Show baseline/reference form in a modal with live month preview

Replaces the small inline form with a centred modal dialog. When both
dates are selected, a live chip list shows every month covered (up to
36 months) so it is immediately clear what periods will be loaded.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/app.js

@@ -375,10 +375,48 @@ function showLoadForm(op) {
     state.loadDataOp = op;
     document.getElementById('load-data-title').textContent =
         op === 'baseline' ? 'Load Baseline' : 'Load Reference';
-    document.getElementById('load-data-form').classList.remove('hidden');
+    document.getElementById('load-date-from').value  = '';
+    document.getElementById('load-date-to').value    = '';
+    document.getElementById('load-note').value       = '';
+    document.getElementById('load-date-preview').classList.add('hidden');
+    document.getElementById('load-data-modal').classList.remove('hidden');
     document.getElementById('load-date-from').focus();
 }
 
+function hideLoadModal() {
+    document.getElementById('load-data-modal').classList.add('hidden');
+}
+
+function updateDatePreview() {
+    const fromVal = document.getElementById('load-date-from').value;
+    const toVal   = document.getElementById('load-date-to').value;
+    const preview = document.getElementById('load-date-preview');
+    const chips   = document.getElementById('load-date-chips');
+    const label   = preview.querySelector('.load-preview-label');
+
+    if (!fromVal || !toVal) { preview.classList.add('hidden'); return; }
+
+    const from = new Date(fromVal + 'T00:00:00');
+    const to   = new Date(toVal   + 'T00:00:00');
+    if (isNaN(from) || isNaN(to) || from > to) { preview.classList.add('hidden'); return; }
+
+    const months = [];
+    const cur = new Date(from.getFullYear(), from.getMonth(), 1);
+    const end = new Date(to.getFullYear(),   to.getMonth(),   1);
+    while (cur <= end) { months.push(new Date(cur)); cur.setMonth(cur.getMonth() + 1); }
+
+    const fmt = new Intl.DateTimeFormat('en-US', { month: 'short', year: 'numeric' });
+    label.textContent = `${months.length} month${months.length !== 1 ? 's' : ''} covered`;
+
+    if (months.length <= 36) {
+        chips.innerHTML = months.map(m => `<span class="date-chip">${fmt.format(m)}</span>`).join('');
+    } else {
+        chips.innerHTML = `<span class="date-chip-summary">${months.length} months — ${fmt.format(months[0])} → ${fmt.format(months[months.length - 1])}</span>`;
+    }
+
+    preview.classList.remove('hidden');
+}
+
 async function submitLoadData() {
     const date_from = document.getElementById('load-date-from').value;
     const date_to   = document.getElementById('load-date-to').value;
@@ -394,7 +432,7 @@ async function submitLoadData() {
     try {
         showStatus(`Loading ${state.loadDataOp}...`, 'info');
         const result = await api('POST', `/versions/${state.selectedVersionId}/${state.loadDataOp}`, body);
-        document.getElementById('load-data-form').classList.add('hidden');
+        hideLoadModal();
         showStatus(`${state.loadDataOp} loaded — ${result.rows_affected} rows`, 'success');
     } catch (err) {
         showStatus(err.message, 'error');
@@ -879,9 +917,10 @@ document.addEventListener('DOMContentLoaded', () => {
     document.getElementById('vbtn-toggle').addEventListener('click', toggleVersionStatus);
     document.getElementById('vbtn-delete').addEventListener('click', deleteVersion);
     document.getElementById('btn-load-submit').addEventListener('click', submitLoadData);
-    document.getElementById('btn-load-cancel').addEventListener('click', () => {
+    document.getElementById('btn-load-cancel').addEventListener('click', hideLoadModal);
-        document.getElementById('load-data-form').classList.add('hidden');
+    document.getElementById('btn-load-close').addEventListener('click', hideLoadModal);
-    });
+    document.getElementById('load-date-from').addEventListener('change', updateDatePreview);
+    document.getElementById('load-date-to').addEventListener('change', updateDatePreview);
 
