diff --git a/web-server/src/motions/motion.dto.ts b/web-server/src/motions/motion.dto.ts
new file mode 100644
index 0000000..ea8c902
--- /dev/null
+++ b/web-server/src/motions/motion.dto.ts
@@ -0,0 +1,58 @@
+import { Type } from 'class-transformer';
+import { IsBoolean, IsEnum, IsInt, IsNumber, IsOptional, IsString, MaxLength, Min } from 'class-validator';
+import { MotionFormat, PublishStatus } from '../common/enums';
+import { PageQueryDto } from '../common/pagination';
+import { PartialSourceFieldsDto } from '../common/source.dto';
+
+/**
+ * 动作上传走 multipart/form-data，字段以字符串到达（见 MotionsService.create），
+ * 因此上传路径不使用 DTO，只在此处校验更新与查询。
+ */
+export class UpdateMotionDto extends PartialSourceFieldsDto {
+  @IsOptional()
+  @IsString()
+  @MaxLength(200)
+  name?: string;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  songId?: number;
+
+  /** 显式解绑曲目 */
+  @IsOptional()
+  @Type(() => Boolean)
+  @IsBoolean()
+  detachSong?: boolean;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsNumber()
+  @Min(1)
+  fps?: number;
+
+  @IsOptional()
+  @IsEnum(PublishStatus)
+  status?: PublishStatus;
+}
+
+export class QueryMotionDto extends PageQueryDto {
+  @IsOptional()
+  @IsString()
+  @MaxLength(200)
+  q?: string;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  songId?: number;
+
+  @IsOptional()
+  @IsEnum(MotionFormat)
+  format?: MotionFormat;
+
+  @IsOptional()
+  @IsEnum(PublishStatus)
+  status?: PublishStatus;
+}
diff --git a/web-server/src/motions/motion.serializer.ts b/web-server/src/motions/motion.serializer.ts
new file mode 100644
index 0000000..53afc8b
--- /dev/null
+++ b/web-server/src/motions/motion.serializer.ts
@@ -0,0 +1,61 @@
+import { MotionFormat, PreprocessState, PublishStatus, SourceType } from '../common/enums';
+import { Motion } from '../entities/motion.entity';
+
+/** 契约 data-models.md §3 的对外表示 */
+export interface MotionDto {
+  id: number;
+  songId: number | null;
+  name: string;
+  format: MotionFormat;
+  fileUrl: string | null;
+  fileSize: number | null;
+  fps: number | null;
+  frameCount: number | null;
+  durationMs: number | null;
+  keypointFormat: string | null;
+  keypointUrl: string | null;
+  keypointFrames: number | null;
+  preprocessState: PreprocessState;
+  preprocessError: string | null;
+  sourceType: SourceType;
+  sourceName: string;
+  sourceUrl: string;
+  license: string;
+  author: string;
+  status: PublishStatus;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface MotionUrlLookup {
+  fileUrl: string | null;
+  keypointUrl: string | null;
+  fileSize?: number | null;
+}
+
+export function toMotionDto(motion: Motion, urls: MotionUrlLookup): MotionDto {
+  return {
+    id: motion.id,
+    songId: motion.songId,
+    name: motion.name,
+    format: motion.format,
+    fileUrl: urls.fileUrl,
+    fileSize: urls.fileSize ?? null,
+    fps: motion.fps,
+    frameCount: motion.frameCount,
+    durationMs: motion.durationMs,
+    keypointFormat: motion.keypointFormat,
+    keypointUrl: urls.keypointUrl,
+    keypointFrames: motion.keypointFrames,
+    preprocessState: motion.preprocessState,
+    preprocessError: motion.preprocessError,
+    sourceType: motion.sourceType,
+    sourceName: motion.sourceName,
+    sourceUrl: motion.sourceUrl,
+    license: motion.license,
+    author: motion.author,
+    status: motion.status,
+    createdAt: motion.createdAt.toISOString(),
+    updatedAt: motion.updatedAt.toISOString(),
+  };
+}
diff --git a/web-server/src/motions/motions.controller.ts b/web-server/src/motions/motions.controller.ts
new file mode 100644
index 0000000..c9858e6
--- /dev/null
+++ b/web-server/src/motions/motions.controller.ts
