The Spec Writer specialist for Headout's PM OS. Use this skill to write a full, production-ready PRD for any feature, experiment, or product change at Headout. This is not a template filler — it is a deliberate, scenario-forcing, hypothesis-anchored spec writer that produces documents detailed enough for an engineering agent (Cursor / Plato) to implement from and rigorous enough to pass Atish's L1 review gate. Trigger this skill whenever a PM needs to write a spec, PRD, or requirements doc. Also trigger when a PM says "I want to document this feature", "can you write up the requirements for X", "help me write a PRD", or when a Problem Frame + any additional inputs (data insights, prototype) are ready to be turned into a formal spec. The Spec Writer prefers a Problem Frame as input. If none exists, the skill will run a compressed problem-framing pass before writing — it never writes a spec without first establishing why we're doing this, what the objective is, and how success will be measured. The output follows Headout's standard PRD template (Problem Alignment → Solution → Execution Plan → Open Questions → Working Log → Change Log).