Almost every feature you add to a One Shot app is the same shape: a model, a policy, a controller,
a set of views, routes, and specs, all scoped to the current account. The kit ships one working
example of this shape, the `Project` resource, specifically so you can copy it rather than design
it from scratch each time. The fastest way to add one is the **`crud-with-billing`** skill in Claude
Code, which generates exactly this shape for you.

```
/crud-with-billing
```

Tell it the resource name (for example `Invoice`), its attributes (`amount:integer note:text`), and
whether it's a paid feature or a free one.

## The shape, piece by piece

1. **Model and migration.** `bin/rails g model Invoice account:references amount:integer note:text`,
   then add `null: false` where it belongs and any validations. Every model gets `belongs_to
   :account`; see [Accounts and Tenancy](/docs/core-concepts/accounts-and-tenancy) for why that's
   non-negotiable.
2. **The account association.** `has_many :invoices, dependent: :destroy` on `app/models/account.rb`,
   so `Current.account.invoices` works everywhere else.
3. **A Pundit policy.** `app/policies/invoice_policy.rb`, subclassing `ApplicationPolicy`. Its
   inherited `Scope` already filters to the acting user's account; you don't write that part
   yourself. See [Authorization](/docs/core-concepts/authorization).
4. **A controller.** Query only through `Current.account.invoices`, never `Invoice.all`. Call
   `authorize` and `policy_scope`. If this is a paid feature, `include RequireEntitlement`; if it's
   free, leave it out. See [Gating a Feature](/docs/billing-entitlements/gating-a-feature).
5. **Views.** `index`, `show`, `new`, `edit`, and `_form`, using the Terminal design system classes
   already defined in `app/assets/stylesheets/application.css` (`.card`, `.btn`, `.field`,
   `.eyebrow`). Copy the `Project` views as a starting layout.
6. **Routes.** `resources :invoices` in `config/routes.rb`.
7. **Billing, only if this introduces a new plan or tier.** Extend `Billing::PLANS` in
   `app/adapters/billing.rb` and add the price id to `Billing::Stripe::PRICE_ENV`; manage the actual
   Stripe product and price through the Stripe MCP server or `bin/rails console`.
8. **Specs.** A model spec, a policy spec, and a request spec, always including the
   tenant-isolation test: fetching a record that belongs to a different account by id must 404, not
   500 and not silently succeed. A paid resource also gets an entitlement-gate test: an unsubscribed
   account should be redirected to pricing, not shown the feature.

## Verify

Run `bin/check`. The tenant-isolation test is the one that matters most here: if it's missing or
passing for the wrong reason, a new resource can quietly leak data across accounts the moment it
ships.

## Next

If the resource needs work outside the request cycle, see
[Background Jobs](/docs/building-features/background-jobs).