Oh, is that what they mean? I set "Search Mode" to "newEditor" immediately whenever I configure VSCode on a new computer, since the default behavior of opening in the side panel is such hot garbage. I entirely forgot that some people don't have that and took for granted in my post that everyone knew about opening the results in an "editor".
But the point is that "editor" is non-functional. It's nice for browsing the results and has syntax highlighting and surrounding context, but you can't actualy edit from there. You can only use it to open the source file and then edit the source file.
In Zed, the search results "editor" is actually functional. You can make changes to the text that you see from the surrounding context, right in the search results, and then hit save, and have those changes propagated to all the touched files.
So, say you update a function to take another argument, and you want to update your codebase appropriately. Well then you do a global search for that function name, and then scan down the results list. The irrelevant search results (maybe you mention the function in a comment, but aren't actually invoking it) you can skip. The complicated updates you can open the source file like you do in VSCode. But the trivial ones where you can see what you need to pass as the new argument, you can just update right then and there.
I only half-conveyed what I was aiming to; I'm able to do what you're describing by editing the search-results scratch-file then saving it. The changes propagate to the target files with the save.
I've had a look though, and you were right: it's due to an extension that I can save from the scratch file:
