design

A guided interview tool for turning a loosely defined idea into a product requirements document (PRD), a written description of what to build and why.

In plain words
What is it for?
Use it to explore a feature through structured questions, define its scope, and produce a PRD for approval.
Why use it?
It helps uncover unanswered questions and unclear boundaries before coding begins, reducing costly changes caused by incomplete requirements.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/bugroger/beastmode/design
Any agent
npx skills add BugRoger/beastmode --skill design
Clone the repo
git clone --depth 1 https://github.com/BugRoger/beastmode

Made for: Claude Code, Codex.

Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,801 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00040 $0.01801
Opus 5 $0.00020 $0.00901
Sonnet 5 $0.00008 $0.00360
Haiku 4.5 $0.00004 $0.00180

Measured 2d ago against content hash cf4cb4c188ba, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

design 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 2d 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.

plugin/skills/design/SKILL.md · 235 lines

How it starts

The opening of the file, as written. The whole thing — 235 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/design

Create PRDs through structured decision-tree interviews and collaborative dialogue.

Guiding Principles

  • No implementation until PRD is approved. No Plan Mode — this skill operates in normal mode. EnterPlanMode/ExitPlanMode restrict Write/Edit tools and break the workflow.
  • The session-start hook injects a metadata block into the session context with epic-id, epic-slug, and output-target. Use these values verbatim — do NOT re-derive, re-extract, or generate alternatives.
  • Do NOT invoke any implementation skill, write any code, scaffold any project, or take any implementation action until you have presented a PRD and the user has approved it. This applies to EVERY project regardless of perceived simplicity.
  • Every feature gets a PRD. A config change, a single-function utility, a rename — all of them. Short is fine; skipping is not.
  • The user frames the problem. Their words drive the design. Ask before exploring; listen before loading context.
  • Decision tree before document. Walk every branch, sweep for gray areas, then write. The PRD is the output, not the process.
  • Scope is protected by default. New capabilities get deferred unless the user explicitly pulls them in.

Phase 0: Pre-Execute

1. Problem-First Question

Before exploring the codebase, ask the user what they are trying to solve.

Do NOT:

  • Explore the codebase yet
  • Load project context yet

Wait for the user's response. Their framing drives the entire design — do not proceed until they answer.

2. Express Path Check

If the user's response points to an existing PRD, spec, or requirements document (not a .beastmode/artifacts/design/ file):

  1. Read the document
  2. Skip decision tree walk in execute
  3. Jump directly to "Gray Areas" (Execute step 2) with the doc as input

3. Existing Design Check

If a prior PRD exists for the same topic (matching feature name):

  • Ask: "Found existing PRD for this topic. What do you want to do?"
  • Options: Update existing / View first / Start fresh

Read the full file on GitHub · 235 lines

Changes

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.

  1. 2d ago First seen · 235 lines · 40 tokens per session scan A cf4cb4c188ba

Subscribe to this mod's changes

design is a skill published in the GitHub repository BugRoger/beastmode (16 stars, last pushed 4mo ago), licensed MIT. It adds 40 tokens to every session and 1,801 once invoked, about $0.0002 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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