diff --git a/apps/api/src/app.module.ts b/apps/api/src/app.module.ts
index 8cd6181..bbf571a 100644
--- a/apps/api/src/app.module.ts
+++ b/apps/api/src/app.module.ts
@@ -1,6 +1,8 @@
 import { Module } from "@nestjs/common";
 import { ConfigModule } from "@nestjs/config";
 import { AuthModule } from "./auth/auth.module";
+import { PrismaModule } from "./prisma/prisma.module";
+import { TaskModule } from "./task/task.module";
 
 @Module({
   imports: [
@@ -8,7 +10,9 @@ import { AuthModule } from "./auth/auth.module";
       isGlobal: true,
       envFilePath: ".env"
     }),
-    AuthModule
+    PrismaModule,
+    AuthModule,
+    TaskModule
   ]
 })
 export class AppModule {}
diff --git a/apps/api/src/prisma/prisma.module.ts b/apps/api/src/prisma/prisma.module.ts
new file mode 100644
index 0000000..7a94e73
--- /dev/null
+++ b/apps/api/src/prisma/prisma.module.ts
@@ -0,0 +1,9 @@
+import { Global, Module } from "@nestjs/common";
+import { PrismaService } from "./prisma.service";
+
+@Global()
+@Module({
+  providers: [PrismaService],
+  exports: [PrismaService]
+})
+export class PrismaModule {}
diff --git a/apps/api/src/prisma/prisma.service.ts b/apps/api/src/prisma/prisma.service.ts
new file mode 100644
index 0000000..72e40f6
--- /dev/null
+++ b/apps/api/src/prisma/prisma.service.ts
@@ -0,0 +1,13 @@
+import { Injectable, OnModuleDestroy, OnModuleInit } from "@nestjs/common";
+import { PrismaClient } from "../../generated/prisma/client";
+
+@Injectable()
+export class PrismaService extends PrismaClient implements OnModuleInit, OnModuleDestroy {
+  async onModuleInit(): Promise<void> {
+    await this.$connect();
+  }
+
+  async onModuleDestroy(): Promise<void> {
+    await this.$disconnect();
+  }
+}
diff --git a/apps/api/src/task/dto/create-task.dto.ts b/apps/api/src/task/dto/create-task.dto.ts
new file mode 100644
index 0000000..69c2000
--- /dev/null
+++ b/apps/api/src/task/dto/create-task.dto.ts
@@ -0,0 +1,64 @@
+import { Transform } from "class-transformer";
+import {
+  IsArray,
+  IsDateString,
+  IsEnum,
+  IsObject,
+  IsOptional,
+  IsString,
+  MaxLength,
+  MinLength
+} from "class-validator";
+import { TaskPriority, TaskStatus } from "../../../generated/prisma/client";
+
+function normalizeString(value: unknown): unknown {
+  if (typeof value !== "string") {
+    return value;
+  }
+
+  return value.trim();
+}
+
+export class CreateTaskDto {
+  @Transform(({ value }) => normalizeString(value))
+  @IsString()
+  @MinLength(1)
+  @MaxLength(120)
+  title!: string;
+
+  @IsOptional()
+  @IsObject()
+  contentJson?: Record<string, unknown>;
+
+  @Transform(({ value }) => normalizeString(value))
+  @IsOptional()
+  @IsString()
+  @MaxLength(20000)
+  contentText?: string;
+
+  @IsOptional()
+  @IsEnum(TaskPriority)
+  priority?: TaskPriority;
+
+  @IsOptional()
+  @IsEnum(TaskStatus)
+  status?: TaskStatus;
+
+  @IsOptional()
+  @IsDateString()
+  ddl?: string;
+
+  @Transform(({ value }) => {
+    if (!Array.isArray(value)) {
+      return value;
+    }
+
+    return value.map((item) => normalizeString(item));
+  })
+  @IsOptional()
+  @IsArray()
+  @IsString({ each: true })
+  @MinLength(1, { each: true })
+  @MaxLength(30, { each: true })
+  tagNames?: string[];
+}
diff --git a/apps/api/src/task/dto/list-tasks-query.dto.ts b/apps/api/src/task/dto/list-tasks-query.dto.ts
new file mode 100644
index 0000000..baa5afb
--- /dev/null
+++ b/apps/api/src/task/dto/list-tasks-query.dto.ts
@@ -0,0 +1,92 @@
+import { Transform, Type } from "class-transformer";
+import { IsArray, IsEnum, IsInt, IsOptional, IsString, Max, MaxLength, Min } from "class-validator";
+import { TaskPriority, TaskStatus } from "../../../generated/prisma/client";
+
+export enum TaskSortBy {
+  CREATED_AT = "createdAt",
+  UPDATED_AT = "updatedAt",
+  DDL = "ddl"
+}
+
+export enum TaskSortOrder {
+  ASC = "asc",
+  DESC = "desc"
+}
+
+function normalizeString(value: unknown): string | undefined {
+  if (typeof value !== "string") {
+    return undefined;
+  }
+
+  const normalized = value.trim();
+  if (!normalized) {
