diff --git a/game/README.md b/game/README.md
index 20bd3e7..72d9af1 100644
--- a/game/README.md
+++ b/game/README.md
@@ -27,3 +27,12 @@ JSON-hash atlases with `idle-00` frames and feet pivots `(0.5, 1)`, plus matchin
 rover: 25 px; crab: 40 px; drone: 45 px; Jenny: 200×70.
 They are development stand-ins for the [production contracts](../docs/13-PRODUCTION-PIPELINE.md),
 and are never copied to `art/`. No gameplay, HUD, or collision is included yet.
+
+Stage exports from lane A belong at `public/assets/stages/<region>/stage.json`.
+The loader preserves their list order and scroll factors, caches shared plates,
+and loads the named sprite boards from `public/assets/sprites/`. Animation tables
+are cached as `<board>.anims`. Development rejects missing assets with their URL;
+production reports the error and substitutes a bundled actor or plain stage plate.
+Use `?region=rusty-creek&state=anomaly&inspect` on the dev URL to drag-pan the stage.
+`state=clean` selects the calm version. Export the assets before starting dev;
+the loader does not generate or copy art.
diff --git a/game/src/core/scaffold.ts b/game/src/core/scaffold.ts
index 45e1996..3b64b7b 100644
--- a/game/src/core/scaffold.ts
+++ b/game/src/core/scaffold.ts
@@ -1,6 +1,7 @@
 import Phaser from 'phaser';
-
-export const PLACEHOLDERS = ['hero', 'dexter', 'rover', 'crab', 'drone', 'jenny'] as const;
+import { Assets, BOARDS } from '../stage/assets';
+import { drawStage } from '../stage/render';
+import type { StageManifest, RegionState } from '../stage/manifest';
 
 // Bootstrap-only scenes live in lane B until lane A provides story/UI scenes.
 export class Boot extends Phaser.Scene {
@@ -10,19 +11,32 @@ export class Boot extends Phaser.Scene {
 
 export class Preload extends Phaser.Scene {
   constructor() { super('Preload'); }
-  preload() {
-    for (const board of PLACEHOLDERS) {
-      const path = `/assets/placeholder/${board}`;
-      this.load.atlas(board, `${path}.png`, `${path}.json`);
-      this.load.json(`${board}.anims`, `${path}.anims.json`);
-    }
+  async create() {
+    const query = new URLSearchParams(location.search);
+    const region = query.get('region') ?? 'rusty-creek';
+    const state: RegionState = query.get('state') === 'clean' ? 'clean' : 'anomaly';
+    const assets = new Assets(this);
+    const manifest = await assets.stage(region, state);
+    for (const board of BOARDS) await assets.board(board);
+    this.scene.start('Stage', { manifest, state });
   }
-  create() { this.scene.start('Stage'); }
 }
 
 export class Stage extends Phaser.Scene {
   constructor() { super('Stage'); }
-  create() { this.scene.launch('UI'); }
+  create(data: { manifest: StageManifest; state: RegionState }) {
+    drawStage(this, data.manifest, data.state);
+    this.scene.launch('UI');
+    // Development inspection only; camera follow is implemented separately in #32.
