Service & Business Logic Architecture

TaskFlow Phase 14 reference snapshot

This snapshot contains only the files changed or emphasized by Phase 14. It assumes the completed Phase 13 project already exists.

Core rules demonstrated:
- Controllers remain thin and delegate use cases to TasksService.
- TasksService owns Task business invariants.
- Task status changes follow an explicit transition policy.
- completedAt is synchronized with DONE/reopen transitions.
- A Task assignee must be a member of the Task Project's Workspace.
- New due dates cannot be in the past (course policy for this application).
- A transaction is used for the explicit assignment workflow because the operation reads membership context and then writes the assignment as one use case.
- We do not introduce Repository Pattern yet; PrismaService remains the persistence boundary for this phase.

import {
  BadRequestException,
  ConflictException,
  NotFoundException,
} from "@nestjs/common";

export class TaskNotFoundException extends NotFoundException {
  constructor(taskId: string) {
    super({
      code: "TASK_NOT_FOUND",
      message: `Task ${taskId} was not found.`,
    });
  }
}

export class ProjectNotFoundException extends NotFoundException {
  constructor(projectId: string) {
    super({
      code: "PROJECT_NOT_FOUND",
      message: `Project ${projectId} was not found.`,

import {
  Body,
  Controller,
  Delete,
  Get,
  HttpCode,
  HttpStatus,
  Param,
  Patch,
  Post,
} from "@nestjs/common";
import { StandardSchemaValidationPipe } from "@nestjs/common";
import { z } from "zod";
import { TasksService } from "./tasks.service";
import {
  createTaskSchema,
  taskIdSchema,
  updateTaskSchema,
} from "./tasks.schemas";

import { z } from "zod";
import {
  TaskPriority,
  TaskStatus,
} from "../generated/prisma/client";

const taskTitleSchema = z.string().trim().min(1).max(200);
const taskDescriptionSchema = z.string().trim().max(2000).nullable();

export const taskIdSchema = z.uuid();

export const createTaskSchema = z.strictObject({
  projectId: z.uuid(),
  title: taskTitleSchema,
  description: taskDescriptionSchema.optional(),
  assigneeId: z.uuid().nullable().optional(),
  priority: z.enum(TaskPriority).optional(),
  dueAt: z.iso.datetime({ offset: true }).nullable().optional(),
});

import { Injectable } from "@nestjs/common";
import {
  Prisma,
  TaskStatus,
} from "../generated/prisma/client";
import { PrismaService } from "../prisma/prisma.service";
import {
  AssigneeNotWorkspaceMemberException,
  DueDateInPastException,
  ProjectNotFoundException,
  TaskNotFoundException,
  TaskStatusTransitionException,
} from "../common/errors/application.exceptions";
import {
  CreateTaskDto,
  UpdateTaskDto,
} from "./tasks.schemas";

const ALLOWED_STATUS_TRANSITIONS: Record<TaskStatus, readonly TaskStatus[]> = {
  TODO: [TaskStatus.IN_PROGRESS, TaskStatus.CANCELED],

# Phase 14 business-rule smoke checks.
# Replace placeholders with IDs from your development seed/database.

$api = "http://127.0.0.1:4000"
$taskId = "<TASK_UUID>"
$workspaceMemberUserId = "<MEMBER_USER_UUID>"
$nonMemberUserId = "<NON_MEMBER_USER_UUID>"

# Allowed transition: TODO -> IN_PROGRESS
Invoke-RestMethod -Method Patch `
  -Uri "$api/tasks/$taskId" `
  -ContentType "application/json" `
  -Body '{"status":"IN_PROGRESS"}'

# Allowed transition: IN_PROGRESS -> DONE. completedAt should be populated.
Invoke-RestMethod -Method Patch `
  -Uri "$api/tasks/$taskId" `
  -ContentType "application/json" `
  -Body '{"status":"DONE"}'