🎨 Palette: Add robust async loading states to authentication forms

.Jules/palette.md

@@ -0,0 +1,4 @@
+
+## 2026-05-29 - [Robust Async Loading States for Form Submits]
+**Learning:** When adding loading states (disabled, aria-busy, text updates) to submit buttons in Vanilla JS forms where the submit event binds to the form itself, it's critical to access the specific button via `e.submitter`. Always implement state restoration (e.g. restoring original text, enabling the button, and removing the aria-busy attribute) inside a `finally` block to ensure UI recovery regardless of whether the async logic (e.g., login, register) resolves successfully or throws an error.
+**Action:** Use `e.submitter` inside a null-check alongside `try/finally` for implementing loading states in form submit handlers where direct button clicks aren't individually targeted.

web-demo/css/style.css

@@ -1198,4 +1198,8 @@ body {
     body {
         padding: 0;
     }
-}
+}
+@keyframes spin {
+    from { transform: rotate(0deg); }
+    to { transform: rotate(360deg); }
+}

web-demo/js/app.js

@@ -145,6 +145,14 @@ class ClimaAI {
         const email = document.getElementById('loginEmail').value;
         const password = document.getElementById('loginPassword').value;
 
+        let originalText = '';
+        if (e.submitter) {
+            originalText = e.submitter.innerHTML;
+            e.submitter.disabled = true;
+            e.submitter.setAttribute('aria-busy', 'true');
+            e.submitter.innerHTML = '<span style="display:inline-block;animation:spin 1s linear infinite;margin-right:8px;">⏳</span> Signing in...';
+        }
+
         try {
             this.showToast('Logging in...', 'info');
             const response = await api.login(email, password);
@@ -155,6 +163,12 @@ class ClimaAI {
             this.checkSubscription();
         } catch (error) {
             this.showToast(error.message || 'Login failed', 'error');
+        } finally {
+            if (e.submitter) {
+                e.submitter.disabled = false;
+                e.submitter.removeAttribute('aria-busy');
+                e.submitter.innerHTML = originalText;
+            }
         }
     }
 
@@ -164,6 +178,14 @@ class ClimaAI {
         const email = document.getElementById('registerEmail').value;
         const password = document.getElementById('registerPassword').value;
 
+        let originalText = '';
+        if (e.submitter) {
+            originalText = e.submitter.innerHTML;
+            e.submitter.disabled = true;
+            e.submitter.setAttribute('aria-busy', 'true');
+            e.submitter.innerHTML = '<span style="display:inline-block;animation:spin 1s linear infinite;margin-right:8px;">⏳</span> Signing up...';
+        }
+
         try {
             this.showToast('Creating account...', 'info');
             const response = await api.register(email, password, name);
@@ -174,6 +196,12 @@ class ClimaAI {
             this.checkSubscription();
         } catch (error) {
             this.showToast(error.message || 'Registration failed', 'error');
+        } finally {
+            if (e.submitter) {
+                e.submitter.disabled = false;
+                e.submitter.removeAttribute('aria-busy');
+                e.submitter.innerHTML = originalText;
+            }
         }
     }