay with (set by the Game to the player's skin). */
+  skin: string | null = null;
+
   /** RexView for Sprite.drawRex (Player satisfies the same shape). */
   get view(): RexView {
     return {
@@ -113,6 +116,7 @@ export class GhostPlayer {
       invulnT: 0,
       dead: false,
       rot: 0,
+      skin: this.skin ?? undefined,
     };
   }
 }
diff --git a/src/input.ts b/src/input.ts
index fba8907..ee7a1ab 100644
--- a/src/input.ts
+++ b/src/input.ts
@@ -1,4 +1,6 @@
 export type GameKey =
+  | 'skinPrev'
+  | 'skinNext'
   | 'restart'
   | 'mute'
   | 'reducedMotion'
@@ -57,6 +59,8 @@ export class Input {
       if (e.code === 'KeyM') this.onGameKey?.('mute');
       if (e.code === 'KeyV') this.onGameKey?.('reducedMotion');
       if (e.code === 'KeyG') this.onGameKey?.('ghost');
+      if (e.code === 'BracketLeft') this.onGameKey?.('skinPrev');
+      if (e.code === 'BracketRight') this.onGameKey?.('skinNext');
       if (e.code === 'F2') {
         e.preventDefault();
         this.onGameKey?.('debug');
diff --git a/src/player.ts b/src/player.ts
index 2016bd1..0ad2433 100644
--- a/src/player.ts
+++ b/src/player.ts
@@ -62,6 +62,8 @@ export class Player {
   jumpCutPending = false;
   /** Konami code: rainbow skin. */
   rainbow = false;
+  /** Cosmetic skin id (see SKINS in sprite.ts); set by the Game. */
+  skin = 'classic';
   private readonly game: GameCtx;
 
   constructor(x: number, y: number, game: GameCtx) {
diff --git a/src/sprite.ts b/src/sprite.ts
index ecfb68c..a8a1b9f 100644
--- a/src/sprite.ts
+++ b/src/sprite.ts
@@ -2,6 +2,39 @@ import { TAU } from './config';
 import type { Enemy } from './enemy';
 import type { PlayerState } from './player';
 
+/** Rex skin palettes. Mint unlocks after finding 3 hidden fossils. */
+export type RexSkinId = 'classic' | 'ember' | 'glacier' | 'mint';
+
+export interface RexSkin {
+  id: RexSkinId;
+  name: string;
+  /** Main body / tail / head color. */
+  body: string;
+  /** Legs, arms, head spikes. */
+  dark: string;
+  /** Belly. */
+  belly: string;
+  /** Nostril, smile, eyes. */
+  line: string;
+}
+
+export const SKINS: RexSkin[] = [
+  { id: 'classic', name: 'Classic', body: '#59b25f', dark: '#4c9d52', belly: '#f7ecd4', line: '#2f6e36' },
+  { id: 'ember', name: 'Ember', body: '#ef8a4c', dark: '#d9672c', belly: '#ffe9cf', line: '#8a3d16' },
+  { id: 'glacier', name: 'Glacier', body: '#7cc4e8', dark: '#55a3d4', belly: '#eaf7ff', line: '#2b6e94' },
+  { id: 'mint', name: 'Mint', body: '#63e0a8', dark: '#3ecf96', belly: '#eafff5', line: '#1e7a58' },
+];
+
+/** Resolve an arbitrary stored id to a known skin (fallback: Classic). */
+export function getSkin(id?: string): RexSkin {
+  return SKINS.find((s) => s.id === id) ?? SKINS[0];
+}
+
+/** Mint is the fossil reward; every other skin is free. */
+export function skinUnlocked(id: string, fossilsFound: string[]): boolean {
+  return id !== 'mint' || fossilsFound.length >= 3;
+}
+
 /** The state fields Sprite.drawRex reads (Player satisfies this structurally). */
 export interface RexView {
   x: number;
@@ -18,8 +51,10 @@ export interface RexView {
   dead: boolean;
   /** Death-tumble rotation (radians); 0 outside the dead state. */
   rot: number;
-  /** Konami code: cycle body colors through the rainbow. */
+  /** Konami code: cycle body colors through the rainbow (overrides skin). */
   rainbow?: boolean;
+  /** Cosmetic skin id (see SKINS); defaults to Classic. */
+  skin?: string;
 }
 
