diff --git a/public/components/assistant.html b/public/components/assistant.html
index 404a516..3c71aa5 100644
--- a/public/components/assistant.html
+++ b/public/components/assistant.html
@@ -64,7 +64,6 @@
                   <input type="file" id="assistant-attach-input" accept="image/png,image/jpeg,image/webp" multiple hidden>
                   <button id="btn-assistant-voice" class="assistant-voice-btn" type="button" title="Voice conversation"><i class="fas fa-headset"></i></button>
                   <button id="btn-assistant-mic" class="assistant-mic" type="button" title="Dictate your question"><i class="fas fa-microphone"></i></button>
-                  <button id="btn-assistant-cancel" class="btn-sm btn-ghost" type="button" hidden><i class="fas fa-stop"></i> Cancel search</button>
                   <button id="btn-assistant-send" class="btn-send" type="submit"><i class="fas fa-arrow-up"></i></button>
                 </div>
               </form>
diff --git a/public/css/assistant.css b/public/css/assistant.css
index 796bc6b..728bb3c 100644
--- a/public/css/assistant.css
+++ b/public/css/assistant.css
@@ -306,3 +306,5 @@ body.assistant-workspace .assistant-learning-view { min-height: 0; height: 100vh
 .assistant-model-pill[hidden] { display:none; }
 .assistant-model-control { border:1px solid var(--g200); background:white; border-radius:999px; padding:3px 10px; font-size:11px; color:var(--g600); cursor:pointer; max-width:220px; }
 .assistant-model-pick { display:block; }
+/* Send button becomes a red stop while the assistant works */
+.btn-send.busy { background:var(--danger,#dc2626); }
diff --git a/public/js/clinicalAssistant.js b/public/js/clinicalAssistant.js
index a6e4439..95afb74 100644
--- a/public/js/clinicalAssistant.js
+++ b/public/js/clinicalAssistant.js
@@ -126,7 +126,7 @@ import {
   function bindEvents() {
     var form = document.getElementById('assistant-form');
     var clearBtn = document.getElementById('btn-assistant-clear');
-    var cancelBtn = document.getElementById('btn-assistant-cancel');
+
     var exportBtn = document.getElementById('btn-assistant-export-pdf');
     var attachInput = document.getElementById('assistant-attach-input');
     var input = document.getElementById('assistant-input');
@@ -144,6 +144,11 @@ import {
     });
 
     if (form) form.addEventListener('submit', onAsk);
+    var sendBtn = document.getElementById('btn-assistant-send');
+    if (sendBtn) sendBtn.addEventListener('click', function(e) {
+      // Open WebUI behavior: the send button becomes Stop while working.
+      if (assistantBusy) { e.preventDefault(); cancelAssistantSearch(); }
+    });
     if (clearBtn) clearBtn.addEventListener('click', clearConversation);
     document.getElementById('btn-assistant-download-chat').addEventListener('click', downloadTranscript);
     if (goBackBtn) goBackBtn.addEventListener('click', goBackToMainMenu);
@@ -151,7 +156,7 @@ import {
       input.addEventListener('input', updateConversationBudget);
       input.addEventListener('input', resizeAssistantInput);
     }
-    if (cancelBtn) cancelBtn.addEventListener('click', cancelAssistantSearch);
+
     if (exportBtn) exportBtn.addEventListener('click', exportAnswerPdf);
     var takehomeBtn = document.getElementById('btn-assistant-takehome');
     if (takehomeBtn) takehomeBtn.addEventListener('click', openPatientTakehome);
@@ -1053,6 +1058,11 @@ import {
     resizeAssistantInput();
     if (status) status.textContent = 'Asking…';
     var send = document.getElementById('btn-assistant-send');
+    if (send) {
+      send.classList.toggle('busy', !!isBusy);
+      var sendIcon = send.querySelector('i');
+      if (sendIcon) sendIcon.className = isBusy ? 'fas fa-stop' : 'fas fa-arrow-up';
+    }
     if (send) send.click();
   }
 
@@ -2001,7 +2011,6 @@ import {
     var status = document.getElementById('assistant-status');
     var label = document.getElementById('assistant-status-text');
     var send = document.getElementById('btn-assistant-send');
-    var cancel = document.getElementById('btn-assistant-cancel');
     var input = document.getElementById('assistant-input');
     var attachInput = document.getElementById('assistant-attach-input');
     if (status) {
@@ -2013,13 +2022,6 @@ import {
       send.disabled = !!isBusy;
       send.innerHTML = isBusy ? '<i class="fas fa-spinner fa-spin"></i> Searching' : '<i class="fas fa-paper-plane"></i> Ask';
     }
-    if (cancel) {
-      var canCancel = !!isBusy && !!activeAssistantRequest;
-      if (canCancel) cancel.removeAttribute('hidden');
-      else cancel.setAttribute('hidden', '');
-      cancel.disabled = !canCancel;
-      cancel.style.display = canCancel ? 'inline-flex' : 'none';
-    }
     if (input) input.disabled = !!isBusy;
     if (attachInput) attachInput.disabled = !!isBusy;
   }