fix(chat): preserve regenerate session context

static/js/chat.js

@@ -4917,7 +4917,7 @@ import { wireArrowUpRecall, getUserMessagesFromChatHistory } from './composerArr
       if (replaceFromHere) {
         // Regenerate flows intentionally trim history to this point before
         // resubmitting. The plain "Resend message" action must not do this.
-        const keepCount = msgIndex;
+        const keepCount = msgIndex + 1;
         await fetch(`${API_BASE}/api/session/${sessionId}/truncate`, {
           method: 'POST',
           headers: { 'Content-Type': 'application/json' },
@@ -5031,7 +5031,7 @@ import { wireArrowUpRecall, getUserMessagesFromChatHistory } from './composerArr
       variants.push({ raw: oldRaw, html: oldHtml, label: 'original' });
     }
 
-    const keepCount = userIndex;
+    const keepCount = userIndex + 1;
 
     try {
       await fetch(`${API_BASE}/api/session/${sessionId}/truncate`, {

static/js/document.js

@@ -5428,7 +5428,10 @@ import { bindMenuDismiss, dismissOrRemove } from './escMenuStack.js';
       const target = rawTarget && rawTarget.nodeType === Node.TEXT_NODE ? rawTarget.parentElement : rawTarget;
       const sendButtons = Array.from(document.querySelectorAll('#doc-email-send-btn'));
       const targetBtn = target && target.closest ? target.closest('#doc-email-send-btn') : null;
-      const rectBtn = sendButtons.find((candidate) => _eventInsideElement(e, candidate));
+      const rectBtn = sendButtons.find((candidate) => {
+        const rect = candidate.getBoundingClientRect();
+        return candidate.offsetParent !== null && rect.width > 0 && rect.height > 0 && _eventInsideElement(e, candidate);
+      });
       const btn = targetBtn || rectBtn || null;
       if (!btn || btn.disabled) return;
       if (e) {

tests/test_document_email_send_intent.py

@@ -0,0 +1,25 @@
+from pathlib import Path
+
+
+SRC = Path("static/js/document.js")
+
+
+def _send_intent_body():
+    source = SRC.read_text(encoding="utf-8")
+    start = source.index("const handleSendIntent = (e) => {")
+    end = source.index("window.odysseusEmailSendIntent = handleSendIntent;", start)
+    return source[start:end]
+
+
+def test_email_send_intent_ignores_hidden_zero_rect_buttons():
+    body = _send_intent_body()
+
+    rect_idx = body.index("const rect = candidate.getBoundingClientRect();")
+    visible_idx = body.index("candidate.offsetParent !== null")
+    width_idx = body.index("rect.width > 0")
+    height_idx = body.index("rect.height > 0")
+    hit_idx = body.index("_eventInsideElement(e, candidate)")
+
+    assert rect_idx < visible_idx < hit_idx
+    assert rect_idx < width_idx < hit_idx
+    assert rect_idx < height_idx < hit_idx

tests/test_resend_message_nondestructive.py

@@ -41,3 +41,20 @@ def test_only_regenerate_callers_opt_into_replace_from_here():
 
     assert "window.chatModule.resendUserMessage(msgElement);" in renderer
     assert "window.chatModule.resendUserMessage(userMsgEl, { replaceFromHere: true });" in renderer
+
+
+def test_replace_and_regenerate_keep_the_original_user_message():
+    chat = _CHAT_JS.read_text(encoding="utf-8")
+    resend = chat[
+        chat.index("export async function resendUserMessage("):
+        chat.index("export async function regenerateFrom(")
+    ]
+    regenerate = chat[
+        chat.index("export async function regenerateFrom("):
+        chat.index("// Pending variants from a regeneration", chat.index("export async function regenerateFrom("))
+    ]
+
+    assert "const keepCount = msgIndex + 1;" in resend
+    assert "const keepCount = userIndex + 1;" in regenerate
+    assert "const keepCount = msgIndex;" not in resend
+    assert "const keepCount = userIndex;" not in regenerate