Add loader title hint for SPA navigation feedback

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/RSpade/Core/Js/Rsx.js

@@ -491,9 +491,11 @@ class Rsx {
         }
 
         // Collect any extra parameters for query string
+        // Filter out internal parameters that should not appear in URLs
+        const internal_params = ['_loader_title_hint'];
         const query_params = {};
         for (const key in params) {
-            if (!used_params[key]) {
+            if (!used_params[key] && !internal_params.includes(key)) {
                 query_params[key] = params[key];
             }
         }

app/RSpade/Core/SPA/Spa.js

@@ -465,7 +465,19 @@ class Spa {
 
                 console_debug('Spa', 'Intercepting link click: ' + href);
                 e.preventDefault();
-                Spa.dispatch(href, { history: 'auto' });
+
+                // Check for loader title hint - provides immediate title feedback while page loads
+                const loader_title_hint = link.getAttribute('data-loader-title-hint');
+                const dispatch_options = { history: 'auto' };
+
+                if (loader_title_hint) {
+                    // Set document title immediately for instant feedback
+                    document.title = loader_title_hint;
+                    dispatch_options.loader_title_hint = loader_title_hint;
+                    console_debug('Spa', 'Loader title hint: ' + loader_title_hint);
+                }
+
+                Spa.dispatch(href, dispatch_options);
             } else {
                 console_debug('Spa', 'No SPA route match, letting server handle: ' + href);
             }
@@ -514,6 +526,7 @@ class Spa {
                 history: options.history || 'auto',
                 scroll: 'scroll' in options ? options.scroll : undefined,
                 triggers: options.triggers !== false,
+                loader_title_hint: options.loader_title_hint || null,
             };
 
             console_debug('Spa', 'Dispatching to: ' + url + ' (history: ' + opts.history + ')');
@@ -660,18 +673,25 @@ class Spa {
             const action_class = route_match.action_class;
             const action_name = action_class.name;
 
+            // Merge loader title hint into action args if provided
+            // This allows the action to show a placeholder title while loading
+            let action_args = route_match.args;
+            if (opts.loader_title_hint) {
+                action_args = { ...route_match.args, _loader_title_hint: opts.loader_title_hint };
+            }
+
             // Log successful SPA navigation
             console.warn('[Spa.dispatch] Executing SPA navigation', {
                 url: url,
                 path: parsed.path,
-                params: route_match.args,
+                params: action_args,
                 action: action_name,
                 layouts: target_layouts,
                 history_mode: opts.history
             });
 
             // Resolve layout chain - find divergence point and reuse matching layouts
-            await Spa._resolve_layout_chain(target_layouts, action_name, route_match.args, url);
+            await Spa._resolve_layout_chain(target_layouts, action_name, action_args, url);
 
             // Scroll Restoration #1: Immediate (after action starts)
             // This occurs synchronously after the action component is created

app/RSpade/man/spa.txt

@@ -523,6 +523,37 @@ NAVIGATION
             Spa.action.reload();           // Reload current action
             Spa.layout.update_nav();       // Call layout method
 
+    Loader Title Hint:
+        When navigating from a list to a detail page, you can provide a hint
+        for the page title to display while the action loads its data. This
+        provides immediate visual feedback instead of showing a blank or
+        generic title during the loading state.
+
+        Add data-loader-title-hint attribute to links:
+
+            <a href="<%= Rsx.Route('Contacts_View_Action', {id: contact.id}) %>"
+               data-loader-title-hint="<%= contact.name %>">
+              <%= contact.name %>
+            </a>
+
+        When the link is clicked:
+        1. document.title is immediately set to the hint value
+        2. The hint is passed to the action as this.args._loader_title_hint
+        3. Action can use the hint while loading, then replace with real title
+
+        Using the Hint in Actions:
+            async page_title() {
+                // Show hint while loading, real title when data is ready
+                if (this.is_loading() && this.args._loader_title_hint) {
+                    return this.args._loader_title_hint;
+                }
+                return `Contact: ${this.data.contact.name}`;
+            }
+
+        The _loader_title_hint parameter is automatically filtered from URLs
+        generated by Rsx.Route(), so it never appears in the browser address
+        bar or generated links.
+
 SESSION VALIDATION
     After each SPA navigation (except initial load and back/forward), the client
     validates its state against the server by calling Rsx.validate_session().