KaleidoSwap SDK Python Bindings

Python bindings for the KaleidoSwap SDK: atomic swaps (Boltz protocol) between Bitcoin, Lightning, and Liquid.

Installation

python -m pip install kaleidorg_swap_sdk

Python 3.10+ is supported. Prebuilt wheels cover Linux x86_64/aarch64, macOS x86_64/arm64, and Windows x86_64; other platforms build the published source distribution and need a Rust 1.88+ toolchain.

Quick Start

⚠️ WARNING: All examples are only to be used in REGTEST.

import kaleidorg_swap_sdk
import asyncio

async def main():
    # Initialize for regtest (do NOT use this example in production)
    network = kaleidorg_swap_sdk.Network.REGTEST
    boltz_api = kaleidorg_swap_sdk.SwapClient.default(network)

    # Example: Create a submarine swap (Lightning → Bitcoin)
    key_pair = kaleidorg_swap_sdk.KeyPair()
    btc_chain = kaleidorg_swap_sdk.btc_chain_from_network(network)

    invoice = "lightning-invoice-to-pay"

    request = kaleidorg_swap_sdk.CreateSubmarineRequest(
        _from=btc_chain,
        to=btc_chain,
        invoice=invoice,
        refund_public_key=key_pair.public(),
    )

    swap = await boltz_api.create_swap(request)
    print(f"Send {swap.expected_amount} sats to {swap.address}")

asyncio.run(main())

Partner attribution (organization API keys)

A partner organization can have the swaps it originates attributed to it. That needs an organization API key from the KaleidoSwap partner panel — a kld_test_… key for signet and staging, kld_live_… for mainnet and production. Without one, SwapClient behaves exactly as before and creates unattributed swaps.

import os
import kaleidorg_swap_sdk

client = kaleidorg_swap_sdk.SwapClient.kaleido_maker(
    "https://maker.signet.kaleidoswap.com/v2",
    os.environ["KALEIDOSWAP_API_KEY"],
    None,  # timeout in seconds
)

client.api_key_environment()  # "test"
client.api_key_id()           # the key id the partner panel shows

Scrub the key in error reporters that capture locals. It crosses the binding as a plain str, so it is a function argument on a stack frame for the length of the call. The SDK keeps it out of its own errors, logs and repr, but anything that renders frame locals — pytest --showlocals, Sentry's with_locals, some logging formatters — reads it off the frame regardless. Scrub it in your reporter's before-send hook.

The result is an ordinary client — every swap route works the same way — that sends the key as Authorization: Bearer … to that maker URL, and only to that maker URL. The key answers which partner organization created this swap? and nothing else: it authorizes no claim, no refund, no fund movement and no panel access. The per-swap swap_auth credential the maker returns on create stays separate and unchanged.

The URL must be https unless it is a loopback address, since a bearer credential over plain HTTP is readable by anything on the path. A value that cannot be a key is rejected here rather than reaching the maker as a 401 — which is the same answer a revoked key gets. There is no accessor for the secret half: api_key_id() and api_key_environment() are all the client will tell you, and UniFFI renders no string form of the object at all.

Keep the key in server-side configuration. It is permanent until revoked, so never ship it inside a mobile or desktop application, where every user holds it.

Swap Types

• Submarine swaps - Lightning → On-chain Bitcoin/Liquid
• Reverse swaps - On-chain Bitcoin/Liquid → Lightning
• Chain swaps - Bitcoin ↔ Liquid atomic swaps

Examples

Complete working examples are available in the examples/ directory:

• reverse.py - Lightning to Bitcoin
• submarine.py - Bitcoin to Lightning
• chain.py - Bitcoin to Liquid (and vice versa)

USDT-RGB swaps

Set rgb_contract_id on CreateSubmarineRequest or CreateReverseRequest and select Currency.USDT_RGB for the on-chain side. The pin is required before the POST and checked against the returned contract. It stays local; the maker wire request is unchanged. RGB chain swaps are unsupported. Other currencies retain the existing create defaults.

The caller's rgb-lib wallet funds submarine locks and validates reverse lock consignments. The SDK validates the HTLC, builds the claim/refund PSBT and signs its script path. RGB proof validation and wallet state remain in rgb-lib.

SwapScript.prepare_rgb_claim / prepare_rgb_refund take RgbPsbtParams: output_address, funding, max_fee (sats), swap_id, chain_client, boltz_api, and optional lockup_tx. Parse a lock transaction with BtcLikeTransaction.from_hex_bitcoin(hex). Use the original lock transaction for refunds. The payout address must come from an RGB wallet witness receive.

• RgbSpendFunding.HTLC_VALUE(fee_rate_sat_vb=rate) uses the HTLC's sats. Reverse locks are sized for the advertised rgb.claim_fee_rate.
• RgbSpendFunding.CALLER_INPUTS() requires BTC funding. Add wallet inputs/change without coloring or signing, then retain spend.fund(funded_psbt). Its template() returns the frozen PSBT and current HTLC input index.

Color that PSBT with rgb-lib's psbt_op_prepare_with_expiry, assigning the full RGB amount to the template's payment output. Return the actual RGB allocations in ColoredRgbPsbt to finalize_claim(colored, keys, preimage) or finalize_refund(colored, keys). FinalizedRgbSpend contains psbt, swap_input_index and optional transaction. Sign/finalize remaining wallet inputs while preserving the SDK's HTLC witness. Error.RgbFeeInputRequired means the HTLC cannot pay the fee while keeping the minimum payout; prepare with caller inputs instead.

Keep the rgb-lib operation ID and complete psbt_op_mark_broadcast, broadcast, psbt_op_apply and psbt_op_provide_receive_consignment. Enforce reverse lock confirmations using the chain and rgb-lib: there is no reverse transaction.confirmed event. Refunds wait for the timeout; claims must confirm before it. Asset amounts use contract units; htlc_sat and fees use sats.

Submarine BTC collateral is capped at 1000 sats by default, independently of maxFee/max_fee. The maker receives all of it on a successful claim. Choose any larger cap locally before reading the response: set rgb_max_htlc_sat on CreateSubmarineRequest. The cap is never sent to the maker. RGB spend preparation requires the actual colored lock transaction; address discovery can select unrelated BTC outputs. Before paying a reverse invoice, compare its claimFeeRate with your current fee estimates and remaining timeout; reject an inadequate quote. If fees rise, use a higher spend rate and wallet BTC inputs when needed. A maker fee quote does not guarantee confirmation before the timeout. Contract-id chunk dashes are cosmetic; pin a valid id from your trusted wallet or asset registry.

The adapter example demonstrates both spend directions. It requires an application-provided RGB wallet adapter. Actual RGB wallet validation is recorded in the native regtest example.