diff --git a/cocoscreator_projects/YouleNexus/assets/framework/sdk/runtime/game-session-host.ts b/cocoscreator_projects/YouleNexus/assets/framework/sdk/runtime/game-session-host.ts
new file mode 100644
index 0000000..7063323
--- /dev/null
+++ b/cocoscreator_projects/YouleNexus/assets/framework/sdk/runtime/game-session-host.ts
@@ -0,0 +1,165 @@
+import type {
+  GameEntry,
+  GameHost,
+  GameModule,
+  GameServerMessage,
+  PlatformToGameEvent,
+} from '../contracts/index.ts';
+
+const RESERVED_ROUTES = new Set(['platform', 'agent', 'room']);
+
+export type GameSessionState =
+  | 'idle'
+  | 'attaching'
+  | 'active'
+  | 'restoring'
+  | 'disposing'
+  | 'disposed';
+
+/** Validates the compile-time game identity before it reaches the runtime. */
+export function assertGameEntry(entry: GameEntry): void {
+  assertNonEmptyText(entry.key, 'key');
+  assertGameId(entry.gameId);
+  assertNonEmptyText(entry.route, 'route');
+  if (RESERVED_ROUTES.has(entry.route)) {
+    throw new Error(`GameEntry reserved route: ${entry.route}`);
+  }
+  if (typeof entry.resolveSeatCount !== 'function') {
+    throw new Error('GameEntry resolveSeatCount must be a function');
+  }
+  const seatCount = entry.resolveSeatCount([]);
+  if (!Number.isInteger(seatCount) || seatCount <= 0) {
+    throw new Error(`GameEntry seat count must be a positive integer: ${seatCount}`);
+  }
+  if (typeof entry.createModule !== 'function') {
+    throw new Error('GameEntry createModule must be a function');
+  }
+  assertGameModule(entry.createModule());
+}
+
+/** Owns one isolated game module for one room at a time. */
+export class GameSessionHost {
+  private module: GameModule | undefined;
+  private currentState: GameSessionState = 'idle';
+
+  constructor(readonly entry: GameEntry) {
+    assertGameEntry(entry);
+  }
+
+  get state(): GameSessionState {
+    return this.currentState;
+  }
+
+  open(host: GameHost): void {
+    if (this.currentState === 'disposed') {
+      throw new Error('Cannot open a disposed game session');
+    }
+    if (this.currentState !== 'idle') {
+      throw new Error(`Cannot open game session while ${this.currentState}`);
+    }
+
+    this.currentState = 'attaching';
+    try {
+      const module = this.entry.createModule();
+      assertGameModule(module);
+      this.module = module;
+      module.attach(host);
+      this.currentState = 'active';
+    } catch (error) {
+      this.module = undefined;
+      this.currentState = 'idle';
+      throw error;
+    }
+  }
+
+  publish(event: PlatformToGameEvent): void {
+    this.requireActive('publish').handlePlatformEvent(event);
+  }
+
+  dispatchGameMessage(route: string, message: GameServerMessage): void {
+    if (route !== this.entry.route) {
+      throw new Error(`Game message route mismatch: expected ${this.entry.route}, received ${route}`);
+    }
+    this.requireActive('dispatch a game message').handleGameMessage(message);
+  }
+
+  restore(deskinfo: unknown): void {
+    const module = this.requireActive('restore');
+    this.currentState = 'restoring';
+    try {
+      module.restore(deskinfo);
+    } finally {
+      this.currentState = 'active';
+    }
+  }
+
+  close(): void {
+    if (this.currentState === 'disposed') {
+      throw new Error('Cannot close a disposed game session');
+    }
+    if (this.currentState === 'idle') return;
+    if (this.currentState !== 'active') {
+      throw new Error(`Cannot close game session while ${this.currentState}`);
+    }
+
+    const module = this.module;
+    if (!module) {
+      throw new Error('Active game session has no module');
+    }
+    this.currentState = 'disposing';
+    this.module = undefined;
+    try {
+      module.dispose();
+    } finally {
+      this.currentState = 'idle';
+    }
+  }
+
+  dispose(): void {
+    if (this.currentState === 'disposed') return;
+    try {
+      if (this.currentState !== 'idle') this.close();
+    } finally {
+      this.module = undefined;
+      this.currentState = 'disposed';
+    }
+  }
+
+  private requireActive(operation: string): GameModule {
+    if (this.currentState === 'disposed') {
+      throw new Error(`Cannot ${operation} on a disposed game session`);
+    }
+    if (this.currentState !== 'active' || !this.module) {
