feat(build): type generated event constants

Generate EventName constants for data-slhx-on metadata and exercise them through typed event emission in techdemo.

req: codegen/006

REQUIREMENTS.md

@@ -238,7 +238,7 @@ a `data-*` handle param is statically known or runtime-extracted.
 005	Generated module `atoms` exports `Atom<T>` for values that must be addressable, bootstrapped, or synced. Ordinary Rust fields on app/components are not automatically atoms.
 
 ### req: codegen/006
-006	`slhx-build` discovers `data-slhx-on` event names from hemplate Surface inputs and emits generated event constants. Event constants are metadata for checked Rust authoring and diagnostics; they do not create a trigger mini-language or new browser runtime semantics. [north_star]
+006	`slhx-build` discovers `data-slhx-on` event names from hemplate Surface inputs and emits generated `slhx::EventName` constants. Event constants are metadata for checked Rust authoring and diagnostics; they do not create a trigger mini-language or new browser runtime semantics. [north_star]
 
 ---
 

examples/techdemo/src/lib.rs

@@ -74,6 +74,10 @@ mod tests {
     // req: codegen/006
     #[test]
     fn techdemo_exports_generated_event_constants() {
-        assert_eq!(ui::issue_lane::events::drop, "drop");
+        assert_eq!(ui::issue_lane::events::drop.as_str(), "drop");
+        assert!(matches!(
+            slhx::event(ui::issue_lane::events::drop, "card-1"),
+            Effect::Emit { name, payload } if name == "drop" && payload == "card-1"
+        ));
     }
 }

slhx-build/src/lib.rs

@@ -408,7 +408,7 @@ impl Resources {
                 continue;
             }
             out.push_str(&format!(
-                "{inner}pub const {}: &'static str = {};\n",
+                "{inner}pub const {}: ::slhx::EventName = ::slhx::EventName::new({});\n",
                 event.ident,
                 rust_str(&event.name)
             ));
@@ -1031,8 +1031,8 @@ mod tests {
         assert!(generated.contains("pub mod atoms"));
         assert!(generated.contains("pub const filter"));
         assert!(generated.contains("pub mod events"));
-        assert!(generated.contains("pub const click: &'static str = \"click\""));
+        assert!(generated.contains("pub const click: ::slhx::EventName = ::slhx::EventName::new(\"click\")"));
-        assert!(generated.contains("pub const keydown: &'static str = \"keydown\""));
+        assert!(generated.contains("pub const keydown: ::slhx::EventName = ::slhx::EventName::new(\"keydown\")"));
         assert!(generated.contains("pub const new_todo"));
         assert!(generated.contains("pub mod todo"));
         assert!(generated.contains("pub const ALL_IDS"));

slhx-core/src/lib.rs

@@ -186,6 +186,41 @@ impl core::fmt::Display for CssClass {
     }
 }
 
+/// A generated, checked event token.
+/// req: codegen/006
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+pub struct EventName {
+    name: &'static str,
+}
+
+impl EventName {
+    pub const fn new(name: &'static str) -> Self {
+        Self { name }
+    }
+
+    pub const fn as_str(self) -> &'static str {
+        self.name
+    }
+}
+
+impl AsRef<str> for EventName {
+    fn as_ref(&self) -> &str {
+        self.name
+    }
+}
+
+impl From<EventName> for String {
+    fn from(event: EventName) -> Self {
+        event.name.to_string()
+    }
+}
+
+impl core::fmt::Display for EventName {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.write_str(self.name)
+    }
+}
+
 /// A small displayable list of generated CSS class tokens for hemplate `+class`.
 /// req: style/003
 #[derive(Clone, Debug, Eq, PartialEq, Hash)]

slhx/src/lib.rs

@@ -9,7 +9,7 @@ pub use slhx_derive::{app, component, form, handler, surface};
 pub mod prelude {
     pub use slhx_core::{
         navigate, push, redirect, replace, Atom, BuildFingerprint, CssClass, CssClasses, Effect,
-        Form, FormModel, FormValue, Handle, IntoEffect, KeyedSlot, Slot,
+        EventName, Form, FormModel, FormValue, Handle, IntoEffect, KeyedSlot, Slot,
     };
     pub use slhx_derive::{app, component, form, handler, surface};
 }