codebase-onboarding

codebase-onboarding is a skill for Claude Code from kumaran-is/claude-code-onboarding. It costs 61 tokens per session (2,180 once invoked), scanned A, original, MIT.

A structured guide for examining an unfamiliar codebase and producing an architecture map, key entry points, coding conventions, and a tailored CLAUDE.md file. A codebase is the complete collection of files that make up a software project.

In plain words
What is it for?
Use it when joining a project, analyzing a client repository, or creating or updating its CLAUDE.md onboarding instructions.
Why use it?
It reduces the time needed to understand a new repository and helps prevent incorrect documentation based only on filenames or assumptions.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions CLAUDE.md; mentions Claude Code.

Good fit Use it when joining a project, analyzing a client repository, or creating or updating its CLAUDE.md onboarding instructions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kumaran-is/claude-code-onboarding/codebase-onboarding
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 kumaran-is/claude-code-onboarding --skill codebase-onboarding
Clone the repo
git clone --depth 1 https://github.com/kumaran-is/claude-code-onboarding

Made for: Claude Code.

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-onboarding

README.md
[![agentmods](https://agentmods.dev/badge/skills/kumaran-is/claude-code-onboarding/codebase-onboarding/github.svg)](https://agentmods.dev/skills/kumaran-is/claude-code-onboarding/codebase-onboarding)
Your own site
<a href="https://agentmods.dev/skills/kumaran-is/claude-code-onboarding/codebase-onboarding"><img src="https://agentmods.dev/badge/skills/kumaran-is/claude-code-onboarding/codebase-onboarding/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-onboarding

Your own site · 80×15
<a href="https://agentmods.dev/skills/kumaran-is/claude-code-onboarding/codebase-onboarding"><img src="https://agentmods.dev/badge/skills/kumaran-is/claude-code-onboarding/codebase-onboarding.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,180 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 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 5.1 $0.00061 $0.02180
Opus 5 $0.00030 $0.01090
Sonnet 5 $0.00012 $0.00436
Haiku 4.5 $0.00006 $0.00218

Measured 6d ago against content hash ed9ce5056398, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

codebase-onboarding 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 6d 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.

.claude/skills/codebase-onboarding/SKILL.md · 229 lines

How it starts

The opening of the file, as written. The whole thing — 229 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Iron Law: Read actual files before making any claims about the codebase. Never infer stack from directory names alone — read the config files. A wrong CLAUDE.md is worse than no CLAUDE.md.

Codebase Onboarding Skill

Systematically maps an unfamiliar codebase in 4 phases, then generates two artifacts: a structured Onboarding Guide and a tailored CLAUDE.md.

When to Use

  • Opening a new client project with Claude Code for the first time
  • Joining a new team repository
  • User asks "onboard me", "analyze this codebase", "generate a CLAUDE.md"
  • Updating an existing CLAUDE.md to reflect current project state

Four-Phase Analysis Workflow

Phase 1: Reconnaissance (read config files, not source)

Gather signals without reading all source files. Run these in sequence:

# 1. Package manifest detection
ls pom.xml package.json pyproject.toml pubspec.yaml angular.json go.mod Cargo.toml Gemfile 2>/dev/null

# 2. Framework fingerprinting — read the detected manifests
cat pom.xml 2>/dev/null | grep -E "<artifactId>spring-boot|webflux|r2dbc" | head -5
cat package.json 2>/dev/null | grep -E "@nestjs/core|@angular/core|fastify|prisma" | head -5
cat pyproject.toml 2>/dev/null | grep -E "fastapi|langchain|langgraph" | head -5
cat pubspec.yaml 2>/dev/null | grep -E "^name:|flutter:|riverpod|go_router" | head -5

# 3. Entry point identification
ls src/main/java 2>/dev/null || ls src/app 2>/dev/null || ls lib/main.dart 2>/dev/null || ls main.py 2>/dev/null

# 4. Directory snapshot (top 2 levels, ignore noise)
find . -maxdepth 2 -type d \
  ! -path "*/node_modules/*" ! -path "*/.git/*" ! -path "*/build/*" \
  ! -path "*/dist/*" ! -path "*/.dart_tool/*" ! -path "*/target/*" \
  ! -path "*/__pycache__/*" ! -path "*/.gradle/*" 2>/dev/null | sort

# 5. CI/CD and tooling detection
ls .github/workflows/ Dockerfile docker-compose*.yml .env.example 2>/dev/null

Stack fingerprint → skill mapping:

Detected Stack Load Skill
pom.xml + spring-boot Java 21 / Spring Boot 3.5.x WebFlux java-spring-api
package.json + @nestjs/core NestJS 11.x / Fastify / Prisma nestjs-api
pyproject.toml + fastapi Python 3.14 / FastAPI 0.135.2 python-dev
pyproject.toml + langchain/langgraph Agentic AI / LangGraph agentic-ai-dev
angular.json Angular 21.x / daisyUI angular-spa
pubspec.yaml + flutter: Flutter 3.41.x / Dart 3.10.9 flutter-mobile

Read the full file on GitHub · 229 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. 6d ago First seen · 229 lines · 61 tokens per session scan A ed9ce5056398

Subscribe to this mod's changes

codebase-onboarding is a skill published in the GitHub repository kumaran-is/claude-code-onboarding (35 stars, last pushed 2mo ago), licensed MIT. It adds 61 tokens to every session and 2,180 once invoked, about $0.0003 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 2026-09-03.

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