diff --git a/apps/web/src/views/detail.ejs b/apps/web/src/views/detail.ejs
index 6e75bef..a251d03 100644
--- a/apps/web/src/views/detail.ejs
+++ b/apps/web/src/views/detail.ejs
@@ -465,13 +465,23 @@
         while (tbody.children.length > 100) tbody.removeChild(tbody.lastChild);
       }
 
-      // Chart — push new ping and re-render locally
+      // Chart — push new ping, evict oldest complete runs to cap at ~50 runs
       chartPings.push({
         latency_ms: ping.latency_ms, region: ping.region || '__none__',
         checked_at: ping.checked_at, up: ping.up, run_id: ping.run_id || null,
         status_code: ping.status_code
       });
-      if (chartPings.length > 200) chartPings.shift();
+      // Count distinct runs and remove oldest runs as a group
+      const MAX_RUNS = 50;
+      const seen = []; const runSet = new Set();
+      for (const p of chartPings) {
+        const rid = p.run_id || p.checked_at;
+        if (!runSet.has(rid)) { runSet.add(rid); seen.push(rid); }
+      }
+      if (seen.length > MAX_RUNS) {
+        const stale = new Set(seen.slice(0, seen.length - MAX_RUNS));
+        chartPings = chartPings.filter(p => !stale.has(p.run_id || p.checked_at));
+      }
       renderChart();
     });
   </script>