Fifty-one runnable concept bundles taking a reader from the value/reference/pointer trichotomy to move semantics & RAII, through templates/concepts and the concurrency memory model, to undefined behavior (the central expert topic) and the C++23 standard library.
Each is a .cpp file (ground truth) + .md guide; every value is printed by the .cpp — never hand-computed.
Run any with just run <name> (C++23). Plus 18 companion library walkthroughs (Boost.Asio / Crow / redis-plus-plus) at the bottom.
Built subagent-per-bundle (max 4/batch) and verified via just sweep + just sanitize — 0 compile errors across all 51 bundles; C++23 with -Wall -Wextra -Wpedantic, spot-checked under ASan/UBSan/TSan.
Tailwind Play CDN needs internet to style.