+    if (import.meta.env.DEV && new URLSearchParams(location.search).has('inspect')) {
+      this.input.on('pointermove', (pointer: Phaser.Input.Pointer) => {
+        if (pointer.isDown) {
+          this.cameras.main.scrollX -= pointer.x - pointer.prevPosition.x;
+          this.cameras.main.scrollY -= pointer.y - pointer.prevPosition.y;
+        }
+      });
+    }
+  }
 }
 
 export class UI extends Phaser.Scene {
diff --git a/game/src/stage/assets.test.ts b/game/src/stage/assets.test.ts
new file mode 100644
index 0000000..fc8c7ae
--- /dev/null
+++ b/game/src/stage/assets.test.ts
@@ -0,0 +1,102 @@
+import { describe, expect, it, vi } from 'vitest';
+import type Phaser from 'phaser';
+import { Assets } from './assets';
+import { parseManifest, stageLayers } from './manifest';
+
+const manifest = () => ({ region: 'rusty-creek', chunkSize: [2160, 720],
+  chunks: [0, 1, 2].map(x => ({ id: `rc-${x}-0`, x, y: 0, states: { anomaly: {
+    layers: [1, 2, 3, 5, 6, 7, 4].map((z, n) => ({ id: `layer-${n}`, z,
+      scroll: z === 1 ? 0.2 : z === 7 ? 1.15 : 1, file: z === 1 ? 'shared.png' : `${x}-${z}.png` })),
+    collision: `rc-${x}-0.anomaly.collision.json` } } })) });
+const clips = { idle: { frames: 1, fps: 12, loop: true } };
+const atlas = { frames: { 'idle-00': { frame: { x: 0, y: 0, w: 28, h: 80 }, pivot: { x: 0.5, y: 1 } } } };
+
+function harness(missing = '') {
+  const textures = new Set<string>(), queued: string[] = [];
+  const complete: (() => void)[] = [];
+  const image = vi.fn((key: string) => queued.push(key));
+  const loadAtlas = vi.fn((key: string) => queued.push(key));
+  const scene = { load: { image, atlas: loadAtlas, on: vi.fn(), off: vi.fn(),
+    once: (_: string, fn: () => void) => complete.push(fn),
+    start: () => { queued.splice(0).forEach(key => textures.add(key)); complete.shift()?.(); } },
+    textures: { exists: (key: string) => textures.has(key), remove: (key: string) => textures.delete(key) },
+    cache: { json: { add: vi.fn(), get: () => clips } } };
+  const request = vi.fn(async (url: string | URL | Request) => ({ ok: !String(url).includes(missing || '\0'), status: 404,
+    json: async () => String(url).endsWith('stage.json') ? manifest() : String(url).endsWith('anims.json') ? clips : atlas }));
+  return { scene: scene as unknown as Phaser.Scene, request: request as unknown as typeof fetch, image, loadAtlas };
+}
+
+describe('stage manifest', () => {
+  it('keeps all 21 layers in blend order, offsets chunks and preserves scroll', () => {
+    const layers = stageLayers(parseManifest(manifest()), 'anomaly');
+    expect(layers).toHaveLength(21);
+    expect(layers.slice(0, 7).map(l => l.z)).toEqual([1, 2, 3, 5, 6, 7, 4]);
+    expect(layers[7].x).toBe(2160); expect(layers[14].x).toBe(4320);
+    expect(layers[0].scroll).toBe(0.2); expect(layers[5].scroll).toBe(1.15);
+  });
+  it('handles negative grid rows and rejects missing states', () => {
+    const input = manifest(); input.chunks[0].y = -1;
+    const stage = parseManifest(input);
+    expect(stageLayers(stage, 'anomaly')[0].y).toBe(-720);
+    expect(() => stageLayers(stage, 'clean')).toThrow('Missing');
+  });
+  it('rejects duplicate cells and unsafe file paths', () => {
+    const input = manifest(); input.chunks[1].x = 0;
+    expect(() => parseManifest(input)).toThrow('duplicate grid');
+    input.chunks[1].x = 1; input.chunks[0].states.anomaly.layers[0].file = '../private.png';
+    expect(() => parseManifest(input)).toThrow('layer id/file');
+  });
+});
+
+describe('asset loading', () => {
+  it('does not bind the native browser fetch receiver to the asset loader', async () => {
+    const h = harness();
+    vi.stubGlobal('fetch', function(this: unknown, ...args: Parameters<typeof fetch>) {
+      expect(this).not.toBeInstanceOf(Assets);
+      return h.request(...args);
+    });
+    try { await new Assets(h.scene, true).board('hero-move'); }
+    finally { vi.unstubAllGlobals(); }
