Free harness engineering course: same Opus 4.5 costs $200 with full harness vs $9 without
JafarNajafov · x · 2026-09-26
Jafar Najafov highlights a free open-source course on "harness engineering," arguing it's the most valuable AI skill right now. The key evidence is Anthropic's experiment: same model (Opus 4.5), same prompt ("build a 2D retro game editor") —
- No harness: $9, 20 minutes, unusable output
- Full harness: $200, 6 hours, a game you can actually play
The model didn't change; the environment around it did. The course has 14 lectures, 8 hands-on projects, 15 languages, and 15.4k GitHub stars. You build one real Electron knowledge-base app end to end, watching the agent evolve from breaking tests and claiming "done" to verifying its own work.
Suggested starting point: drop 4 starter files (AGENTS.md, init.sh, featurelist., progress log) into your project and run the audit-harness.sh script.
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