codebase-study-guide

A skill that creates a teaching-oriented guide to an unfamiliar codebase. A codebase is the collection of source code and related project files that make up a software project.

In plain words
What is it for?
Creating developer onboarding material, explaining project architecture, preparing team learning guides, and studying an existing codebase.
Why use it?
It helps new contributors understand how a project is organised and how its parts fit together, instead of learning by guessing from individual files.

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/petekp/agent-skills/codebase-study-guide
Any agent
npx skills add petekp/agent-skills --skill codebase-study-guide
Clone the repo
git clone --depth 1 https://github.com/petekp/agent-skills

Made for: Claude Code, Codex.

Per session 131 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,521 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00131 $0.01521
Opus 5 $0.00066 $0.00760
Sonnet 5 $0.00026 $0.00304
Haiku 4.5 $0.00013 $0.00152

Measured yesterday against content hash 7a36900b8822, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-study-guide 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 yesterday.

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.

skills/codebase-study-guide/SKILL.md · 125 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

2 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. yesterday First seen · 125 lines · 131 tokens per session scan A 7a36900b8822

Subscribe to this mod's changes

codebase-study-guide is a skill published in the GitHub repository petekp/agent-skills (7 stars, last pushed 2mo ago), with no licence file. It adds 131 tokens to every session and 1,521 once invoked, about $0.0007 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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