Guidance for Claude Code working in this repo: the Nix-shell command prefix, the build/test/oracle commands with the fuzz and cross-target knobs, the four-engines-behind-one-program architecture and how a pattern is routed among them, the parser's caller-buffer design that makes comptime compilation possible, and the two standing policies a newcomer would otherwise miss -- follow PCRE where behavior diverges, and treat the resource bounds as load-bearing. REUSE.toml annotates it, since Markdown carries no license header. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017rAYVEujnHZbvRuNLJ3BuE