🎨 Palette: Add async loading states to authentication forms

.Jules/palette.md

@@ -0,0 +1,3 @@
+## 2026-06-17 - Adding loading states to async form submissions
+**Learning:** When adding visual loading states to vanilla JS form submit buttons, accessing `e.submitter` provides a reliable way to target the specific button used, avoiding issues with generalized button selectors. A `finally` block with awaitable promises is crucial for guaranteed state cleanup, especially since users can submit forms multiple ways (enter key, pointer click).
+**Action:** Use `e.submitter` safely in form submission event handlers and ensure `aria-busy`, `disabled`, and `innerHTML` restoration is wrapped in `try/finally` blocks.

web-demo/js/app.js

@@ -144,6 +144,15 @@ class ClimaAI {
         e.preventDefault();
         const email = document.getElementById('loginEmail').value;
         const password = document.getElementById('loginPassword').value;
+        const submitBtn = e.submitter;
+        let originalText = '';
+
+        if (submitBtn) {
+            originalText = submitBtn.innerHTML;
+            submitBtn.innerHTML = '<span class="spinner" aria-hidden="true">⏳</span> Logging in...';
+            submitBtn.disabled = true;
+            submitBtn.setAttribute('aria-busy', 'true');
+        }
 
         try {
             this.showToast('Logging in...', 'info');
@@ -155,6 +164,12 @@ class ClimaAI {
             this.checkSubscription();
         } catch (error) {
             this.showToast(error.message || 'Login failed', 'error');
+        } finally {
+            if (submitBtn) {
+                submitBtn.innerHTML = originalText;
+                submitBtn.disabled = false;
+                submitBtn.removeAttribute('aria-busy');
+            }
         }
     }
 
@@ -163,6 +178,15 @@ class ClimaAI {
         const name = document.getElementById('registerName').value;
         const email = document.getElementById('registerEmail').value;
         const password = document.getElementById('registerPassword').value;
+        const submitBtn = e.submitter;
+        let originalText = '';
+
+        if (submitBtn) {
+            originalText = submitBtn.innerHTML;
+            submitBtn.innerHTML = '<span class="spinner" aria-hidden="true">⏳</span> Signing up...';
+            submitBtn.disabled = true;
+            submitBtn.setAttribute('aria-busy', 'true');
+        }
 
         try {
             this.showToast('Creating account...', 'info');
@@ -174,6 +198,12 @@ class ClimaAI {
             this.checkSubscription();
         } catch (error) {
             this.showToast(error.message || 'Registration failed', 'error');
+        } finally {
+            if (submitBtn) {
+                submitBtn.innerHTML = originalText;
+                submitBtn.disabled = false;
+                submitBtn.removeAttribute('aria-busy');
+            }
         }
     }