Been working on a new developer overlay system in Ghostty and majorly improving the inspector. Here is an example of the "semantic prompt" overlay in the renderer, plus the right pane shows that this screen has seen semantic content at least once (showing proper integration).

The overlay system works by using CPU-rendered 2D graphics and compositing them on top of the terminal screen via the GPU using the same image shaders we use for features like Kitty Graphics Protocol.

Choosing to use a CPU renderer for the overlay is a pragmatic one: it lets us iterate more quickly on these debug tools, its immediately cross-platform (no per-platform shaders), and the debug overlay is not typically on so it doesn't need to be as optimized as everything else.

Enabling these debug overlays does "blow up" our frame draw times from ~30us to ~600us but just remember there are 8300us in a 120fps frame. So, we're going to be okay.