The Two Files That Make Claude Code Actually Useful

When developers first install Claude Code and request assistance with a project, the initial interaction often involves spending several minutes explaining database schemas, API structures, and coding conventions.

The following day, when requesting help again, the same explanations must be repeated. This cycle continues with each new conversation session.

Many developers abandon the tool at this point, concluding that Claude Code doesn't understand their specific project needs. However, the limitation isn't inherent to Claude Code—it's that the two configuration files that enable persistent project memory are not widely known.

Why Claude Code Doesn't Retain Project Context

Each new conversation with Claude Code begins with zero context about a specific project. Without configuration, Claude Code has no knowledge of:

• Database table structures and relationships
• API endpoint patterns and conventions
• Testing frameworks and file locations
• Team naming conventions
• Project-specific file organization

This results in developers repeatedly providing the same project information:

"The database uses PostgreSQL with a users table and posts table. Users have an id, email, and created_at. Posts belong to users through user_id. All API endpoints follow the pattern /api/v1/..."

By the third repetition, 15 minutes of development time has been consumed on context explanation rather than actual development work. Over a week, this overhead accumulates to hours of lost productivity.

While the documentation mentions "context files" in configuration pages, the practical implementation and significance of this feature often goes unnoticed.

The Missing Configuration Layer

Claude Code is designed as a generic tool compatible with any project in any programming language. This universality is powerful, but it means Claude Code cannot make assumptions about specific project configurations.

The observation is that most projects follow stable patterns:

• Database schemas remain relatively constant
• API structure maintains consistency across endpoints
• Testing approaches don't change frequently
• Coding standards stay stable over time

These stable patterns should be persistently available rather than repeatedly explained. However, the default Claude Code installation provides no mechanism for this persistent context storage.

The solution exists in the documentation but is characterized as "optional configuration" rather than "essential setup for effective usage."

The Two Configuration Files

The effective approach involves two files that provide Claude Code with comprehensive project context.

File 1: config.json (30-Second Setup)

Create or edit ~/.claude/config.json with the following configuration:

{
  "contextFiles": [
    "ARCHITECTURE.md",
    "README.md"
  ]
}

This configuration instructs Claude Code to automatically load these files as context in every conversation.

Result: Claude Code begins every conversation with the contents of these files already loaded, eliminating the need for repeated explanations.

File 2: ARCHITECTURE.md (10-Minute Setup)

Create a file named ARCHITECTURE.md in the project root directory. This file documents everything Claude Code should persistently remember about the project.

Template example (customize for specific technology stacks—this example uses React and Node.js, but the pattern applies to Django, Go, Vue, or any other stack):

# Project Architecture

## Tech Stack & Frameworks
**Frontend:**
- React 18 with TypeScript
- Functional components only (no class components)
- Tailwind CSS for styling
- React Query for data fetching

**Backend:**
- Node.js 20 with Express
- TypeScript for type safety
- PostgreSQL 15 for database
- Prisma ORM for database access

**Key Patterns:**
- Repository pattern for data access (keep DB logic in repositories/)
- Async/await throughout (no callbacks)
- Error handling with try/catch and custom error classes
- Input validation with Zod schemas

## Database Schema
**Main tables:**
- users: id, email, name, created_at, subscription_tier
- posts: id, user_id, title, content, published_at
- comments: id, post_id, user_id, content, created_at

**Key relationships:**
- User hasMany Posts (through user_id)
- Post hasMany Comments (through post_id)
- Comment belongsTo User (through user_id)

## API Structure
**Pattern:** /api/v1/{resource}

**Authentication:** JWT token in Authorization header

**Error responses:**
```json
{
  "error": {
    "message": "Description here",
    "code": "ERROR_CODE"
  }
}
```

## Testing
- Unit tests: `src/**/*.test.js`
- Run with: `npm test`
- Always test: authentication, data validation, core features

## Code Standards
- Use async/await (not callbacks)
- Naming: camelCase for functions, PascalCase for classes
- Max function length: 50 lines
- Always handle errors with try/catch

Content Selection Guidelines

Include:

• Technology stack details: Languages, frameworks, versions, and key libraries in active use
• Framework preferences: Patterns the team follows (functional vs class components, ORM vs raw SQL, etc.)
• Database table names and essential columns
• Table relationships and foreign key patterns
• API endpoint naming conventions
• Test file locations and execution commands
• Coding conventions actually enforced in the codebase

Exclude:

• Complete column listings for every table (focus on key columns only)
• Deployment procedures (not relevant to Claude Code's function)
• Detailed business logic (Claude Code can read the actual code)
• Information that changes frequently

Recommended length: under 200 lines. Longer documentation becomes too detailed to be effectively processed.

Observable Improvements

After implementing these configuration files, the interaction pattern changes noticeably:

Claude Code proceeds directly to implementation because database structure and API patterns are already known from the persistent context.

Observed Results in Practice

• Time spent on context explanation: Reduction from 5 minutes per task to approximately 30 seconds
• Incorrect assumptions: Decrease from 3-4 per session to less than 1
• Code matching project conventions: Improvement from approximately 60% to 95%

Additional Benefit: Team Documentation

An unexpected secondary benefit: ARCHITECTURE.md serves as valuable documentation for human developers.

• New developers reference it during onboarding
• It remains current (Claude Code prompts updates when inconsistencies are detected)
• Code reviewers use it as a consistency reference

Implementation Consideration

If ARCHITECTURE.md exceeds 500 lines, Claude Code may not load the complete file. Maintain focus on patterns and structure rather than implementation details to stay within effective length limits.

Implementation Steps

Total time investment: approximately 15 minutes.

1. Create ~/.claude/config.json with the contextFiles configuration (1 minute)
2. Create ARCHITECTURE.md in the project root (10 minutes)
3. Document database tables, API patterns, and testing approach (keep documentation concise)
4. Start a new Claude Code conversation to observe the difference in behavior

The improvement in suggestion quality becomes immediately apparent, with Claude Code providing context-aware recommendations without requiring repeated explanations.