How to Code Better with Claude Code (2026)

How to Code Better with Claude Code (2026)

Claude Code is Anthropic's command-line tool that brings Claude directly into your terminal and codebase. It can read your files, write code, run commands, manage git workflows, and handle complex multi-file refactors -- all from a single terminal session. But like any powerful tool, your results depend heavily on how you use it.

This guide covers practical tips, prompt techniques, and workflows that will help you get significantly better results from Claude Code, whether you are using it for greenfield development, debugging, refactoring, or learning a new codebase.

Setting Up for Success

Before writing a single prompt, invest time in setting up your environment properly. This has a bigger impact on output quality than most prompt engineering techniques.

Create a CLAUDE.md File

The CLAUDE.md file is the single most important configuration you can create. It sits in your project root and provides persistent context that Claude Code reads at the start of every session.

# CLAUDE.md

## Project Overview
This is a Next.js 15 application using TypeScript, Tailwind CSS, and Prisma ORM with PostgreSQL.

## Tech Stack
- Next.js 15 (App Router)
- TypeScript 5.6 (strict mode)
- Tailwind CSS 4.0
- Prisma ORM 6.x with PostgreSQL
- NextAuth.js v5 for authentication
- Zod for validation

## Code Conventions
- Use named exports, not default exports
- All components are functional with TypeScript interfaces for props
- API routes use Route Handlers in app/api/
- Database queries go through service files in src/services/
- Error handling uses custom AppError class from src/lib/errors.ts

## Commands
- `npm run dev` - Start development server
- `npm run build` - Production build
- `npm run test` - Run test suite with Vitest
- `npm run lint` - ESLint + Prettier check
- `npx prisma migrate dev` - Run database migrations

## Important Patterns
- All API responses use the standard format: { success: boolean, data?: T, error?: string }
- Authentication checks use the getServerSession() helper
- File uploads go to S3 via the uploadFile() helper in src/lib/storage.ts

Claude Code reads this file automatically. The more specific your conventions and patterns, the better the generated code matches your project's style.

Configure Permission Modes

Claude Code has three permission modes that control how much autonomy you give it:

Mode	File Edits	Command Execution	Best For
default	Asks permission	Asks permission	Learning, reviewing changes
plan	Read-only	Read-only	Architecture analysis, code review
auto-edit	Auto-approved	Asks permission	Rapid development, refactoring

For active coding, auto-edit mode is the most productive:

claude --permission-mode auto-edit

For code review and analysis, use plan mode:

claude --permission-mode plan "review this PR for potential bugs"

Prompt Techniques That Work

1. Be Specific About What You Want

Vague prompts produce vague results. Compare these:

Bad:

Make the auth better

Good:

Add rate limiting to the POST /api/auth/login endpoint. Limit to 5 attempts per IP
address per 15 minutes. Use the existing Redis client in src/lib/redis.ts. Return a
429 status with a Retry-After header when the limit is exceeded.

The good prompt specifies: the endpoint, the limit, the time window, the technology to use, and the expected error behavior.

2. Reference Existing Code

Claude Code can read your files, so tell it where to look:

Look at how the user service in src/services/user.service.ts handles CRUD operations.
Create a new src/services/project.service.ts following the exact same patterns for
the Project model defined in prisma/schema.prisma.

This is far more effective than describing patterns from scratch because Claude Code will read the referenced files and replicate the patterns exactly.

3. Break Large Tasks into Steps

Instead of asking Claude Code to build an entire feature in one prompt, break it into logical steps:

Step 1: Create the Prisma schema for a "Comment" model with fields: id, content,
authorId (relation to User), postId (relation to Post), createdAt, updatedAt.
Run the migration.

Step 2: Create src/services/comment.service.ts with create, findByPostId, update,
and delete functions following the pattern in user.service.ts.

Step 3: Create the API routes at app/api/posts/[postId]/comments/route.ts with
GET and POST handlers. Use the auth middleware pattern from the existing routes.

Step 4: Write Vitest tests for the comment service in tests/services/comment.test.ts.

You can either send these as four separate prompts or as a single numbered list. Claude Code handles both approaches well, but separate prompts give you a chance to review each step before moving on.

4. Use the "Look at X, then do Y" Pattern

This pattern consistently produces high-quality results:

Read the test file at tests/services/user.test.ts. Understand the testing patterns,
mocking approach, and assertion style. Then write equivalent tests for the project
service at src/services/project.service.ts.