 /** Procedural character & enemy art. */
@@ -43,10 +78,13 @@ export const Sprite = {
     const legB = run ? Math.sin(phase + Math.PI) * 7 : 0;
     const tailWag = run ? Math.sin(phase * 1.5) * 4 : Math.sin(t * 2.4) * 2;
     const breathe = 1 + Math.sin(t * 3) * 0.02;
-    // Rainbow Rex (Konami): hue-cycle the body, keep the cream belly.
+    // Rainbow Rex (Konami) overrides any skin: hue-cycle the body.
+    const skin = getSkin(p.skin);
     const hue = (t * 160) % 360;
-    const bodyC = p.rainbow ? `hsl(${hue.toFixed(0)}, 78%, 55%)` : '#59b25f';
-    const darkC = p.rainbow ? `hsl(${((hue + 160) % 360).toFixed(0)}, 60%, 44%)` : '#4c9d52';
+    const bodyC = p.rainbow ? `hsl(${hue.toFixed(0)}, 78%, 55%)` : skin.body;
+    const darkC = p.rainbow ? `hsl(${((hue + 160) % 360).toFixed(0)}, 60%, 44%)` : skin.dark;
+    const bellyC = p.rainbow ? '#f7ecd4' : skin.belly;
+    const lineC = p.rainbow ? '#2f6e36' : skin.line;
 
     // Tail (behind body)
     ctx.fillStyle = bodyC;
@@ -71,7 +109,7 @@ export const Sprite = {
     ctx.ellipse(0, -20 + bob * 0.4, 15, 13 * breathe, 0, 0, TAU);
     ctx.fill();
     // Cream belly
-    ctx.fillStyle = '#f7ecd4';
+    ctx.fillStyle = bellyC;
     ctx.beginPath();
     ctx.ellipse(3, -17 + bob * 0.4, 9, 8 * breathe, 0, 0, TAU);
     ctx.fill();
@@ -99,12 +137,12 @@ export const Sprite = {
     ctx.ellipse(12, hy + 4, 8.5, 6.5, 0, 0, TAU);
     ctx.fill();
     // Nostril
-    ctx.fillStyle = '#2f6e36';
+    ctx.fillStyle = lineC;
     ctx.beginPath();
     ctx.arc(16, hy + 2, 1.2, 0, TAU);
     ctx.fill();
     // Smile
-    ctx.strokeStyle = '#2f6e36';
+    ctx.strokeStyle = lineC;
     ctx.lineWidth = 1.6;
     ctx.beginPath();
     ctx.arc(11, hy + 5, 4.5, 0.15 * Math.PI, 0.75 * Math.PI);
@@ -116,7 +154,7 @@ export const Sprite = {
     ctx.fill();
     if (dead) {
       // X eyes
-      ctx.strokeStyle = '#2f6e36';
+      ctx.strokeStyle = lineC;
       ctx.lineWidth = 2;
       ctx.beginPath();
       ctx.moveTo(2.5, hy - 6);
@@ -125,13 +163,13 @@ export const Sprite = {
       ctx.lineTo(2.5, hy - 1);
       ctx.stroke();
     } else if (p.state === 'hurt') {
-      ctx.fillStyle = '#2f6e36';
+      ctx.fillStyle = lineC;
       ctx.beginPath();
       ctx.arc(5.5, hy - 3, 2.2, 0, TAU);
       ctx.fill();
     } else if (jump) {
       // wide eyes in the air
-      ctx.fillStyle = '#2f6e36';
+      ctx.fillStyle = lineC;
       ctx.beginPath();
       ctx.arc(6, hy - 3.5, 3.2, 0, TAU);
       ctx.fill();
@@ -140,7 +178,7 @@ export const Sprite = {
       ctx.arc(7, hy - 4.5, 1.1, 0, TAU);
       ctx.fill();
     } else {
-      ctx.fillStyle = '#2f6e36';
+      ctx.fillStyle = lineC;
       const lookY = p.vy < -50 ? -1 : 0;
       ctx.beginPath();
       ctx.arc(6, hy - 3 + lookY, 2.8, 0, TAU);
diff --git a/src/store.ts b/src/store.ts
index b551a83..f779a7c 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -1,5 +1,8 @@
 import type { GhostTrack } from './ghost';
 import { MIN_TRACK_POINTS } from './ghost';
+import { SKINS } from './sprite';
+
+const SKIN_IDS: string[] = SKINS.map((s) => s.id);
 
