Fix bugs from Codex review: deadlock, schema mismatch, timing

- loadRes: wrap in try/catch/finally so `loading` flag always resets
  on query failure (was permanent deadlock — finding #2)
- Schema fix: cluster-click query used `n as source` but the lite
  parquet has column named `source` (finding #4)
- Remove unnecessary ORDER BY on H3 loads (finding isamplesorg#8)
- Use .pop() instead of [0] for performance timing entries (finding isamplesorg#11)
- Add rel="noopener noreferrer" to target="_blank" link (finding isamplesorg#7)

Deferred: XSS escaping (trusted data), antimeridian handling,
detail click caching, startup error fallback.

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

Author: rdhyee

tutorials/progressive_globe.qmd

@@ -221,7 +221,7 @@ function updateSampleDetail(detail) {
         : '';
     el.innerHTML = `${desc ? `<div style="font-size: 12px; color: #444; margin-top: 6px; line-height: 1.4;">${desc}</div>` : ''}
         <div style="margin-top: 8px;">
-            <a class="detail-link" href="zenodo_isamples_analysis.html" target="_blank">Open in Analysis Tool →</a>
+            <a class="detail-link" href="zenodo_isamples_analysis.html" target="_blank" rel="noopener noreferrer">Open in Analysis Tool →</a>
         </div>`;
 }
 
@@ -363,7 +363,7 @@ viewer = {
             const delta = meta.resolution === 4 ? 2.0 : meta.resolution === 6 ? 0.5 : 0.1;
             try {
                 const samples = await db.query(`
-                    SELECT pid, label, n as source, latitude, longitude, description
+                    SELECT pid, label, source, latitude, longitude, description
                     FROM read_parquet('${lite_url}')
                     WHERE latitude BETWEEN ${meta.lat - delta} AND ${meta.lat + delta}
                       AND longitude BETWEEN ${meta.lng - delta} AND ${meta.lng + delta}
@@ -393,7 +393,6 @@ phase1 = {
         SELECT h3_cell, sample_count, center_lat, center_lng,
                dominant_source, source_count
         FROM read_parquet('${h3_res4_url}')
-        ORDER BY sample_count DESC
     `);
 
     const scalar = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.5);
@@ -414,7 +413,7 @@ phase1 = {
 
     performance.mark('p1-end');
     performance.measure('p1', 'p1-start', 'p1-end');
-    const elapsed = performance.getEntriesByName('p1')[0].duration;
+    const elapsed = performance.getEntriesByName('p1').pop().duration;
 
     updateStats('H3 Res4', data.length, totalSamples, `${(elapsed/1000).toFixed(1)}s`);
     updatePhaseMsg(`${data.length.toLocaleString()} clusters, ${totalSamples.toLocaleString()} samples. Zoom in for finer detail.`, 'done');
@@ -453,40 +452,45 @@ zoomWatcher = {
         loading = true;
         updatePhaseMsg(`Loading H3 res${res}...`, 'loading');
 
-        performance.mark(`r${res}-s`);
-        const data = await db.query(`
-            SELECT h3_cell, sample_count, center_lat, center_lng,
-                   dominant_source, source_count
-            FROM read_parquet('${url}')
-            ORDER BY sample_count DESC
-        `);
-
-        viewer.h3Points.removeAll();
-        const scalar = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.3);
-        let total = 0;
+        try {
+            performance.mark(`r${res}-s`);
+            const data = await db.query(`
+                SELECT h3_cell, sample_count, center_lat, center_lng,
+                       dominant_source, source_count
+                FROM read_parquet('${url}')
+            `);
 
-        for (const row of data) {
-            total += row.sample_count;
-            const size = Math.min(3 + Math.log10(row.sample_count) * 3.5, 18);
-            viewer.h3Points.add({
-                id: { count: row.sample_count, source: row.dominant_source, lat: row.center_lat, lng: row.center_lng, resolution: res },
-                position: Cesium.Cartesian3.fromDegrees(row.center_lng, row.center_lat, 0),
-                pixelSize: size,
-                color: Cesium.Color.fromCssColorString(SOURCE_COLORS[row.dominant_source] || '#666').withAlpha(0.85),
-                scaleByDistance: scalar,
-            });
-        }
+            viewer.h3Points.removeAll();
+            const scalar = new Cesium.NearFarScalar(1.5e2, 1.5, 8.0e6, 0.3);
+            let total = 0;
+
+            for (const row of data) {
+                total += row.sample_count;
+                const size = Math.min(3 + Math.log10(row.sample_count) * 3.5, 18);
+                viewer.h3Points.add({
+                    id: { count: row.sample_count, source: row.dominant_source, lat: row.center_lat, lng: row.center_lng, resolution: res },
+                    position: Cesium.Cartesian3.fromDegrees(row.center_lng, row.center_lat, 0),
+                    pixelSize: size,
+                    color: Cesium.Color.fromCssColorString(SOURCE_COLORS[row.dominant_source] || '#666').withAlpha(0.85),
+                    scaleByDistance: scalar,
+                });
+            }
 
-        performance.mark(`r${res}-e`);
-        performance.measure(`r${res}`, `r${res}-s`, `r${res}-e`);
-        const elapsed = performance.getEntriesByName(`r${res}`)[0].duration;
+            performance.mark(`r${res}-e`);
+            performance.measure(`r${res}`, `r${res}-s`, `r${res}-e`);
+            const elapsed = performance.getEntriesByName(`r${res}`).pop().duration;
 
-        updateStats(`H3 Res${res}`, data.length, total, `${(elapsed/1000).toFixed(1)}s`);
-        updatePhaseMsg(`${data.length.toLocaleString()} clusters, ${total.toLocaleString()} samples. ${res < 8 ? 'Zoom in for finer detail.' : 'Zoom closer for individual samples.'}`, 'done');
+            updateStats(`H3 Res${res}`, data.length, total, `${(elapsed/1000).toFixed(1)}s`);
+            updatePhaseMsg(`${data.length.toLocaleString()} clusters, ${total.toLocaleString()} samples. ${res < 8 ? 'Zoom in for finer detail.' : 'Zoom closer for individual samples.'}`, 'done');
 
-        currentRes = res;
-        loading = false;
-        console.log(`Res${res}: ${data.length} clusters in ${elapsed.toFixed(0)}ms`);
+            currentRes = res;
+            console.log(`Res${res}: ${data.length} clusters in ${elapsed.toFixed(0)}ms`);
+        } catch(err) {
+            console.error(`Failed to load res${res}:`, err);
+            updatePhaseMsg(`Failed to load H3 res${res} — try zooming again.`, 'loading');
+        } finally {
+            loading = false;
+        }
     };
 
     // --- Get camera viewport bounds ---