feat(chat): retry the last answer — redo-in-place Retry button on the latest brain bubble

tests/unit/test_frontend_scroll.py

@@ -108,11 +108,17 @@ def test_submit_reveals_user_message() -> None:
     """User intent kept by the owner: submitting scrolls the viewport down
     so the user's own message is visible — the submit addMessage passes
     the scroll intent; the streaming brain-bubble creations in the same
-    function never do."""
+    turn handler never do.
+
+    Phase 49: the turn handler is runTurn (extracted from handleSend) —
+    the user append + persistence save point 1 sit in its `!reask`
+    block (the redo-in-place retry path skips both: the question is
+    already in the DOM + conversation)."""
     js = _js()
-    send = js.find("async function handleSend")
-    assert send != -1, "handleSend must exist"
-    body = js[send : js.find("\n}\n", send)]
+    turn = js.find("async function runTurn")
+    assert turn != -1, "runTurn must exist (phase 49 extraction)"
+    body = js[turn : js.find("\n}\n", turn)]
+    assert "if (!reask) {" in body, "the user append is gated on !reask"
     assert 'addMessage("user", renderMarkdown(text), true)' in body, (
         "the submit must reveal the user message (scroll intent true)"
     )