Agent skill
ddd-feature
Use when creating new domain features or adding new business capabilities. Triggers on requests to "create feature", "add new domain", "new module", "scaffold feature", or when implementing complete business features.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/ddd-feature
SKILL.md
DDD Feature Creation Guide
Create new domain features following the project's Domain-Driven Design structure.
Domain Structure
src/app/
<domain>/ # Business domain (tasks, user, order, etc.)
feature/ # Feature/container components
<feature-name>/
<feature-name>.ts
<feature-name>.html
<feature-name>.scss
<feature-name>.spec.ts
ui/ # Presentational components
<component-name>/
<component-name>.ts
...
data/ # Data access layer
models/
<domain>.model.ts # Domain models/interfaces
infrastructure/
<domain>.ts # API service
state/
<domain>-store.ts # NgRx Signals Store
util/ # Domain utilities
<util-name>/
<util-name>.ts
Step-by-Step Feature Creation
1. Create Domain Model
src/app/tasks/data/models/task.model.ts:
export interface Task {
id: string;
title: string;
description: string;
completed: boolean;
priority: "low" | "medium" | "high";
dueDate: string | null;
createdAt: string;
updatedAt: string;
}
export type CreateTaskDto = Omit<Task, "id" | "createdAt" | "updatedAt">;
export type UpdateTaskDto = Partial<CreateTaskDto>;
2. Create Infrastructure Service
src/app/tasks/data/infrastructure/task.ts:
import { inject, Injectable } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { Observable } from "rxjs";
import { Task, CreateTaskDto, UpdateTaskDto } from "../models/task.model";
@Injectable({ providedIn: "root" })
export class TaskInfrastructure {
private readonly http = inject(HttpClient);
private readonly baseUrl = "http://localhost:3000/tasks";
getTasks(): Observable<Task[]> {
return this.http.get<Task[]>(this.baseUrl);
}
getTaskById(id: string): Observable<Task> {
return this.http.get<Task>(`${this.baseUrl}/${id}`);
}
createTask(task: CreateTaskDto): Observable<Task> {
return this.http.post<Task>(this.baseUrl, task);
}
updateTask(id: string, changes: UpdateTaskDto): Observable<Task> {
return this.http.patch<Task>(`${this.baseUrl}/${id}`, changes);
}
deleteTask(id: string): Observable<void> {
return this.http.delete<void>(`${this.baseUrl}/${id}`);
}
}
3. Create Signal Store
src/app/tasks/data/state/task-store.ts:
import { computed, inject } from "@angular/core";
import {
signalStore,
withState,
withComputed,
withMethods,
patchState,
type,
} from "@ngrx/signals";
import {
withEntities,
entityConfig,
addEntity,
updateEntity,
removeEntity,
setAllEntities,
} from "@ngrx/signals/entities";
import { rxMethod } from "@ngrx/signals/rxjs-interop";
import { tapResponse } from "@ngrx/operators";
import { pipe, switchMap } from "rxjs";
import { TaskInfrastructure } from "../infrastructure/task";
import { Task, CreateTaskDto, UpdateTaskDto } from "../models/task.model";
export interface TaskState {
selectedTaskId: string | null;
loading: boolean;
error: string | null;
}
const initialState: TaskState = {
selectedTaskId: null,
loading: false,
error: null,
};
const taskEntityConfig = entityConfig({
entity: type<Task>(),
collection: "tasks",
selectId: (task: Task) => task.id,
});
export const TaskStore = signalStore(
{ providedIn: "root" },
withState(initialState),
withEntities(taskEntityConfig),
withComputed(({ tasksEntities, tasksEntityMap, selectedTaskId }) => ({
selectedTask: computed(() => {
const id = selectedTaskId();
return id ? tasksEntityMap()[id] : undefined;
}),
taskCount: computed(() => tasksEntities().length),
})),
withMethods((store, taskService = inject(TaskInfrastructure)) => ({
selectTask(id: string | null): void {
patchState(store, { selectedTaskId: id });
},
loadTasks: rxMethod<void>(
pipe(
switchMap(() => {
patchState(store, { loading: true, error: null });
return taskService.getTasks().pipe(
tapResponse({
next: (tasks) =>
patchState(store, setAllEntities(tasks, taskEntityConfig), {
loading: false,
}),
error: (error: Error) =>
patchState(store, {
loading: false,
error: error.message,
}),
}),
);
}),
),
),
createTask: rxMethod<CreateTaskDto>(
pipe(
switchMap((dto) => {
