Struct TransientContext 

pub struct TransientContext {
    pub major_mode: Option<String>,
    pub minor_modes: Vec<String>,
    pub buffer: Option<BufferId>,
    pub args: Args,
}

Registry of named transient builders, populated at boot by each owning mode crate (magit registers magit-dispatch / magit-file-dispatch; per the module doc, which-key / command palette / future plugin transients are meant to reuse the same mechanism). Effect::OpenTransient { source } carries only the name — resolving it to an actual TransientSpec (which can’t cross into lattice-grammar’s Effect enum directly, since TransientSpec lives downstream of it) happens here, at the renderer’s effect-handling site. Mirrors PickerRegistry’s named-source shape, simplified: transients have no candidate generator or arg-schema concept, just a name and a builder.

Read-only after boot in practice (each owning crate’s install populates it once), so this stays a plain mutex-guarded map rather than an ArcSwap RCU registry like PickerRegistry — there’s no runtime plugin-load use case for it yet. MG.23h: where a transient was opened from, so a builder can vary its rows.

A dispatch menu bound globally has to degrade: rows that act on the thing under the cursor are meaningless in a buffer that has no such thing, and a row whose only useful reading depends on which buffer you are in should say the useful thing. Emacs magit answers both with predicates on its prefix definitions — :if-derived for “any buffer of this family” and :if-mode for “exactly this major” — and this is the same question, asked of the two mode axes.

Major and minors are separate fields on purpose. A flat list of active mode ids can only answer one of those two questions; magit’s dispatch asks both of them about the same key (j is “jump to section” in magit-status and “display status” everywhere else, while its whole “Applying changes” group is gated on the looser family test).

What is deliberately absent: the buffer id, the cursor, and the selection. A builder produces rows; it does not act. The row’s action receives its own ActionContext, which already carries the underlying buffer, its cursor and any Visual region — resolved at fire time, when they are current. Duplicating them here would be speculative surface that could also go stale between build and fire.

Fields

major_mode: Option<String>

The active major mode’s id, if the buffer has one. The :if-mode question.

minor_modes: Vec<String>

The active minor mode ids. The :if-derived question is asked here: a magit buffer is one where magit-core-mode is active, whatever its major happens to be.

buffer: Option<BufferId>

MR.4: the buffer the menu was opened over.

A builder whose rows depend on something the buffer owns — magit’s dispatch offers rebase --continue only while a rebase is stopped, and which repository that is depends on the buffer — cannot answer from the mode axes alone. None mid-boot, where the builder degrades exactly as it does for the mode fields.

Still not the cursor or the selection: a row’s own action receives those at fire time, when they are current.

args: Args

TR.3a: the arguments the open carried (Effect::OpenTransient { args }).

The one field here that is not a fact about WHERE the menu was opened — it is what it was opened FOR, and it is what lets a menu drill down. Org’s capture menu has a row per template; the fields menu that row opens reads the template key from here rather than from guest memory, which <Esc> never clears.

Implementations

impl TransientContext

pub fn is_major(&self, id: &str) -> bool

True iff id is the active major — :if-mode.

pub fn has_minor(&self, id: &str) -> bool

True iff id is an active minor — the family test a mode’s shared minor answers, standing in for :if-derived.

Trait Implementations

impl Clone for TransientContext

fn clone(&self) -> TransientContext

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TransientContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TransientContext

fn default() -> TransientContext

Returns the “default value” for a type.

impl PartialEq for TransientContext

fn eq(&self, other: &TransientContext) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for TransientContext