Over the past few years I’ve had the opportunity to observe a lot of AI-assisted software development. In my experience there was a clear shift in November 2025 when Claude Opus 4.5 launched. What we can trust AI systems to do changed materially.

While I have a day job managing a few teams and little opportunity to write code there, I do spend a lot of time observing and talking with my team about how they use LLMs in the development process. It’s been fascinating watching each person adopt this technology at their own pace.

To stay current, I write a lot of code on TrueMath in my evenings and weekends. This post outlines what has changed in my development process—and what has not—in my 40 years of writing software.

Before Claude Opus 4.5

I started developing with ChatGPT in early 2024. Of course compared to today’s models it was very primitive and often wrong. Nonetheless, I found a pattern that worked:

1. Start with a general prompt about the structure of the project and copy into ChatGPT the code it needs to start.
2. Work together on a plan. Go back and forth as long as necessary to make sure we are aligned and all corner cases are covered at a high level. Copy that plan off to Asana (which I use for task management).
3. Have it tackle each phase, writing code in ChatGPT. Sometimes we needed to break the current phase into sub-phases. I reviewed every line of code as I copied it into the code base, copying code back to ChatGPT so it could review what I did.
4. Review every test it writes, run them, and also test every phase or sub-phase manually.

As the project grew I found myself copying more and more code into the prompt. Eventually the model would start struggling earlier and earlier in the development cycle as we ran past the context window.

After Claude Opus 4.5

When the reviews of Claude Opus came out, I started thinking more and more about bringing Claude into VSCode and let it do more. I was seeing the efficiency gains from those at my day job who were embracing new approaches. We had seminars from leading companies in the space walking us through how to use their systems.

Time for a change! So just a couple of weeks ago I got around to installing Claude Code in VSCode and signing up for an account. Now my process looks like this:

1. I use CLAUDE.md to define the project overview and actually have Claude updating and maintaining it.
2. I start any body of work with Claude in plan mode and we work back and forth on the plan until I’m happy with it. This includes breaking it down into small phases of work. Every phase should be small enough for me to review and manually test.
3. Once I have a plan I like and broken down, I copy it off to Asana (which is what I use for tasks but even a text file will do) and have Claude save it to memory.
4. For each phase of work I start a new chat and try hard to keep the context from overflowing and needing to condense. If I need to break down the task further so it is reviewable I do that as sub-phases.
5. I tell Claude to write the code, during which I watch its thinking mode and often multitask on something else.
6. When done I review the code. I run the automated test suite, which it should have just done. I review the code coverage metrics. I review all the code. I manually test. If there is any code smell, any code I can’t really follow easily, any code that looks duplicative, I just point it out to Claude and ask it if this is the best way to do this. It usually says it can do better and does.
7. I work back and forth with Claude on any issues until complete, at which point I have it update its memory, save to my branch, and move on to the next chunk or sub-chunk.

In short, exactly as before except almost no copy and paste.

I never let Claude do anything destructive, especially data migrations. It prepares the code commit but I’m the one who hits the button. It’s my safety valve to make sure I’m properly testing.

How We Wrote Code Before LLMs

How I use Claude now isn’t that different from how I have written code for 40 years. Back then, though, I did all the planning myself and wrote every line of code. Now, I work with Claude to plan and have it write the code. Every other step in this process is still me.

Efficiency Gains

I’m working on a capability right now that would have taken me 3–4 weeks full-time to build by hand. With Claude Code it took 2–3 days. (Note to my boss: it actually took longer since I’m only working evenings and weekends on TrueMath.)

This is incredible efficiency gains! I’ll be honest: I feel like I’ve been given a super power using AI for software development. Before, there were many things I would have never taken on. Now, any idea I have can be realized in working code.

That’s a remarkable shift in what an individual developer can accomplish.