How to Keep Claude Code Consistent Across Files

Introduction

Consistency is the foundation of maintainable code. When every file in your codebase follows the same patterns, uses the same naming conventions, and adheres to the same style, developers can navigate the codebase with confidence. They know what to expect. They can read unfamiliar code quickly because the structure is predictable. They can make changes without wondering if they are following the right conventions.

When working with Claude Code, maintaining this consistency becomes both more important and more challenging. Claude is stateless between sessions. It does not inherently remember the patterns you established yesterday or the naming conventions you prefer. Each interaction starts fresh, and without explicit guidance, Claude will make reasonable but potentially inconsistent choices about how to write your code.

The good news is that Claude excels at following explicit instructions. When you clearly define your conventions and provide examples of what you want, Claude will match those patterns with remarkable fidelity. The challenge is not getting Claude to write consistent code. The challenge is communicating your standards effectively and ensuring those standards persist across files, sessions, and team members.

This article presents a systematic approach to maintaining code consistency when working with Claude Code. You will learn how to define your conventions clearly, provide effective examples, leverage automated tools, review Claude's output efficiently, and maintain consistency across extended projects and teams.

The Inconsistency Problem

Before solving a problem, you need to understand it fully. Code inconsistency when working with Claude Code manifests in several distinct ways, each with its own causes and solutions.

Style Variations Across Files

The most visible form of inconsistency is stylistic variation. In one file, functions might use arrow syntax. In another, traditional function declarations. One component might destructure props in the function signature while another destructures them in the body. One module might use single quotes while another uses double quotes.

These variations often happen because Claude makes reasonable default choices when explicit guidance is missing. Arrow functions and traditional functions are both valid JavaScript. Single and double quotes both work. Without specific instructions, Claude will pick one, and that choice might not match what it picked in a different context.

Naming Convention Drift

Naming conventions are particularly prone to drift. You might establish that event handlers should be named with the prefix "handle" followed by the event type: handleClick, handleSubmit, handleChange. But in a later session, Claude might name a handler onClick or submitForm. Both are reasonable names, but the inconsistency makes the codebase harder to navigate.

This drift often happens because naming conventions are implicit knowledge. You know your project uses handleClick, but unless you tell Claude explicitly, it has no way to know this. It will use whatever naming pattern seems most appropriate for the immediate context.

Architectural Pattern Inconsistencies

More serious than stylistic variations are architectural inconsistencies. Perhaps your project separates business logic into service files and keeps components purely presentational. Claude implements this pattern perfectly in one session, but in a later session without that context, it puts business logic directly in the component. Now you have two different architectural patterns competing in the same codebase.

Architectural inconsistencies are expensive to fix because they require understanding and restructuring code, not just reformatting it. They also create confusion about which pattern is correct, leading to more inconsistency as future code follows whichever pattern the developer encountered most recently.

Documentation Style Differences

Even documentation can become inconsistent. One file might have detailed JSDoc comments on every function. Another might have minimal inline comments. One module might explain the "why" while another only documents the "what." These differences make the codebase feel fragmented and unprofessional.

CLAUDE.md Conventions

The primary tool for maintaining consistency is your CLAUDE.md file. This file is read at the start of every Claude Code session, giving your conventions maximum weight and visibility. A well-structured CLAUDE.md transforms consistency from something you hope for into something you can rely on.

Structure Your Conventions Hierarchically

Organize your conventions from most important to least important. Critical constraints that must never be violated go at the top. Stylistic preferences that have flexibility go lower. This hierarchy helps Claude prioritize when conventions might conflict and helps you maintain the file as it grows.

