I don't use any of the chat or agent features, but for me Cursor's tab completion is a step forward in work efficiency that Zeta and Copilot were not. Sometimes it's subtle, and sometimes it is very obvious. Cursor seems to have sources of context that the others don't, like file names from the directory tree, and maybe even the relevant .pyi type annotations and docs for python modules. It also jumps to the next relevant problem site very effectively. It feels like the Cursor devs have done a ton of practical work that will be hard to match with anything other than a full-on competitive effort.
I want to see Zed succeed. I think it's very important that VS Code and its ultra-funded derivatives not dominate the modern editor landscape too thoroughly. Tab completion used to seem like a straightforward thing, but if the state of the art requires a very elaborate, whole-workspace-as-context environment to operate in, then I wonder if it's going to become a go big or go home kind of feature.
I can't help wonder what the actual internal API for this kind of thing is going to look like in the future. It used to be something like, what's the current token behind the cursor, and look in a big prefix tree of indexed words. Then maybe it got more elaborate with things like tree-sitter, like what's the incomplete parse tree up to this point. Then when editors started using AI, I stopped having any idea of what the actual inputs are. I'd love to hear about real implementation experience at any stage of this evolution.