> ## Documentation Index > Fetch the complete documentation index at: https://docs.basaltic.sh/llms.txt > Use this file to discover all available pages before exploring further. # Confirm a subscription from a link > UNAUTHENTICATED. The single-click half, used by the link in a confirmation email. ## OpenAPI ````yaml /api-reference/specs/notifications.yaml get /v1/subscription-confirmations/{token} openapi: 3.0.3 info: title: Basaltic Notifications API version: 1.0.0 description: | Publish/subscribe notification topics with email and webhook delivery. A topic is a fan-out root. Subscriptions bind it to endpoints; publishing to the topic delivers to every confirmed subscription whose filter policy matches the message. **Publishing is asynchronous.** Publish returns 202 as soon as the notification is durable and queued: no delivery has happened yet. Fan-out into per-subscription deliveries runs on a worker, so publish latency does not grow with subscriber count. Poll `GET /v1/messages/{message_id}` for the fan-out state and `GET /v1/deliveries?message_id=...` for per-endpoint outcomes. **Subscriptions must be confirmed.** Subscribe creates the subscription in `pending_confirmation` and sends a token to the endpoint — a link for email, a `subscription_confirmation` POST for webhooks. Nothing is delivered until the endpoint owner presents that token back. The confirmation window is 72 hours; unconfirmed subscriptions are reclaimed after it. If the handshake never arrived, `POST /v1/subscriptions/{id}/resend-confirmation` mints a fresh one — the original token is not recoverable, only its hash is stored. **Webhook endpoints must be publicly routable.** Endpoints resolving to loopback, RFC1918, link-local, or unique-local addresses are refused at subscribe time and again at delivery time. **Webhook deliveries are signed.** Each POST carries `X-Basaltic-Signature: v1,t=,s=`, an HMAC-SHA256 over `"."` keyed by the subscription's signing secret. The secret is returned once by Subscribe and is readable afterwards via the signing-secret endpoint. Verify by recomputing the MAC over the raw body you received — not a re-serialised copy — and reject timestamps more than five minutes from now. contact: name: Basaltic Support email: ping@basaltic.sh license: name: Proprietary url: https://basaltic.sh/terms servers: - url: https://notifications.{region}.basaltic.sh description: Regional API endpoint variables: region: default: sa-saopaulo-1 description: Region code security: - SignatureAuth: [] tags: - name: Topics description: Fan-out topics - name: Subscriptions description: Endpoint subscriptions and their confirmation handshake - name: Messages description: Publishing and delivery status - name: Confirmations description: Unauthenticated endpoint-owner actions paths: /v1/subscription-confirmations/{token}: parameters: - $ref: '#/components/parameters/Token' get: tags: - Confirmations summary: Confirm a subscription from a link description: | UNAUTHENTICATED. The single-click half, used by the link in a confirmation email. operationId: confirmSubscriptionByLink responses: '200': description: Subscription confirmed; delivery begins. content: application/json: schema: $ref: '#/components/schemas/ConfirmationResponse' '400': description: The token is unknown, malformed, or already used. content: application/json: schema: $ref: '#/components/schemas/Error' '410': description: The confirmation window has elapsed; subscribe again. content: application/json: schema: $ref: '#/components/schemas/Error' security: [] components: parameters: Token: name: token in: path required: true description: The opaque token sent to the subscribed endpoint. schema: type: string example: 0lFqQyF5W3xJ0Zx2mE8t6bN1pKcR4vT7aY9uS3dG2hI schemas: ConfirmationResponse: type: object required: - subscription_id - endpoint - status properties: subscription_id: type: string format: uuid example: b2c3d4e5-6f7a-4b8c-9d0e-1f2a3b4c5d6e topic_name: type: string example: prod-alerts endpoint: type: string example: https://hooks.example.com/basaltic status: type: string enum: - confirmed - unsubscribed example: confirmed Error: type: object required: - error properties: error: type: object required: - code - message - request_id properties: code: type: string description: Error code identifying the type of error example: INVALID_INPUT message: type: string description: Human-readable error message example: Invalid request parameters request_id: type: string format: uuid description: Request ID for debugging example: 550e8400-e29b-41d4-a716-446655440000 securitySchemes: SignatureAuth: type: apiKey in: header name: Authorization description: > Request signing with an access key issued to a service account. An HMAC-SHA256 over a canonical form of the request, close to AWS SigV4. The `basaltic` CLI signs for you. Send `Authorization`, `X-Date` (UTC, `YYYYMMDDTHHMMSSZ`) and `X-Nonce` (random per request); add `X-Content-Sha256` to bind a body, and `X-Amz-Security-Token` when using temporary credentials. ``` Authorization: BASALTIC-HMAC-SHA256 Credential=///basaltic/basaltic_request, SignedHeaders=host;x-date;x-nonce, Signature= ``` `` is the region code you are calling, or `global` for the global services. A signature is valid for 5 minutes from `X-Date`, and mutating requests are replay-guarded on the nonce. **Full signing procedure, including a working implementation:** https://docs.basaltic.sh/authentication ## Rate limits There is no global request budget. A limit applies only where an operation documents a `429`, and that operation says what it counts. Those responses carry `X-RateLimit-Limit`, `X-RateLimit-Remaining`, `X-RateLimit-Reset` and, on a `429`, `Retry-After` — read them rather than hard-coding a number. Retrying before `Retry-After` is refused and extends the window. Everything else is bounded by quota, not by request rate. ````