feat(timeline-editor): Final UI polish - auto-apply, stack-order priority

Implemented final UI improvements:
- Removed sequence info text (Start:, Priority)
- Removed 'Properties updated' message
- Auto-apply properties with oninput handlers
- Stack-order-based priority with Up/Down buttons
- Added 'Same as Above' toggle for = priority modifier

New functions: autoApplyProperties(), moveEffectUp(), moveEffectDown(), toggleSamePriority()

Task #57 Phase 1 complete: Interactive editor with drag-drop, resize handles, snap-to-beat, and stack-based priority.

handoff(Claude): Timeline editor Phase 1 feature-complete. All dragging bugs fixed, dynamic bounds working, stack-order priority operational. Ready for Phase 2 planning.

1 files changed, 61 insertions, 37 deletions

diff --git a/tools/timeline_editor/index.html b/tools/timeline_editor/index.html
index c6c54bd..5ab8ed0 100644
--- a/tools/timeline_editor/index.html
+++ b/tools/timeline_editor/index.html
@@ -663,28 +663,12 @@
                 seq._yPosition = cumulativeY;
                 cumulativeY += seqHeight + sequenceGap;
 
-                // Format time display based on mode (show visual start, not seq.startTime)
-                let seqTimeDisplay;
-                if (showBeats) {
-                    const beatDuration = 60.0 / bpm;
-                    const startBeat = (seqVisualStart / beatDuration).toFixed(1);
-                    seqTimeDisplay = `Start: ${startBeat}b`;
-                } else {
-                    seqTimeDisplay = `Start: ${seqVisualStart.toFixed(2)}s`;
-                }
-
                 // Create sequence name overlay (large, centered, fades on hover)
                 const seqNameDiv = document.createElement('div');
                 seqNameDiv.className = 'sequence-name';
                 seqNameDiv.textContent = seq.name || `Sequence ${seqIndex + 1}`;
 
-                // Create small info text in corner
-                const seqInfoDiv = document.createElement('div');
-                seqInfoDiv.className = 'sequence-info';
-                seqInfoDiv.innerHTML = `${seqTimeDisplay} | Priority: ${seq.priority}`;
-
                 seqDiv.appendChild(seqNameDiv);
-                seqDiv.appendChild(seqInfoDiv);
 
                 if (selectedItem && selectedItem.type === 'sequence' && selectedItem.index === seqIndex) {
                     seqDiv.classList.add('selected');
@@ -912,70 +896,110 @@
                 propertiesContent.innerHTML = `
                     <div class="property-group">
                         <label>Name</label>
-                        <input type="text" id="propName" value="${seq.name || ''}" placeholder="Sequence name">
+                        <input type="text" id="propName" value="${seq.name || ''}" placeholder="Sequence name" oninput="autoApplyProperties()">
                     </div>
                     <div class="property-group">
                         <label>Start Time (seconds)</label>
-                        <input type="number" id="propStartTime" value="${seq.startTime}" step="0.1" min="0">
-                    </div>
-                    <div class="property-group">
-                        <label>Priority</label>
-                        <input type="number" id="propPriority" value="${seq.priority}" step="1">
+                        <input type="number" id="propStartTime" value="${seq.startTime}" step="0.1" min="0" oninput="autoApplyProperties()">
                     </div>
-                    <button onclick="applyProperties()">Apply</button>
                 `;
             } else if (selectedItem.type === 'effect') {
                 const effect = sequences[selectedItem.seqIndex].effects[selectedItem.effectIndex];
+                const effects = sequences[selectedItem.seqIndex].effects;
+                const canMoveUp = selectedItem.effectIndex < effects.length - 1;
+                const canMoveDown = selectedItem.effectIndex > 0;
+                const samePriority = effect.priorityModifier === '=';
+
                 propertiesContent.innerHTML = `
                     <div class="property-group">
                         <label>Effect Class</label>
-                        <input type="text" id="propClassName" value="${effect.className}">
+                        <input type="text" id="propClassName" value="${effect.className}" oninput="autoApplyProperties()">
                     </div>
                     <div class="property-group">
                         <label>Start Time (relative to sequence)</label>
-                        <input type="number" id="propStartTime" value="${effect.startTime}" step="0.1" min="0">
+                        <input type="number" id="propStartTime" value="${effect.startTime}" step="0.1" oninput="autoApplyProperties()">
                     </div>
                     <div class="property-group">
                         <label>End Time (relative to sequence)</label>
-                        <input type="number" id="propEndTime" value="${effect.endTime}" step="0.1" min="0">
+                        <input type="number" id="propEndTime" value="${effect.endTime}" step="0.1" oninput="autoApplyProperties()">
                     </div>
                     <div class="property-group">
-                        <label>Priority</label>
-                        <input type="number" id="propPriority" value="${effect.priority}" step="1">
+                        <label>Constructor Arguments</label>
+                        <input type="text" id="propArgs" value="${effect.args || ''}" oninput="autoApplyProperties()">
                     </div>
                     <div class="property-group">
-                        <label>Constructor Arguments</label>
-                        <input type="text" id="propArgs" value="${effect.args}">
+                        <label>Stack Position (determines priority)</label>
+                        <div style="display: flex; gap: 5px; margin-bottom: 10px;">
+                            <button onclick="moveEffectUp()" ${!canMoveUp ? 'disabled' : ''} style="flex: 1;">↑ Up</button>
+                            <button onclick="moveEffectDown()" ${!canMoveDown ? 'disabled' : ''} style="flex: 1;">↓ Down</button>
+                        </div>
+                        <button onclick="toggleSamePriority()" style="width: 100%;">
+                            ${samePriority ? '✓ Same as Above (=)' : 'Increment (+)'}
+                        </button>
                     </div>
-                    <button onclick="applyProperties()">Apply</button>
                 `;
             }
         }
 