+  });
+  it('loads shared stage plates once and reuses already loaded textures', async () => {
+    const h = harness(), assets = new Assets(h.scene, true, h.request);
+    await assets.stage('rusty-creek', 'anomaly');
+    expect(h.image).toHaveBeenCalledTimes(19);
+    await assets.stage('rusty-creek', 'anomaly');
+    expect(h.image).toHaveBeenCalledTimes(19);
+  });
+  it('loads any named production board using the exporter contract', async () => {
+    const h = harness();
+    expect(await new Assets(h.scene, true, h.request).board('hero-move')).toEqual(clips);
+    expect(h.loadAtlas).toHaveBeenCalledWith('hero-move', '/assets/sprites/hero-move.png', atlas);
+    expect(h.scene.cache.json.add).toHaveBeenCalledWith('hero-move.anims', clips);
+  });
+  it('rejects missing assets loudly in development', async () => {
+    const h = harness('/sprites/');
+    await expect(new Assets(h.scene, true, h.request).board('hero-move')).rejects.toThrow('Missing asset');
+    expect(h.loadAtlas).not.toHaveBeenCalled();
+  });
+  it('rejects a missing stage manifest in development', async () => {
+    const h = harness('stage.json');
+    await expect(new Assets(h.scene, true, h.request).stage('rusty-creek', 'anomaly'))
+      .rejects.toThrow('/assets/stages/rusty-creek/stage.json');
+  });
+  it('provides a stage plate when the production manifest is missing', async () => {
+    const log = vi.spyOn(console, 'error').mockImplementation(() => {});
+    try {
+      const h = harness('stage.json');
+      const stage = await new Assets(h.scene, false, h.request).stage('rusty-creek', 'anomaly');
+      expect(stageLayers(stage, 'anomaly')[0].file).toBe('missing.png');
+      expect(h.image).toHaveBeenCalledWith('rusty-creek:missing.png', '/assets/stages/rusty-creek/missing.png');
+    } finally { log.mockRestore(); }
+  });
+  it('uses a bundled placeholder only after a production board fails', async () => {
+    const log = vi.spyOn(console, 'error').mockImplementation(() => {});
+    try {
+      const h = harness('/sprites/');
+      await new Assets(h.scene, false, h.request).board('enemy-rover');
+      expect(h.loadAtlas).toHaveBeenCalledWith('enemy-rover', '/assets/placeholder/rover.png', atlas);
+      expect(log).toHaveBeenCalled();
+    } finally { log.mockRestore(); }
+  });
+});
diff --git a/game/src/stage/assets.ts b/game/src/stage/assets.ts
new file mode 100644
index 0000000..c1ef035
--- /dev/null
+++ b/game/src/stage/assets.ts
@@ -0,0 +1,94 @@
+import type Phaser from 'phaser';
+import { parseManifest, stageLayers, type StageManifest, type RegionState } from './manifest';
+
+export const BOARDS = ['hero-move', 'hero-run', 'hero-idle', 'hero-air', 'hero-hurt', 'hero-death',
+  'chair-side', 'chair-overhead', 'chair-block', 'enemy-rover', 'enemy-crab', 'enemy-drone', 'fx'] as const;
+export interface AnimationClip { frames: number; fps: number; loop: boolean }
+export type AnimationTable = Record<string, AnimationClip>;
+export const stageBase = (region: string) => `/assets/stages/${region}/`;
+export const textureKey = (region: string, file: string) => `${region}:${file}`;
+
+export class Assets {
+  constructor(private scene: Phaser.Scene, private strict = import.meta.env.DEV,
+    private request: typeof fetch = (...args) => fetch(...args)) {}
+
+  private async json(url: string): Promise<unknown> {
+    const response = await this.request(url);
+    if (!response.ok) throw new Error(`Missing asset ${url}: HTTP ${response.status}`);
+    return response.json();
+  }
+
+  private queue(add: () => void): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const errors: string[] = [];
+      const failed = (file: Phaser.Loader.File) => errors.push(file.key);
+      this.scene.load.on('loaderror', failed);
+      this.scene.load.once('complete', () => {
+        this.scene.load.off('loaderror', failed);
+        errors.length ? reject(new Error(`Failed assets: ${errors.join(', ')}`)) : resolve();
