What is onboarding-codebase?

A phased codebase analysis that creates navigation and onboarding documents for a software repository. It writes notes about the project structure, boundaries, domain, and quick references without changing source code.

Use it when joining a project, refreshing stale onboarding material, or asking to analyse a codebase. It writes documents under .cursor/onboarding-docs/ and adds a pointer from the root AGENTS.md file.

It gives someone new to a repository a map of where things are and how the code is organised. This reduces the time needed to understand an unfamiliar project before making changes.

How GoranErhartic/backend-onboarding configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to GoranErhartic/backend-onboarding. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/GoranErhartic/backend-onboarding/master/.agents/skills/onboarding-codebase/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/GoranErhartic/backend-onboarding

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/goranerhartic/backend-onboarding/onboarding-codebase/github.svg)](https://agentmods.dev/skills/goranerhartic/backend-onboarding/onboarding-codebase)

Your own site

<a href="https://agentmods.dev/skills/goranerhartic/backend-onboarding/onboarding-codebase"><img src="https://agentmods.dev/badge/skills/goranerhartic/backend-onboarding/onboarding-codebase/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/goranerhartic/backend-onboarding/onboarding-codebase"><img src="https://agentmods.dev/badge/skills/goranerhartic/backend-onboarding/onboarding-codebase.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 1,401 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.

Model	Per session	Once invoked
Fable 5.1	$0.00061	$0.01401
Opus 5	$0.00030	$0.00700
Sonnet 5	$0.00012	$0.00280
Haiku 4.5	$0.00006	$0.00140

Measured yesterday against content hash 9326f88b80fe, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

onboarding-codebase 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.

.agents/skills/onboarding-codebase/SKILL.md · 144 lines

How it starts

The opening of the file, as written. The whole thing — 144 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Onboarding Codebase

Orchestrates 6-step codebase analysis. Writes agent-optimized docs to .cursor/onboarding-docs/ and, during the final step, adds an idempotent pointer to them in the target project's root AGENTS.md. Does not modify source code.

When to use

New repo onboarding or refreshing stale onboarding docs
User says /onboard, "analyze this codebase", or "generate onboarding docs"

Shared rules

Read references/boilerplate.md before any step.

Step reference

Phase	Step ID	Reference	Output
0	`init`	`references/steps/init.md`	Manifest, `PROJECT_MAP.txt`, `EVENT_DRIVEN_STATUS.json`
1	`discover`	`references/steps/discover.md`	`NAVIGATION.md`
1	`structure`	`references/steps/structure.md`	`STRUCTURE.md`
1	`boundaries`	`references/steps/boundaries.md`	`BOUNDARIES.md`
2	`domain`	`references/steps/domain.md`	`DOMAIN.md`
3	`index`	`references/steps/index.md`	`QUICK_REFERENCE.md`, `REFERENCE_METADATA.json`

Phase 1 steps run in parallel via Task subagents.

Orchestration workflow

1. Assess state

Read references/boilerplate.md.
Follow its Project Agent Instructions protocol before inspecting the workspace or deciding which steps to skip.
If .cursor/onboarding-docs/CURSOR-ONBOARDING.md exists, refresh only its Project Agent Instructions path-and-scope index when the discovered set changes, then Read it and parse Step Completion Status.
Build execution plan from status:
- [x] → skip
- [P] → report in-progress; do not duplicate (wait or ask user)
- [E] → retry that step
- [ ] → schedule

2. Phase 0 — init (sequential)

If init is not [x]:

Execute references/steps/init.md directly (parent agent) or launch one Task:

Read references/boilerplate.md and references/steps/init.md in the
onboarding-codebase skill. Follow Project Agent Instructions before
exploring the target workspace. Write only to .cursor/onboarding-docs/.
Mark init [P] then [x] in CURSOR-ONBOARDING.md (only that line).
Return: files written, counts, errors.

Re-read manifest. If init is [E] or still [ ], stop and report.

Read the full file on GitHub · 144 lines

Files

What ships with it

10 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.

yesterday First seen · 144 lines · 61 tokens per session scan A 9326f88b80fe

Subscribe to this mod's changes

onboarding-codebase is a skill published in the GitHub repository GoranErhartic/backend-onboarding (11 stars, last pushed yesterday), licensed MIT. It adds 61 tokens to every session and 1,401 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 2026-09-11.

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backend-onboarding: Skill for Claude Code