+      throw new Error(`Cannot ${operation} without an active game session`);
+    }
+    return this.module;
+  }
+}
+
+function assertNonEmptyText(value: unknown, field: string): asserts value is string {
+  if (typeof value !== 'string' || value.trim() === '') {
+    throw new Error(`GameEntry ${field} must be a non-empty string`);
+  }
+}
+
+function assertGameId(value: unknown): void {
+  if (typeof value === 'string') {
+    if (value.trim() === '') throw new Error('GameEntry gameId must be a non-empty string or number');
+    return;
+  }
+  if (typeof value !== 'number' || !Number.isFinite(value)) {
+    throw new Error('GameEntry gameId must be a non-empty string or number');
+  }
+}
+
+function assertGameModule(module: unknown): asserts module is GameModule {
+  if (!module || typeof module !== 'object') {
+    throw new Error('GameEntry module factory must return a module');
+  }
+  const candidate = module as Record<string, unknown>;
+  for (const method of ['attach', 'handlePlatformEvent', 'handleGameMessage', 'restore', 'dispose']) {
+    if (typeof candidate[method] !== 'function') {
+      throw new Error(`GameEntry module must implement ${method}`);
+    }
+  }
+}
diff --git a/cocoscreator_projects/YouleNexus/assets/framework/sdk/testing/game-contract-harness.ts b/cocoscreator_projects/YouleNexus/assets/framework/sdk/testing/game-contract-harness.ts
new file mode 100644
index 0000000..e95018d
--- /dev/null
+++ b/cocoscreator_projects/YouleNexus/assets/framework/sdk/testing/game-contract-harness.ts
@@ -0,0 +1,54 @@
+import { strict as assert } from 'node:assert';
+import type {
+  GameEntry,
+  GameHost,
+} from '../contracts/index.ts';
+import { assertGameEntry, GameSessionHost } from '../runtime/game-session-host.ts';
+
+/** A supplied fake host and its explicit invalidation assertion. */
+export interface GameContractHost {
+  readonly host: GameHost;
+  invalidate(): void;
+}
+
+export type GameContractHostFactory = () => GameContractHost;
+
+/** Runs the shared lifecycle checks required of the app's sole GameEntry. */
+export function assertGameContract(entry: GameEntry, makeHost: GameContractHostFactory): void {
+  assertGameEntry(entry);
+  for (const route of ['platform', 'agent', 'room']) {
+    assert.throws(() => assertGameEntry({ ...entry, route }), /reserved.*route/);
+  }
+  for (const seatCount of [2, 4, 10]) {
+    assert.equal(entry.resolveSeatCount([seatCount]), seatCount, `roomtype must resolve ${seatCount} seats`);
+  }
+
+  const firstFactoryModule = entry.createModule();
+  const secondFactoryModule = entry.createModule();
+  assert.notEqual(firstFactoryModule, secondFactoryModule, 'createModule must create isolated modules');
+
+  const sessions = new GameSessionHost(entry);
+  runCycle(sessions, makeHost(), entry, 1);
+  runCycle(sessions, makeHost(), entry, 2);
+  assert.equal(sessions.state, 'idle');
+}
+
+function runCycle(
+  sessions: GameSessionHost,
+  contractHost: GameContractHost,
+  entry: GameEntry,
+  cycle: number,
+): void {
+  const roomtype = [4] as const;
+  const deskinfo = { cycle };
+  sessions.open(contractHost.host);
+  sessions.publish({ type: 'room.entered', roomtype });
+  sessions.dispatchGameMessage(entry.route, { rpc: 'conformance.message', data: { cycle } });
+  assert.throws(
+    () => sessions.dispatchGameMessage(`${entry.route}.other`, { rpc: 'conformance.message', data: { cycle } }),
+    /route/,
+  );
+  sessions.restore(deskinfo);
+  sessions.close();
+  contractHost.invalidate();
+}
diff --git a/cocoscreator_projects/framework-tests/sdk/game-contract-harness.test.ts b/cocoscreator_projects/framework-tests/sdk/game-contract-harness.test.ts
new file mode 100644
index 0000000..f4d11ce
--- /dev/null
+++ b/cocoscreator_projects/framework-tests/sdk/game-contract-harness.test.ts
@@ -0,0 +1,85 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import type {
+  GameEntry,
+  GameHost,
+  GameModule,
+  PlatformGameSnapshot,
+} from '../../YouleNexus/assets/framework/sdk/contracts/index.ts';
+import {
+  assertGameContract,
+  type GameContractHost,
+} from '../../YouleNexus/assets/framework/sdk/testing/game-contract-harness.ts';
+
+test('assertGameContract runs the reusable isolated session conformance suite', () => {
