ad-prd

name	ad-prd
description	Draft or update a Product Requirements Document at doc/product/PRD.md (single-product) or doc/product/<product-slug>.md (multi-product). Layer 3 of the six-layer artifact stack (Constitution → Domain → Product → Spec → Plan/Decisions → Code). Captures product-level scope — target user, problem, goals, non-goals, success metrics, multi-feature roadmap, cross-feature constraints — that feature specs inherit from. Use when the user wants to write, draft, scaffold, or open a product brief, PRD, product requirements, product vision, target user / persona definition, product success metrics, product roadmap, or any product-level (multi-feature) scoping. Distinct from `ad-spec` (feature-level, one feature per spec). Status lifecycle draft → accepted → superseded. Skill is lazy — file only exists when product is being scoped.
summary	Lazy lifecycle owner of `doc/product/PRD.md` (or `doc/product/<slug>.md` multi-product). Layer 3 — product-level scope (target user, problem, success metrics, multi-feature roadmap) that feature specs inherit from. Distinct from `ad-spec` (feature-level).

<background_information> Layer 3 of the artifact stack. Lazy lifecycle owner of the PRD (Product Requirements Document). One product = one PRD; multi-product repos use a PRODUCT-MAP.md index plus per-product <slug>.md files.

PRD is product-level scope, not feature-level scope. A feature spec (ad-spec, Layer 4) implements part of a PRD; a PRD is never implemented by a single task. If the user's ask is single-feature, route to ad-spec instead.

Codex auto-trigger on description keywords is less mature than Claude Code's. If auto-invocation does not fire when the user mentions PRD, product requirements, target user, product roadmap, or product success metrics, invoke this skill manually. </background_information>

Step 0 — confirm regime. Run when the user wants to scope or update product-level context: new product framing, existing PRD update, cross-feature constraint surfaced.

Route elsewhere when:

• Scope is one feature → ad-spec (Layer 4).
• Scope is a vocabulary question → ad-domain (Layer 2).
• Scope is an architectural decision → ad-adr.
• Scope is fuzzy and needs interview-before-research → ad-grill-me, which can route back here once the product framing is sharp.

A spike or one-off change does not need a PRD. If the user invokes ad-prd, their request establishes that a durable product contract is in scope; write only the scope the work needs.

Step 1 — codebase-first scan. Before asking a single question, look. The repo often answers half the fields.

• Check doc/product/ — does a PRD already exist?
• Read AGENTS.md ## Project Overview — pulls product name, one-line description, deployment target.
• Read README.md head — pulls product framing for users who land via the public README.
• Read CONTEXT.md if it exists — anchors the canonical nouns the PRD must use.
• Read doc/specs/ index — existing feature specs surface the implicit product scope.
• Read package.json name / description / keywords for product framing signal.

Only after the scan produces no answer does the skill ask the user. Asking the user about something the repo already states wastes their attention.

Step 2 — determine slug and target file. Single product (default): doc/product/PRD.md. Multi-product: ask whether this is a multi-product repo; if yes, file path is doc/product/<product-slug>.md and a doc/product/PRODUCT-MAP.md index lists each product. Slug: kebab-case, ≤4 words, derived from the product name.

Status starts at draft. Created: today, ISO format. Updated: today, ISO format. Owner: ask once — defaults to the repo's primary committer (from git config user.name) if unset.

Step 3 — interview to fill. Ask one question at a time, in this order. Skip questions whose answers are already obvious from the Step 1 scan; surface what the scan found and ask only for confirmation.

If the product framing is vague ("improve efficiency", "build a dashboard", "use AI", "make it easier"), run a short sharpening pass before filling the PRD fields. Keep these as facilitation notes, not PRD sections:

• Today statement. "Today, <target user> must <painful workflow> when <trigger>. They need a way to <unmet need>."
• How Might We. Reframe the problem broad enough to allow multiple solutions, narrow enough to exclude generic improvement.
• North Star. "Deploy <what> to change <metric 1> and <metric 2> so that <ultimate outcome>." Require baseline, target, and measurement source when available.

If the user starts with a solution, validate it against the Today statement and North Star before accepting it into Roadmap. If it serves a different user, fails to move the named metrics, or prescribes implementation before the problem is clear, route back to ad-grill-me.

• Product. Name and one-sentence positioning. "X is a Y that does Z for W."
• Target User. Specific role / persona, not "developers" or "users". Cite the primary success-bearing user; secondary users go under Personas if they affect the product shape.
• Problem. What the target user can't do today, or does badly today. The cost of the status quo. "What breaks if this product does not exist?"
• Goals. 3–5 measurable outcomes the product is for. State each as a plain bullet (no checkbox — PRD is definition, not tracking). Pass/fail must be observable; tracking of whether each goal is met lives in per-feature tasks.
• Non-goals. Explicit out-of-scope items readers might assume are in scope. Prevents scope creep without an audit trail.
• Success Metrics. Product-level KPIs — measurable and durable, not procedural. "Weekly active users above N at 90 days" — yes. "Users love it" — no. Each metric carries the measurement source.
• Roadmap. Multi-feature scope. Each line names a feature, the user value it carries, and the (rough) sequence. Concrete enough to drive ad-spec later; not a binding commitment. Mark MVP, Next, Later; no dates.
• Constraints. What binds across the entire product — regulatory, business, technical. Skip if none; do not invent.
• Personas (optional). If the product has secondary users whose needs reshape it. Skip when one persona drives everything.
• Open Questions. Deferred decisions. Each line becomes a future ADR, a spec-time decision, or an explicit punt with rationale.
• Related. ADRs touched, feature specs implementing parts of it, other PRDs this one supersedes. Filled lazily.

Do not invent values. When the user does not know, leave <TODO> in the field and continue.

Step 4 — interview UX. Codex has no AskUserQuestion primitive. Use inline numbered text for multi-choice prompts. One question per turn; do not chain three text questions in one message.

Step 5 — write the file. Path: doc/product/PRD.md (single-product) or doc/product/<slug>.md (multi-product). Use the template at references/prd-template.md. Stop after writing. Do not flip status to accepted — that requires user review.

Step 6 — editing guidance for later turns. When the user later works on the PRD:

• Update Success Metrics phrasing only when a metric definition changes; per-metric status tracking lives in per-feature tasks, not in the PRD.
• Append to Open Questions — close them with a resolution paragraph; never delete the original question line.
• Flip Status to accepted once the user signs off and feature specs start being written against this PRD.
• Flip Status to superseded by <slug> when a later PRD replaces this one.
• Add Roadmap lines as the product grows; mark superseded roadmap items with a strikethrough and a one-line note, do not delete them.
• Add Related → Specs entries as ad-spec runs reference this PRD.

Never rewrite existing prose — append rationale to Open Questions as a resolution paragraph rather than mutating the original requirement text. Open Questions is the append-only resolution surface.

<output_contract>

• Primary output: doc/product/PRD.md or doc/product/<slug>.md.
• Multi-product side-effect: doc/product/PRODUCT-MAP.md written or updated.
• Status starts draft; never flipped to accepted by the skill.
• No dates inside narrative prose; the Created and Updated lifecycle fields are decision-record primitives, exempt from the no-dates rule.

After writing the PRD: route to ad-spec for each MVP roadmap item. When the PRD surfaces an architectural commitment, route to ad-adr. When a roadmap item is technique-uncertain, route to ad-spike (WORKFLOW §14). When the PRD framing is fuzzy, route to ad-grill-me to sharpen and return. Periodic drift check: ad-drift flags feature specs whose target user or success metrics contradict the PRD. </output_contract>