Pragmatic Development, first of all, I sincerely thank you for giving me the opportunity to take this course for free (the free lecture support program for national merit recipients & socially disadvantaged groups). At first, I found it a little hard to believe that I could take a course totaling more than 17 hours for free. But after actually taking it, I felt even more grateful because the content was so comprehensive that I found myself wondering, "Is it really okay to take this for free?" I believe that listening diligently and leaving an honest review is the best way to give back, so I am writing this review. This review is based on my experience after completing about half of the course. ■ What Led Me to Take the Course I have been using Claude Code for quite some time while working on AI-related development projects. Looking back, however, I was mostly using it based on "intuition." When things worked well, I did not know why, and when they did not work, I did not know why either. All I could do was tweak the prompts here and there. Just as I was thinking, "I want to understand the principles properly before using it," I came across this course. ■ Best Part 1 — A Course That Explains "Why" The biggest strength of this course is that it does not end with simply saying, "Use it like this." In the early sections, the course first explains what coding agents are and how Claude Code works. As a result, the commands and settings introduced later felt less like isolated pieces of knowledge and more like parts of a single, coherent flow. I especially appreciated that the course also covers the pricing structure separately. It was quite practical and helpful from the perspective of someone who uses the tool every day. ■ Best Part 2 — Essential Commands and Settings for Immediate Use in Practice The key command sections in Sections 2–3 are organized by category, covering session management, model/execution control, harness configuration, coding tasks, and diagnosing agents and their status. This made them easy to revisit as a reference. The explanations of how to properly write CLAUDE.md, configure settings.json, and handle token compression and auto-compaction were areas I had previously glossed over, so I listened to those parts with a particularly strong sense of self-reflection(?). I also felt that the fact that the course incorporates the latest updates was a major advantage for a course covering a tool that changes so quickly. ■ Best Part 3 — The Big Picture of Harness Engineering Personally, I think the highlights of this course are the sections on the history of harness engineering and its four-layer structure. By looking at agents through the framework of Context, Tools, Control Flow, and Feedback, I became able to think more systematically about "what to show the model, what to give it access to, how to control the flow, and how to provide feedback." I believe that this perspective alone gave me a way of thinking that I can continue to apply for a long time—not only when using Claude Code, but also when working with other agent tools in the future. The process of directly examining publicly available production code in the Claude Code harness deep dive was also extremely interesting, as it offered a level of depth that is difficult to find in other courses. ■ Points to Keep in Mind To be honest, this is not an easy course. Because it goes into considerable depth, some parts do not sink in completely after just one viewing, so I watched several lectures twice. Also, since the hands-on exercises are based on Java / Spring Boot, those who primarily use other languages will need to put in a little extra effort to adapt the concepts to their own environments. That said, I did not find this to be a major obstacle, because the core of the course is not any particular language but rather "how to design and work with agents." ■ What I’m Looking Forward To There are still sections on Hooks, Skills, MCP, sub-agents, advanced agents, and more remaining. I am very much looking forward to learning how these elements fit together within the four-layer harness perspective built up in the earlier sections. I will complete the rest of the course to the end and apply what I have learned directly to my projects. Once again, thank you for providing such a great course—and for giving me the opportunity to take it for free. This course helped me find a direction for what developers need to prepare for in the age of AI agents. I look forward to your future courses as well. Thank you!