0.1 — The Landscape
What Is a Harness?
The model is 1.6% of the system. The harness is the other 98.4%. Every harness does three jobs: loop, tools, safety. Miss any one and it's a prompt, not a harness.
15
minutes
8
artifacts
5
diagrams
The Three Jobs
01
Loop
Run the model repeatedly until a stop condition. Turns a stateless function into an agent.
02
Tools
Named, schema-validated functions. The model requests; the harness executes. A security boundary.
03
Safety
Permission flags, approval gates, sandboxing, stop conditions, trust boundaries.
Convergent Evolution
Four independent teams in 2025–2026 — Anthropic, OpenAI, Google, and the open-source community — built production harnesses without coordinating. They produced architecturally identical systems. The structure is the invariant. Thickness is the variable.
Artifacts
01
Teaching Document
The canonical definition. Three jobs, model-vs-harness split, why the harness matters more.
READ
02
Diagrams
Three-layer architecture, thickness spectrum, convergent evolution, component map, ReAct loop.
READ
03
Slide Deck
reveal.js, dark theme, 10 slides. The 1.6% number lands here.
READ
04
Teaching Script
Verbatim transcript with slide cues. AI-read-ready.
READ
05
Flashcards
Anki TSV. Definitions, the three jobs, convergent evolution.
TEST
06
Exam
JSON question bank with Bloom's taxonomy distribution and rationale.
TEST
07
Lab Specification
Identify the three jobs in a real harness source tree. Hands-on.
DO
08
Module Web Page
This page. You are here.
HERE