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

# Link a signal card

> Attach a generated signal card to a stored score, claim it for the caller's account.

Attach a generated signal card to a stored score, or claim an anonymous signal card for the caller's account after sign-up. Symmetric with `/api/score/link` but for the IC-tier signal card flow.

```bash theme={null}
curl -X POST https://app.dacard.ai/api/signal-card/sigc_xyz/link \
  -H "Authorization: Bearer $DACARD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "scoreId": "scr_xyz" }'
```

| Property       | Value                        |
| -------------- | ---------------------------- |
| **Auth**       | Required                     |
| **Idempotent** | Yes (second call is a no-op) |

## Body

| Field     | Type   | Required | Notes                                                                                                                         |
| --------- | ------ | -------- | ----------------------------------------------------------------------------------------------------------------------------- |
| `scoreId` | string | no       | Pass when linking the signal card to an existing stored score. Otherwise the card is just claimed against the user's account. |

## Errors

| Status | Code                                | When                      |
| ------ | ----------------------------------- | ------------------------- |
| 401    | `AUTH_REQUIRED`                     | No session.               |
| 404    | `Signal card not found`             | Bad `id`.                 |
| 409    | `Already linked to another account` | Card was already claimed. |
| 500    | `INTERNAL_ERROR`                    | Write failed.             |