Context Patterns

Context Patterns

Context is the secret sauce of AI-powered development. Master these patterns to transform vague AI responses into precise, production-ready code. Learn to provide just enough context - not too little, not too much.

Understanding Context Windows

What is a Context Window?

• Token Limit: Models process ~128k tokens (≈10,000 lines of code)
• Quality vs Quantity: More context ≠ better responses
• Cost Factor: Larger context = higher API costs
• Response Time: More context = slower responses

Context Impact on Quality

Context Quality	AI Response	Developer Time
Too Little	Generic, wrong assumptions	High rework
Just Right	Precise, aligned with codebase	Minimal edits
Too Much	Confused, slow, expensive	Debugging AI

Core Context Patterns

Surgical Context

Precise, focused context for specific tasks

Layered Context

Build context progressively for complex tasks

Semantic Context

Use AI to find relevant context automatically

Compressed Context

Reduce token usage while maintaining meaning

Pattern 1: Surgical Context

When to Use

• Quick fixes and small changes
• Performance-critical operations
• Clear, isolated problems

Implementation

# Bad: Kitchen Sink Approach
@folder src/  # 50,000 lines included
Fix the login bug

# Good: Surgical Precision
@file src/auth/login.ts
@file src/auth/validation.ts
@code validateEmail  # specific function
Fix the email validation rejecting valid addresses with + symbols

Real-World Example

JavaScript

// Context: Only these specific items
@file utils/validation.js
@code EMAIL_REGEX
@code validateEmail

// Prompt
Update email validation to accept plus addressing (user+tag@domain.com)
Keep existing validation for other rules

Python

# Context: Focused on the issue
@file validators/email.py
@code EmailValidator.__init__
@code EmailValidator.validate

# Prompt
Add support for subaddressing (+ tags) in email validation
Maintain RFC 5322 compliance

Pattern 2: Layered Context Building

The Onion Approach

Start narrow, expand as needed:

1. Core Layer: The exact code/file with the issue
2. Integration Layer: Directly connected code
3. System Layer: Architecture and patterns
4. Domain Layer: Business rules and requirements

Example: Adding Payment Feature

## Layer 1: Core Focus
@file models/Order.ts
@file models/Payment.ts

Task: Add payment processing to orders

## Layer 2: Add Integration Context
@file services/PaymentService.ts
@file api/payments/webhook.ts

## Layer 3: Add System Context
@folder lib/payments/
@code PaymentProvider interface

## Layer 4: Add Domain Context
@file docs/payment-requirements.md
@docs Stripe integration guide

Pattern 3: Semantic Context Gathering

Let AI help you find relevant context:

The Discovery Pattern

# Step 1: Ask AI to find context
"What files and functions handle user authentication in this codebase?"

# Step 2: Review AI findings
# AI responds with: auth/, middleware/auth.ts, utils/jwt.ts

# Step 3: Use findings as context
@file auth/login.ts
@file middleware/auth.ts
@code generateJWT

"Add two-factor authentication to the login flow"

Smart Context Queries

Query Type	Example	Use Case
Architecture	”Show me all Redux actions”	Understanding patterns
Dependencies	”What calls UserService?”	Impact analysis
Similar Code	”Find pagination implementations”	Consistency
Error Patterns	”Where do we handle API errors?”	Error handling

Pattern 4: Context Compression

Techniques to Reduce Token Usage

1. Summary Files

.cursor/summaries/auth-system.md

## Authentication System Overview
- JWT-based auth with refresh tokens
- Roles: admin, user, guest
- Session timeout: 24h
- Password requirements: 8+ chars, 1 special

Key files:
- auth/login.ts - Main login flow
- auth/jwt.ts - Token generation
- middleware/auth.ts - Route protection

2. Interface Extraction

// Instead of including entire implementation files
@file types/auth.d.ts  // Just interfaces
@file api/auth/routes.ts  // Just route definitions

3. Selective Inclusion

# Include only public methods
@code "class UserService" "public"
@code "export function" auth/utils.ts

Advanced Context Patterns

Multi-Repository Context

# Working across multiple repos
@folder ../shared-components/Button
@file ../api-server/src/endpoints/user.ts
@web https://api-docs.company.com/users

Ensure Button component matches API response structure

Historical Context

# Include relevant history
@git PR #1234  # Previous implementation
@git commit abc123  # When feature was added
@docs decisions/adr-auth.md  # Architecture decision

