Struct FoldLevel 

pub struct FoldLevel;

Folds nested deeper than this level are closed; the rest are open. The outermost fold is level 1, so foldlevel=0 closes everything and foldlevel=1 shows only the top level’s structure. In a multibuffer view that means 0 gives one row per file and 1 gives one row per excerpt.

Setting it is a bulk action, applied at the moment of the :set. Afterwards za / zo / zc adjust individual folds without changing the option, and a fold whose state the user has touched keeps it across rebuilds – foldlevel only decides the initial state of folds that appear later.

Default deviates from vim deliberately. Vim defaults this to 0, which is why practically every vimrc carries set foldlevelstart=99 – the default means “open every file fully collapsed”, which few people want. Lattice would suffer that worse than vim does: foldmethod defaults to manual, so an ordinary document has no folds, but overlay fold sources are always registered (multibuffer file/excerpt folds, diff hunk folds, the AI conversation’s tool-call folds). A 0 default would open every search result, project diff and agent transcript collapsed to nothing. 99 is the effective-infinity value the vim idiom settled on, and it keeps the shipped behaviour.

Implementations

impl FoldLevel

pub fn build_spec() -> Option<i64>

Build the runtime spec for this declaration. Used by the registry’s self-registration boot path; not generally called by hand. Direct construction of Option<T> is the macro’s internal-only path – consumer code uses config.get_typed::<#name_ident>() to read and config.set_typed::<#name_ident>(...) to write.

Trait Implementations

impl HasGroup for FoldLevel

const GROUP_NAME: &'static str = <crate::Editor as ::lattice_config::OptionGroup>::NAME

Group display name ("editor", "lsp", …). The macro pulls this from the group = SomeGroup; directive at the declaration block’s head.

impl OptionDecl for FoldLevel

const NAME: &'static str = FoldLevel

Public display name. Boundary-facing only – :set <NAME>=…, TOML keys, completion candidates, :describe-option. Internal access is type-driven. The macro derives this from the option’s identifier (with namespace prefix when declared via mode_options!); manually-typed NAMEs are not supported for built-in options.

const DOC: &'static str = FoldLevel

Doc string. Shown in :describe-option, the :customize form’s per-row help, and :apropos results.

const CUSTOMIZABLE: bool = true

Customize-visibility flag. true (the default) ⇒ option appears in :set autocomplete + the :customize group view. false ⇒ plugin / engine-internal state, hidden from user surfaces. Equivalent of emacs’s defvar vs defcustom. (See mode-architecture.md §6.5.3.)

type Value = i64

The runtime value type. bool, i64, String, plus any domain enum that impls OptionType.

fn default_value() -> Self::Value

Default value. Returned by a function (rather than a const) so non-const-constructible types like String can be defaults.

fn type_id() -> TypeId

where Self: Sized,

TypeId of the declaration type itself. Hot-path key for the registry’s type-driven storage. Default impl works for every concrete impl.