Ah, but getting the Zig language server working turned tab completions back on, somehow. Jebus. This edit to `keymap.json` seems to have fixed that:
```
{
"context": "Editor && showing_completions",
"bindings": {
"tab": "editor::Tab"
}
},
{
"context": "Editor && edit_prediction && !showing_completions",
"bindings": {
"tab": "editor::Tab"
}
```
This may be made more complicated and insane by me using vim mode in Zed, I dunno.