Interactive walkthrough (Background → Intuition → Code → Quiz) of commit
20bc1ae, with a playground that mirrors the serve-dir safety guard and a
debiased 5-question quiz. Refresh the explanations gallery index.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0126QvdMrv2WNeUVShFiLTc3
