The editor only triggers autocomplete on /, @, and #. Extensions can add providers via addAutocompleteProvider, but there's no way to make the editor actually call them on a different character.

I hit this building an inline skill reference extension. $skill-name autocomplete. The provider works, but $ never fires it. Ended up using # instead, which works but could conflict with other extensions. The alternative is calling tryTriggerAutocomplete() through a runtime cast, which is fragile.

Could the editor or provider accept additional trigger characters?

// Either on the editor:
editor.addAutocompleteTrigger("$");

// Or on the provider:
interface AutocompleteProvider {
  triggerCharacters?: string[];
}

The trigger logic in insertCharacter would treat registered characters the same as @/#. Fire at token boundaries. The continuation regex ([@#][^\s]*$) would need to include them too.

Right now extensions can add autocomplete providers but can't actually trigger them. Three hardcoded characters isn't really extensible.