Lesson Content

Codebase navigation – asking Claude to find things.

In Code mode, Claude Code can read directory structures, search for files, grep for patterns, and follow import chains – without you manually doing any of it. Navigation requests:

• "Where is the authentication middleware applied in this Express app?"
• "Find all the places where the UserProfile type is used"
• "What does the flow look like from the API endpoint to the database for a user creation request?"

These requests produce structural understanding of the codebase – the same understanding a senior engineer builds up over months of context, compressed into a session.

Understanding unfamiliar systems.

When onboarding to a new codebase or a complex feature:

1. Ask Claude Code to describe the high-level architecture of a directory or module
2. Ask it to trace a specific user flow end-to-end through the code
3. Ask it to identify what a specific file or class is responsible for and how it connects to adjacent code
4. Ask it to summarize the most important things to understand about a module before working in it

This produces a working model faster than manual code reading – and you can verify it against the actual code as you go.

Multi-file changes.

For changes that span multiple files, Claude Code can:

• Identify all the files that need to change
• Propose a change plan before making any edits
• Apply changes sequentially and consistently

When requesting a multi-file change, specify: "Before making any edits, tell me which files you will change and what change you will make to each." This produces a change plan you can review before any edits happen – a critical oversight step for broad changes.

Onboarding to new codebases.

A structured Claude Code onboarding session for a new codebase:

1. Run a high-level architecture overview: "Describe the top-level structure of this repository"
2. Trace the main user flow: "Trace the flow from a user login request through to session creation"
3. Identify the conventions: "What naming conventions and patterns do you observe in this codebase?"
4. Find the entry points: "Where would I start if I needed to add a new API endpoint?"

Twenty to thirty minutes with Claude Code can provide the structural context that would otherwise take days of manual reading.