+  let invalidations = 0;
+  let nextModuleId = 0;
+  const entry: GameEntry = {
+    key: 'fixture',
+    gameId: 41,
+    route: 'fixture-route',
+    resolveSeatCount: (roomtype) => {
+      const seats = roomtype[0];
+      if (seats === 2 || seats === 4 || seats === 10) return seats;
+      return 4;
+    },
+    createModule: () => makeModule(++nextModuleId),
+  };
+
+  assert.doesNotThrow(() => assertGameContract(entry, makeConformanceHost(() => { invalidations++; })));
+  assert.equal(invalidations, 2);
+  assert.ok(nextModuleId >= 2);
+});
+
+function makeModule(id: number): GameModule {
+  let host: GameHost | undefined;
+  let restored: unknown;
+  let eventCount = 0;
+  let messageCycle: number | undefined;
+  return {
+    attach(value) { host = value; },
+    handlePlatformEvent(event) {
+      eventCount++;
+      if (event.type === 'room.entered') {
+        assert.equal(event.roomtype[0], 4);
+      }
+    },
+    handleGameMessage(message) {
+      assert.equal(message.rpc, 'conformance.message');
+      const data = message.data as { cycle: number };
+      assert.equal(typeof data.cycle, 'number');
+      messageCycle = data.cycle;
+    },
+    restore(deskinfo) { restored = deskinfo; },
+    dispose() {
+      assert.ok(host);
+      assert.equal(eventCount, 1);
+      assert.deepEqual(restored, deskinfoFor(messageCycle!));
+    },
+  };
+}
+
+function deskinfoFor(cycle: number): { readonly cycle: number } {
+  return { cycle };
+}
+
+function makeConformanceHost(onInvalidate: () => void): () => GameContractHost {
+  return () => {
+    const snapshot: PlatformGameSnapshot = {
+      connection: { phase: 'connected' },
+      self: { playerId: 1, seat: 0 },
+      room: { roomcode: 'fixture', roomtype: [], stage: 0, needprepare: 0, infinite: 0 },
+      seats: [],
+    };
+    return {
+      host: {
+        seat: { toView: (seat) => seat, toServer: (seat) => seat },
+        getSnapshot: () => snapshot,
+        subscribe: () => () => {},
+        sendGameMessage: () => {},
+        execute: () => {},
+      },
+      invalidate: onInvalidate,
+    };
+  };
+}
diff --git a/cocoscreator_projects/framework-tests/sdk/game-session-host.test.ts b/cocoscreator_projects/framework-tests/sdk/game-session-host.test.ts
new file mode 100644
index 0000000..d9d60ba
--- /dev/null
+++ b/cocoscreator_projects/framework-tests/sdk/game-session-host.test.ts
@@ -0,0 +1,165 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import type {
+  GameEntry,
+  GameHost,
+  GameModule,
+  GameServerMessage,
+  PlatformGameSnapshot,
+  PlatformToGameEvent,
+} from '../../YouleNexus/assets/framework/sdk/contracts/index.ts';
+import {
+  assertGameEntry,
+  GameSessionHost,
+} from '../../YouleNexus/assets/framework/sdk/runtime/game-session-host.ts';
+
+function makeHost(): GameHost {
+  const snapshot: PlatformGameSnapshot = {
+    connection: { phase: 'connected' },
+    self: { playerId: 1, seat: 0 },
+    room: { roomcode: 'fixture', roomtype: [], stage: 0, needprepare: 0, infinite: 0 },
+    seats: [],
+  };
+  return {
+    seat: { toView: (seat) => seat, toServer: (seat) => seat },
+    getSnapshot: () => snapshot,
+    subscribe: () => () => {},
+    sendGameMessage: () => {},
+    execute: () => {},
+  };
+}
+
+function makeEntry(createModule: () => GameModule): GameEntry {
+  return {
+    key: 'fixture',
+    gameId: 41,
+    route: 'fixture-route',
+    resolveSeatCount: () => 4,
+    createModule,
+  };
+}
+
+function makeModule(log: string[], onRestore?: (deskinfo: unknown) => void): GameModule {
+  return {
+    attach: () => log.push('attach'),
+    handlePlatformEvent: (event) => log.push(`event:${event.type}`),
+    handleGameMessage: (message) => log.push(`message:${message.rpc}`),
+    restore: (deskinfo) => {
+      log.push('restore');
+      onRestore?.(deskinfo);
+    },
+    dispose: () => log.push('dispose'),
+  };
+}
+
+test('assertGameEntry rejects invalid identity, routes, seat counts, and module factories', () => {
+  const entry = makeEntry(() => makeModule([]));
+
+  assert.throws(() => assertGameEntry({ ...entry, key: '' }), /key/);
+  assert.throws(() => assertGameEntry({ ...entry, gameId: '' }), /gameId/);
+  for (const route of ['platform', 'agent', 'room']) {
