Creating Elysia Domains

This skill guides creation of new feature domains in the Nexus API following established patterns for type-safe API development.

Capabilities

Create domain directory structure
Define Drizzle database schemas
Create Elysia t.* types for API contracts
Implement repository and service layers
Build typed route handlers
Enable Eden Treaty type inference for consumers

Domain Structure

Create in apps/nexus/src/domains/<domain-name>/:

domains/<domain-name>/
├── schema.ts      # Drizzle table definitions
├── types.ts       # Elysia t.* types for API contracts
├── service.ts     # Business logic
├── repository.ts  # Database queries
├── routes.ts      # Elysia route handlers
└── index.ts       # Re-exports

File Templates

schema.ts

typescript

import { sqliteTable, text, integer } from "drizzle-orm/sqlite-core";

export const items = sqliteTable("items", {
  id: text("id").primaryKey(),
  name: text("name").notNull(),
  status: text("status", { enum: ["active", "inactive"] }).notNull().default("active"),
  createdAt: integer("created_at", { mode: "timestamp" }).notNull(),
  updatedAt: integer("updated_at", { mode: "timestamp" }).notNull(),
});

export type Item = typeof items.$inferSelect;
export type NewItem = typeof items.$inferInsert;

types.ts

typescript

import { t } from "elysia";

export const ItemParams = t.Object({
  id: t.String(),
});

export const CreateItemBody = t.Object({
  name: t.String({ minLength: 1 }),
  status: t.Optional(t.Union([t.Literal("active"), t.Literal("inactive")])),
});

export const UpdateItemBody = t.Object({
  name: t.Optional(t.String({ minLength: 1 })),
  status: t.Optional(t.Union([t.Literal("active"), t.Literal("inactive")])),
});

export const ItemResponse = t.Object({
  id: t.String(),
  name: t.String(),
  status: t.Union([t.Literal("active"), t.Literal("inactive")]),
  createdAt: t.String(),
  updatedAt: t.String(),
});

export const ItemListResponse = t.Array(ItemResponse);

repository.ts

typescript

import { eq } from "drizzle-orm";
import { db } from "../../infra/database";
import { items, type Item, type NewItem } from "./schema";

export const itemRepository = {
  async findAll(): Promise<Item[]> {
    return db.select().from(items);
  },

  async findById(id: string): Promise<Item | undefined> {
    const results = await db.select().from(items).where(eq(items.id, id));
    return results[0];
  },

  async create(data: NewItem): Promise<Item> {
    const results = await db.insert(items).values(data).returning();
    return results[0];
  },

  async update(id: string, data: Partial<NewItem>): Promise<Item | undefined> {
    const results = await db
      .update(items)
      .set({ ...data, updatedAt: new Date() })
      .where(eq(items.id, id))
      .returning();
    return results[0];
  },

  async delete(id: string): Promise<boolean> {
    const results = await db.delete(items).where(eq(items.id, id)).returning();
    return results.length > 0;
  },
};

service.ts

typescript

import { randomUUID } from "crypto";
import { itemRepository } from "./repository";
import type { Item } from "./schema";

export const itemService = {
  async list(): Promise<Item[]> {
    return itemRepository.findAll();
  },

  async get(id: string): Promise<Item | null> {
    return (await itemRepository.findById(id)) ?? null;
  },

  async create(data: { name: string; status?: "active" | "inactive" }): Promise<Item> {
    const now = new Date();
    return itemRepository.create({
      id: randomUUID(),
      name: data.name,
      status: data.status ?? "active",
      createdAt: now,
      updatedAt: now,
    });
  },

  async update(id: string, data: Partial<{ name: string; status: "active" | "inactive" }>): Promise<Item | null> {
    return (await itemRepository.update(id, data)) ?? null;
  },

  async delete(id: string): Promise<boolean> {
    return itemRepository.delete(id);
  },
};

routes.ts

typescript

import { Elysia } from "elysia";
import { itemService } from "./service";
import {
  ItemParams,
  CreateItemBody,
  UpdateItemBody,
  ItemResponse,
  ItemListResponse,
} from "./types";

const formatItem = (item: any) => ({
  ...item,
  createdAt: item.createdAt.toISOString(),
  updatedAt: item.updatedAt.toISOString(),
});

export const itemRoutes = new Elysia({ prefix: "/items" })
  .get("/", async () => {
    const items = await itemService.list();
    return items.map(formatItem);
  }, {
    response: ItemListResponse,
    detail: { tags: ["Items"], summary: "List all items" },
  })

  .get("/:id", async ({ params, error }) => {
    const item = await itemService.get(params.id);
    if (!item) return error(404, { message: "Item not found" });
    return formatItem(item);
  }, {
    params: ItemParams,
    response: ItemResponse,
  })

  .post("/", async ({ body }) => {
    const item = await itemService.create(body);
    return formatItem(item);
  }, {
    body: CreateItemBody,
    response: ItemResponse,
  })

  .patch("/:id", async ({ params, body, error }) => {
    const item = await itemService.update(params.id, body);
    if (!item) return error(404, { message: "Item not found" });
    return formatItem(item);
  }, {
    params: ItemParams,
    body: UpdateItemBody,
    response: ItemResponse,
  })

  .delete("/:id", async ({ params, error }) => {
    const deleted = await itemService.delete(params.id);
    if (!deleted) return error(404, { message: "Item not found" });
    return { success: true };
  }, {
    params: ItemParams,
  });

Registration

Add to apps/nexus/src/app.ts:

typescript

import { itemRoutes } from "./domains/items/routes";

const app = new Elysia()
  .use(itemRoutes)

Eden Treaty Usage

Dashboard (React)

typescript

import { treaty } from "@elysiajs/eden";
import type { App } from "@nexus/app";

const api = treaty<App>(import.meta.env.VITE_API_URL);

const { data: items } = await api.items.get();
const { data: item } = await api.items({ id: "123" }).get();
const { data: newItem } = await api.items.post({ name: "Test" });

The Machine (Discord Bot)

typescript

import { treaty } from "@elysiajs/eden";
import type { App } from "@nexus/app";

const api = treaty<App>(process.env.API_URL!);
const items = await api.items.get();

Critical Rules

Never duplicate types - Dashboard and The Machine import from Nexus via Eden Treaty
Use t.* types - Enables Eden type inference
Export App type - Required for consumers
Format dates as ISO strings - JSON serialization compatibility

Protected Routes

typescript

import { autheliaMiddleware } from "../../middleware/authelia";

export const protectedRoutes = new Elysia({ prefix: "/admin" })
  .use(autheliaMiddleware)
  .get("/dashboard", async ({ user }) => {
    return { message: `Hello ${user.name}` };
  });

Commands

bash

bun run db:push          # Push schema changes
bun run typecheck:api    # Verify types
bun run dev:api          # Start dev server

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creating-elysia-domains

Install this agent skill to your Project

SKILL.md

Creating Elysia Domains

Capabilities

Domain Structure

File Templates

schema.ts

types.ts

repository.ts

service.ts

routes.ts

Registration

Eden Treaty Usage

Dashboard (React)

The Machine (Discord Bot)

Critical Rules

Protected Routes

Commands