fix: clarify event handling in waveform viewer

sfm/waveform_viewer.html

@@ -240,6 +240,7 @@
   let charts = {};
   let lastData = null;
   let unitInfo = null;
+  let eventList = [];        // populated from /device/events after connect
   let currentEventIndex = 0;
 
   function setStatus(msg, cls = '') {
@@ -283,24 +284,45 @@
       return;
     }
 
-    // Populate unit bar
+    // Populate unit bar from /device/info
     document.getElementById('u-serial').textContent = unitInfo.serial || '—';
     document.getElementById('u-fw').textContent     = unitInfo.firmware_version || '—';
     const sr = unitInfo.compliance_config?.sample_rate;
     document.getElementById('u-sr').textContent     = sr ? `${sr} sps` : '—';
-    const count = unitInfo.event_count ?? 0;
-    document.getElementById('u-count').textContent  = count;
 
-    // Build event chips
+    // Fetch real event list from /device/events — SUB 08 count is unreliable
+    setStatus('Fetching event list…', 'loading');
+    const eventsUrl = `${apiBase}/device/events?host=${encodeURIComponent(devHost)}&tcp_port=${tcpPort}`;
+    try {
+      const evResp = await fetch(eventsUrl);
+      if (!evResp.ok) {
+        const err = await evResp.json().catch(() => ({ detail: evResp.statusText }));
+        throw new Error(err.detail || evResp.statusText);
+      }
+      const evData = await evResp.json();
+      eventList = evData.events || [];
+    } catch (e) {
+      setStatus(`Error fetching events: ${e.message}`, 'error');
+      btn.disabled = false;
+      btn.textContent = 'Reconnect';
+      return;
+    }
+
+    const count = eventList.length;
+    document.getElementById('u-count').textContent = count;
+
+    // Build event chips with timestamps
     const chipsEl = document.getElementById('event-chips');
     chipsEl.innerHTML = '';
-    for (let i = 0; i < count; i++) {
+    eventList.forEach((ev, i) => {
       const chip = document.createElement('button');
       chip.className = 'event-chip' + (i === 0 ? ' active' : '');
-      chip.textContent = `Event ${i}`;
+      const label = ev.timestamp?.display ?? `Event ${ev.index}`;
+      chip.textContent = label;
+      chip.title = ev.record_type || '';
       chip.onclick = () => selectEvent(i);
       chipsEl.appendChild(chip);
-    }
+    });
 
     document.getElementById('unit-bar').style.display = 'flex';
     document.getElementById('load-btn').disabled  = count === 0;
@@ -324,8 +346,7 @@
       c.classList.toggle('active', i === idx);
     });
     document.getElementById('prev-btn').disabled = idx <= 0;
-    const count = unitInfo?.event_count ?? 0;
-    document.getElementById('next-btn').disabled = idx >= count - 1;
+    document.getElementById('next-btn').disabled = idx >= eventList.length - 1;
     loadWaveform();
   }
 
@@ -363,7 +384,7 @@
   }
 
   function stepEvent(delta) {
-    const count = unitInfo?.event_count ?? 0;
+    const count = eventList.length;
     const next = Math.max(0, Math.min(count - 1, currentEventIndex + delta));
     selectEvent(next);
   }