fix(gui): remove orphan pop_style_color in render_comms_history_panel

ROOT CAUSE: In a previous fix (df7bda6e 'explicit child size for
comms_scroll and prior_scroll'), the code that pushed a child_bg style
color at the start of render_comms_history_panel was removed when the
section was rewritten to use imgui.get_content_region_avail() for
explicit child sizing. However, the matching pop_style_color at the end
of the function (guarded by 'if app.is_viewing_prior_session') was left
in place.

RESULT: When viewing a prior session, the imscope.style_color in
_gui_func pushes 1 color at the start of the frame, then the orphaned
pop in render_comms_history_panel decrements the imGui style counter
by 1, then _gui_func's imscope __exit__ tries to pop again — triggering
IM_ASSERT 'PopStyleColor() too many times!'.

This caused a cascade of imGui state corruption on every frame after
loading a prior session log, manifesting as 'too many times' assertions
on the next frame and 'Must call EndChild() and not End()' once the
style stack underflowed.

FIX: Remove the orphan pop_style_color at gui_2.py:3761. No matching
push exists, so the pop is unconditionally wrong.

TESTS:
- New test_comms_no_extraneous_pop.py asserts push/pop balance in
  render_comms_history_panel when is_viewing_prior_session is True
- 43/43 broad regression pass

src/gui_2.py

@@ -3757,9 +3757,8 @@ def render_comms_history_panel(app: App) -> None:
   imgui.set_scroll_here_y(1.0)
   app._scroll_comms_to_bottom = False
   
- imgui.end_child()
- if app.is_viewing_prior_session: imgui.pop_style_color()
- if app.perf_profiling_enabled: app.perf_monitor.end_component("_render_comms_history_panel")
+  imgui.end_child()
+  if app.perf_profiling_enabled: app.perf_monitor.end_component("_render_comms_history_panel")
 
 def render_takes_panel(app: App) -> None:
  imgui.text("Takes & Synthesis")

tests/test_comms_no_extraneous_pop.py

@@ -0,0 +1,49 @@
+from unittest.mock import patch, MagicMock
+from src.gui_2 import render_comms_history_panel
+
+def test_render_comms_history_panel_no_extraneous_pop_in_prior_mode(app_instance):
+ """Regression test: render_comms_history_panel must not pop_style_color
+  more times than it pushes when is_viewing_prior_session is True.
+  Previously, line 3761 had a stray pop with no matching push (the push
+  was removed during the comms_scroll child-size fix).
+ """
+ app_instance.is_viewing_prior_session = True
+ app_instance.perf_profiling_enabled = False
+ app_instance._scroll_comms_to_bottom = False
+ app_instance._comms_log_cache = []
+ app_instance.cb_load_prior_log = MagicMock()
+ app_instance.controller = MagicMock()
+ app_instance.controller.event_queue.put = MagicMock()
+ push_calls = []
+ pop_calls = []
+ with patch("src.gui_2.imgui") as mock_imgui, patch("src.gui_2.imscope") as mock_imscope, patch("src.gui_2.theme") as mock_theme:
+  mock_imgui.push_style_color.side_effect = lambda *a, **k: push_calls.append(a)
+  mock_imgui.pop_style_color.side_effect = lambda *a, **k: pop_calls.append(a)
+  mock_imgui.text = MagicMock()
+  mock_imgui.text_colored = MagicMock()
+  mock_imgui.same_line = MagicMock()
+  mock_imgui.separator = MagicMock()
+  mock_imgui.button = MagicMock(return_value=False)
+  mock_imgui.set_scroll_here_y = MagicMock()
+  mock_imgui.begin_child = MagicMock(return_value=True)
+  mock_imgui.end_child = MagicMock()
+  mock_imgui.get_content_region_avail = MagicMock(return_value=MagicMock(x=800.0, y=600.0))
+  mock_imgui.begin = MagicMock(return_value=True)
+  mock_imgui.end = MagicMock()
+  mock_imgui.ImVec2 = lambda *a: MagicMock(x=float(a[0]) if a else 0, y=float(a[1]) if len(a) > 1 else 0)
+  mock_imgui.ImVec4 = lambda *a: ("ImVec4", a)
+  for attr in ["Col_", "WindowFlags_", "TableFlags_", "TableColumnFlags_", "SelectableFlags_", "TreeNodeFlags_", "Cond_", "StyleVar_", "StyleColor_", "HoveredFlags_", "Key", "TabItemFlags_"]:
+   setattr(mock_imgui, attr, MagicMock())
+  def _scope_enter(): return True
+  def _scope_exit(*a): return False
+  for sc in [mock_imscope.style_color, mock_imscope.style_var, mock_imscope.child, mock_imscope.tab_bar, mock_imscope.tab_item, mock_imscope.tree_node_ex, mock_imscope.group, mock_imscope.indent, mock_imscope.id, mock_imscope.text_wrap, mock_imscope.tooltip, mock_imscope.menu, mock_imscope.menu_bar, mock_imscope.popup, mock_imscope.popup_modal, mock_imscope.window, mock_imscope.table]:
+   sc.return_value.__enter__ = MagicMock(side_effect=_scope_enter)
+   sc.return_value.__exit__ = MagicMock(side_effect=_scope_exit)
+  mock_theme.ai_text_style.return_value.__enter__ = MagicMock()
+  mock_theme.ai_text_style.return_value.__exit__ = MagicMock(side_effect=_scope_exit)
+  try:
+   render_comms_history_panel(app_instance)
+  except Exception as e:
+   import pytest
+   pytest.fail(f"render_comms_history_panel raised: {e}")
+ assert len(push_calls) == len(pop_calls), f"push_style_color/pop_style_color imbalance in prior mode: {len(push_calls)} pushes vs {len(pop_calls)} pops"