Agent skill · research science · github
doc-and-modernize
Two related workflows for a locally-cloned codebase, in one skill. Documentation mode produces a single, comprehensive, verifiable architecture document primarily by reading files on disk (local-first) — use it whenever the user wants to understand, map, document, research, or onboard onto a codebase ("research this repo", "write up the architecture", "do an architecture deep dive", "document how this codebase works", "map the system design", "create an onboarding doc"). Modernization mode generates a phased plan to modernize, migrate, upgrade, or rewrite a legacy system ("modernize this", "plan the migration", "how would we rewrite this", "how do we get off this legacy stack"); if no architecture document exists yet it first runs Documentation mode, then continues straight through to the plan. It assumes the legacy stack may be dead, runs a time-boxed feasibility spike, and picks the highest achievable rung on a safety ladder instead of demanding a fully-green legacy CI gate up front.
Why this skill is useful
Generates a comprehensive architecture document and modernization plan that the AI wouldn't reliably create on its own.
What it needs
About 12k tokens when loaded. Last updated 2026-08-07. 37,534 stars on the source repository.
What this skill does
Documentation & Modernization Two complementary workflows for a repository the user already has checked out locally, bundled as one skill: Documentation mode — produce one definitive, cited architecture document from the code on disk. Ideal for onboarding, system-design maps, or as the evidence base for a modernization effort. Modernization mode — turn that architecture into a phased, safety-laddered plan to upgrade, migrate, or rewrite a legacy system. Mode selection If the user wants to understand, document, map, research, or onboard onto a codebase, run Documentation mode. If the user wants to modernize, migrate, upgrade, or rewrite a system, run Modernization mode. Modernization mode is self-sufficient: if no architecture document exists yet, it runs the Documentation mode workflow first (in the same pass), then continues straight through to the plan. When in doubt, produce the architecture document first — it is the audited evidence base both modes rely on. Documentation mode Generate one definitive, cited architecture document for a repository the user already has checked out locally. The goal is a writeup someone could hand to a new engineer as their onboarding reference — broad enough to cover the whole system, deep enough on the hard parts to be useful, and trustworthy because every claim traces back to a file on disk. Why local-first Reading from the local checkout (not the GitHub API or the web) is the deliberate default. It is faster, free, avoids rate limits, and — most importantly — it describes the exact code in front of you rather than whatever main happens to look like remotely. The one tradeoff is that remote-only facts (star counts, full CI run history, sibling repos) aren't visible. That's fine: state those as out-of-scope or mark them [UNVERIFIED] rather than guessing. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills github/doc-and-modernize