Struct EmacsKeysMode 

pub struct EmacsKeysMode;

The emacs-keys minor mode. A marker mode: it owns a keymap layer and an activation policy, but allocates no per-buffer resources.

Implementations

impl EmacsKeysMode

pub fn mode_id() -> ModeId

The canonical id, "emacs-keys-mode" — also the key of the MinorMode keymap layer the host pushes. Distinct from the user-facing option name emacs-keys.

Trait Implementations

impl Mode for EmacsKeysMode

fn activation_policy(&self) -> ActivationPolicy

Default-on in every buffer — the tribute is universal, so the <C-x> navigation chords (switch buffer, switch pane, quit) work everywhere the user can focus, including synthetic buffers like *messages* / help / file-tree (mirroring emacs, whose C-x map is live in *Messages*). Hence Universal, not Global (Global is document-only — the right scope for content modes like snippets, not a universal leader).

The enable toggle (:set noemacs-keys) is NOT gated here: the mode stays unconditionally active and the layer carries the gate — enabled=false rebuilds the leader map empty (see emacs_keys_layer_bindings), so disabling reclaims <C-x> without churning the per-buffer mode set. The layer is Normal-mode-only, so Terminal-Insert keystroke passthrough is unaffected and the leader never shadows a synthetic buffer’s own Normal-mode chords (Help’s Esc/Enter/- are distinct keys).

type Guard = ()

Owned cleanup token returned by Self::on_activate.

fn id(&self) -> ModeId

Canonical identity. Same value every call.

fn kind(&self) -> ModeKind

Major or minor. Read at registration and on every activation call (activate_major on a minor, or vice versa, is ModeActivationError::WrongKind).

fn on_activate(&self, _ctx: ModeContext) -> LifecycleFuture<'_, ()>

Lifecycle. Called once per (buffer, activation) cycle after the registry has applied the declarative contributions. Returns an owned Guard carrying every resource the mode allocated. The dispatcher stashes the Guard until deactivation, at which point dropping it performs cleanup via the Guard’s Drop impl.

fn target_buffer_kind(&self) -> Option<BufferKind>

For major modes, the [BufferKind] this mode is the default major for (H.2, 2026-05-31). ModeRegistry::register indexes this so ModeRegistry::find_major_for_kind can dispatch buffer-creation events to the right major without host-side match BufferKind { ... } blocks.

fn target_language(&self) -> Option<&str>

For major modes, the language this mode is the default major for, by canonical name (Lang::name() — "rust", "org") (OM.1). The peer of target_buffer_kind for the dispatch path [BufferKind::Document] takes: language detection rather than kind dispatch.

fn options(&self) -> OptionOverrideSet

Option overrides this mode contributes. Pure declarative (same return value every call); the host merges these into the buffer’s option-resolution layer stack while the mode is active, at the mode’s layer (later-activated minors win ties), and drops them on deactivation. Build with lattice_config::overrides! { lattice_config::Wrap = true, … }.

fn keymap(&self) -> Keymap

Keymap chord → command additions / overrides.

fn decorations(&self) -> Vec<DecorationProvider>

Decoration providers (gutter / inline / overlay / statusline). Stub — reserved for the WIT plugin path (M.10).

fn gutter_decorations(&self, _ctx: &DecorationCtx<'_>) -> Vec<GutterDecoration>

Gutter sign decorations this mode contributes while active. Called once per pane per frame with a DecorationCtx carrying relevant render-state snapshots (diff sign map, LSP diagnostics arc). Returns per-line GutterDecoration values; the renderer partitions them by variant into the appropriate gutter column. Default: empty (no contribution).

fn completion_sources(&self) -> Vec<CompletionSourceContribution>

Insert-mode completion sources this mode contributes while active on a buffer. Empty by default; minors that own a completion source (lsp-completion-mode, snippet-completion-mode, buffer-words-mode, tree-sitter-completion-mode, path-completion-mode, plugin sources) override.

fn action_handlers(&self) -> Vec<ActionHandlerContribution>

Global (buffer-agnostic) action handlers this mode contributes (SN.3c.0). The host walks every registered mode’s action_handlers() once at boot, resolves each action_name → CommandId, registers the handler in the ActionHandlerRegistry, and holds the tokens for the app’s lifetime. Use this for handlers that read the active buffer / cursor / services from the ActionContext at call time and close over no per-buffer state (e.g. snippet expand). Per-buffer, session-scoped handlers register in on_activate instead, so their tokens drop with the Guard. Default: none. See feedback_effect_vocabulary_is_host_boundary.

fn required_capabilities(&self) -> CapabilitySet

Capabilities the mode requires. Validated at activation; missing capability ⇒ ModeActivationError::MissingCapability, never silent skip.

fn conflicts_with(&self) -> &[ModeId]

Modes this one cannot be active alongside.

fn implies(&self) -> &[ModeId]

Minor modes activating this mode also activates. Used by relative-line-numbers-mode ⇒ line-numbers-mode, and by read-only majors ⇒ read-only-mode.

fn presents_extensions(&self) -> &[&'static str]

File extensions (lowercase, no dot) this major PRESENTS rather than edits — the file is never loaded as text.

fn mirrors_option(&self) -> Option<&'static str>

Declarative mirror hint for “this mode is the on/off switch for a typed option of the same observable state”. Some(canonical_name) ⇒ a host-driven cascade keeps the mode’s active state and the option’s value in sync.

fn invocation_runner(&self) -> Option<ModeId>

Invocation-runner discovery (2026-05-26). Modes that own command-invocation dispatch for their buffer kind (terminal-mode, oil-mode, file-tree-mode, help-mode, …) return their canonical ModeId; the host registers a runner function under that id at boot, and Editor::run_invocation looks it up by walking the active modes on the active pane’s buffer (minors first, then major) before falling back to the central grammar Action gate.

fn refresh_action(&self) -> Option<&'static str>

Which of this mode’s own actions refreshes its view, or None (the default) when the mode backs nothing refreshable (RV.1, 2026-08-10).

fn fold_toggle_action(&self) -> Option<&'static str>

Which of this mode’s actions <Tab> fires, and the declaration that pulls in foldable-view-mode — the shared minor owning the chord.

fn refresh_on_open(&self) -> bool

Should re-opening this view re-run its refresh?

fn editable_tail(&self) -> Option<EditableTail>

The mode’s editable tail on an otherwise read-only buffer, or None (the default) for a fully read-only / fully writable buffer (AU‑3).