@@ -0,0 +1,76 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  Header,
+  HttpCode,
+  HttpStatus,
+  Param,
+  ParseIntPipe,
+  Patch,
+  Post,
+  Query,
+  Res,
+  UploadedFile,
+  UseInterceptors,
+} from '@nestjs/common';
+import { FileInterceptor } from '@nestjs/platform-express';
+import { Response } from 'express';
+import { Paged } from '../common/pagination';
+import { UploadedFileLike } from '../common/upload.util';
+import { QueryMotionDto, UpdateMotionDto } from './motion.dto';
+import { MotionDto } from './motion.serializer';
+import { MotionsService } from './motions.service';
+
+@Controller('api/motions')
+export class MotionsController {
+  constructor(private readonly motions: MotionsService) {}
+
+  @Get()
+  list(@Query() query: QueryMotionDto): Promise<Paged<MotionDto>> {
+    return this.motions.list(query);
+  }
+
+  /** multipart/form-data：file + name + 来源五元组 + 可选 songId/fps/status/autoPreprocess */
+  @Post()
+  @UseInterceptors(FileInterceptor('file'))
+  create(
+    @Body() body: Record<string, unknown>,
+    @UploadedFile() file: UploadedFileLike | undefined,
+  ): Promise<MotionDto> {
+    return this.motions.create(body, file);
+  }
+
+  @Get(':id')
+  detail(@Param('id', ParseIntPipe) id: number): Promise<MotionDto> {
+    return this.motions.findOne(id);
+  }
+
+  @Patch(':id')
+  update(@Param('id', ParseIntPipe) id: number, @Body() dto: UpdateMotionDto): Promise<MotionDto> {
+    return this.motions.update(id, dto);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  remove(@Param('id', ParseIntPipe) id: number): Promise<void> {
+    return this.motions.remove(id);
+  }
+
+  /** T-WEB-006：BVH/FBX → MediaPipe33 关键点序列 */
+  @Post(':id/preprocess')
+  @HttpCode(HttpStatus.OK)
+  preprocess(@Param('id', ParseIntPipe) id: number): Promise<MotionDto> {
+    return this.motions.runPreprocess(id);
+  }
+
+  /** 关键点序列下载（NDJSON），契约 rest-api.yaml /api/motions/{id}/keypoints */
+  @Get(':id/keypoints')
+  @Header('Content-Type', 'application/x-ndjson; charset=utf-8')
+  async keypoints(@Param('id', ParseIntPipe) id: number, @Res() res: Response): Promise<void> {
+    const ndjson = await this.motions.keypointsNdjson(id);
+    res.setHeader('Content-Disposition', `attachment; filename="motion-${id}-keypoints.ndjson"`);
+    res.send(ndjson);
+  }
+}
diff --git a/web-server/src/motions/motions.module.ts b/web-server/src/motions/motions.module.ts
new file mode 100644
index 0000000..37bc578
--- /dev/null
+++ b/web-server/src/motions/motions.module.ts
@@ -0,0 +1,16 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { Motion } from '../entities/motion.entity';
+import { Song } from '../entities/song.entity';
+import { PreprocessModule } from '../preprocess/preprocess.module';
+import { StorageModule } from '../storage/storage.module';
+import { MotionsController } from './motions.controller';
+import { MotionsService } from './motions.service';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([Motion, Song]), StorageModule, PreprocessModule],
+  controllers: [MotionsController],
+  providers: [MotionsService],
+  exports: [MotionsService],
+})
+export class MotionsModule {}
diff --git a/web-server/src/motions/motions.service.ts b/web-server/src/motions/motions.service.ts
new file mode 100644
index 0000000..aee6ff4
--- /dev/null
+++ b/web-server/src/motions/motions.service.ts
@@ -0,0 +1,219 @@
+import { BadRequestException, ConflictException, Injectable, NotFoundException } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Brackets, Repository } from 'typeorm';
+import {
+  AssetKind,
+  MOTION_EXTENSION_MAP,
+  MotionFormat,
+  PublishStatus,
+  canTransition,
+} from '../common/enums';
+import { Paged, toPaged } from '../common/pagination';
