system-design-interview-guide

Build system design interview materials for a named problem (e.g. "Design Twitter Search", "Design a Rate Limiter", "Design Uber") from source books such as Alex Xu's System Design Interview and Grokking the System Design Interview, filling gaps with web research. Produces (1) a student-facing study guide — problem, why it is asked, real-world use, requirements, worked estimation, API/data model, architecture diagrams, deep dives, trade-off tables, practice questions with hint ladders, self-assessment checklist, glossary — rendered to a styled PDF, and (2) an interviewer-facing scenario context pack usable as input to a Tough Tongue AI (or similar) mock-interview scenario. Use this skill whenever the user asks for a reading guide, study material, context pack, scenario pack, interview prep doc, or "make a PDF like the last one" for any system design topic, mentions Xu/Grokking chapters, or wants to turn a system design chapter into an AI interview scenario — even if they don't say "guide" or "PDF".