Design and implement `whatifd`, a trust-first LLM experiment runner that produces defensible verdicts (Ship / Don't Ship / Inconclusive) from forked production traces, replayed against a proposed change, scored, and reported. Use this skill whenever the user asks to design, architect, implement, plan, or build any part of whatifd — including the runner contract, trust floor, failure taxonomy, scorer cache, JSON schema, decision policy, report rendering, GitHub Action wrapper, or any milestone of the v0.1 → v1.0 trajectory. Also use this skill when discussing similar trust-first experiment-runner systems, CI-grade verdict tooling for LLM behavior changes, or any architectural question about replay-based regression testing for AI agents.
Deferred-work catalog for `whatifd`. Use when triaging whether an idea belongs in the active plan now or as future work, when proposing a refactor, or when looking for post-v0.1 candidates.