Kernel and What It Can Do (Bitcoin Core Dev Tech, May 2026)

An overview of the Bitcoin Core kernel — the reusable consensus-validation library — whose public interface was merged about eight months earlier. People have begun using it, with the caveat that the interface can and will still break, and a design goal of minimizing differences in the public-interface code.

Early users include Floresta (a Utreexo-based light client well-suited to mobile wallets, using the script interpreter), a SwiftSync proof of concept and hints-file generation, and a Rust kernel-node full node. The discussion covered scope questions — whether Chainstate belongs in the kernel or the kernel should be pure validation, the ergonomics of the C API (such as who frees returned pointers), exposing intermediate validation states like CheckBlock, and multi-threading safety (with no race-checking fuzzer yet) — and a current limitation that the kernel cannot run in parallel to Bitcoin Core.