# Code Standards

## Critical (Never Violate)
- TypeScript strict mode with no any types
- All async functions must have error handling
- No console.log in production code

## Required Patterns
- Use named exports, not default exports
- Prefer composition over inheritance
- Keep functions under 30 lines

## Style Conventions
- camelCase for variables and functions
- PascalCase for components and classes
- SCREAMING_SNAKE_CASE for constants
- Prefix event handlers with "handle": handleClick
- Prefix boolean variables with "is", "has", "can"

## Documentation
- JSDoc comments on all exported functions
- Explain "why" not just "what"
- Include @param and @returns tags

Be Specific and Concrete

Vague conventions lead to inconsistent interpretation. "Write clean code" means different things to different people and different AI sessions. "Functions should be under 30 lines" is unambiguous. "Use descriptive names" is vague. "Variables should describe their purpose: userEmail not e, orderTotal not t" is concrete.

For each convention, ask yourself: could this be interpreted in multiple valid ways? If yes, add more specificity until only one interpretation is possible.

Cover All Domains

Your conventions should address every area where inconsistency might emerge. This typically includes naming conventions for different identifier types, file organization and naming, import ordering and grouping, error handling patterns, logging and debugging approaches, testing conventions, and documentation standards.

# File Organization
- One component per file
- Filename matches component name: UserProfile.tsx
- Group by feature, not by type
- Index files only for public API re-exports

# Import Order
1. External packages (react, lodash, etc.)
2. Internal packages (@company/*)
3. Relative imports (../, ./)
4. Styles and assets
- Blank line between groups
- Alphabetical within groups

# Error Handling
- Use custom error classes extending Error
- Always include error code and user message
- Log errors with context: logger.error(err, { userId, action })
- Never swallow errors silently

# Testing
- Test file next to source: Button.tsx, Button.test.tsx
- Describe blocks mirror component/function structure
- One assertion per test when possible
- Mock external dependencies, not internal modules

Code Examples

Written conventions are essential, but examples are even more powerful. Claude learns patterns exceptionally well from examples. When you show Claude what good code looks like in your project, it will match that pattern more reliably than if you only describe it in words.

Include Reference Files in CLAUDE.md

Point Claude to exemplary files in your codebase. These files serve as living documentation of your conventions, showing not just what the rules are but how they look in practice.

# Reference Examples

When writing code, match the patterns in these files:

- Components: src/components/UserProfile/UserProfile.tsx
- Services: src/services/UserService.ts
- Hooks: src/hooks/useAuth.ts
- Tests: src/components/Button/Button.test.tsx
- API Routes: src/api/users/route.ts

Read these files before implementing similar functionality.

Show Before and After

For conventions that address common mistakes, show both the wrong way and the right way. This contrast makes the convention memorable and helps Claude recognize patterns to avoid.

# Error Handling Examples

WRONG - Swallowing errors:
```typescript
try {
  await saveUser(user);
} catch (e) {
  // Silent failure
}
```

CORRECT - Proper error handling:
```typescript
try {
  await saveUser(user);
} catch (error) {
  logger.error('Failed to save user', {
    userId: user.id,
    error: error.message
  });
  throw new UserSaveError('Could not save user profile', { cause: error });
}
```

Provide Templates for Common Patterns

For recurring patterns like new components, services, or tests, provide complete templates. These templates ensure consistency from the very first line and save Claude from having to infer structure.

# Component Template

All new components should follow this structure:

```typescript
import { type FC } from 'react';
import styles from './ComponentName.module.css';

interface ComponentNameProps {
  // Props with JSDoc comments
}

/**
 * Brief description of what the component does.
 */
export const ComponentName: FC<ComponentNameProps> = ({
  prop1,
  prop2,
}) => {
  // Hooks first
  // Derived state second
  // Event handlers third
  // Render
  return (
    <div className={styles.root}>
      {/* Content */}
    </div>
  );
};
```

Linting and Formatting

Automated tools provide a safety net for consistency that does not depend on memory or attention. Linters catch convention violations. Formatters enforce style automatically. Together, they ensure that even if Claude generates slightly inconsistent code, it gets normalized before it enters your codebase.