Refactor auth to address issues from PR #1234

Dynamic Context

# Context that changes based on task
{{if FEATURE_FLAGS}}
  @file config/features.ts
  @code getFeatureFlag
{{/if}}

{{if DATABASE_CHANGE}}
  @file prisma/schema.prisma
  @folder migrations/
{{/if}}

Context Anti-Patterns to Avoid

Caution

Common Context Mistakes:

1. The Dump Truck

   @folder src/  # 100,000 lines
   Fix the bug somewhere in here

2. The Time Traveler

   @file old-implementation.backup.js
   @file new-implementation.js
   @file newer-implementation.js
   # Confusing AI with multiple versions

3. The Mind Reader

   Fix the thing we discussed
   # No context about "the thing"

4. The Noise Machine

   @file package-lock.json  # 30,000 lines
   @folder node_modules/  # Why???

Measuring Context Effectiveness

Context Quality Metrics

Metric	Good Context	Poor Context
Token Usage	5-15k tokens	50k+ tokens
Response Time	2-5 seconds	20+ seconds
Accuracy	90%+ correct	under 70% correct
Iterations Needed	1-2	5+

Context Optimization Checklist

• Relevance: Every file/symbol directly relates to task
• Completeness: All necessary context included
• Clarity: Clear relationship between context items
• Efficiency: Minimal tokens for maximum understanding
• Currency: Using latest versions of files

Technology-Specific Context Patterns

React/Next.js

Component Development Context

# Minimal context for new component
@file components/ui/Button.tsx  # Pattern reference
@file styles/theme.ts  # Design system
@code useTheme hook  # Theme integration

Create Card component following Button patterns

State Management Context

# Redux/Zustand context pattern
@folder store/slices/  # See patterns
@file store/types.ts  # Type definitions
@code specific slice only

Node.js/Express

API Endpoint Context

# RESTful endpoint context
@file routes/users.js  # Pattern reference
@file middleware/auth.js  # Auth pattern
@file validators/user.js  # Validation
@code specific route only

Add DELETE /users/:id endpoint

Database Context

# Minimal DB context
@file models/User.js  # Schema only
@code specific query functions
@file db/migrations/latest.sql

Python

Class Development Context

# Python class context
@file models/base.py  # Base patterns
@code AbstractModel class
@file models/user.py  # Example

Create Product model following patterns

Testing Context

# Test context pattern
@file tests/test_user.py  # Test patterns
@file src/user.py  # Implementation
@code specific test class

Context Pattern Workflows

Workflow 1: Bug Investigation

1. Start with error context
   @error "TypeError: Cannot read property 'name'"
   @file src/components/UserCard.tsx

2. Expand to data flow
   @code getUserData
   @file api/users.ts

3. Add type context if needed
   @file types/User.ts

Workflow 2: Feature Implementation

1. Requirements context
   @file specs/feature-x.md
   @figma design-link

2. Pattern context
   @file similar-feature.ts
   @folder patterns/

3. Integration context
   @file routes/index.ts
   @file types/index.ts

Workflow 3: Refactoring

1. Current implementation
   @file old-service.ts
   @code specific methods

2. Target pattern
   @file patterns/service-template.ts
   @docs architecture/services.md

3. Test context
   @file tests/old-service.test.ts

Pro Tips for Context Mastery

1. Build Context Templates

   • Create reusable context patterns for common tasks
   • Store in .cursor/contexts/

2. Use Context Aliases

   # Define once, reuse
   AUTH_CONTEXT = @file auth/* @code JWT*
   
   Using AUTH_CONTEXT, add refresh token rotation

3. Progressive Enhancement

   • Start minimal
   • Add context based on AI questions
   • Remove irrelevant context

4. Context Comments

   @file api/user.ts  # Current implementation
   @file api/user.v2.ts  # Target pattern
   @docs api-standards.md  # Must follow these

Next Steps

Master these context patterns to:

• Reduce development time by 40-60%
• Improve AI response accuracy to 90%+
• Cut API costs by optimizing token usage
• Handle complex multi-file changes confidently

Continue with:

• Snippet Management - Reusable code patterns
• Debugging Workflows - Context for bug hunting
• Testing Patterns - Test-specific context strategies

Remember: Context is about signal, not noise. Every piece of context should earn its place by directly contributing to better AI understanding.