+    assert.throws(() => assertGameEntry({ ...entry, route }), /reserved.*route/);
+  }
+  assert.throws(() => assertGameEntry({ ...entry, resolveSeatCount: () => 0 }), /seat count/);
+  assert.throws(() => assertGameEntry({ ...entry, resolveSeatCount: () => 2.5 }), /seat count/);
+  assert.throws(() => assertGameEntry({ ...entry, createModule: () => undefined as never }), /module/);
+});
+
+test('GameSessionHost delivers room events and deskinfo to one active module in order', () => {
+  const log: string[] = [];
+  const deskinfo = { turn: 7 };
+  let restoredValue: unknown;
+  const sessions = new GameSessionHost(makeEntry(() => makeModule(log, (value) => { restoredValue = value; })));
+
+  sessions.open(makeHost());
+  sessions.publish({ type: 'room.entered', roomtype: ['raw', { players: 4 }] });
+  sessions.restore(deskinfo);
+  sessions.close();
+
+  assert.deepEqual(log, ['attach', 'event:room.entered', 'restore', 'dispose']);
+  assert.equal(restoredValue, deskinfo);
+  assert.equal(sessions.state, 'idle');
+});
+
+test('GameSessionHost preserves raw platform events and game messages by identity', () => {
+  let receivedEvent: PlatformToGameEvent | undefined;
+  let receivedMessage: GameServerMessage | undefined;
+  const sessions = new GameSessionHost(makeEntry(() => ({
+    attach() {},
+    handlePlatformEvent(event) { receivedEvent = event; },
+    handleGameMessage(message) { receivedMessage = message; },
+    restore() {},
+    dispose() {},
+  })));
+  const rawRoomtype = ['raw', { players: 4 }];
+  const rawData = { cards: [3, 7] };
+  const message: GameServerMessage = { rpc: 'draw', data: rawData };
+  const event: PlatformToGameEvent = { type: 'room.entered', roomtype: rawRoomtype };
+
+  sessions.open(makeHost());
+  sessions.publish(event);
+  sessions.dispatchGameMessage('fixture-route', message);
+
+  assert.equal(receivedEvent, event);
+  assert.equal(receivedEvent?.roomtype, rawRoomtype);
+  assert.equal(receivedMessage, message);
+  assert.equal(receivedMessage?.data, rawData);
+});
+
+test('GameSessionHost rejects illegal state transitions and mismatched game routes', () => {
+  const log: string[] = [];
+  const sessions = new GameSessionHost(makeEntry(() => makeModule(log)));
+  const message: GameServerMessage = { rpc: 'draw', data: { card: 3 } };
+
+  assert.throws(() => sessions.publish({ type: 'room.dissolved' }), /active/);
+  assert.throws(() => sessions.restore({}), /active/);
+  sessions.open(makeHost());
+  assert.throws(() => sessions.open(makeHost()), /open/);
+  assert.throws(() => sessions.dispatchGameMessage('other-route', message), /route/);
+  sessions.dispatchGameMessage('fixture-route', message);
+  assert.deepEqual(log, ['attach', 'message:draw']);
+});
+
+test('GameSessionHost disposes a module exactly once and becomes terminal after dispose', () => {
+  const log: string[] = [];
+  const sessions = new GameSessionHost(makeEntry(() => makeModule(log)));
+
+  sessions.open(makeHost());
+  sessions.dispose();
+  sessions.dispose();
+
+  assert.deepEqual(log, ['attach', 'dispose']);
+  assert.equal(sessions.state, 'disposed');
+  assert.throws(() => sessions.open(makeHost()), /disposed/);
+  assert.throws(() => sessions.publish({ type: 'room.dissolved' }), /disposed/);
+});
+
+test('GameSessionHost creates a fresh module after close', () => {
+  const log: string[] = [];
+  const modules: GameModule[] = [];
+  const sessions = new GameSessionHost(makeEntry(() => {
+    const module = makeModule(log);
+    modules.push(module);
+    return module;
+  }));
+
+  sessions.open(makeHost());
+  sessions.close();
+  sessions.open(makeHost());
+  sessions.close();
+
+  assert.notEqual(modules[modules.length - 1], modules[modules.length - 2]);
+  assert.deepEqual(log, ['attach', 'dispose', 'attach', 'dispose']);
+});
+
+test('GameSessionHost returns to active after a restore handler throws', () => {
+  const log: string[] = [];
+  const sessions = new GameSessionHost(makeEntry(() => ({
+    ...makeModule(log),
+    restore: () => { throw new Error('restore failed'); },
+  })));
+
+  sessions.open(makeHost());
+  assert.throws(() => sessions.restore({}), /restore failed/);
+  assert.equal(sessions.state, 'active');
+});