+      });
+      add();
+      this.scene.load.start();
+    });
+  }
+
+  async stage(region: string, state: RegionState): Promise<StageManifest> {
+    if (!/^[a-z][a-z0-9-]*$/.test(region)) throw new Error('Invalid region id');
+    let manifest: StageManifest;
+    try {
+      manifest = parseManifest(await this.json(`${stageBase(region)}stage.json`));
+      if (manifest.region !== region) throw new Error(`Region mismatch: ${region}`);
+      stageLayers(manifest, state);
+    } catch (error) {
+      if (this.strict) throw error;
+      console.error(error);
+      manifest = { region, chunkSize: [2160, 720], chunks: [{ id: 'fallback', x: 0, y: 0,
+        states: { [state]: { layers: [{ id: 'missing-stage', z: 5, scroll: 1, file: 'missing.png' }], collision: null } } }] };
+    }
+    const files = [...new Set(stageLayers(manifest, state).map(layer => layer.file))];
+    const missing = files.filter(file => !this.scene.textures.exists(textureKey(region, file)));
+    if (missing.length) {
+      try {
+        await this.queue(() => missing.forEach(file => this.scene.load.image(textureKey(region, file), stageBase(region) + file)));
+      } catch (error) {
+        if (this.strict) throw error;
+        console.error(error);
+        for (const file of missing) if (!this.scene.textures.exists(textureKey(region, file))) {
+          const texture = this.scene.textures.createCanvas(textureKey(region, file), ...manifest.chunkSize);
+          if (texture) { texture.context.fillStyle = '#76516f'; texture.context.fillRect(0, 0, ...manifest.chunkSize); texture.refresh(); }
+        }
+      }
+    }
+    return manifest;
+  }
+
+  private async atlas(board: string, base: string): Promise<AnimationTable> {
+    const atlas = await this.json(`${base}.json`);
+    const clips = await this.json(`${base}.anims.json`) as AnimationTable;
+    const frames = (atlas as { frames?: Record<string, unknown> }).frames;
+    if (!frames || !clips || !Object.keys(clips).length) throw new Error(`Invalid atlas ${board}`);
+    for (const [name, clip] of Object.entries(clips)) {
+      if (!Number.isInteger(clip.frames) || clip.frames < 1 || !Number.isFinite(clip.fps)
+        || clip.fps <= 0 || typeof clip.loop !== 'boolean') throw new Error(`Invalid clip ${board}:${name}`);
+      for (let n = 0; n < clip.frames; n++) if (!frames[`${name}-${String(n).padStart(2, '0')}`]) {
+        throw new Error(`Missing frame ${board}:${name}-${n}`);
+      }
+    }
+    await this.queue(() => this.scene.load.atlas(board, `${base}.png`, atlas as object));
+    this.scene.cache.json.add(`${board}.anims`, clips);
+    return clips;
+  }
+
+  async board(board: string): Promise<AnimationTable> {
+    if (!/^[a-z][a-z0-9-]*$/.test(board)) throw new Error('Invalid board id');
+    if (this.scene.textures.exists(board)) return this.scene.cache.json.get(`${board}.anims`);
+    try { return await this.atlas(board, `/assets/sprites/${board}`); }
+    catch (error) {
+      if (this.strict) throw error;
+      console.error(error);
+      const fallback = board.startsWith('enemy-') ? board.slice(6) : board === 'fx' ? 'dexter' : 'hero';
+      if (this.scene.textures.exists(board)) this.scene.textures.remove(board);
+      return this.atlas(board, `/assets/placeholder/${fallback}`);
+    }
+  }
+}
diff --git a/game/src/stage/manifest.ts b/game/src/stage/manifest.ts
new file mode 100644
index 0000000..266eb8e
--- /dev/null
+++ b/game/src/stage/manifest.ts
@@ -0,0 +1,52 @@
+export type RegionState = 'clean' | 'anomaly';
+export interface StageLayer { id: string; z: number; scroll: number; file: string }
+export interface ChunkState { layers: StageLayer[]; collision: string | null }
+export interface StageChunk { id: string; x: number; y: number; states: Partial<Record<RegionState, ChunkState>> }
+export interface StageManifest { region: string; chunkSize: [number, number]; chunks: StageChunk[] }
