ChiFungHillmanChan
UserReason about your stack, don't reflex into it. Interview-driven system design skills for AI agents — every component must justify itself, then emit an interactive diagram and a buildable spec.
Categories
Indexed Skills (5)
architecture-review
Audit an architecture that already exists. Infers the current stack from the repo, then checks every component against the requirement it should be serving — finding what is over-provisioned, what is about to break, and what nobody can justify. Use when the user asks to review or audit an existing architecture, asks "is my stack right", "am I over-engineering", "what will break first", "why is my bill so high", "should we still be on X", or is inheriting a system they did not design.
capacity-estimate
Fast back-of-envelope capacity and cost arithmetic with the working shown. Answers "what does 100k users cost", "can one Postgres handle this", "how much storage will a year of this need", "is serverless cheaper than a container here" — without running a full design. Use when the user wants a number rather than an architecture.
diagram-only
Turn an architecture you have already decided into an interactive diagram, with no interview. Use when the user describes a system they have already designed and wants the artifact — for a slide deck, a design doc, an RFC, or onboarding material. Triggers on "diagram this", "draw this architecture", "make a diagram of our stack", "I need this for a deck".
interview-drill
Practise system design interviews with an interviewer who pushes back. Poses a question, holds you to the requirements-first order, probes the data layer the way real interviewers do, and scores the answer against what actually gets graded. Use when the user wants to practise or prepare for a system design interview, asks to be quizzed on system design, or wants feedback on a design they just gave.
stackreason
Interview-driven system design. Narrows scope, extracts real requirements (TPS, latency, availability, consistency, budget), reasons from access patterns, picks the application stack and repo shape, challenges default choices in both directions, then emits an interactive HTML architecture diagram plus a buildable markdown spec. Use when the user asks to design a system or architecture, asks "what stack should I use", "what database should I use", "monolith or microservices", "how should I build X at scale", "design YouTube/Uber/Airbnb", is preparing for a system design interview, or is about to commit to infrastructure choices for a new project or a rewrite.
Bio shown is the top-scored skill's repo description as a fallback — real GitHub bios land in a future update.