SKILL GUIDE
Understanding Codebases
Build an evidence-based map of an unfamiliar repository. Find entry points, trace data flow, and identify the right change surface before editing.
understanding-codebasesOn this page
When to use it
- You are joining an unfamiliar repository or subsystem.
- You need to understand how a feature works across modules.
- You want to locate the files and tests relevant to a future change.
Workflow
Establish the repository shape
Inspect the stack, important directories, build configuration, and project instructions. Start broad, then narrow the investigation.
Confirm entry points and boundaries
Follow actual imports, calls, and runtime wiring rather than inferring responsibilities from folder names.
Trace the requested behavior
Follow control and data from the visible entry point through services, persistence, and integrations. Record relevant files and symbols.
Inspect adjacent implementations and tests
Search related domain terms and interfaces. Use tests and configuration as evidence about intended behavior.
Produce a working map
Explain the stack, structure, execution flow, conventions, and likely change surface. Separate observations, inferences, and unknowns.
Practical use cases and prompts
Understanding an unfamiliar repository
You have inherited a repository and need to understand how requests reach storage before making changes.
Use understanding-codebases. Trace one main request from its entry point through business logic to persistence. Cite the relevant files and symbols, identify tests and conventions, and separate facts from assumptions. Do not edit code.Expected output: A focused repository map, request flow, key files, and a list of unresolved questions.
Locate a feature before changing it
A requested behavior spans several modules and its implementation is not obvious.
Use understanding-codebases. Find how this project implements authentication, including entry points, runtime wiring, state, and tests. Identify the likely change surface for adding a new sign-in method. Do not implement it yet.Expected output: An evidence-based authentication flow and the smallest likely set of files to change.
Trace an event across services
An event is produced in one module and handled elsewhere.
Use understanding-codebases. Trace the event discussed in this task from producer to definition, dispatcher, consumers, and downstream actions. Check actual wiring and tests. Report what is observed and what remains unknown without editing files.Expected output: A producer-to-consumer flow with source references, dependencies, and uncertainties.
Expected outputs
- A concise codebase map with important files, symbols, and their responsibilities.
- An execution and data-flow explanation supported by repository evidence.
- Relevant tests, conventions, likely change locations, and unresolved questions.
Requirements and optional helpers
- A coding agent with Agent Skills support and permission to read the target repository.
- Repository search and shell access are recommended. Investigation stays read-only unless implementation is explicitly requested afterward.
Repository inspector
Optional inspect-project.mjs inventories root-level project indicators. It needs Node.js 18+ and accepts --root for the target repository; it does not establish semantic architecture or complete workspace coverage.
Installation
Open a terminal in your target project and install this package. Project scope is the default; choose your agent when prompted.
npx skills add https://github.com/GiovanniL30/ai-skills/tree/main/skills --skill understanding-codebasesRefresh your agent session, confirm the skill is available, and give it a concrete task. Keep the whole package, including references and helpers.
Choose an agent and installation scope →Source and focused references
This guide summarizes the original package. Read its complete workflow and supporting references on GitHub.
Read the original SKILL.md ↗