+    return undefined;
+  }
+
+  return normalized;
+}
+
+export class ListTasksQueryDto {
+  @IsOptional()
+  @IsEnum(TaskStatus)
+  status?: TaskStatus;
+
+  @IsOptional()
+  @IsEnum(TaskPriority)
+  priority?: TaskPriority;
+
+  @Transform(({ value }) => {
+    if (value === undefined || value === null || value === "") {
+      return undefined;
+    }
+
+    if (Array.isArray(value)) {
+      const normalized = value
+        .map((item) => normalizeString(item))
+        .filter((item): item is string => item !== undefined);
+      return normalized.length > 0 ? normalized : undefined;
+    }
+
+    if (typeof value === "string") {
+      const normalized = value
+        .split(",")
+        .map((item) => normalizeString(item))
+        .filter((item): item is string => item !== undefined);
+      return normalized.length > 0 ? normalized : undefined;
+    }
+
+    return undefined;
+  })
+  @IsOptional()
+  @IsArray()
+  @IsString({ each: true })
+  @MaxLength(30, { each: true })
+  tags?: string[];
+
+  @Transform(({ value }) => normalizeString(value))
+  @IsOptional()
+  @IsString()
+  @MaxLength(120)
+  keyword?: string;
+
+  @Type(() => Number)
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  page?: number;
+
+  @Type(() => Number)
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  @Max(100)
+  pageSize?: number;
+
+  @IsOptional()
+  @IsEnum(TaskSortBy)
+  sortBy?: TaskSortBy;
+
+  @IsOptional()
+  @IsEnum(TaskSortOrder)
+  sortOrder?: TaskSortOrder;
+}
diff --git a/apps/api/src/task/dto/update-task.dto.ts b/apps/api/src/task/dto/update-task.dto.ts
new file mode 100644
index 0000000..23b8894
--- /dev/null
+++ b/apps/api/src/task/dto/update-task.dto.ts
@@ -0,0 +1,65 @@
+import { Transform } from "class-transformer";
+import {
+  IsArray,
+  IsDateString,
+  IsEnum,
+  IsObject,
+  IsOptional,
+  IsString,
+  MaxLength,
+  MinLength
+} from "class-validator";
+import { TaskPriority, TaskStatus } from "../../../generated/prisma/client";
+
+function normalizeString(value: unknown): unknown {
+  if (typeof value !== "string") {
+    return value;
+  }
+
+  return value.trim();
+}
+
+export class UpdateTaskDto {
+  @Transform(({ value }) => normalizeString(value))
+  @IsOptional()
+  @IsString()
+  @MinLength(1)
+  @MaxLength(120)
+  title?: string;
+
+  @IsOptional()
+  @IsObject()
+  contentJson?: Record<string, unknown>;
+
+  @Transform(({ value }) => normalizeString(value))
+  @IsOptional()
+  @IsString()
+  @MaxLength(20000)
+  contentText?: string;
+
+  @IsOptional()
+  @IsEnum(TaskPriority)
+  priority?: TaskPriority;
+
+  @IsOptional()
+  @IsEnum(TaskStatus)
+  status?: TaskStatus;
+
+  @IsOptional()
+  @IsDateString()
+  ddl?: string;
+
+  @Transform(({ value }) => {
+    if (!Array.isArray(value)) {
+      return value;
+    }
+
+    return value.map((item) => normalizeString(item));
+  })
+  @IsOptional()
+  @IsArray()
+  @IsString({ each: true })
+  @MinLength(1, { each: true })
+  @MaxLength(30, { each: true })
+  tagNames?: string[];
+}
diff --git a/apps/api/src/task/task.controller.ts b/apps/api/src/task/task.controller.ts
new file mode 100644
index 0000000..33b9710
--- /dev/null
+++ b/apps/api/src/task/task.controller.ts
@@ -0,0 +1,71 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  Headers,
+  Param,
+  Patch,
+  Post,
+  Query,
+  UnauthorizedException
+} from "@nestjs/common";
+import { CreateTaskDto } from "./dto/create-task.dto";
+import { ListTasksQueryDto } from "./dto/list-tasks-query.dto";
+import { UpdateTaskDto } from "./dto/update-task.dto";
+import { ListTasksResponse, TaskResponse, TaskService } from "./task.service";
+
+@Controller("tasks")
+export class TaskController {
+  constructor(private readonly taskService: TaskService) {}
+
+  @Get()
+  async listTasks(
+    @Headers("x-user-id") userIdHeader: string | string[] | undefined,
+    @Query() query: ListTasksQueryDto
+  ): Promise<ListTasksResponse> {
+    return this.taskService.listTasks(this.resolveUserId(userIdHeader), query);
+  }
+
+  @Get(":taskId")
+  async getTaskById(