 /** Lifetime play statistics shown on the main menu. */
 export interface GameStats {
@@ -92,6 +95,17 @@ export function findFossil(id: string): void {
   Store.set('tinyrex_fossils', [...found, id]);
 }
 
+/** Selected Rex skin id; unknown/corrupt values fall back to Classic. */
+export function getSkinId(): string {
+  const v = Store.get<string | null>('tinyrex_skin', null);
+  return v && SKIN_IDS.includes(v) ? v : 'classic';
+}
+
+/** Persist the selected Rex skin (validated against SKINS). */
+export function setSkinId(id: string): void {
+  Store.set('tinyrex_skin', SKIN_IDS.includes(id) ? id : 'classic');
+}
+
 /** Safe localStorage wrapper (settings + best records). */
 export const Store = {
   get<T>(key: string, fallback: T): T {
diff --git a/tests/game.test.ts b/tests/game.test.ts
index 2a4c11c..b432881 100644
--- a/tests/game.test.ts
+++ b/tests/game.test.ts
@@ -1,7 +1,8 @@
 import { describe, it, expect, beforeEach } from 'vitest';
 import { Game } from '../src/game';
 import { LEVEL_DATA, LEVELS } from '../src/level-data';
-import { Store, getGhostEnabled, getFoundFossils, type GameStats } from '../src/store';
+import { Store, getGhostEnabled, getFoundFossils, getSkinId, type GameStats } from '../src/store';
+import type { RexView } from '../src/sprite';
 
