cursor-context-management

Cursor Context Management

Optimize how Cursor AI uses context to produce accurate, relevant responses. Context is everything the model sees when generating a response -- managing it well is the single biggest lever for output quality.

Context Sources

Cursor assembles context from multiple sources before each AI request:

┌─ Always Included ─────────────────────────────────────┐
│  System prompt (Cursor internal)                      │
│  Active .cursor/rules/*.mdc with alwaysApply: true    │
│  Current file (for Tab, Inline Edit)                  │
└───────────────────────────────────────────────────────┘
┌─ Conditionally Included ──────────────────────────────┐
│  Selected code (highlighted before Cmd+L/Cmd+K)       │
│  @-mention targets (@Files, @Folders, @Code)          │
│  Glob-matched rules (.mdc with matching globs)        │
│  Conversation history (prior turns in chat)           │
│  Open editor tabs (lightweight reference)             │
└───────────────────────────────────────────────────────┘
┌─ On-Demand (explicit @-mention) ──────────────────────┐
│  @Codebase  → semantic search across indexed files    │
│  @Docs      → crawled external documentation          │
│  @Web       → live web search results                 │
│  @Git       → uncommitted diff or branch diff         │
│  @Lint Errors → current file lint diagnostics         │
└───────────────────────────────────────────────────────┘

Context Pills

Active context appears as pills at the top of the Chat/Composer panel:

[main.ts] [src/utils/] [@Web: next.js 15] [Rule: typescript-standards]

• Click a pill to expand and see its contents
• Click x on a pill to remove it from context
• Adding too many pills fills the context window, degrading response quality

@-Mention Strategy by Task

Code Understanding

@src/auth/middleware.ts @src/types/user.ts
Explain how the JWT validation works and what happens when a token expires.

Use @Files for specific files. Avoid @Folders unless you need the full directory -- it consumes a lot of context.

Bug Investigation

@src/hooks/useCart.ts @Lint Errors @Recent Changes
The cart total is NaN after the latest changes. What broke?

@Recent Changes + @Lint Errors gives the model forensic context.

Architecture Questions

@Codebase where are database queries made?

@Codebase triggers semantic search across the indexed codebase. Good for discovery when you do not know which files are relevant. Costs more context than targeted @Files mentions.

Using External Knowledge

@Docs Prisma @Web prisma client extensions 2025
How do I add soft-delete as a Prisma Client extension?

@Docs uses pre-indexed documentation. @Web does a live search. Combine both for comprehensive answers about third-party tools.

Context Budget Management

Each model has a context limit. Overloading it causes the model to drop information silently:

Model	Context Window	Practical Limit
GPT-4o	128K tokens	~80K usable
Claude Sonnet	200K tokens	~150K usable
Claude Opus	200K tokens	~150K usable
cursor-small	8K tokens	~5K usable

Signs of Context Overflow

• Model forgets instructions from earlier in the conversation
• Responses become generic or repetitive
• Model contradicts what it said 3 turns ago
• Suggested code ignores file context you provided

Mitigation Strategies

1. Start new conversations frequently. One topic per conversation.
2. Use specific @Files, not @Folders. @src/api/users.ts is better than @src/api/.
3. Remove context pills you no longer need. Click x to drop stale files.
4. Avoid @Codebase for narrow questions. It pulls in many code chunks. Use @Files when you know the location.
5. Break large tasks into steps. Ask for the type definitions first, then the implementation, then the tests -- in separate turns or chats.

Automatic vs Manual Context

Cursor automatically includes context in some cases:

Feature	Automatic Context
Tab Completion	Current file + open tabs + recent edits
Inline Edit (Cmd+K)	Selected code + surrounding file
Chat (Cmd+L)	Conversation history + explicitly added context
Composer (Cmd+I)	Referenced files + codebase search

For Chat and Composer, you control context through @-mentions. Tab and Inline Edit manage their own context automatically.

.cursorignore for Context Control

Prevent files from ever being included in AI context:

# .cursorignore (project root)

# Secrets and credentials
.env
.env.*
**/secrets/
**/credentials/

# Large generated files
dist/
build/
node_modules/
*.min.js
*.bundle.js

# Data files that consume context budget
*.csv
*.sql
*.sqlite
fixtures/

Note: .cursorignore is best-effort. It prevents files from appearing in indexing and AI features, but is not a security boundary for protecting secrets. Use .gitignore and environment variables for actual secret management.

Advanced: Scoped Rules as Context

Project rules automatically inject context when relevant files are opened:

# .cursor/rules/database-patterns.mdc
---
description: "Database query patterns and conventions"
globs: "src/db/**/*.ts,src/repositories/**/*.ts"
alwaysApply: false
---
# Database Conventions
- Use parameterized queries exclusively
- All queries go through repository pattern
- Wrap multi-table operations in transactions
- Use connection pooling (pool size: 10)

This rule automatically loads when editing database files, giving the AI the right conventions without you manually adding context each time.

Enterprise Considerations

• Data sensitivity: Use .cursorignore to exclude files with PII, credentials, or regulated data
• Privacy Mode: Ensures code sent as context has zero data retention at model providers
• Conversation hygiene: Train teams to start new chats per task to avoid context bleed
• Cost awareness: Larger context = more tokens = higher API costs when using BYOK

Resources

• @ Symbols Overview
• Codebase Indexing
• Ignore Files