+    @Headers("x-user-id") userIdHeader: string | string[] | undefined,
+    @Param("taskId") taskId: string
+  ): Promise<TaskResponse> {
+    return this.taskService.getTaskById(this.resolveUserId(userIdHeader), taskId);
+  }
+
+  @Post()
+  async createTask(
+    @Headers("x-user-id") userIdHeader: string | string[] | undefined,
+    @Body() body: CreateTaskDto
+  ): Promise<TaskResponse> {
+    return this.taskService.createTask(this.resolveUserId(userIdHeader), body);
+  }
+
+  @Patch(":taskId")
+  async updateTask(
+    @Headers("x-user-id") userIdHeader: string | string[] | undefined,
+    @Param("taskId") taskId: string,
+    @Body() body: UpdateTaskDto
+  ): Promise<TaskResponse> {
+    return this.taskService.updateTask(this.resolveUserId(userIdHeader), taskId, body);
+  }
+
+  @Delete(":taskId")
+  async deleteTask(
+    @Headers("x-user-id") userIdHeader: string | string[] | undefined,
+    @Param("taskId") taskId: string
+  ): Promise<{ success: boolean }> {
+    return this.taskService.deleteTask(this.resolveUserId(userIdHeader), taskId);
+  }
+
+  private resolveUserId(userIdHeader: string | string[] | undefined): string {
+    const userId = Array.isArray(userIdHeader) ? userIdHeader[0] : userIdHeader;
+    if (!userId) {
+      throw new UnauthorizedException("缺少用户上下文");
+    }
+
+    return userId;
+  }
+}
diff --git a/apps/api/src/task/task.module.ts b/apps/api/src/task/task.module.ts
new file mode 100644
index 0000000..8226093
--- /dev/null
+++ b/apps/api/src/task/task.module.ts
@@ -0,0 +1,11 @@
+import { Module } from "@nestjs/common";
+import { PrismaModule } from "../prisma/prisma.module";
+import { TaskController } from "./task.controller";
+import { TaskService } from "./task.service";
+
+@Module({
+  imports: [PrismaModule],
+  controllers: [TaskController],
+  providers: [TaskService]
+})
+export class TaskModule {}
diff --git a/apps/api/src/task/task.service.ts b/apps/api/src/task/task.service.ts
new file mode 100644
index 0000000..3f62dea
--- /dev/null
+++ b/apps/api/src/task/task.service.ts
@@ -0,0 +1,390 @@
+import { Injectable, NotFoundException } from "@nestjs/common";
+import { Prisma, TaskPriority, TaskStatus } from "../../generated/prisma/client";
+import { PrismaService } from "../prisma/prisma.service";
+import { CreateTaskDto } from "./dto/create-task.dto";
+import { ListTasksQueryDto, TaskSortBy, TaskSortOrder } from "./dto/list-tasks-query.dto";
+import { UpdateTaskDto } from "./dto/update-task.dto";
+
+type TaskEntity = Prisma.TaskGetPayload<{
+  include: {
+    taskTags: {
+      include: {
+        tag: {
+          select: {
+            name: true;
+          };
+        };
+      };
+    };
+  };
+}>;
+
+export type TaskResponse = {
+  id: string;
+  title: string;
+  contentJson: unknown | null;
+  contentText: string | null;
+  priority: TaskPriority;
+  status: TaskStatus;
+  ddl: string | null;
+  completedAt: string | null;
+  version: number;
+  tags: string[];
+  createdAt: string;
+  updatedAt: string;
+};
+
+export type ListTasksResponse = {
+  items: TaskResponse[];
+  page: number;
+  pageSize: number;
+  total: number;
+};
+
+@Injectable()
+export class TaskService {
+  constructor(private readonly prismaService: PrismaService) {}
+
+  async listTasks(userId: string, query: ListTasksQueryDto): Promise<ListTasksResponse> {
+    const page = query.page ?? 1;
+    const pageSize = query.pageSize ?? 20;
+    const skip = (page - 1) * pageSize;
+
+    const where = this.buildWhereInput(userId, query);
+    const orderBy = this.buildOrderByInput(query);
+
+    const [items, total] = await Promise.all([
+      this.prismaService.task.findMany({
+        where,
+        orderBy,
+        skip,
+        take: pageSize,
+        include: {
+          taskTags: {
+            include: {
+              tag: {
+                select: {
+                  name: true
+                }
+              }
+            }
+          }
+        }
+      }),
+      this.prismaService.task.count({ where })
+    ]);
+
+    return {
