breadboarding

breadboarding is a skill for Claude Code, Codex from marchatton/agent-skills. It costs 74 tokens per session (1,978 once invoked), scanned A, original, MIT.

A lightweight map of a software change showing what users can do or see, what the code does, and how the parts connect. “Breadboarding” here means outlining the structure without writing the full implementation or specifying every pixel.

In plain words
What is it for?
It helps understand current behaviour, plan new features, map screens and code connections, decide whether to share or duplicate logic, and check whether the proposed parts fit together.
Why use it?
It makes an existing system and a proposed change concrete enough to build while avoiding premature detail.

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/marchatton/agent-skills/breadboarding
Any agent
npx skills add marchatton/agent-skills --skill breadboarding
Clone the repo
git clone --depth 1 https://github.com/marchatton/agent-skills

Made for: Claude Code, Codex.

Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,978 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 $0.00074 $0.01978
Opus 5 $0.00037 $0.00989
Sonnet 5 $0.00015 $0.00396
Haiku 4.5 $0.00007 $0.00198

Measured 3d ago against content hash cb8dd97c49e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

breadboarding 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 3d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/render_mermaid_from_edges.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

.agents/skills/02-shape/breadboarding/SKILL.md · 218 lines

How it starts

The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Breadboarding

Purpose

Produce a Shape Up style breadboard that is concrete enough to guide a build, without collapsing into pixel-perfect UI spec or a full-code hairball.

Based on Shape Up and Ryan Singer's work.

Treat affordances as the simplifying primitive.

  • UI affordances: things a user can do (type, click, scroll) or see (states/messages) that matter to the flow.
  • Code affordances: things the system can do (call a function, observe an observable, write/read state, navigate) that cause the UI affordances to change.

Use those to build a lightweight model of the current system and the proposed change.

When to use

  • Reach the “rough out the elements” stage and need to turn an idea into buildable parts.
  • Shape a change to a pre-existing system and need to understand what the system actually does today.
  • Compare a new concept against an existing feature and decide whether to duplicate vs extract shared logic.
  • Pick up a shaping effort after a gap and need a fast re-orientation: current state, chosen approach, and what’s still unsolved.

Inputs to request or infer

Prefer working with whatever exists. If inputs are missing, use ask-questions-if-underspecified skill

  • Appetite / timebox and any hard boundaries.
  • Problem statement and success definition.
  • Brief (problem, goals, in/out scope). If missing, pause and draft a brief first.
  • Requirements list (or a rough list of must-haves).
  • Entry point(s): where the user starts, how they discover the feature.
  • Existing system context: routes/screens, key components, services, data stores.
  • Any comparable feature(s) to analyse for reuse.

Workflow

1) Establish the “right level of abstraction”

  • Avoid full wireframes and visual design.
  • Prefer words and connections over pictures.
  • Focus on “what’s connected to what” (topology) and “what changes state”.

Use the breadboard primitives:

  • Places: screens/pages/modals/menus that can be navigated to.
  • Affordances: actions and information at a place (buttons, fields, copy, empty/loading states).
  • Connection lines: how an affordance moves between places or triggers work.

Read the full file on GitHub · 218 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. 3d ago First seen · 218 lines · 74 tokens per session scan A cb8dd97c49e5

Subscribe to this mod's changes

breadboarding is a skill published in the GitHub repository marchatton/agent-skills (5 stars, last pushed 5mo ago), licensed MIT. It adds 74 tokens to every session and 1,978 once invoked, about $0.0004 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 2026-08-31.

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