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

# POST /api/sessions

> Creates a registration session for an identifier after enforcing reserved-name, duplicate-DID, and per-IP rate-limit checks against the D1 database.

Creates a registration session for an identifier. Checks reserved identifiers, duplicate registrations, and per-IP registration limits before writing to D1.

The route extracts the identifier from the request body, resolves the `Vault` Durable Object by name (`env.VAULT.getByName(identifier)`), and calls the corresponding RPC method on the DO instance.

## Request body

| Field        | Type     | Required | Description                                                                  |
| ------------ | -------- | -------- | ---------------------------------------------------------------------------- |
| `identifier` | `string` | Yes      | Registration identifier (also accepts `handle`)                              |
| `channel`    | `string` | Yes      | Channel type (also inferred as `"handle"` if only `handle` field is present) |
| `did`        | `string` | Yes      | DID to associate                                                             |

## Response (200)

```json theme={null}
{ "ok": true, "identifier": "alice", "channel": "handle", "did": "did:new:0x..." }
```

## Errors

| Code  | `error`                                               | Condition                                     |
| ----- | ----------------------------------------------------- | --------------------------------------------- |
| `400` | `"Missing required fields: identifier, channel, did"` | Field absent                                  |
| `409` | `"identifier_reserved"`                               | Identifier is in reserved list                |
| `409` | `"identifier_taken"`                                  | Identifier already registered                 |
| `429` | `"ip_limit_reached"`                                  | IP has reached `MAX_REGISTRATIONS_PER_IP` (3) |