Borrowing it
Nothing to install: this file belongs to lglucas/ai-dev-operating-system. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/lglucas/ai-dev-operating-system/main/.claude/skills/product-brief/SKILL.mdgit clone --depth 1 https://github.com/lglucas/ai-dev-operating-systemWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/lglucas/ai-dev-operating-system/product-brief)<a href="https://agentmods.dev/skills/lglucas/ai-dev-operating-system/product-brief"><img src="https://agentmods.dev/badge/skills/lglucas/ai-dev-operating-system/product-brief/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/lglucas/ai-dev-operating-system/product-brief"><img src="https://agentmods.dev/badge/skills/lglucas/ai-dev-operating-system/product-brief.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00109 | $0.00406 |
| Opus 5 | $0.00055 | $0.00203 |
| Sonnet 5 | $0.00022 | $0.00081 |
| Haiku 4.5 | $0.00011 | $0.00041 |
Grade A, and why
product-brief scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Product Brief Skill
Runs at Phase 4.1 of WIZARD.md.
Use after BP v0.0.2 is accepted and a prototype direction has been approved in Phase 3.
Create docs/product/PRODUCT-BRIEF.md as the operational product document. Not investor copy — that is the Business Plan's job.
Method: reverse engineering, not invention
The product was designed in Phase 3. This skill reads docs/product/DESIGN-DIRECTION.md and prototype-lab/<chosen>/ and writes down what is already there.
Required checks:
- Every screen in the approved prototype appears in the brief, or is explicitly marked as cut.
- The user flow section matches the flow that was actually clickable in the prototype.
- UX tone is derived from
DESIGN-DIRECTION.md, not invented. - Anything the prototype implied but never showed — empty states, errors, permissions, offline, edge cases — is listed as a gap, not silently filled in.
That last check is the reason the prototype comes first. A written spec invents its own completeness; a prototype makes the holes visible.
Contents
One-liner, personas, jobs to be done, user flows, MVP, Phase 1, Phase 2, non-goals, activation moment, retention loop, monetization logic, trust/compliance requirements, UX tone, product risks.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 30 lines · 109 tokens per session scan A fdd5df6c9e63
product-brief is a skill published in the GitHub repository lglucas/ai-dev-operating-system (11 stars, last pushed 1mo ago), licensed MIT. It adds 109 tokens to every session and 406 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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