+import { SourceTuple, assertSourceTupleComplete } from '../common/source.dto';
+import {
+  UploadedFileLike,
+  parseOptionalBool,
+  parseOptionalInt,
+  parseOptionalNumber,
+  requireUploadedFile,
+  resolveFormatByExtension,
+} from '../common/upload.util';
+import { Motion } from '../entities/motion.entity';
+import { Song } from '../entities/song.entity';
+import { PreprocessService } from '../preprocess/preprocess.service';
+import { StorageService } from '../storage/storage.service';
+import { QueryMotionDto, UpdateMotionDto } from './motion.dto';
+import { MotionDto, toMotionDto } from './motion.serializer';
+
+@Injectable()
+export class MotionsService {
+  constructor(
+    @InjectRepository(Motion) private readonly motions: Repository<Motion>,
+    @InjectRepository(Song) private readonly songs: Repository<Song>,
+    private readonly storage: StorageService,
+    private readonly preprocess: PreprocessService,
+  ) {}
+
+  async list(query: QueryMotionDto): Promise<Paged<MotionDto>> {
+    const qb = this.motions.createQueryBuilder('m').orderBy('m.id', 'DESC');
+    if (query.status) qb.andWhere('m.status = :status', { status: query.status });
+    if (query.format) qb.andWhere('m.format = :format', { format: query.format });
+    if (query.songId) qb.andWhere('m.song_id = :songId', { songId: query.songId });
+    if (query.q) {
+      const pattern = `%${query.q.replace(/[\\%_]/g, (ch) => `\\${ch}`)}%`;
+      qb.andWhere(
+        new Brackets((w) => {
+          w.where('m.name LIKE :pattern', { pattern }).orWhere('m.author LIKE :pattern', { pattern });
+        }),
+      );
+    }
+
+    const [rows, total] = await qb.skip(query.skip).take(query.pageSize).getManyAndCount();
+    return toPaged(await this.toDtos(rows), total, query);
+  }
+
+  async findOne(id: number): Promise<MotionDto> {
+    const motion = await this.getEntity(id);
+    const [dto] = await this.toDtos([motion]);
+    return dto;
+  }
+
+  async getEntity(id: number): Promise<Motion> {
+    const motion = await this.motions.findOne({ where: { id } });
+    if (!motion) throw new NotFoundException(`动作 #${id} 不存在`);
+    return motion;
+  }
+
+  /**
+   * 上传动作文件 + 来源字段。
+   * multipart 的字段均为字符串，这里显式解析并强制来源五元组齐备。
+   */
+  async create(body: Record<string, unknown>, file: UploadedFileLike | undefined): Promise<MotionDto> {
+    const upload = requireUploadedFile(file);
+
+    const name = typeof body.name === 'string' ? body.name.trim() : '';
+    if (!name) throw new BadRequestException('name 不能为空');
+    if (name.length > 200) throw new BadRequestException('name 长度不能超过 200');
+
+    const { format } = resolveFormatByExtension(upload.originalname, MOTION_EXTENSION_MAP, '动作文件');
+
+    const tuple = assertSourceTupleComplete({
+      sourceType: body.sourceType as SourceTuple['sourceType'],
+      sourceName: body.sourceName as string,
+      sourceUrl: body.sourceUrl as string,
+      license: body.license as string,
+      author: body.author as string,
+    });
+    if (!tuple) {
+      throw new BadRequestException('上传动作必须填写完整的来源信息（sourceType/sourceName/sourceUrl/license/author）');
+    }
+
+    const songId = parseOptionalInt(body.songId, 'songId') ?? null;
+    if (songId !== null) await this.assertSongExists(songId);
+
+    const stored = await this.storage.persistTempFile(
+      AssetKind.Motion,
+      upload.path,
+      upload.originalname,
+      upload.mimetype,
+    );
+
+    const motion = this.motions.create({
+      songId,
+      name,
+      format: format as MotionFormat,
+      fileAssetId: stored.asset.id,
+      fps: parseOptionalNumber(body.fps, 'fps') ?? null,
+      sourceType: tuple.sourceType as Motion['sourceType'],
