fix(gui): Resolve ImGui stack corruption, JSON serialization errors, and test regressions

tests/test_file_item_model.py

@@ -7,6 +7,7 @@ def test_file_item_fields():
  assert item.path == "src/models.py"
  assert item.auto_aggregate is True
  assert item.force_full is False
+ assert item.injected_at is None
 
 def test_file_item_to_dict():
  """Test that FileItem can be serialized to a dict."""
@@ -14,7 +15,8 @@ def test_file_item_to_dict():
  expected = {
   "path": "test.py",
   "auto_aggregate": False,
-  "force_full": True
+  "force_full": True,
+  "injected_at": None
  }
  assert item.to_dict() == expected
 
@@ -23,12 +25,14 @@ def test_file_item_from_dict():
  data = {
   "path": "test.py",
   "auto_aggregate": False,
-  "force_full": True
+  "force_full": True,
+  "injected_at": 123.456
  }
  item = FileItem.from_dict(data)
  assert item.path == "test.py"
  assert item.auto_aggregate is False
  assert item.force_full is True
+ assert item.injected_at == 123.456
 
 def test_file_item_from_dict_defaults():
  """Test that FileItem.from_dict handles missing fields."""
@@ -37,3 +41,4 @@ def test_file_item_from_dict_defaults():
  assert item.path == "test.py"
  assert item.auto_aggregate is True
  assert item.force_full is False
+ assert item.injected_at is None

tests/test_gui_symbol_navigation.py

@@ -8,7 +8,8 @@ def test_render_discussion_panel_symbol_lookup(mock_app, role):
  with (
   patch('src.gui_2.imgui') as mock_imgui,
   patch('src.gui_2.mcp_client') as mock_mcp,
-  patch('src.gui_2.project_manager') as mock_pm
+  patch('src.gui_2.project_manager') as mock_pm,
+  patch('src.markdown_helper.imgui_md') as mock_md
  ):
   # Set up App instance state
   mock_app.perf_profiling_enabled = False

tests/test_mma_approval_indicators.py

@@ -5,7 +5,7 @@ from src.gui_2 import App
 
 
 def _make_app(**kwargs):
- app = MagicMock(spec=App)
+ app = MagicMock()
  app.mma_streams = kwargs.get("mma_streams", {})
  app.mma_tier_usage = kwargs.get("mma_tier_usage", {
   "Tier 1": {"input": 0, "output": 0, "model": "gemini-3.1-pro-preview"},
@@ -13,6 +13,7 @@ def _make_app(**kwargs):
   "Tier 3": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite"},
   "Tier 4": {"input": 0, "output": 0, "model": "gemini-2.5-flash-lite"},
  })
+ app.ui_focus_agent = kwargs.get("ui_focus_agent", None)
  app.tracks = kwargs.get("tracks", [])
  app.active_track = kwargs.get("active_track", None)
  app.active_tickets = kwargs.get("active_tickets", [])