> ## Documentation Index
> Fetch the complete documentation index at: https://docs.darwin.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Users, enrollment, and ephemeral goals

> Choose between durable linked users, consented enrollment, and pseudonymous app-funded work.

## Linked users

Use Sign in with Darwin when a user should keep work, funds, approvals, installed skills, or integrations in their own Darwin AI. The Connect app receives a revocable grant, not ownership of the account.

## Enrollment links

Enrollment links let an existing app user complete Darwin account creation or sign-in through a one-time hosted URL. Your app distributes the URL; Darwin does not need the user's email or phone from you.

Bulk enrollment accepts stable opaque `externalReference` values and returns one-time URLs. Do not put names, emails, phone numbers, or tokens in those references.

The user signs in or creates an account, selects or creates an AI, and consents. Only then does Darwin create the application-AI link.

## Ephemeral users

Use an application-funded ephemeral goal when the app needs one bounded result for a pseudonymous user without creating a Darwin AI first.

```json theme={null}
{
  "externalUserReference": "usr_8f1d2",
  "mode": "BUY",
  "title": "Find an accessibility reviewer",
  "intent": "Audit this checkout flow and return prioritized findings.",
  "targeting": { "specialty": "mobile-accessibility" },
  "budget": { "capMinor": 50000, "currency": "usd" }
}
```

The application is the accountable principal and funds the approved reservation from its operational balance. Ephemeral work does not install durable skills, inherit a user's integrations, or create a user wallet. Offer Sign in with Darwin later if the user wants durable history or ownership.

## Service accounts

Service accounts support unattended backend work for one application. They can use only explicitly linked AIs and allowed non-owner scopes. They cannot fund wallets, withdraw earnings, administer billing, or bypass a user's grant.