+      sourceName: tuple.sourceName,
+      sourceUrl: tuple.sourceUrl,
+      license: tuple.license,
+      author: tuple.author,
+      status: this.parseStatus(body.status),
+    });
+
+    const saved = await this.motions.save(motion);
+
+    if (parseOptionalBool(body.autoPreprocess)) {
+      // 预处理失败不阻塞上传：失败原因已写入 motion.preprocessError
+      try {
+        const refreshed = await this.getEntity(saved.id);
+        await this.preprocess.run(refreshed);
+      } catch {
+        /* 已记录在 preprocessError */
+      }
+    }
+
+    const final = await this.getEntity(saved.id);
+    const [dto] = await this.toDtos([final]);
+    return dto;
+  }
+
+  async update(id: number, dto: UpdateMotionDto): Promise<MotionDto> {
+    const motion = await this.getEntity(id);
+
+    if (dto.status && dto.status !== motion.status && !canTransition(motion.status, dto.status)) {
+      throw new ConflictException(
+        `状态不允许从 ${motion.status} 直接变更为 ${dto.status}，请使用 /api/reviews 接口`,
+      );
+    }
+
+    const tuple = assertSourceTupleComplete({
+      sourceType: dto.sourceType,
+      sourceName: dto.sourceName,
+      sourceUrl: dto.sourceUrl,
+      license: dto.license,
+      author: dto.author,
+    });
+    if (tuple) Object.assign(motion, tuple);
+
+    if (dto.name !== undefined) motion.name = dto.name.trim();
+    if (dto.fps !== undefined) motion.fps = dto.fps;
+    if (dto.status !== undefined) motion.status = dto.status;
+    if (dto.detachSong) {
+      motion.songId = null;
+    } else if (dto.songId !== undefined) {
+      await this.assertSongExists(dto.songId);
+      motion.songId = dto.songId;
+    }
+
+    const saved = await this.motions.save(motion);
+    const [result] = await this.toDtos([saved]);
+    return result;
+  }
+
+  async remove(id: number): Promise<void> {
+    const motion = await this.getEntity(id);
+    await this.motions.softRemove(motion);
+  }
+
+  /** T-WEB-006：触发预处理 */
+  async runPreprocess(id: number): Promise<MotionDto> {
+    const motion = await this.getEntity(id);
+    const saved = await this.preprocess.run(motion);
+    const [dto] = await this.toDtos([saved]);
+    return dto;
+  }
+
+  async keypointsNdjson(id: number): Promise<string> {
+    const motion = await this.getEntity(id);
+    return this.preprocess.readKeypointsNdjson(motion);
+  }
+
+  /** 已发布动作的关键点序列（供 catalog 使用） */
+  async keypointTextFor(motion: Motion): Promise<string | null> {
+    try {
+      return await this.preprocess.readKeypointsNdjson(motion);
+    } catch {
+      return null;
+    }
+  }
+
+  private parseStatus(value: unknown): PublishStatus {
+    if (typeof value !== 'string' || value === '') return PublishStatus.Draft;
+    if (!Object.values(PublishStatus).includes(value as PublishStatus)) {
+      throw new BadRequestException(`status 非法：${value}`);
+    }
+    return value as PublishStatus;
+  }
+
+  private async assertSongExists(songId: number): Promise<void> {
+    const exists = await this.songs.exist({ where: { id: songId } });
+    if (!exists) throw new BadRequestException(`关联曲目 #${songId} 不存在`);
+  }
+
+  async toDtos(rows: Motion[]): Promise<MotionDto[]> {
+    const assets = await this.storage.findMany(
+      rows.flatMap((row) => [row.fileAssetId, row.keypointAssetId]),
+    );
+    return rows.map((row) => {
+      const file = row.fileAssetId ? assets.get(row.fileAssetId) : undefined;
+      const keypoints = row.keypointAssetId ? assets.get(row.keypointAssetId) : undefined;
+      return toMotionDto(row, {
+        fileUrl: file ? this.storage.url(file) : null,
+        keypointUrl: keypoints ? this.storage.url(keypoints) : null,
+        fileSize: file?.size ?? null,
+      });
+    });
+  }
+}