     // forecast view buttons
     document.getElementById('btn-forecast-refresh').addEventListener('click', loadForecastData);

public/index.html

@@ -94,18 +94,6 @@
                 <button class="btn" id="vbtn-toggle">Close Version</button>
                 <button class="btn btn-danger" id="vbtn-delete">Delete</button>
             </div>
-            <div id="load-data-form" class="inline-form hidden">
-                <h3 id="load-data-title">Load Baseline</h3>
-                <div class="form-row">
-                    <label>Date From<input type="date" id="load-date-from" /></label>
-                    <label>Date To<input type="date" id="load-date-to" /></label>
-                    <label>Note<input type="text" id="load-note" placeholder="optional" /></label>
-                </div>
-                <div class="form-actions">
-                    <button id="btn-load-submit" class="btn btn-primary">Load</button>
-                    <button id="btn-load-cancel" class="btn">Cancel</button>
-                </div>
-            </div>
         </div>
 
         <!-- ===== FORECAST VIEW ===== -->
@@ -170,6 +158,31 @@
     </main>
 </div>
 
+<!-- Load baseline / reference modal -->
+<div id="load-data-modal" class="modal-overlay hidden">
+    <div class="modal load-data-modal">
+        <div class="modal-header">
+            <span id="load-data-title">Load Baseline</span>
+            <button id="btn-load-close" class="btn-icon">×</button>
+        </div>
+        <div id="load-data-body">
+            <div class="load-form-fields">
+                <label>Date From<input type="date" id="load-date-from" /></label>
+                <label>Date To<input type="date" id="load-date-to" /></label>
+                <label>Note<input type="text" id="load-note" placeholder="optional" /></label>
+            </div>
+            <div id="load-date-preview" class="load-date-preview hidden">
+                <div class="load-preview-label"></div>
+                <div id="load-date-chips" class="date-chips"></div>
+            </div>
+        </div>
+        <div class="modal-footer">
+            <button id="btn-load-submit" class="btn btn-primary">Load</button>
+            <button id="btn-load-cancel" class="btn">Cancel</button>
+        </div>
+    </div>
+</div>
+
 <!-- Table preview modal -->
 <div id="modal-overlay" class="modal-overlay hidden">
     <div class="modal">

public/styles.css

@@ -312,6 +312,83 @@ body {
 #modal-body { padding: 16px 18px; overflow-y: auto; flex: 1; font-size: 12px; }
 .modal-footer { padding: 10px 18px; border-top: 1px solid #eee; display: flex; justify-content: flex-end; gap: 8px; }
 
+/* ============================================================
+   LOAD BASELINE / REFERENCE MODAL
+   ============================================================ */
+.load-data-modal { width: 480px; max-height: 80vh; }
+
+#load-data-body {
+    padding: 20px 24px;
+    display: flex;
+    flex-direction: column;
+    gap: 20px;
+    overflow-y: auto;
+}
+
+.load-form-fields {
+    display: flex;
+    flex-direction: column;
+    gap: 12px;
+}
+
+.load-form-fields label {
+    font-size: 11px;
+    color: #555;
+    display: flex;
+    flex-direction: column;
+    gap: 4px;
+}
+
+.load-form-fields input[type=date],
+.load-form-fields input[type=text] {
+    border: 1px solid #dce1e7;
+    padding: 7px 10px;
+    border-radius: 3px;
+    font-size: 13px;
+    color: #333;
+    width: 100%;
+}
+
+.load-form-fields input[type=date]:focus,
+.load-form-fields input[type=text]:focus {
+    outline: none;
+    border-color: #2980b9;
+    box-shadow: 0 0 0 2px rgba(41,128,185,.15);
+}
+
+.load-date-preview { display: flex; flex-direction: column; gap: 8px; }
+.load-date-preview.hidden { display: none; }
+
+.load-preview-label {
+    font-size: 11px;
+    font-weight: 600;
+    color: #7f8c8d;
+    text-transform: uppercase;
+    letter-spacing: 0.04em;
+}
+
+.date-chips {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 5px;
+}
+
+.date-chip {
+    background: #eaf4fb;
+    color: #1a6fa8;
+    border: 1px solid #c5dff0;
+    padding: 3px 9px;
+    border-radius: 12px;
+    font-size: 11px;
+    white-space: nowrap;
+}
+
+.date-chip-summary {
+    font-size: 12px;
+    color: #555;
+    font-style: italic;
+}
+
 .preview-section h4 { font-size: 12px; margin-bottom: 6px; color: #555; }
 .preview-section + .preview-section { margin-top: 16px; }
 .preview-table { border-collapse: collapse; width: 100%; font-size: 11px; }