Generate Comprehensive Codebase Onboarding Guides

This skill generates two complementary onboarding documents from a codebase, invoked via the /deep-wiki:onboard command, together covering engineers from newcomer to principal level. It first detects the repository's primary language from its build files (package.json/tsconfig.json for TypeScript/JavaScript, .csproj/.sln for C#/.NET, Cargo.toml for Rust, pyproject.toml/setup.py/requirements.txt for Python, go.mod for Go, pom.xml/build.gradle for Java) so all code examples match the actual stack.

The first document, a Principal-Level Onboarding guide for senior/staff+ engineers, requires twelve sections centered on the "why" behind decisions: system philosophy and invariants, an architecture overview with a component-map Mermaid diagram, the load-bearing key abstractions everything depends on, a decision log with alternatives considered and tradeoffs, dependency rationale (why each major dependency was chosen and what it replaced), data flow traced from actual code rather than guessed, failure modes and error propagation, performance characteristics and bottlenecks, the security model (auth, trust boundaries, data sensitivity), testing strategy including what's NOT tested, operational concerns (deployment, monitoring, feature flags), and an honest accounting of known technical debt. Every claim must carry a (file_path:line_number) citation, and the guide requires a minimum of three Mermaid diagrams (architecture, data flow, dependency graph) rendered in dark-mode colors.

The second document, a Zero-to-Hero Contributor Guide for new contributors, requires fourteen sections built around practical step-by-step guidance: a 2-3 sentence elevator pitch, prerequisites, environment setup with exact copy-pasteable commands and expected output at each step, an annotated project structure, an end-to-end first-task walkthrough, the development workflow (branching, commit conventions, PR process), how to run and add tests, a debugging guide for common issues, key domain concepts with code examples, reusable "if you want to add X, follow this pattern" code templates, common new-contributor pitfalls, where to get help, a glossary, and a quick-reference command cheat sheet - again grounded in (file_path:line_number) citations and dark-mode Mermaid diagrams for workflows.

Use this skill when a user asks for onboarding docs or a getting-started guide, runs the /deep-wiki:onboard command, or wants to help new team members understand a codebase - producing both the deep architectural rationale a senior engineer needs and the concrete step-by-step path a newcomer needs, rather than a single document trying to serve both audiences.

It is a codebase-grounded documentation generator specifically - every claim is tied to a real file/line citation, so it's not suited to documenting a system that hasn't been implemented yet or producing purely aspirational architecture docs.

Input is a repository to onboard someone onto. Output is two documents: a Principal-Level Onboarding guide (12 sections, 3+ Mermaid diagrams, decision-log style) and a Zero-to-Hero Contributor Guide (14 sections, copy-pasteable commands, glossary, cheat sheet), both citing (file_path:line_number) for every claim and using the detected primary language for code examples.

Generates Mermaid diagrams using dark-mode colors per a companion wiki-vitepress skill's convention, and detects language/framework from standard build manifest files across TypeScript/JavaScript, C#/.NET, Rust, Python, Go, and Java ecosystems.

Teams onboarding both senior engineers, who need architectural rationale and tradeoffs, and new contributors, who need a concrete step-by-step path, onto an existing codebase, wanting both documents grounded in the actual code rather than written from memory or assumption.