+      items: items.map((item) => this.serializeTask(item)),
+      page,
+      pageSize,
+      total
+    };
+  }
+
+  async getTaskById(userId: string, taskId: string): Promise<TaskResponse> {
+    const task = await this.prismaService.task.findFirst({
+      where: {
+        id: taskId,
+        userId
+      },
+      include: {
+        taskTags: {
+          include: {
+            tag: {
+              select: {
+                name: true
+              }
+            }
+          }
+        }
+      }
+    });
+
+    if (!task) {
+      throw new NotFoundException("任务不存在");
+    }
+
+    return this.serializeTask(task);
+  }
+
+  async createTask(userId: string, body: CreateTaskDto): Promise<TaskResponse> {
+    const tagNames = this.normalizeTagNames(body.tagNames);
+    const nextStatus = body.status ?? TaskStatus.TODO;
+    const contentJson =
+      body.contentJson !== undefined ? (body.contentJson as Prisma.InputJsonValue) : undefined;
+
+    const task = await this.prismaService.$transaction(async (tx) => {
+      const createdTask = await tx.task.create({
+        data: {
+          userId,
+          title: body.title,
+          contentJson,
+          contentText: body.contentText ?? null,
+          priority: body.priority ?? TaskPriority.MEDIUM,
+          status: nextStatus,
+          ddl: body.ddl ? new Date(body.ddl) : null,
+          completedAt: nextStatus === TaskStatus.DONE ? new Date() : null
+        }
+      });
+
+      await this.replaceTaskTags(tx, userId, createdTask.id, tagNames);
+
+      return tx.task.findUniqueOrThrow({
+        where: { id: createdTask.id },
+        include: {
+          taskTags: {
+            include: {
+              tag: {
+                select: {
+                  name: true
+                }
+              }
+            }
+          }
+        }
+      });
+    });
+
+    return this.serializeTask(task);
+  }
+
+  async updateTask(userId: string, taskId: string, body: UpdateTaskDto): Promise<TaskResponse> {
+    const currentTask = await this.prismaService.task.findFirst({
+      where: {
+        id: taskId,
+        userId
+      },
+      select: {
+        id: true,
+        status: true
+      }
+    });
+
+    if (!currentTask) {
+      throw new NotFoundException("任务不存在");
+    }
+
+    const data: Prisma.TaskUpdateInput = {
+      version: {
+        increment: 1
+      }
+    };
+
+    if (body.title !== undefined) {
+      data.title = body.title;
+    }
+    if (body.contentJson !== undefined) {
+      data.contentJson = body.contentJson as Prisma.InputJsonValue;
+    }
+    if (body.contentText !== undefined) {
+      data.contentText = body.contentText;
+    }
+    if (body.priority !== undefined) {
+      data.priority = body.priority;
+    }
+    if (body.status !== undefined) {
+      data.status = body.status;
+      if (body.status === TaskStatus.DONE && currentTask.status !== TaskStatus.DONE) {
+        data.completedAt = new Date();
+      } else if (body.status !== TaskStatus.DONE) {
+        data.completedAt = null;
+      }
+    }
+    if (body.ddl !== undefined) {
+      data.ddl = body.ddl ? new Date(body.ddl) : null;
+    }
+
+    const shouldReplaceTags = body.tagNames !== undefined;
+    const nextTagNames = this.normalizeTagNames(body.tagNames);
+
+    const task = await this.prismaService.$transaction(async (tx) => {
+      await tx.task.update({
+        where: { id: taskId },
+        data
+      });
+
+      if (shouldReplaceTags) {
+        await this.replaceTaskTags(tx, userId, taskId, nextTagNames);
+      }
+
+      return tx.task.findUniqueOrThrow({
+        where: { id: taskId },
+        include: {
+          taskTags: {
+            include: {
+              tag: {
+                select: {
+                  name: true
+                }
+              }
+            }
+          }
+        }
+      });
+    });
+
+    return this.serializeTask(task);
+  }
+
+  async deleteTask(userId: string, taskId: string): Promise<{ success: boolean }> {
+    const deleted = await this.prismaService.task.deleteMany({
