Implementing Replace-By-Fee (BIP 125) in LDK Node
summary
LDK Node implements BIP 125 using BDK as the wallet backend and ships a new pending payment store that persists to file/SQLite/Postgres and tracks a tree of conflicting transaction ids so replaced TXIDs remain linked. Only outbound onchain payments are bumpable. Fee bumping uses a hybrid flow: user fee or BDK’s required fee with auto-retry and a 1.5× sanity cap; replacement events are applied before unconfirmed events, transactions are rebroadcast each block, and confirmed replacements prune the pending store.
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chapters (10)
- 0:00Replace-By-Fee and LDK Node
- 1:57BIP 125 rules and requirements
- 3:23LDK Node architecture and BDK wallet
- 7:18On-chain payment flow
- 9:26Pending payment store design
- 14:45Bumpable transaction detection
- 15:54Hybrid fee bumping with auto-retry
- 17:22Q&A: Conflicting transaction IDs
- 21:45Q&A: Store persistence and anti-reorg
- 24:37Q&A: Privacy in payment storage
