/cs-grill-product

disable-model-invocation: true
description: Matt Pocock-style interrogation of a product plan against the product canon (Torres, Cagan Transformed, Reinertsen/WSJF, Amplitude North Star, evals-as-PRD). One forcing question per turn with a recommended answer; refuses to invoke any sub-skill or start a loop until the outcome-defining decisions are locked. Use before running /cs-product or /cs-product-loop on a fuzzy plan.
argument-hint: "<product plan, roadmap, feature idea, or strategy to interrogate>"

/cs-grill-product — grill a product plan before running it

Interrogate this plan — do not execute anything yet:

**$ARGUMENTS**

Five rules (preserved from Matt Pocock, MIT): one question per turn · always give a recommended answer · explore the workspace before asking · walk the decision tree depth-first · track answered questions and their dependencies.

Decision tree

• **Branch 1 — Outcome**: "What single measurable outcome does this serve, with a number?

Recommended: write it as the OST root before anything else. Canon: Torres, *Continuous Discovery Habits*."

• **Branch 2 — Evidence**: "Which tested assumption says this will work — and how many

independent participants back it? Recommended: link the surviving assumption test; singletons are anecdotes. Canon: Bland, *Testing Business Ideas*; Torres."

• **Branch 3 — Structure**: "Does the tree pass the linter? Recommended: run

`ost_linter.py` — exit 0 before any roadmap cites it; feature-phrased opportunities (O2) and untested solutions (O4) are the usual failures. Canon: Torres OST discipline."

• **Branch 4 — Prioritization honesty**: "Would delaying any item a quarter erode its

value? Recommended: if yes, run WSJF/cost-of-delay next to RICE and flag rank flips on one-step estimate changes. Canon: Reinertsen; the WSJF false-precision critique."

• **Branch 5 — Measurement**: "Is your North Star a leading value metric with an input

tree, or revenue/vanity? Recommended: leading value metric; funnel verdicts need benchmark bands. Canon: Amplitude, *The North Star Playbook*; ProductLed benchmarks."

• **Branch 6 — AI features**: "If any feature is probabilistic: where is the eval —

golden set, rubric, guardrail SLOs? Recommended: write the eval spec into the PRD before building; vibe-check launches are shipping without tests. Canon: evals-as-PRD (Lenny's/Braintrust)."

Per-turn output format:

Q[i]/[total]: [precise question]
Recommended: [answer + canon-cited rationale]

(Confirm, or override?)

Stop conditions

• All branches resolved → invoke `/cs-product` (question) or `/cs-product-loop`

(recurring discovery) with the locked decisions inlined.

• User says "stop grilling, just run it" → run with unresolved branches flagged in the

digest.

• Abandoned → save the partial grill to `product-grill-{timestamp}.md`.

Distinct from

• `engineering/grill-me` — generic plan interrogation. This grills against the product

canon.

• `/cs-product` — routes; this refuses to route until decisions are locked.