Macro register_event 

macro_rules! register_event {
    ($ty:ty, $name:literal, $doc:literal, $source_crate:literal $(,)?) => { ... };
}

Declare and register an event type. Generates:

1. An impl of Event for $ty returning the registered EventTypeId.
2. A linkme-aggregated EventDescriptor entry pushed into EVENT_DESCRIPTORS.

Conventions:

• $name is the user-facing identifier ("lsp.buffer-attached"); lowercase, dot-separated, namespaced by feature.
• $doc is the short summary :describe-events prints.
• $source_crate records who owns the declaration; useful for :describe-events --by-crate and plugin host tooling.

Examples

use lattice_protocol::event_registry::{Event, descriptor_by_name};
use lattice_protocol::register_event;

#[derive(Debug)]
pub struct IndexFinished {
    pub files: usize,
}
register_event!(
    IndexFinished,
    "demo.index-finished",
    "Fired when the demo indexer finishes a pass.",
    "demo-crate",
);

let event = IndexFinished { files: 3 };
assert_eq!(event.event_type_id().name(), "demo.index-finished");
let desc = descriptor_by_name("demo.index-finished").unwrap();
assert_eq!(desc.source_crate, "demo-crate");
assert_eq!((desc.type_id)(), std::any::TypeId::of::<IndexFinished>());

The macro can’t be invoked from within a cfg(test) module alone – linkme requires the slice entry at the top level of a binary’s link graph. For tests that need a registered event, declare it at module scope.

Caller crates must add linkme as a direct dependency (proc-macro attribute paths can’t route through re-exports). Same constraint lattice-config callers face.