🎨 Palette: Improve loading state on Generate button

.Jules/palette.md

@@ -0,0 +1,6 @@
+This journal is for Palette's critical UX/accessibility learnings only.
+
+**Format:**
+`## YYYY-MM-DD - [Title]`
+`**Learning:** [UX/a11y insight]`
+`**Action:** [How to apply next time]`

web_app/static/index.html

@@ -143,10 +143,6 @@ <h2>Poster</h2>
         </main>
     </div>
     <div id="toastContainer" class="toast-container"></div>
-    <div id="loadingOverlay" class="loading-overlay" style="display: none;">
-        <div class="spinner"></div>
-        <p>Generating your masterpiece...</p>
-    </div>
     <script src="/static/script.js?v=21"></script>
 </body>
 

web_app/static/script.js

@@ -613,7 +613,16 @@ function handleLyricLineClick(lineNumber) {
 async function generatePoster() {
     if (!currentMetadata) return;
 
-    loadingOverlay.style.display = 'flex';
+    const originalButtonHTML = generateBtn.innerHTML;
+    generateBtn.disabled = true;
+    generateBtn.classList.add('loading');
+    generateBtn.innerHTML = `<span class="spinner-small"></span>Generating...`;
+
+    const restoreButton = () => {
+        generateBtn.disabled = false;
+        generateBtn.classList.remove('loading');
+        generateBtn.innerHTML = originalButtonHTML;
+    };
 
     const indexingToggle = document.getElementById('indexingToggle');
     const accentToggle = document.getElementById('accentToggle');
@@ -635,8 +644,8 @@ async function generatePoster() {
         const end = endVal;
 
         if (isNaN(start) || isNaN(end) || start >= end) {
-            loadingOverlay.style.display = 'none';
             showToast("Please enter a valid range (Start must be less than End).", "error");
+            restoreButton();
             return;
         }
 
@@ -669,13 +678,17 @@ async function generatePoster() {
             posterContainer.innerHTML = '';
             posterContainer.appendChild(img);
             showDownloadButton(imageUrl, data.filename);
-            loadingOverlay.style.display = 'none';
+            restoreButton();
+        };
+        img.onerror = () => {
+            showToast("Error: Failed to load the generated poster image.", "error");
+            restoreButton();
         };
 
     } catch (error) {
         console.error("Generation failed", error);
         showToast(`Error: ${error.message}`, "error");
-        loadingOverlay.style.display = 'none';
+        restoreButton();
     }
 }
 

web_app/static/style.css

@@ -908,4 +908,26 @@ input:focus {
 
 .result-action svg {
     pointer-events: none;
+}
+
+/* --- Button Loading State --- */
+.primary-btn.loading {
+    cursor: wait;
+    opacity: 0.8;
+    pointer-events: none;
+}
+
+.primary-btn.loading .spinner-small {
+    display: inline-block;
+    margin-right: 8px; /* space between spinner and text */
+}
+
+.spinner-small {
+    display: none; /* hidden by default */
+    width: 20px;
+    height: 20px;
+    border: 2px solid rgba(0, 0, 0, 0.3);
+    border-top-color: #1a1a1f;
+    border-radius: 50%;
+    animation: spin 0.8s linear infinite;
 }