+      where: {
+        id: taskId,
+        userId
+      }
+    });
+
+    if (deleted.count === 0) {
+      throw new NotFoundException("任务不存在");
+    }
+
+    return { success: true };
+  }
+
+  private buildWhereInput(userId: string, query: ListTasksQueryDto): Prisma.TaskWhereInput {
+    const where: Prisma.TaskWhereInput = {
+      userId
+    };
+
+    if (query.status !== undefined) {
+      where.status = query.status;
+    }
+
+    if (query.priority !== undefined) {
+      where.priority = query.priority;
+    }
+
+    if (query.tags !== undefined && query.tags.length > 0) {
+      where.taskTags = {
+        some: {
+          tag: {
+            name: {
+              in: query.tags
+            }
+          }
+        }
+      };
+    }
+
+    if (query.keyword !== undefined && query.keyword.length > 0) {
+      where.OR = [
+        {
+          title: {
+            contains: query.keyword,
+            mode: "insensitive"
+          }
+        },
+        {
+          contentText: {
+            contains: query.keyword,
+            mode: "insensitive"
+          }
+        }
+      ];
+    }
+
+    return where;
+  }
+
+  private buildOrderByInput(query: ListTasksQueryDto): Prisma.TaskOrderByWithRelationInput {
+    const order: Prisma.SortOrder =
+      query.sortOrder === TaskSortOrder.ASC ? Prisma.SortOrder.asc : Prisma.SortOrder.desc;
+
+    if (query.sortBy === TaskSortBy.CREATED_AT) {
+      return { createdAt: order };
+    }
+
+    if (query.sortBy === TaskSortBy.DDL) {
+      return { ddl: order };
+    }
+
+    return { updatedAt: order };
+  }
+
+  private normalizeTagNames(tagNames: string[] | undefined): string[] {
+    if (!tagNames) {
+      return [];
+    }
+
+    const result: string[] = [];
+    const uniqueNames = new Set<string>();
+
+    for (const rawTagName of tagNames) {
+      const normalized = rawTagName.trim();
+      if (!normalized) {
+        continue;
+      }
+
+      const uniqueKey = normalized.toLocaleLowerCase();
+      if (uniqueNames.has(uniqueKey)) {
+        continue;
+      }
+
+      uniqueNames.add(uniqueKey);
+      result.push(normalized);
+    }
+
+    return result;
+  }
+
+  private async replaceTaskTags(
+    tx: Prisma.TransactionClient,
+    userId: string,
+    taskId: string,
+    tagNames: string[]
+  ): Promise<void> {
+    await tx.taskTag.deleteMany({
+      where: {
+        taskId
+      }
+    });
+
+    if (tagNames.length === 0) {
+      return;
+    }
+
+    const tags = await Promise.all(
+      tagNames.map((name) =>
+        tx.tag.upsert({
+          where: {
+            userId_name: {
+              userId,
+              name
+            }
+          },
+          update: {},
+          create: {
+            userId,
+            name
+          }
+        })
+      )
+    );
+
+    await tx.taskTag.createMany({
+      data: tags.map((tag) => ({
+        taskId,
+        tagId: tag.id
+      })),
+      skipDuplicates: true
+    });
+  }
+
+  private serializeTask(task: TaskEntity): TaskResponse {
+    return {
+      id: task.id,
+      title: task.title,
+      contentJson: task.contentJson,
+      contentText: task.contentText,
+      priority: task.priority,
+      status: task.status,
+      ddl: task.ddl?.toISOString() ?? null,
+      completedAt: task.completedAt?.toISOString() ?? null,
+      version: task.version,
+      tags: task.taskTags.map((taskTag) => taskTag.tag.name),
+      createdAt: task.createdAt.toISOString(),
+      updatedAt: task.updatedAt.toISOString()
+    };
+  }
+}
diff --git a/apps/api/tsconfig.json b/apps/api/tsconfig.json
index a6aded2..17d29bc 100644
--- a/apps/api/tsconfig.json
+++ b/apps/api/tsconfig.json
@@ -2,9 +2,9 @@
   "$schema": "https://json.schemastore.org/tsconfig",
   "extends": "../../packages/tsconfig/nest-app.json",
   "compilerOptions": {
-    "rootDir": "src",
+    "rootDir": ".",
     "outDir": "dist"
   },
-  "include": ["src/**/*.ts"],
+  "include": ["src/**/*.ts", "generated/prisma/**/*.ts"],
   "exclude": ["dist", "node_modules"]
 }