# monk-code-screen

Billing/subscriptions/invoicing backend skeleton. Bun + Hono + `bun:sqlite` (zero network deps at runtime; TS runs natively, no build step).

## ⚡ START COMMAND (sticky)

```sh
bun run dev          # http://localhost:3000, hot reload
```

Other commands:

```sh
bun run start        # no watch
bun run db:reset     # wipe data.db and reseed
bunx tsc --noEmit    # typecheck
```

## Layout

```
src/index.ts    Hono app + routes
src/db.ts       opens data.db, applies schema, seeds if empty (runs on import)
src/schema.sql  customers / plans / subscriptions / invoices (idempotent)
```

DB is `data.db` at repo root (WAL, FK on). Boot always re-applies schema, so adding a table = edit schema.sql + restart.

## Routes

```sh
curl localhost:3000/health
curl localhost:3000/customers
curl localhost:3000/customers/cus_ada/invoices
curl -X POST localhost:3000/subscriptions \
  -H 'content-type: application/json' \
  -d '{"customer_id":"cus_grace","plan_id":"plan_basic"}'
```

`POST /subscriptions` is the happy path: validates with zod, creates subscription + first invoice in one transaction, returns both (201).

## Seed data

- customers: `cus_ada`, `cus_grace`
- plans: `plan_basic` ($10/mo), `plan_pro` ($50/mo)
- `cus_ada` has an active `sub_1` on pro with open `inv_1`

## Extension cheatsheet (interview)

- New route: add to `src/index.ts`, `db.query(...).all()/get()`, `db.run(sql, [params])`
- Multi-write: `db.transaction(() => { ... })()`
- Validation: `z.object({...}).safeParse(await c.req.json())`
- New table: append `CREATE TABLE IF NOT EXISTS` to schema.sql, restart (or `db:reset` if changing existing tables)