feat(examples): add saas settings page fallback

Make the SaaS tutorial's settings route render a distinct full-page fallback while the enhanced handler still swaps the generated page panel and pushes history. This proves page-swap shape without relying only on the enhanced interaction path.

req: examples/001

req: page_swap/002

examples/saas/src/lib.rs

@@ -181,6 +181,8 @@ pub struct Dashboard {
     summary: String,
     rows: Vec<ProjectRow>,
     project_count: usize,
+    show_projects: bool,
+    settings: SettingsPage,
 }
 
 impl Dashboard {
@@ -191,9 +193,18 @@ impl Dashboard {
             flash: "Signed in with a demo session".to_owned(),
             summary: project_summary(projects.len()),
             project_count: projects.len(),
+            show_projects: true,
+            settings: SettingsPage::production_boundaries(),
             rows: projects.into_iter().map(ProjectRow::from).collect(),
         }
     }
+
+    pub fn settings(ctx: &AppContext) -> Self {
+        let mut dashboard = Self::from_context(ctx);
+        dashboard.show_projects = false;
+        dashboard.flash.clear();
+        dashboard
+    }
 }
 
 #[derive(Hemplate)]
@@ -226,6 +237,14 @@ pub struct SettingsPage {
     message: &'static str,
 }
 
+impl SettingsPage {
+    fn production_boundaries() -> Self {
+        Self {
+            message: "Auth, CSRF, persistence, metrics, and deploy stay explicit app integrations.",
+        }
+    }
+}
+
 #[derive(Hemplate)]
 pub struct AppShell {
     title: &'static str,
@@ -239,6 +258,13 @@ pub fn home_page(ctx: &AppContext) -> Html {
     })
 }
 
+pub fn settings_page(ctx: &AppContext) -> Html {
+    hemx::page(&AppShell {
+        title: "hemx SaaS tutorial settings",
+        body: hemx::page(&Dashboard::settings(ctx)),
+    })
+}
+
 #[hemx::app(dashboard_handlers)]
 pub fn registry(ctx: AppContext) -> Registry {
     interactions(ui::BUILD_FINGERPRINT)
@@ -277,10 +303,7 @@ mod dashboard_handlers {
     #[hemx::handler]
     pub async fn open_settings(State(_ctx): State<AppContext>) -> impl IntoEffect {
         (
-            dashboard::page_panel.put(&SettingsPage {
+            dashboard::page_panel.put(&SettingsPage::production_boundaries()),
-                message:
-                    "Auth, CSRF, persistence, metrics, and deploy stay explicit app integrations.",
-            }),
             dashboard::nav.set("Settings"),
             push("/settings"),
         )
@@ -355,6 +378,31 @@ mod tests {
         assert!(html.as_str().contains("/metrics.js"));
     }
 
+    #[test]
+    fn settings_page_renders_the_full_page_fallback() {
+        // req: examples/001 req: page_swap/002
+        let ctx = AppContext::demo();
+        let html = settings_page(&ctx);
+        let document = ParsedHtml::parse_document(html.as_str());
+
+        assert_eq!(
+            document
+                .select(&selector("[data-hemx-root='dashboard']"))
+                .count(),
+            1
+        );
+        assert_eq!(
+            document
+                .select(&selector("[data-hemx-slot='page_panel'] .settings-page"))
+                .count(),
+            1
+        );
+        assert!(html.as_str().contains("explicit app integrations"));
+        assert!(!html
+            .as_str()
+            .contains("form data-hemx-handle=\"create_project\""));
+    }
+
     #[tokio::test]
     async fn create_project_is_auth_csrf_checked_and_persisted_locally() {
         // req: examples/001 req: auth/002 req: auth/004 req: form/001 req: failure/004

examples/saas/src/main.rs

@@ -6,7 +6,7 @@ use axum::Router;
 use futures_util::stream;
 use hemx::IntoEffect;
 use hemx_axum::{runtime_js, sse, EffectResponse, InteractionRequest};
-use hemx_saas_example::{home_page, live_status, registry, ui, AppContext};
+use hemx_saas_example::{home_page, live_status, registry, settings_page, ui, AppContext};
 use std::collections::BTreeMap;
 use std::convert::Infallible;
 
@@ -37,7 +37,7 @@ async fn home(State(ctx): State<AppContext>) -> impl IntoResponse {
 }
 
 async fn settings(State(ctx): State<AppContext>) -> impl IntoResponse {
-    axum::response::Html(home_page(&ctx).into_string())
+    axum::response::Html(settings_page(&ctx).into_string())
 }
 
 async fn interact(

examples/saas/templates/dashboard.heml

@@ -11,6 +11,7 @@
   </nav>
 
   <section class="panel" data-hemx-slot="page_panel">
+    <div h-if="self.show_projects">
       <form class="project-form" data-hemx-handle="create_project" data-hemx-form="new_project" data-hemx-disable-while-pending>
         <input type="hidden" name="csrf" +value="self.csrf">
         <label>Project name
@@ -28,6 +29,10 @@
           {+ row +}
         </template>
       </ul>
+    </div>
+    <div h-if="!self.show_projects">
+      {+ self.settings +}
+    </div>
   </section>
 
   <section class="status-row">