Capstone: Build a Production Harness
Module 12 · Master Course · 90 min
Build the whole thing from scratch. Every module applied. Your portfolio artifact.
The capstone
You've spent 11 modules learning the components. Now you integrate them into a working production harness — designed, built, audited, attacked, and defended by you.
This is the Course 1 credential: a portfolio artifact that proves you can do the whole job.
12 decisions BEFORE code
| # | Decision | From |
|---|
| 1 | Loop architecture | Module 1 |
| 2 | Tool design (count, schemas) | Module 2 |
| 3 | Context management | Module 3 |
| 4 | Memory tiers | Module 4 |
| 5 | Sandboxing (inside/outside) | Module 5 |
| 6 | Permission model | Module 6 |
| 7 | Error taxonomy | Module 7 |
| 8 | Checkpointing | Module 8 |
| 9 | Prompt assembly | Module 3/9 |
| 10 | Subagents | Module 1.3 |
| 11 | Verification | Module 9 |
| 12 | Observability | Module 10 |
Plus: the security threat model (Module 11) — which of the 9 defense layers in v1?
Minimum viable production harness
- ReAct loop + 5 stop conditions (Module 1)
- 4 tools with schemas + structured errors (Module 2)
- Compaction threshold (Module 3)
- 2-tier memory: working files + episodic log (Module 4)
- Sandbox: Docker, scoped fs/network (Module 5)
- Risk-tiered permissions + capabilities (Module 6)
- Error taxonomy: 4 categories (Module 7)
- Atomic checkpointing (Module 8)
- Computed verification (Module 9)
- 8-field observability (Module 10)
- Security: tagging + caps + scoping (Module 11)
Self-audit + attack
6-phase methodology on your own harness (Module 0.3).
12-module scoring sheet — score yourself /60.
3 attacks from Module 11: indirect injection, memory poisoning, tool abuse. Fix what you find.
Architect's Verdict (3 sentences) + MLSecOps note (1 sentence) — for YOUR work.
Course 1 complete
- You can design a harness — 12 decisions, defended.
- You can build one — every module integrated.
- You can audit one — 6 phases, /60 score.
- You can attack one — 3 offensive techniques.
- You can defend one — the 9-layer stack.
This is the Harness Engineer credential. Next: Course 2 — push this harness into offensive/defensive security. Or: the 21 deep-dives — apply the 6-phase method to real production harnesses.