Configure Comprehensive Linting

Your linter configuration should encode as many of your conventions as possible. ESLint with TypeScript support can enforce naming conventions, import ordering, code complexity limits, and hundreds of other rules.

module.exports = {
  extends: [
    'eslint:recommended',
    'plugin:@typescript-eslint/strict',
  ],
  rules: {
    // Naming conventions
    '@typescript-eslint/naming-convention': [
      'error',
      { selector: 'variable', format: ['camelCase', 'UPPER_CASE'] },
      { selector: 'function', format: ['camelCase'] },
      { selector: 'typeLike', format: ['PascalCase'] },
    ],

    // Complexity limits
    'max-lines-per-function': ['error', { max: 30 }],
    'complexity': ['error', { max: 10 }],

    // Import organization
    'import/order': ['error', {
      groups: ['builtin', 'external', 'internal', 'parent', 'sibling'],
      'newlines-between': 'always',
      alphabetize: { order: 'asc' },
    }],

    // Error handling
    'no-empty-catch': 'error',
    '@typescript-eslint/no-floating-promises': 'error',
  },
};

Automate Formatting

Prettier or similar formatters eliminate style debates entirely. Configure them once, and every file in your codebase will have consistent indentation, quote style, line length, and spacing. This removes an entire category of potential inconsistency.

{
  "semi": true,
  "singleQuote": true,
  "tabWidth": 2,
  "trailingComma": "es5",
  "printWidth": 100,
  "bracketSpacing": true,
  "arrowParens": "avoid"
}

Tell Claude About Your Tooling

Include your tooling configuration in CLAUDE.md so Claude knows what automated enforcement exists. This helps Claude write code that will pass your checks on the first try.

# Automated Enforcement

This project uses:
- ESLint with @typescript-eslint/strict
- Prettier for formatting
- Husky pre-commit hooks that run both

All code must pass `npm run lint` before commit.

Key enforced rules:
- No any types (use unknown for truly unknown types)
- Functions max 30 lines
- Cyclomatic complexity max 10
- Imports alphabetized and grouped

Run Checks as Part of Your Workflow

After Claude generates code, run your linting and formatting tools before reviewing. This normalizes the output and lets you focus your review on logic and architecture rather than style details. Many developers configure their editors to format on save, making this automatic.

Review Patterns

Even with conventions documented and tools configured, human review remains essential. Review is where you catch the inconsistencies that tools cannot detect: architectural patterns, naming semantics, and adherence to project-specific conventions that are too nuanced to encode in linter rules.

Create a Consistency Checklist

Develop a checklist specifically for consistency review. This checklist should cover the areas where inconsistency is most likely and most damaging. Run through it for every significant piece of code Claude generates.

## Naming
- [ ] Variables follow project naming conventions
- [ ] Functions named consistently with existing similar functions
- [ ] Files named to match their primary export

## Structure
- [ ] File organization matches project patterns
- [ ] Import ordering follows conventions
- [ ] Code grouped logically (hooks, handlers, render)

## Patterns
- [ ] Error handling matches project patterns
- [ ] State management uses project approach
- [ ] API calls follow established patterns

## Documentation
- [ ] JSDoc comments match project style
- [ ] Complex logic explained with comments
- [ ] Public API fully documented

Compare Against Existing Code

When reviewing Claude's output, open a similar existing file side by side. This makes inconsistencies immediately visible. If Claude's new UserSettings component structures things differently than your existing UserProfile component, you will see it instantly.

Request Corrections Explicitly

When you find inconsistencies, do not just fix them yourself. Ask Claude to fix them and explain why. This reinforces the convention in the current session and provides context that helps Claude avoid the same inconsistency in future files.

This component puts the event handlers before the hooks.
Our convention is hooks first, then derived state, then handlers.
Please reorder to match our UserProfile component structure:
1. Hooks (useState, useEffect, custom hooks)
2. Derived values (computed from state/props)
3. Event handlers (handleClick, handleSubmit, etc.)
4. Render

Multi-Session Consistency

Single-session consistency is relatively straightforward. Multi-session consistency is where most projects struggle. Claude does not remember previous sessions, so without explicit mechanisms to carry context forward, each session starts from zero knowledge of what came before.

Use ECOSYSTEM.md for Technical Decisions

Beyond code style, projects accumulate technical decisions that affect consistency: which libraries to use, how to structure certain features, what patterns to follow for specific problem types. Track these in ECOSYSTEM.md and have Claude read it at the start of significant work.

