diff --git a/llm_team_ui.py b/llm_team_ui.py
index c79232b..6cefebc 100644
--- a/llm_team_ui.py
+++ b/llm_team_ui.py
@@ -1462,6 +1462,22 @@ async function loadThreats() {
     });
     // Mass action buttons
     var spacer = document.createElement('div'); spacer.style.flex = '1'; toolbar.appendChild(spacer);
+    // Master "select all on this page" checkbox (2026-04-30 J UX request).
+    // Mirrors the per-row .ip-check style; toggles every visible row.
+    // Three-state: unchecked (none selected), checked (all selected),
+    // indeterminate (partial). updateSelCount keeps it in sync as
+    // individual rows are toggled.
+    var selAllWrap = document.createElement('label');
+    selAllWrap.style.cssText = 'display:flex;align-items:center;gap:6px;font-family:JetBrains Mono,monospace;font-size:9px;text-transform:uppercase;letter-spacing:0.5px;color:#7a7872;cursor:pointer';
+    selAllWrap.title = 'Toggle every IP on this page';
+    var selAll = document.createElement('input'); selAll.type = 'checkbox';
+    selAll.id = 'sel-all';
+    selAll.style.cssText = 'width:16px;height:16px;cursor:pointer;accent-color:#e2b55a';
+    selAll.onchange = function(){ toggleAllChecks(this.checked); };
+    selAllWrap.appendChild(selAll);
+    var selAllLabel = document.createElement('span'); selAllLabel.textContent = 'all';
+    selAllWrap.appendChild(selAllLabel);
+    toolbar.appendChild(selAllWrap);
     var selCount = document.createElement('span'); selCount.id = 'sel-count';
     selCount.style.cssText = 'font-family:JetBrains Mono,monospace;font-size:10px;color:#7a7872';
     toolbar.appendChild(selCount);
@@ -1585,9 +1601,33 @@ async function loadThreats() {
 var currentSort = 'hits';
 
 function updateSelCount() {
-  var checks = document.querySelectorAll('.ip-check:checked');
+  var all = document.querySelectorAll('.ip-check');
+  var checked = document.querySelectorAll('.ip-check:checked');
   var el = document.getElementById('sel-count');
-  if (el) el.textContent = checks.length ? checks.length + ' selected' : '';
+  if (el) el.textContent = checked.length ? checked.length + ' selected' : '';
+  // Sync the master "all" checkbox to reflect the page's actual state.
+  // Three states: none → unchecked, all → checked, partial → indeterminate.
+  // Indeterminate is the visual "half-tick" most browsers render — gives
+  // operators a clear "you've got some but not all selected" hint.
+  var master = document.getElementById('sel-all');
+  if (master) {
+    if (checked.length === 0) {
+      master.checked = false; master.indeterminate = false;
+    } else if (checked.length === all.length) {
+      master.checked = true; master.indeterminate = false;
+    } else {
+      master.indeterminate = true;
+    }
+  }
+}
+
+function toggleAllChecks(checked) {
+  // Master "select all" handler — flips every per-row checkbox on the
+  // page to match the master's state. Used by the toolbar's `[ ] all`
+  // checkbox so operators don't have to click each threat individually
+  // before hitting Ban Selected. (2026-04-30 J UX request.)
+  document.querySelectorAll('.ip-check').forEach(function(cb){ cb.checked = checked; });
+  updateSelCount();
 }
 
 async function massAction(action) {