fix(telegram): brief-seeded branches reply and stream in their topic

tests/test_telegram.py

@@ -474,6 +474,27 @@ async def test_commands_status_merge_and_new(stack: Stack) -> None:
     assert stack.bot.topics[-1] == "edit:902:✅ отчёт"
 
 
+async def test_brief_branch_from_the_tool_replies_in_its_topic(stack: Stack) -> None:
+    stack.bot.message("hi")
+    await stack.until(lambda: stack.sent_with("hi"), what="reply")
+    master = await stack.world.conversations.find_bound(
+        frontend="telegram", external_id=GENERAL
+    )
+    child = await stack.world.conversations.spawn(
+        kind="branch",
+        seed="brief",
+        text="найди X",
+        title="X",
+        parent=master,
+        origin="mcp",
+    )
+    reply = await stack.until(lambda: stack.sent_with("найди X"), what="brief reply")
+    assert reply["thread"] == 902
+    assert not any(m["text"].startswith("📝") for m in stack.bot.sent)
+    assert any(d["message_thread_id"] == 902 for d in stack.bot.drafts)
+    assert (await stack.world.conversations.get(child.external_id)).flags == {}
+
+
 async def test_master_topic_survives_rotation(stack: Stack) -> None:
     stack.bot.message("hi")
     await stack.until(lambda: stack.sent_with("hi"), what="reply")