test(techdemo): exercise checked form handler path

Add techdemo coverage for #[slhx::form] plus #[slhx::handler] on the generated launch_work form, and ignore the internal __h hidden handle field in generated form metadata.

req: form/001

req: form/004

req: form/006

req: derive_handler/003

examples/techdemo/src/lib.rs

@@ -5,7 +5,7 @@ pub mod ui {}
 mod tests {
     use super::ui;
     use hemplate::Hemplate;
-    use slhx::{IntoEffect, SafeHtml};
+    use slhx::{Effect, IntoEffect, Payload, SafeHtml};
     use slhx_test::inspect;
 
     #[derive(Hemplate)]
@@ -14,6 +14,15 @@ mod tests {
         label: &'static str,
     }
 
+    #[allow(dead_code)]
+    #[derive(Clone, Debug)]
+    #[slhx::form("launch_work")]
+    struct LaunchWork {
+        title: String,
+        lane: String,
+        impact: Option<u8>,
+    }
+
     // req: examples/001 req: codegen/002 req: public_api/001
     #[test]
     fn techdemo_uses_generated_slots_for_multi_target_updates() {
@@ -38,6 +47,22 @@ mod tests {
         )
     }
 
+    // req: examples/001 req: form/001 req: form/004 req: form/006 req: derive_handler/003
+    #[test]
+    fn techdemo_form_handler_is_checked_against_hemplate_form() {
+        #[slhx::handler]
+        fn launch_work(_form: slhx::Form<LaunchWork>) -> impl IntoEffect {
+            ui::control_center::slots::notice.text("queued")
+        }
+
+        let batch = inspect(launch_work(
+            ui::control_center::forms::launch_work.typed::<LaunchWork>(),
+        ));
+
+        assert!(batch.has_slot(ui::control_center::slots::notice));
+        assert!(matches!(batch.ops(), [Effect::Put { payload: Payload::Text(_), .. }]));
+    }
+
     // req: examples/001 req: form/002 req: codegen/003
     #[test]
     fn techdemo_exports_form_and_interaction_handles() {

slhx-build/src/lib.rs

@@ -276,6 +276,10 @@ impl Resources {
         component: String,
         controls: Vec<GeneratedControl>,
     ) -> io::Result<()> {
+        let controls = controls
+            .into_iter()
+            .filter(|control| control.name != "__h")
+            .collect();
         let resource = make_resource("form", symbol, name, component, false)?;
         match self.forms.get(&resource.ident) {
             Some(existing) if existing.resource.symbol != resource.symbol => Err(io::Error::new(
@@ -1062,6 +1066,7 @@ mod tests {
         std::fs::write(
             templates.join("profile.heml"),
             r#"<form data-slhx-handle="save" data-slhx-form="profile">
+                <input type="hidden" name="__h" value="123">
                 <input name="title" required>
                 <input name="count" type="number" min="1" max="10" step="1">
                 <select name="labels" multiple></select>
@@ -1090,6 +1095,7 @@ mod tests {
 
         let syms = std::fs::read_to_string(out.join("slhx.syms")).unwrap();
         assert!(syms.contains("handle_form\tsave\tprofile\n"));
+        assert!(!syms.contains("form_field\tprofile\t__h\t"));
         assert!(syms.contains("form_field\tprofile\ttitle\ttrue\tfalse\n"));
         assert!(syms.contains("form_field\tprofile\tlabels\tfalse\ttrue\n"));