# Technical Decisions

## State Management
- Global state: Zustand (not Redux, not Context)
- Server state: TanStack Query
- Form state: React Hook Form

## API Patterns
- REST endpoints follow /api/v1/{resource} pattern
- Use kebab-case for URL segments
- Return { data, error, meta } envelope

## Component Library
- Use Radix UI primitives for accessibility
- Style with Tailwind CSS
- No CSS-in-JS (styled-components, emotion)

## Data Fetching
- All fetches through src/lib/api.ts client
- Handle loading/error states with Suspense boundaries
- Cache invalidation through query keys

Track Decisions as They Are Made

When you make a decision during development, immediately add it to ECOSYSTEM.md. Do not rely on remembering to add it later. The decision is freshest and most accurate at the moment it is made.

We just decided to use date-fns instead of moment.js
for date handling. Please add this to ECOSYSTEM.md
under a new "Date Handling" section, noting:
- Use date-fns for all date operations
- Reason: smaller bundle size, tree-shakeable
- Store dates as ISO strings in the database

Start Sessions with Context Loading

Begin each significant session by having Claude read the relevant context files. This ensures the session starts with full knowledge of your established patterns and decisions.

Before we begin, please read:
1. CLAUDE.md for code standards
2. ECOSYSTEM.md for technical decisions
3. src/components/UserProfile/UserProfile.tsx as our component reference

Today we are building the settings page. Let me know
when you have reviewed these files.

Team Consistency

When multiple developers use Claude Code on the same project, consistency becomes a team coordination problem. Each developer might have slightly different ways of prompting Claude, leading to subtle variations even with the same CLAUDE.md file.

Share Configuration Files

All Claude-related configuration should be in version control. This includes CLAUDE.md, ECOSYSTEM.md, and any other files that shape Claude's behavior. When one team member updates conventions, everyone gets the update through normal version control workflows.

Document Prompting Patterns

Create a team guide for how to prompt Claude effectively for your project. Share patterns that work well and anti-patterns to avoid. This ensures everyone is working with Claude in a consistent way.

# Team Prompting Guide

## Starting New Features
Always have Claude read CLAUDE.md and ECOSYSTEM.md first.
Point to a reference file for the type of code being written.

## Requesting Code
Be specific about file location and naming:
"Create src/components/Settings/SettingsForm.tsx"
Not: "Create a settings form component"

## Handling Inconsistencies
If Claude generates inconsistent code:
1. Ask Claude to fix it with explicit reference to the convention
2. Update CLAUDE.md if the convention was not clear
3. Share the issue in #claude-learnings Slack channel

## Review Process
All Claude-generated code goes through standard PR review.
Use the consistency checklist in REVIEW.md.

Regular Convention Reviews

Schedule periodic reviews of your convention files. As the project evolves, conventions may need updating. New patterns emerge that should be documented. Old patterns become obsolete. Keep your conventions current with the actual state of your codebase.

Conclusion

Maintaining code consistency when working with Claude Code requires intentional effort, but that effort pays dividends throughout the life of your project. Clear conventions in CLAUDE.md provide the foundation. Concrete examples show Claude exactly what you want. Automated tools catch what slips through. Careful review ensures quality. And documentation in ECOSYSTEM.md carries decisions across sessions and team members.

The key insight is that Claude is not the source of inconsistency. Claude is remarkably good at following patterns when those patterns are clearly communicated. Inconsistency emerges when communication is unclear, incomplete, or forgotten across sessions. By treating your conventions as first-class project artifacts, maintaining them with the same care as your code, and establishing workflows that ensure they are always present in Claude's context, you can achieve consistency that rivals or exceeds what human-only teams accomplish.

Start with your most critical conventions. Document them in CLAUDE.md. Add examples. Configure your linter. Review with intention. Then expand gradually, adding conventions as you discover new areas where consistency matters. Over time, you will build a comprehensive system that makes consistency automatic rather than effortful.