name: context-compressor description: Context compression and summarization methodology. Techniques for reducing token usage while preserving decision-critical information. version: 1.0 model: sonnet invoked_by: both user_invocable: true tools: [Read, Write] best_practices:

• Preserve decision-critical information
• Remove redundant content
• Use structured formats
• Maintain traceability error_handling: graceful streaming: supported

Context Compressor Skill

Step 1: Identify Compressible Content

Content types that can be compressed:

Step 2: Apply Compression Techniques

Technique 1: Decision Extraction

Before:

User: Should we use Redis or Memcached?
Assistant: Let me analyze both options...
[500 words of analysis]
Recommendation: Redis for pub/sub support.
User: Ok let's use Redis.

After:

Decision: Use Redis (chosen for pub/sub support)

Technique 2: Code Summarization

Before:

// 100 lines of UserService implementation

After:

UserService: CRUD operations for users
- Methods: create, read, update, delete, findByEmail
- Dependencies: db, validator, logger
- Location: src/services/user.js

Technique 3: Error Compression

Before:

Error: Cannot read property 'id' of undefined
    at UserController.getUser (src/controllers/user.js:45:23)
    at Layer.handle [as handle_request] (node_modules/express/lib/router/layer.js:95:5)
    ... 20 more stack frames

After:

Error: Cannot read 'id' of undefined @ src/controllers/user.js:45
Cause: User object is null when accessing .id

Step 3: Structure Compressed Output

Use consistent formats:

## Session Summary

### Decisions Made

- [D1] Use Redis for caching
- [D2] JWT for authentication

### Files Modified

- src/auth/jwt.js (new)
- src/config/redis.js (updated)

### Open Items

- [ ] Add rate limiting
- [ ] Write tests for JWT

Step 4: Validate Compression

Ensure critical info preserved:

• All decisions captured
• Key file locations retained
• Error causes documented
• Next steps clear

</execution_process>

<best_practices>

1. Preserve Decisions: Never lose decision rationale
2. Keep Locations: File paths and line numbers are critical
3. Summarize, Don't Delete: Transform verbose content
4. Use References: Point to files instead of including content
5. Test Recovery: Can you continue work from compressed context?

</best_practices> </instructions>

Compress the last 10 messages for context handoff

Example Response:

## Context Summary (compressed from 10 messages)

### Task

Implementing user authentication with JWT

### Progress

1. Created JWT utility (src/auth/jwt.js)
2. Added login endpoint (src/routes/auth.js)
3. Tests failing - mock issue

### Key Decisions

- Using RS256 for JWT signing (security over performance)
- 1-hour token expiry with refresh tokens

### Current Issue

Jest mock for jwt.sign not working
Location: src/auth/**tests**/jwt.test.js:23

### Next Steps

1. Fix JWT mock
2. Add refresh token endpoint

</usage_example> </examples>

Rules

• Never lose decision rationale
• Always include file locations
• Test that work can continue from compressed context

Workflow Integration

This skill supports multi-agent orchestration by enabling efficient context management:

Router Decision: .claude/workflows/core/router-decision.md

• Router spawns agents that use this skill for context-efficient handoffs
• Used in long-running sessions to maintain continuity

Artifact Lifecycle: .claude/workflows/core/skill-lifecycle.md

• Compression patterns evolve with framework changes
• Session summaries feed into memory protocol

Related Workflows:

• session-handoff skill for complete handoff protocol
• swarm-coordination skill for multi-agent context sharing

Memory Protocol (MANDATORY)

Before starting:

cat .claude/context/memory/learnings.md

After completing:

• New pattern -> .claude/context/memory/learnings.md
• Issue found -> .claude/context/memory/issues.md
• Decision made -> .claude/context/memory/decisions.md

ASSUME INTERRUPTION: Your context may reset. If it's not in memory, it didn't happen.