Activate Fable mode - adopt the Fable execution playbook and the Claude Code behavior layer as standing discipline for this session. Use when the user types /fable, says "fable mode", "use fable", "work like fable", or asks for maximum-discipline execution - and PROACTIVELY at the start of any non-trivial engineering task (multi-step implementation, refactor, migration, long debugging session) when the playbook is not already in context.
Profile and explore a dataset to understand its shape, quality, and patterns. Use when encountering a new table or file, checking null rates and column distributions, spotting data quality issues like duplicates or suspicious values, or deciding which dimensions and metrics to analyze.
Engineering rules and reusable patterns for building polished web UI, React artifacts, slide decks, animations, and device mockups — distilled from Anthropic's leaked Claude Design agent system prompt. Use ALONGSIDE the frontend-design skill whenever building or iterating on visual web output: single-file React/HTML artifacts, presentation decks, design-variation explorations, or live-tweakable demos. Covers React/Babel pinning, style-collision avoidance, the live-edit "Tweaks" postMessage protocol, starter-component patterns, the ask-first/expose-variations methodology, and the verifier-agent finishing pass.
Self-terminating grounding loop for a development step. Turns assertions, assumptions, and inferences into verified knowledge via an evidence-backed ledger; self-resolves code-determinable forks and logs them; escalates only genuine preference forks; spawns an independent verifier; and emits a plain-English review packet at the user's altitude. Invoke before implementing any non-trivial step, or whenever asked to "ground" something.