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description: "Performance: model selection, context management, build troubleshooting" alwaysApply: true

Performance Optimization

Model Selection Strategy

Haiku 4.5 (90% 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 4.6 (Deepest reasoning):

• Complex architectural decisions
• Maximum reasoning requirements
• Research and analysis tasks

Context Window Management

Avoid last 20% 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

Extended Thinking + Plan Mode

Extended thinking is enabled by default, reserving up to 31,999 tokens for internal reasoning.

Control extended thinking via:

• Toggle: Option+T (macOS) / Alt+T (Windows/Linux)
• Config: Set alwaysThinkingEnabled in ~/.claude/settings.json
• Budget cap: export MAX_THINKING_TOKENS=10000 (bash) or $env:MAX_THINKING_TOKENS = "10000" (PowerShell)
• Verbose mode: Ctrl+O to see thinking output

For complex tasks requiring deep reasoning:

1. Ensure extended thinking is enabled (on by default)
2. Enable Plan Mode for structured approach
3. Use multiple critique rounds for thorough analysis
4. Use split role sub-agents for diverse perspectives

Build Troubleshooting

If build fails:

1. Use build-error-resolver agent
2. Analyze error messages
3. Fix incrementally
4. Verify after each fix