← Back to Learning Hub
Guide 8 of 85 min read

Test Harness Pattern Learning Lab

Purpose: Safe sandbox for learning and building phased workflow skills with strict validation.

What's Inside

Reference Implementation

schema-optimization/ - Complete 5-phase workflow skill system

  • Orchestrator that creates session directories, spawns phases, validates outputs
  • 5 phase agents with strict JSON contracts
  • Reference instruction docs
  • Real verification script
  • Sample outputs

Learning Guides

  1. GUIDE-00-START-HERE.md - Introduction (5 min)
  2. GUIDE-01-PATTERN-EXPLAINED.md - Architecture (15 min)
  3. GUIDE-02-BUILDING-YOUR-OWN.md - Build your own (30 min)
  4. GUIDE-03-DEBUGGING-TIPS.md - Debugging (15 min)
  5. ORCHESTRATION-PATTERN.md - Complete reference (60 min)

Why This Pattern Matters

Traditional LLM workflows are fragile. The test harness pattern solves this with:

  • Agent MUST produce file artifact (evidence)
  • Agent MUST return strict JSON (machine-checkable)
  • Orchestrator validates before continuing
  • Each phase builds on validated prior work
  • Failure points are clear and debuggable

Design Principles

  1. Evidence-Based: Every phase writes a file
  2. Machine-Checkable: JSON outputs validated programmatically
  3. Fail-Fast: Orchestrator stops on first validation failure
  4. Composable: Phases are independent, reusable
  5. Debuggable: Clear failure points
  6. Repeatable: Same inputs = same outputs