 function makeGame(): Game {
   const canvas = document.createElement('canvas');
@@ -371,4 +372,89 @@ describe('Fossil discoveries', () => {
     game.level!.reset();
     expect(f.collected).toBe(false);
   });
+
+  it('announces the Mint unlock when the third fossil is unearthed', () => {
+    game.handleKey('primary');
+    game.collectFossil(0, 0, '0:0');
+    game.collectFossil(0, 0, '1:0');
+    game.collectFossil(0, 0, '2:0');
+    expect(game.fossilsFound).toHaveLength(3);
+    expect(game.status.msg).toBe('Mint Rex unlocked! Pick it on the menu');
+  });
+});
+
+describe('Rex skins', () => {
+  let game: Game;
+
+  beforeEach(() => {
+    localStorage.clear();
+    game = makeGame();
+  });
+
+  it('selects and persists a skin from the menu', () => {
+    expect(game.skin).toBe('classic');
+    game.selectSkin('ember');
+    expect(game.skin).toBe('ember');
+    expect(getSkinId()).toBe('ember');
+    // No-op when unchanged (no double SFX path to worry about)
+    game.selectSkin('ember');
+    expect(game.skin).toBe('ember');
+  });
+
+  it('rejects Mint until 3 fossils are found', () => {
+    game.selectSkin('mint');
+    expect(game.skin).toBe('classic');
+    expect(getSkinId()).toBe('classic');
+  });
+
+  it('lets the player wear the chosen skin, and the ghost too', () => {
+    game.selectSkin('glacier');
+    // Store a ghost track so a ghost is replayed on the next run
+    Store.set('tinyrex_ghost_0', {
+      date: 0,
+      score: 100,
+      time: 5,
+      pts: [
+        { t: 0, x: 40, y: 400 },
+        { t: 0.1, x: 44, y: 400 },
+        { t: 0.2, x: 48, y: 400 },
+        { t: 0.3, x: 52, y: 400 },
+      ],
+    });
+    game.handleKey('primary');
+    expect(game.player!.skin).toBe('glacier');
+    const ghost = (game as unknown as { ghost: { view: RexView } | null }).ghost;
+    expect(ghost).not.toBeNull();
+    expect(ghost!.view.skin).toBe('glacier');
+  });
+
+  it('cycles with the bracket keys on the menu, skipping locked skins', () => {
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('ember');
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('glacier');
+    // Mint is locked: wrap around to Classic instead
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('classic');
+    game.handleKey('skinPrev');
+    expect(game.skin).toBe('glacier');
+  });
+
+  it('cycles into Mint once it is unlocked', () => {
+    game.fossilsFound = ['0:0', '1:0', '2:0'];
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('ember');
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('glacier');
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('mint');
+  });
+
+  it('ignores skin keys while playing', () => {
+    game.selectSkin('ember');
+    game.handleKey('primary');
+    expect(game.state).toBe('playing');
+    game.handleKey('skinNext');
+    expect(game.skin).toBe('ember');
+  });
 });
diff --git a/tests/skin.test.ts b/tests/skin.test.ts
new file mode 100644
index 0000000..3ff4847
--- /dev/null
+++ b/tests/skin.test.ts
@@ -0,0 +1,83 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { SKINS, getSkin, skinUnlocked, Sprite, type RexView } from '../src/sprite';
+import { Store, getSkinId, setSkinId } from '../src/store';
+
+function makeView(skin?: string): RexView {
+  return {
+    x: 0,
+    y: 0,
+    w: 34,
+    h: 46,
+    facing: 1,
+    state: 'idle',
+    runPhase: 0,
+    vy: 0,
+    squashX: 1,
+    squashY: 1,
+    invulnT: 0,
+    dead: false,
+    rot: 0,
+    skin,
+  };
+}
+
+describe('Skin table', () => {
+  it('ships four skins with unique ids and full palettes', () => {
+    expect(SKINS).toHaveLength(4);
+    const ids = SKINS.map((s) => s.id);
+    expect(new Set(ids).size).toBe(4);
+    expect(ids).toEqual(['classic', 'ember', 'glacier', 'mint']);
+    for (const s of SKINS) {
+      expect(s.name.length).toBeGreaterThan(0);
+      for (const c of [s.body, s.dark, s.belly, s.line]) {
+        expect(c).toMatch(/^#[0-9a-fA-F]{6}$/);
+      }
+    }
+  });
+
+  it('resolves known ids and falls back to Classic', () => {
+    expect(getSkin('ember').id).toBe('ember');
+    expect(getSkin('nope').id).toBe('classic');
+    expect(getSkin(undefined).id).toBe('classic');
+  });
+
+  it('gates Mint behind 3 fossils and leaves the rest free', () => {
+    expect(skinUnlocked('classic', [])).toBe(true);
+    expect(skinUnlocked('ember', [])).toBe(true);
+    expect(skinUnlocked('glacier', [])).toBe(true);
+    expect(skinUnlocked('mint', [])).toBe(false);
+    expect(skinUnlocked('mint', ['0:0', '1:0'])).toBe(false);
+    expect(skinUnlocked('mint', ['0:0', '1:0', '2:0'])).toBe(true);
+  });
+
+  it('draws every skin without crashing, rainbow overrides all', () => {
+    const ctx = document.createElement('canvas').getContext('2d')!;
+    for (const s of SKINS) {
+      expect(() => Sprite.drawRex(ctx, makeView(s.id), 0.25)).not.toThrow();
+    }
+    expect(() => Sprite.drawRex(ctx, makeView('ember'), 0.5)).not.toThrow();
+    const rainbow = makeView('glacier');
+    rainbow.rainbow = true;
+    expect(() => Sprite.drawRex(ctx, rainbow, 1.25)).not.toThrow();
+  });
+});
+
+describe('Skin persistence', () => {
+  beforeEach(() => {
+    localStorage.clear();
+  });
+
+  it('defaults to Classic and round-trips a chosen skin', () => {
+    expect(getSkinId()).toBe('classic');
+    setSkinId('ember');
+    expect(getSkinId()).toBe('ember');
+    expect(Store.get<string | null>('tinyrex_skin', null)).toBe('ember');
+  });
+
+  it('rejects unknown ids on write and read', () => {
+    setSkinId('rainbow');
+    expect(getSkinId()).toBe('classic');
+    localStorage.setItem('tinyrex_skin', 'totally-bogus');
+    expect(getSkinId()).toBe('classic');
+  });
+});