+
+function assert(condition: unknown, message: string): asserts condition {
+  if (!condition) throw new Error(`Invalid stage manifest: ${message}`);
+}
+const object = (value: unknown): value is Record<string, unknown> =>
+  typeof value === 'object' && value !== null && !Array.isArray(value);
+export const assetFile = (value: unknown): value is string => typeof value === 'string'
+  && /^[a-zA-Z0-9_.\/-]+$/.test(value) && !value.startsWith('/')
+  && value.split('/').every(part => part !== '..' && part !== '.' && part !== '');
+
+/** Validate the stage export without reordering its authored blend sequence. */
+export function parseManifest(value: unknown): StageManifest {
+  assert(object(value), 'expected an object');
+  assert(typeof value.region === 'string' && /^[a-z][a-z0-9-]*$/.test(value.region), 'region');
+  assert(Array.isArray(value.chunkSize) && value.chunkSize.length === 2
+    && value.chunkSize[0] === 2160 && value.chunkSize[1] === 720, 'chunkSize must be 2160×720');
+  assert(Array.isArray(value.chunks) && value.chunks.length > 0, 'chunks');
+  const ids = new Set<string>(), grid = new Set<string>();
+  for (const chunk of value.chunks) {
+    assert(object(chunk) && typeof chunk.id === 'string' && chunk.id.length > 0, 'chunk id');
+    assert(!ids.has(chunk.id), `duplicate chunk ${chunk.id}`); ids.add(chunk.id);
+    assert(Number.isInteger(chunk.x) && Number.isInteger(chunk.y), 'integer grid coordinates');
+    const cell = `${chunk.x},${chunk.y}`;
+    assert(!grid.has(cell), `duplicate grid cell ${cell}`); grid.add(cell);
+    assert(object(chunk.states) && Object.keys(chunk.states).length > 0, 'chunk states');
+    for (const [name, state] of Object.entries(chunk.states)) {
+      assert(name === 'clean' || name === 'anomaly', `unknown state ${name}`);
+      assert(object(state) && Array.isArray(state.layers) && state.layers.length > 0, `${chunk.id}.${name} layers`);
+      assert(state.collision === null || assetFile(state.collision), 'collision file');
+      for (const layer of state.layers) {
+        assert(object(layer) && typeof layer.id === 'string' && assetFile(layer.file), 'layer id/file');
+        assert(Number.isInteger(layer.z) && Number(layer.z) >= 0 && Number(layer.z) <= 7, 'layer z');
+        assert(typeof layer.scroll === 'number' && Number.isFinite(layer.scroll) && layer.scroll >= 0, 'scroll');
+      }
+    }
+  }
+  return value as unknown as StageManifest;
+}
+
+export function stageLayers(manifest: StageManifest, state: RegionState) {
+  return manifest.chunks.flatMap(chunk => {
+    const content = chunk.states[state];
+    if (!content) throw new Error(`Missing ${manifest.region}/${chunk.id}.${state}`);
+    return content.layers.map((layer, order) => ({ ...layer, order,
+      x: chunk.x * manifest.chunkSize[0], y: chunk.y * manifest.chunkSize[1] }));
+  });
+}
diff --git a/game/src/stage/render.ts b/game/src/stage/render.ts
new file mode 100644
index 0000000..7eafa08
--- /dev/null
+++ b/game/src/stage/render.ts
@@ -0,0 +1,15 @@
+import type Phaser from 'phaser';
+import { stageLayers, type StageManifest, type RegionState } from './manifest';
+import { textureKey } from './assets';
+
+/** z describes the art role; manifest list order describes alpha composition. */
+export function drawStage(scene: Phaser.Scene, manifest: StageManifest, state: RegionState) {
+  const images = stageLayers(manifest, state).map(layer => scene.add.image(layer.x, layer.y,
+    textureKey(manifest.region, layer.file)).setOrigin(0).setScrollFactor(layer.scroll).setDepth(layer.order));
+  const xs = manifest.chunks.map(c => c.x * manifest.chunkSize[0]);
+  const ys = manifest.chunks.map(c => c.y * manifest.chunkSize[1]);
+  scene.cameras.main.setBounds(Math.min(...xs), Math.min(...ys),
+    Math.max(...xs) - Math.min(...xs) + manifest.chunkSize[0],
+    Math.max(...ys) - Math.min(...ys) + manifest.chunkSize[1]);
+  return images;
+}