Track: Add chain swap (ARK ↔ BTC) support via Boltz — parity with rust-sdk

[arkanaai]

SDK Parity Tracking Issue

Source: rust-sdk#200 merged 2026-04-01 — adds BTC↔ARK chain swap support via Boltz to ark-client.

Background

The rust-sdk now supports a third Boltz swap type alongside submarine and reverse submarine swaps:

• ARK → BTC: Lock a VHTLC on Ark; Boltz claims it and locks BTC; user claims BTC via MuSig2 HTLC
• BTC → ARK: Send on-chain BTC to a Boltz HTLC; Boltz locks a VHTLC on Ark; user claims the VHTLC

Both flows use the Boltz v2 chain swap API (POST /v2/swap/chain). The TypeScript reference implementation is in boltz-swap/src/arkade-swaps.ts.

New Types (rust-sdk public API, needs dotnet-sdk equivalent)

ChainSwapAmount
ChainSwapData
ChainSwapDirection  // ArkToBtc { btc_address } | BtcToArk
ChainSwapResult
SwapStatusInfo      // unified status across all 3 swap types
SwapType            // Submarine | Reverse | Chain | Unknown

New Methods (rust-sdk, needs dotnet-sdk equivalent)

CreateChainSwap()
WaitForChainSwapServerLockup()
ClaimChainSwap()        // Claim on-chain BTC (ARK→BTC)
ClaimChainSwapBtc()
RefundChainSwap()       // Refund VHTLC (ARK→BTC timeout)
RefundChainSwapBtc()
GetSwapStatus()         // Now covers all 3 swap types

References

• rust-sdk PR: Feat/chain swaps rust-sdk#200
• rust-sdk issue: Chain swap via Boltz rust-sdk#187
• TypeScript reference: https://github.com/arkade-os/boltz-swap/blob/main/src/arkade-swaps.ts
• Recovery path (open): Missing recovery path for pending VHTLC transactions (recoverPendingVHTLCTxs) boltz-swap#98

Opened by Arkana cross-repo impact analyzer