How the harness actually works ?

What is an AI harness, and how do tools like Claude Code work underneath? I build one from scratch in plain Python, one layer at a time, using a car as the map. For beginners moving into AI engineering. No framework, every part visible. Code for every version (one branch per version, v1 to v6): https://github.com/HILAYTRIVEDI/harne... Chapters: 00:00 What is a harness? The car analogy 01:35 V1 The engine: one LLM call 04:14 V2 The chassis: the agent loop 05:57 V3 The wheels: tools 12:58 V4 Steering and GPS: system prompt and streaming 18:55 V5 Brakes and saved places: permissions and memory 27:01 V6 The fuel gauge: context window and auto-compact 29:36 What's next Tools mentioned: • Anthropic Python SDK: https://github.com/anthropics/anthrop... • Claude Code: https://www.anthropic.com/claude-code #AI #AIAgents #ClaudeCode Connect with me: • LinkedIn:   / hilay-trivedi   • GitHub: https://github.com/HILAYTRIVEDI