# Phase 11: Execution Engine

**Purpose:** Load a skill, prepare context, execute steps with deliberate practice.
**TS Module:** `src/tier2-primitives/routines/execution-engine.ts`

## What It Does

- Loads the skill definition and context template
- Executes each step sequentially with lifecycle hooks
- Records timing, quality, and issues per execution
- Validates output against step criteria

## Lifecycle Hooks

```typescript
onBeforeStep(step, context)   // Prepare for step execution
onAfterStep(step, result, context)  // Process step result
onBeforeAll(skill, context)   // Pre-execution setup
onAfterAll(skill, result, context)  // Post-execution processing
```

## Key Rules

- Each execution is fully recorded in the skill's history
- Quality score is calculated from step success ratio minus issue penalty
- Template variables (`{{var}}`) are substituted from context
- Validation criteria are checked after each step