-        function applyProperties() {
+        // Auto-apply properties on input change (no Apply button needed)
+        function autoApplyProperties() {
             if (!selectedItem) return;
 
             if (selectedItem.type === 'sequence') {
                 const seq = sequences[selectedItem.index];
                 seq.name = document.getElementById('propName').value;
                 seq.startTime = parseFloat(document.getElementById('propStartTime').value);
-                seq.priority = parseInt(document.getElementById('propPriority').value);
             } else if (selectedItem.type === 'effect') {
                 const effect = sequences[selectedItem.seqIndex].effects[selectedItem.effectIndex];
                 effect.className = document.getElementById('propClassName').value;
                 effect.startTime = parseFloat(document.getElementById('propStartTime').value);
                 effect.endTime = parseFloat(document.getElementById('propEndTime').value);
-                effect.priority = parseInt(document.getElementById('propPriority').value);
                 effect.args = document.getElementById('propArgs').value;
             }
 
             // Re-render timeline (recalculates sequence bounds)
             renderTimeline();
+        }
 
-            // Update properties panel to reflect any calculated changes
-            updateProperties();
+        // Move effect up in stack (higher priority)
+        function moveEffectUp() {
+            if (!selectedItem || selectedItem.type !== 'effect') return;
 
-            showMessage('Properties updated', 'success');
+            const effects = sequences[selectedItem.seqIndex].effects;
+            const index = selectedItem.effectIndex;
+
+            if (index < effects.length - 1) {
+                // Swap with effect above
+                [effects[index], effects[index + 1]] = [effects[index + 1], effects[index]];
+                selectedItem.effectIndex = index + 1;
+                renderTimeline();
+                updateProperties();
+            }
+        }
+
+        // Move effect down in stack (lower priority)
+        function moveEffectDown() {
+            if (!selectedItem || selectedItem.type !== 'effect') return;
+
+            const effects = sequences[selectedItem.seqIndex].effects;
+            const index = selectedItem.effectIndex;
+
+            if (index > 0) {
+                // Swap with effect below
+                [effects[index], effects[index - 1]] = [effects[index - 1], effects[index]];
+                selectedItem.effectIndex = index - 1;
+                renderTimeline();
+                updateProperties();
+            }
+        }
+
+        // Toggle same priority as previous effect (= modifier)
+        function toggleSamePriority() {
+            if (!selectedItem || selectedItem.type !== 'effect') return;
+
+            const effect = sequences[selectedItem.seqIndex].effects[selectedItem.effectIndex];
+            effect.priorityModifier = effect.priorityModifier === '=' ? '+' : '=';
+            updateProperties();
         }
 
         // File operations