sBTC settlement

Accepted isn't received. Prove a peg-out's BTC actually settled on Bitcoin — confirmation count, confirming block, and a webhook that fires the moment it lands.

A withdrawal's on-Stacks withdrawal-accept event only tells you the signers committed to a Bitcoin sweep. It doesn't prove the sweep confirmed — there's a broadcast→confirmed window where it can be dropped or replaced. Secondlayer verifies the committed sweep_txid against its own Bitcoin node and surfaces the result on the decoded sBTC feed.

Deposits need no such check: completed-deposit only fires after the signers see the BTC confirmations, so a peg-in is already settled when you read it.

Every peg-out lifecycle carries a settlement object. GET /v1/index/sbtc/withdrawals/:request_id:

{
  "request_id": 42,
  "status": "ACCEPTED",
  "settlement": {
    "sweep_txid": "abcd…",
    "btc_confirmations": 7,
    "settlement_confirmed": true,
    "btc_block_height": 880321,
    "confirmed_at": "2026-06-01T00:00:00.000Z"
  }
}

A null field means the committed sweep has not been observed on Bitcoin yet — no record, not a denial. settlement_confirmed is true once the sweep crosses the confirmation threshold, false while it's still shallow, and null before there's any settlement record (or when the withdrawal has no sweep yet, e.g. REQUESTED).

The rolled-up list GET /v1/index/sbtc/withdrawals carries a settlement_confirmed flag per row and a filter:

# only peg-outs whose BTC sweep is confirmed
curl "https://api.secondlayer.tools/v1/index/sbtc/withdrawals?settlement_confirmed=true"

# the pending set — sweeps accepted but not yet confirmed (or no sweep yet)
curl "https://api.secondlayer.tools/v1/index/sbtc/withdrawals?settlement_confirmed=false"

settlement_confirmed=false folds in both the not-yet-confirmed and not-yet-observed cases, so it's the complete "not done" bucket.

Subscribe to sbtc_withdrawal_swept_confirmed and get notified the moment a peg-out's sweep confirms — no polling.

import { trigger } from "@secondlayer/sdk";

await client.subscriptions.create({
  url: "https://your-app.com/webhooks/sbtc-settlement",
  triggers: [trigger.sbtcWithdrawalSweptConfirmed()],
});

Scope it to one withdrawal or one sweep with requestId / sweepTxid. It fires once per sweep, when btc_confirmations first crosses the threshold (default 6). Like every chain subscription it's forward-only — you receive settlements confirmed after you subscribe, never a backfill of history. A rare Bitcoin reorg that un-confirms a sweep never re-fires the webhook (the read self-corrects; the notification doesn't double-send).

The delivery is the standard chain.{type}.apply envelope; event carries the settlement specifics:

{
  "action": "apply",
  "trigger": "sbtc_withdrawal_swept_confirmed",
  "event": {
    "topic": "withdrawal-swept-confirmed",
    "request_id": 42,
    "sweep_txid": "abcd…",
    "btc_confirmations": 6,
    "btc_block_height": 880321,
    "confirmed_at": "2026-06-01T00:00:00.000Z",
    "amount": "100000",
    "sender": "SP…"
  }
}

See Subscriptions for delivery formats, signature verification, and the full trigger list.