> That means the code is sketchy sometimes, sure, but it's in my control. I wrote it, I understand it, and when it breaks, I know exactly where to look.

This resonates with me so hard. I'm not a "no external packages" purist, but there are a number of pieces of functionality that I wrote for myself because there wasn't anything quite like what I wanted.

One example is a function to expand the region (selection) to any arbitrary set of pairing delimiters that I define in a defvar (parens, quotes, brackets, or I can can supply a custom left/right regex for matching). Then, when I execute the function, it waits for a second keypress, which is the trigger key I've defined for that matching pair, and it will expand the region to the left and the right until it meets the applicable delimiter.

Repeating the same key presses results in selecting the left and right delimiters themselves, and another repeat will extend to the next set of matching delimiters, and so on.

Even though I use a treesitter-based expand-region plug-in, my custom function is still invaluable for when I want to jump past a series of valid treesitter object expansions, or when certain text objects are just not defined in treesitter.

Some of the helpful custom expansions I have defined are:

"w" to select what Vim considers a lowercase-w word

Space to select what Vim considers an uppercase-W word

"$" to select ${...}-style expressions

"/" to select everything between forward slashes

"*" to select between asterisks (useful when editing markdown)

It's really an invaluable function for me, personally, but I always talk myself out of trying to open-source it because it has some gotchas and limitations, and I just don't want to be on the hook for trying to make everyone who uses it happy.