实现 SFX V2 T4 生成面板交互

新增独立 SFX Prompt 助手状态机与请求隔离、单层撤销。

抽取通用音频预设跑马灯并接入 SFX 预设、计数和优化入口。

实现自动/手动时长、Loop、模型展示及同步提交参数冻结。

恢复项目布局状态，补齐回归测试并更新 T4 权威文档与共享决策。

src/components/image-editor/ImageCanvasSoundEffectPromptModel.test.ts

@@ -4,6 +4,7 @@ import soundEffectPromptCanonicalizationCases from '../../../packages/shared/tes
 import {
   canonicalizeSoundEffectPrompt,
   countSoundEffectPromptCodePoints,
+  createSoundEffectPromptStateModel,
   SOUND_EFFECT_PROMPT_MAX_CODE_POINTS,
   validateSoundEffectPrompt,
 } from './ImageCanvasSoundEffectPromptModel';
@@ -67,4 +68,94 @@ describe('ImageCanvasSoundEffectPromptModel', () => {
       });
     }
   });
+
+  it('creates one dialog-scoped optimization operation and swaps one undo snapshot', () => {
+    const model = createSoundEffectPromptStateModel();
+    const started = model.beginOperation({
+      dialogId: 'dialog-a',
+      status: 'optimizing',
+      prompt: '\u0085金币落地声\u3000',
+    });
+    expect(started.started).toBe(true);
+    expect(started.canonicalPrompt).toBe('金币落地声');
+    expect(started.state).toMatchObject({
+      status: 'optimizing',
+      undoPromptSnapshot: null,
+      temporaryPromptSnapshot: '金币落地声',
+    });
+    expect(
+      model.beginOperation({
+        dialogId: 'dialog-a',
+        status: 'optimizing',
+        prompt: '另一个输入',
+      }).reason,
+    ).toBe('duplicate');
+
+    const resolved = model.resolveAiOperation(
+      started.operation!,
+      '清脆明亮的金币落地声',
+    );
+    expect(resolved).toMatchObject({
+      applied: true,
+      prompt: '清脆明亮的金币落地声',
+      state: {
+        status: 'idle',
+        undoPromptSnapshot: '金币落地声',
+        temporaryPromptSnapshot: null,
+      },
+    });
+    expect(
+      model.swapUndoSnapshot('dialog-a', '清脆明亮的金币落地声'),
+    ).toMatchObject({
+      applied: true,
+      prompt: '金币落地声',
+      state: { undoPromptSnapshot: '清脆明亮的金币落地声' },
+    });
+  });
+
+  it('clears the replaced snapshot when a later optimization fails', () => {
+    const model = createSoundEffectPromptStateModel();
+    const first = model.beginOperation({
+      dialogId: 'dialog-a',
+      status: 'optimizing',
+      prompt: '原始描述',
+    });
+    model.resolveAiOperation(first.operation!, '第一次优化');
+    const second = model.beginOperation({
+      dialogId: 'dialog-a',
+      status: 'optimizing',
+      prompt: '手动修改后的描述',
+    });
+    expect(second.state.undoPromptSnapshot).toBeNull();
+    expect(model.rejectOperation(second.operation!)).toMatchObject({
+      applied: true,
+      prompt: '手动修改后的描述',
+      state: {
+        status: 'idle',
+        undoPromptSnapshot: null,
+        temporaryPromptSnapshot: null,
+      },
+    });
+  });
+
+  it('keeps submission and preset state isolated by dialog ID', () => {
+    const model = createSoundEffectPromptStateModel();
+    const submission = model.beginOperation({
+      dialogId: 'dialog-a',
+      status: 'submitting',
+      prompt: ' 提交描述 ',
+    });
+    expect(submission.started).toBe(true);
+    expect(model.preparePreset('dialog-a', '不应写入').applied).toBe(false);
+    expect(model.preparePreset('dialog-b', ' 另一面板 ').prompt).toBe(
+      '另一面板',
+    );
+    expect(
+      model.completeSubmittingOperation(submission.operation!),
+    ).toMatchObject({
+      applied: true,
+      prompt: '提交描述',
+      state: { status: 'idle' },
+    });
+  });
 });