patchState(store, { loading: true });
return taskService.createTask(dto).pipe(
tapResponse({
next: (task) =>
patchState(store, addEntity(task, taskEntityConfig), {
loading: false,
}),
error: () => patchState(store, { loading: false }),
}),
);
}),
),
),
updateTask: rxMethod<{ id: string; changes: UpdateTaskDto }>(
pipe(
switchMap(({ id, changes }) => {
return taskService.updateTask(id, changes).pipe(
tapResponse({
next: (task) =>
patchState(
store,
updateEntity({ id, changes: task }, taskEntityConfig),
),
error: () => console.error("Update failed"),
}),
);
}),
),
),
deleteTask: rxMethod<string>(
pipe(
switchMap((id) => {
return taskService.deleteTask(id).pipe(
tapResponse({
next: () => patchState(store, removeEntity(id, taskEntityConfig)),
error: () => console.error("Delete failed"),
}),
);
}),
),
),
})),
);
4. Create UI Component (Presentational)
src/app/tasks/ui/task-item/task-item.ts:
import {
ChangeDetectionStrategy,
Component,
input,
output,
} from "@angular/core";
import { MatCardModule } from "@angular/material/card";
import { MatCheckboxModule } from "@angular/material/checkbox";
import { MatIconModule } from "@angular/material/icon";
import { MatButtonModule } from "@angular/material/button";
import { Task } from "../../data/models/task.model";
@Component({
selector: "app-task-item",
templateUrl: "./task-item.html",
styleUrl: "./task-item.scss",
changeDetection: ChangeDetectionStrategy.OnPush,
imports: [MatCardModule, MatCheckboxModule, MatIconModule, MatButtonModule],
})
export class TaskItem {
readonly task = input.required<Task>();
readonly toggle = output<boolean>();
readonly delete = output<void>();
readonly edit = output<void>();
onToggle(completed: boolean): void {
this.toggle.emit(completed);
}
onDelete(): void {
this.delete.emit();
}
onEdit(): void {
this.edit.emit();
}
}
5. Create Feature Component (Container)
src/app/tasks/feature/task-list/task-list.ts:
import {
ChangeDetectionStrategy,
Component,
inject,
OnInit,
} from "@angular/core";
import { MatProgressSpinnerModule } from "@angular/material/progress-spinner";
import { TaskStore } from "../../data/state/task-store";
import { TaskItemComponent } from "../../ui/task-item/task-item";
@Component({
selector: "app-task-list",
templateUrl: "./task-list.html",
styleUrl: "./task-list.scss",
changeDetection: ChangeDetectionStrategy.OnPush,
imports: [MatProgressSpinnerModule, TaskItem],
})
export class TaskList implements OnInit {
readonly taskStore = inject(TaskStore);
ngOnInit(): void {
this.taskStore.loadTasks();
}
onToggleTask(taskId: string, completed: boolean): void {
this.taskStore.updateTask({ id: taskId, changes: { completed } });
}
onDeleteTask(taskId: string): void {
this.taskStore.deleteTask(taskId);
}
}
6. Create Routes
src/app/tasks/feature/tasks.routes.ts:
import { Routes } from "@angular/router";
export const TASK_ROUTES: Routes = [
{
path: "",
loadComponent: () =>
import("./task-list/task-list").then((m) => m.TaskListComponent),
},
{
path: ":id",
loadComponent: () =>
import("./task-detail/task-detail").then((m) => m.TaskDetailComponent),
},
];
Important Rules
- No Barrel Files: Do NOT create
index.tsfiles for re-exporting - Component Subfolders: Each component MUST be in its own subfolder
- Separation of Concerns:
feature/= Container components (smart, connected to store)ui/= Presentational components (dumb, input/output only)data/= State, models, and API services
- Naming Conventions:
- Files:
kebab-case.ts(e.g.,task-list.ts) - no type suffix - Stores:
kebab-case-store.ts(e.g.,task-store.ts) - dash separator - Classes:
PascalCase(e.g.,TaskListComponent) - Models:
kebab-case.model.ts(e.g.,task.model.ts) - keep .model suffix
- Files:
Checklist for New Feature
- Domain model created in
data/models/ - Infrastructure service created in
data/infrastructure/ - Signal store created in
data/state/ - UI components created in
ui/(each in own subfolder) - Feature components created in
feature/(each in own subfolder) - Routes defined with lazy loading
- All components using OnPush change detection
- Tests created for components, store, and service
- No barrel files (index.ts) created
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