The History Screen
Drive AI agents through a million lines of code you did not write. Recon, surgical navigation, codemods, characterization tests, and a toolkit of four reusable skills you keep.
Time to build something real. First up is the history screen, the Git view, what I've been calling the Journey.
Before I start, a question from earlier episodes that I haven't answered: is this vibe coding? I'm not reading how VS Code is built. I'm trusting Claude. As a senior developer building on top of somebody else's app this big, that feels strange to me. But if I stopped to learn the whole codebase first, I'd never try anything, and the point of this course is to find out what's possible. I think the whole industry is in the same spot with 5,000 and 10,000-line PRs. We're not writing the code by hand, and soon we won't be reviewing it line by line either. We'll be relying on tests, and on checking for ourselves that the thing works.
Now the work. I need to know how VS Code gets its Git data before I can reuse it. That's exploration, so I pick Fable 5.1 and ask it, keeping the answer short: does the source control view read .git directly, or is there an API?
The answer: it shells out to the git binary through the built-in Git extension. That explains why the source control pane takes a second to load. Fable recommends reusing that extension's data, diffs, and rendering through a proposed API, and points out that since this is my fork, I can just call it from core or promote it to stable. I agree. Microsoft probably won't change the Git extension much, and if they do, I'll deal with it then.
Then I switch to Opus 5.5 for the build. The prompt is dictated and long: you have the screens, the docs, and the decisions. Ask your questions up front. Ask me which project to open when it's time to test. Otherwise, go.
For the test project I use Big Mailer, my Kōlea mailer, because I know its Git history. make run, and there it is. The header area is still stubbed, but the commit list is real. There's a "load older commits" button. Nothing is staged in the working tree, so I'll stage something next time to see how that looks.
The cost: 18 minutes and $11 for an entire feature. The context window used a lot, which I expected, and there's still plenty left.
It's still mostly the sidebar moved onto the main screen, and it can do a lot more. But I now have my own page in VS Code using the extension API, and I like it.
Drive AI agents through a million lines of code you did not write. Recon, surgical navigation, codemods, characterization tests, and a toolkit of four reusable skills you keep.