Release v0.2.3 - SessionStartMiddleware: eager session for first-time visitors - 14-lesson tutorial redesign with pedagogical structure - Lesson 5: React vs PHP (frontend-agnostic positioning) - AI agent calls HTTP API with session cookie auth - Mermaid diagrams with pop-out zoom/pan viewer - Event log terminal, note animations, concept check quizzes - Inline auth error feedback via htmx - Notes API JSON content negotiation