codebase-design

codebase-design is a skill for Claude Code, Codex, Cursor from mamahoos/dot-files. It costs 57 tokens per session (1,357 once invoked), scanned A, a copy of codebase-design, MIT.

Guidance for designing deep modules: pieces of code that provide a small, clear interface while handling substantial behaviour internally. It focuses on clean seams, testability, and interfaces that are easy for people and coding agents to use.

In plain words
What is it for?
Use it to design or improve module interfaces, choose where responsibilities should meet, and make code more testable or easier for an AI coding agent to understand.
Why use it?
It helps prevent callers from having to understand too much implementation detail. Clearer boundaries can make code easier to change, test, and navigate.

Skill for Claude CodeCodexCursor

Written for Claude Code and Codex and Cursor: disable-model-invocation in frontmatter, but also agents/openai.yaml present. Also seen: mentions subagents.

Good fit Use it to design or improve module interfaces, choose where responsibilities should meet, and make code more testable or easier for an AI coding agent to understand.

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Install with agentmods
npx agentmods add skills/mamahoos/dot-files/codebase-design
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.

Any agent
npx skills add mamahoos/dot-files --skill codebase-design
Clone the repo
git clone --depth 1 https://github.com/mamahoos/dot-files

Made for: Claude Code, Codex, Cursor.

Wrote 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.

agentmods badge for codebase-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/mamahoos/dot-files/codebase-design/github.svg)](https://agentmods.dev/skills/mamahoos/dot-files/codebase-design)
Your own site
<a href="https://agentmods.dev/skills/mamahoos/dot-files/codebase-design"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/codebase-design/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.

agentmods 80×15 button for codebase-design

Your own site · 80×15
<a href="https://agentmods.dev/skills/mamahoos/dot-files/codebase-design"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/codebase-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,357 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod 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 5.1 $0.00057 $0.01357
Opus 5 $0.00028 $0.00678
Sonnet 5 $0.00011 $0.00271
Haiku 4.5 $0.00006 $0.00136

Measured 5d ago against content hash c5265b8a8279, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

codebase-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 5d 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.

Origin

This is a copy

100% identical to codebase-design — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

home/.cursor/skills/codebase-design/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codebase Design

Design deep modules: a lot of behaviour behind a small interface, placed at a clean seam, testable through that interface. Use this language and these principles wherever code is being designed or restructured. The aim is leverage for callers, locality for maintainers, and testability for everyone.

Glossary

Use these terms exactly: don't substitute "component," "service," "API," or "boundary." Consistent language is the whole point.

Module: anything with an interface and an implementation. Deliberately scale-agnostic: a function, class, package, or tier-spanning slice. Avoid: unit, component, service.

Interface: everything a caller must know to use the module correctly: the type signature, but also invariants, ordering constraints, error modes, required configuration, and performance characteristics. Avoid: API, signature (too narrow, they refer only to the type-level surface).

Implementation: what's inside a module, its body of code. Distinct from Adapter: a thing can be a small adapter with a large implementation (a Postgres repo) or a large adapter with a small implementation (an in-memory fake). Reach for "adapter" when the seam is the topic; "implementation" otherwise.

Depth: leverage at the interface. The amount of behaviour a caller (or test) can exercise per unit of interface they have to learn. A module is deep when a large amount of behaviour sits behind a small interface, shallow when the interface is nearly as complex as the implementation.

Seam (Michael Feathers): a place where you can alter behaviour without editing in that place; the location at which a module's interface lives. Where to put the seam is its own design decision, distinct from what goes behind it. Avoid: boundary (overloaded with DDD's bounded context).

Adapter: a concrete thing that satisfies an interface at a seam. Describes role (what slot it fills), not substance (what's inside).

Leverage: what callers get from depth. More capability per unit of interface they learn. One implementation pays back across N call sites and M tests.

Read the full file on GitHub · 116 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 5d ago First seen · 116 lines · 57 tokens per session scan A c5265b8a8279

Subscribe to this mod's changes

codebase-design is a skill published in the GitHub repository mamahoos/dot-files (4 stars, last pushed today), licensed MIT. It adds 57 tokens to every session and 1,357 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to codebase-design, differing in 1 line, and is treated as a copy.

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