Intelligent Model Selection

Intelligent Model Selection is SpecWeave's automatic system for choosing the right AI model. With Opus 4.5 as the default for maximum quality, SpecWeave uses Haiku for simple mechanical tasks to optimize costs while maintaining quality.

How It Works

Model Tiers

Model	Cost	Best For	Use Cases
Haiku	$	Mechanical tasks	Simple file generation, log parsing, test data
Opus 4.5	$$$	All complex work (default)	Planning, architecture, implementation, code review

Phase Detection

SpecWeave detects the current phase to select the appropriate model:

Phase	Typical Model	Why
Exploration	Haiku	Fast file search, codebase navigation
Research	Opus	Reading docs, understanding context
Planning	Opus	Generating specs, breaking down work
Architecture	Opus	Design decisions, ADRs
Implementation	Opus	Writing code, tests
Review	Opus	Code review, validation
Debugging	Opus	Complex problem solving

Cost Impact

Intelligent model selection can reduce AI costs by 40-60%:

Without intelligent selection:
  10 tasks × Opus = 10 × $15 = $150

With intelligent selection:
  3 research tasks × Haiku = 3 × $0.25 = $0.75
  5 standard tasks × Sonnet = 5 × $3 = $15
  2 complex tasks × Opus = 2 × $15 = $30
  Total: $45.75 (70% savings)

Configuration

Model selection is automatic but can be influenced:

// .specweave/config.json
{
  "ai": {
    "default_model": "opus",
    "use_intelligent_selection": true,
    "prefer_cost_optimization": true
  }
}

Override Model Selection

Force a specific model when needed:

# Force Opus for complex task
/sw:do --model opus

# Use Haiku for simple search
Task agent with model: haiku

How It Works​

Model Tiers​

Phase Detection​

Cost Impact​

Configuration​

Override Model Selection​

Related Terms​