completion-mode

completion-mode: the per-buffer gate for insert-mode completion — active on writable buffers, which is why <C-Space> is a no-op in help or oil.

The gate that decides whether a buffer participates in insert-mode completion at all. It activates automatically on writable buffers when they're created and stays for the buffer's life.

Its whole job is to be checked: the completion trigger consults it before opening the popup. Read-only kinds — help, file tree, oil — never activate it, which is why <C-Space> there is a silent no-op rather than a popup with nothing useful in it.

The pair

completion-mode is persistent; its twin completion-popup-mode is transient and exists only while the popup is open. The split mirrors lsp-mode (umbrella, persistent) and its per-feature sub-modes: one answers "is this available here?", the other owns the keys that only mean something while a popup is up.

Neither contributes options.

Options

None.

Keybindings

None. It is a gate that other code consults; the popup's keys belong to completion-popup-mode.

See also

• completion — sources, triggers, configuration.
• completion-popup-mode — the popup's own keymap.