3D 生成前端提交体跟随平坦落点契约

- buildModel3dSubmissionPlan 不再拼 tagged target，把 projectId 与 canvasCompletion 直接摊进请求体；画布链路仍只落项目资源。
- submitModel3dGenerationRequest 的提交体注释同步落点字段改名。
- 请求体、幂等键与排队用例改为断言扁平落点字段。
- 定向验证：npx vitest run src/components/image-editor/model3d-generation src/components/image-editor/model3d-preview（63 passed）、npm run typecheck 通过。

src/components/image-editor/model3d-generation/Model3dGenerationSubmission.test.ts

@@ -138,11 +138,8 @@ describe('buildModel3dSubmissionPlan', () => {
         smartLowPoly: false,
         generateParts: false,
       },
-      target: {
-        kind: 'projectResource',
-        projectId: 'project-1',
-        canvasCompletion: CANVAS_COMPLETION,
-      },
+      projectId: 'project-1',
+      canvasCompletion: CANVAS_COMPLETION,
     });
   });
 
@@ -172,7 +169,7 @@ describe('buildModel3dSubmissionPlan', () => {
         smartLowPoly: false,
         generateParts: true,
       },
-      target: { kind: 'projectResource', projectId: 'project-1' },
+      projectId: 'project-1',
     });
     expect(result.plan.body).not.toHaveProperty('prompt');
     // 后端显式拒绝 texture=false + textureQuality 的组合，缺位是契约要求。
@@ -322,7 +319,7 @@ describe('Idempotency-Key', () => {
         endpoint: 'text-to-model',
         body: {
           generation: { model: 'v3.1-20260211', prompt: '木椅' },
-          target: { kind: 'projectResource', projectId: 'project-1' },
+          projectId: 'project-1',
         },
       }),
     ).toMatch(/^[\x21-\x7e]{1,128}$/);
@@ -334,7 +331,7 @@ describe('Idempotency-Key', () => {
       endpoint: 'text-to-model',
       body: {
         generation: { texture: true, model: 'v3.1-20260211', prompt: '木椅' },
-        target: { kind: 'projectResource', projectId: 'project-1' },
+        projectId: 'project-1',
       },
     });
     const right = resolveModel3dRequestKey({
@@ -342,7 +339,7 @@ describe('Idempotency-Key', () => {
       endpoint: 'text-to-model',
       body: {
         generation: { model: 'v3.1-20260211', texture: true, prompt: '木椅' },
-        target: { kind: 'projectResource', projectId: 'project-1' },
+        projectId: 'project-1',
       },
     });
     expect(right).toBe(left);

src/components/image-editor/model3d-generation/Model3dGenerationSubmission.ts

@@ -1,7 +1,6 @@
 import type { ExternalGenerationJobStatusRecord } from '../../../../packages/shared/src/contracts/externalGeneration';
 import type {
   Model3dGenerationSource,
-  Model3dGenerationTarget,
   Model3dImageToModelRequest,
   Model3dTextToModelRequest,
 } from '../../../../packages/shared/src/contracts/model3d';
@@ -126,8 +125,9 @@ export function buildModel3dSubmissionPlan({
     smartLowPoly: params.smartLowPoly,
     generateParts: params.generateParts,
   };
-  const target: Model3dGenerationTarget = {
-    kind: 'projectResource',
+  // 落点与其它生成接口同形：平坦的可选字段，不再包一层 tagged enum。
+  // 服务端按「二选一」校验：这里只给 projectId（画布链路没有落素材库的入口）。
+  const placement = {
     projectId: trimmedProjectId,
     ...(canvasCompletion ? { canvasCompletion } : {}),
   };
@@ -153,14 +153,14 @@ export function buildModel3dSubmissionPlan({
     if (!source) {
       return { ok: false, message: MODEL3D_IMAGE_SOURCE_REQUIRED_MESSAGE };
     }
-    return finish({ source, generation, target });
+    return finish({ source, generation, ...placement });
   }
 
   const prompt = dialog.prompt.trim();
   if (!prompt) {
     return { ok: false, message: MODEL3D_TEXT_PROMPT_REQUIRED_MESSAGE };
   }
-  return finish({ generation: { ...generation, prompt }, target });
+  return finish({ generation: { ...generation, prompt }, ...placement });
 }
 
 /**

src/components/image-editor/model3d-generation/useModel3dGenerationTask.test.tsx

@@ -166,7 +166,7 @@ describe('useModel3dGenerationTask', () => {
         smartLowPoly: false,
         generateParts: false,
       },
-      target: { kind: 'projectResource', projectId: 'project-1' },
+      projectId: 'project-1',
     });
 
     expect(applyQueuedGeneration).toHaveBeenCalledTimes(1);

src/services/image-editor/editorProjectClient.ts

@@ -1746,7 +1746,7 @@ export async function submitModel3dGenerationRequest({
   idempotencyKey,
 }: {
   endpoint: Model3dPricingEndpoint;
-  // 提交体直接用端点契约：形状不符（缺 target、generation 结构错）在编译期就会暴露。
+  // 提交体直接用端点契约：形状不符（落点缺失、generation 结构错）在编译期就会暴露。
   body: Model3dTextToModelRequest | Model3dImageToModelRequest;
   idempotencyKey: string;
 }) {