After reading the docs, I found out that the default keybinding for triggering the autocomplete is Alt+`. But it seems that there isn’t even an alt key on MacOS anymore, and the logical alternative— Option+`— doesn’t work.
The following is the code block that declares the keybindings for triggering autocomplete (found in src/index.ts in @codemirror/autocomplete)
/// Basic keybindings for autocompletion.
///
/// - Ctrl-Space (and Alt-\` on macOS): [`startCompletion`](#autocomplete.startCompletion)
/// - Escape: [`closeCompletion`](#autocomplete.closeCompletion)
/// - ArrowDown: [`moveCompletionSelection`](#autocomplete.moveCompletionSelection)`(true)`
/// - ArrowUp: [`moveCompletionSelection`](#autocomplete.moveCompletionSelection)`(false)`
/// - PageDown: [`moveCompletionSelection`](#autocomplete.moveCompletionSelection)`(true, "page")`
/// - PageUp: [`moveCompletionSelection`](#autocomplete.moveCompletionSelection)`(false, "page")`
/// - Enter: [`acceptCompletion`](#autocomplete.acceptCompletion)
export const completionKeymap: readonly KeyBinding[] = [
{key: "Ctrl-Space", run: startCompletion},
{mac: "Alt-`", run: startCompletion},
{key: "Escape", run: closeCompletion},
{key: "ArrowDown", run: moveCompletionSelection(true)},
{key: "ArrowUp", run: moveCompletionSelection(false)},
{key: "PageDown", run: moveCompletionSelection(true, "page")},
{key: "PageUp", run: moveCompletionSelection(false, "page")},
{key: "Enter", run: acceptCompletion}
]
I have read somewhere that CodeMirror aims to match its keybindings with VSCode’s, so perhaps it should be changed to Command+I as in VSCode.