Look at the error handling in src/middleware/error-handler.ts. Then add the same
error handling pattern to all API routes in app/api/projects/.

5. Ask Claude Code to Explain Before Implementing

For complex changes, ask for a plan first:

I need to add WebSocket support for real-time notifications. Before writing any code,
explain your approach: which files you would create or modify, which libraries you
would use, and how it integrates with the existing NextAuth session.

Review the plan, adjust it if needed, then tell Claude Code to proceed.

Effective Workflows

Debugging Workflow

When you hit a bug, provide the error and context:

I am getting this error when I submit the form on /settings/profile:

TypeError: Cannot read properties of undefined (reading 'email')

The error is in src/app/settings/profile/page.tsx. The form submission calls
the updateProfile server action in src/actions/profile.ts.

Find the bug and fix it.

Claude Code will read both files, trace the data flow, find the issue, and apply a fix. This is where auto-edit mode shines -- it can fix the code and run your tests in a single flow.

Refactoring Workflow

For refactors, be explicit about scope:

Refactor all API route handlers in app/api/ to use the new withAuth() higher-order
function from src/lib/auth-middleware.ts instead of manually calling getServerSession()
in each handler. Do not change any business logic, only the auth pattern.

Claude Code will find every file that needs changing, apply the transformation consistently, and preserve the existing logic.

Code Review Workflow

Use plan mode for reviewing code:

git diff main...HEAD | claude -p "Review these changes. Focus on:
1. Security issues
2. Performance concerns
3. Missing error handling
4. TypeScript type safety
Provide specific file names and line numbers for each issue."

Learning a New Codebase

Claude Code is excellent for understanding unfamiliar code:

Give me a high-level architecture overview of this project. What are the main
directories and their purposes? What is the request flow from an HTTP request
to a database query?

Follow up with specific questions:

How does authentication work in this project? Trace the flow from login
to an authenticated API request.

Common Mistakes to Avoid

1. Not Using CLAUDE.md

Without a CLAUDE.md file, Claude Code guesses your conventions. It might use default exports when you use named exports, or pick a different testing library than the one your project uses. Always create this file.

2. Accepting Changes Without Review

Even in auto-edit mode, review the changes before committing. Use /diff to see what Claude Code modified, or run your test suite after each change.

3. Over-Prompting

You do not need to explain basic programming concepts. Claude Code knows how to write Python, JavaScript, SQL, and most other languages. Focus your prompts on project-specific context and requirements, not general programming instructions.

Too much:

Write a Python function. Remember that Python uses indentation for blocks. Use the
def keyword to define functions. Make sure to add a return statement.

Just right:

Add a deduplicate_records() function to src/utils/data.py that takes a list of
dicts and removes duplicates based on the 'id' field, keeping the most recently
updated record (by 'updated_at' field).

4. Not Using /compact

Long conversations accumulate context and increase token usage. Use /compact periodically to compress the conversation history while preserving key information:

/compact

This is especially important during long development sessions where you have discussed many files and changes.

Useful Commands Reference

Command	What It Does
/diff	Show all pending file changes
/cost	Display token usage and cost for the session
/compact	Compress conversation history to reduce tokens
/clear	Clear conversation history entirely
/model	Switch to a different Claude model
/mcp	List connected MCP servers
/review	Ask Claude to review its own recent changes

Performance Tips

Use Specific File Paths

Instead of:

Fix the button component

Use:

Fix the disabled state styling in src/components/ui/Button.tsx

Specific paths help Claude Code find the right file immediately instead of searching.

Batch Related Changes

If you need to make similar changes across multiple files, describe them in one prompt:

Add input validation using Zod schemas to all three route handlers:
- app/api/users/route.ts
- app/api/projects/route.ts
- app/api/comments/route.ts

Use the existing schemas from src/lib/validations/ if they exist, or create
new ones following the same pattern.

Use Pipe Mode for Quick Tasks

For one-off tasks that do not need an interactive session:

claude -p "Write a SQL query that finds all users who signed up in the last 30 days but have not created any projects"

cat package.json | claude -p "Are there any outdated or deprecated dependencies?"

Conclusion

The biggest productivity gains from Claude Code come not from clever prompts, but from good setup: a detailed CLAUDE.md file, consistent project conventions, and the right permission mode for each task. Once the foundation is in place, be specific in your prompts, reference existing code patterns, and break large tasks into reviewable steps.

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