Write PRD

Produce docs/specs/<feature-slug>/_prd.md — the product definition the rest of the pipeline (write-techspec, write-tasks, implement-task, qa-gate) implements from. The PRD owns what and why; the tech spec owns how. Keeping that boundary is what lets each artifact stay small and stay true while the code changes underneath it.

Inputs

$ARGUMENTS is a feature description, or empty when the current conversation already explored the feature (a grilling or brainstorm session). Everything already answered in the conversation counts as answered — do not re-interview.

If docs/specs/<slug>/_idea.md exists (produced by write-idea), it is the exploration: read it first, and treat its research, scoring, council insights, chosen direction, and Out of Scope list as answered ground truth. Clarify only what the idea left open.

Size triage first

Not every change earns a PRD — it pays for itself when there are product decisions to record and multiple tasks to derive. If the work changes no product behavior (a refactor, a bug fix), say so and route to write-techspec, which enters the pipeline directly and mints the spec folder with a minimal _prd.md. If the change is trivial (one-line fix, typo, config tweak), recommend direct implementation with no spec folder.

Ground rules

• Read CONTEXT.md and docs/adr/ before anything else. Use the glossary's vocabulary throughout — titles, user stories, feature names — and never drift to synonyms the glossary lists under _Avoid_. If a concept has no term yet, sharpen one with the user and add it to the glossary right then; a PRD written in fuzzy language produces fuzzy tasks. If either file is missing, proceed silently.
• Decide, then write. Once research and clarifications are done, write the file directly and let the user react to the finished artifact. Do not present outline drafts for approval — reviewing a real PRD is faster than reviewing a promise of one.
• Durability. No file paths, no code snippets, no line numbers, except the mandatory docs/agents/ Project Constraint sources and exact files covered by tooling authorization. The PRD may sit in a queue for weeks while the codebase moves; describe behavior and interfaces, which survive refactors.