# Phase 12: Routine Evolution

**Purpose:** Skills don't stay static — they sharpen with every execution.
**TS Module:** `src/tier2-primitives/routines/routine-evolution.ts`

## What It Does

Analyzes execution history and suggests improvements:

1. **Step fail rates** — identifies steps that fail >30% of the time
2. **Quality trends** — detects improving, stable, or declining quality
3. **Missing validation** — flags steps with issues but no validation criteria
4. **Trivial steps** — identifies steps that always succeed instantly (may be redundant)

## Auto-Evolution

```bash
fable-agent skills evolve <skill-id>
```

Applies top 3 suggestions:
- Adds validation criteria to failing steps
- Modifies step instructions based on failure patterns
- Reorders steps based on historical success rates
- Bumps version number automatically

## Key Rules

- Evolution is the compounding mechanism — each run makes skills sharper
- Minimum 2 executions required for meaningful analysis
- Max 3 changes per auto-evolution
- Changes are visible via `skills inspect` version history