diff --git a/src/app_controller.py b/src/app_controller.py
index 245ff4e0..a1bf4c46 100644
--- a/src/app_controller.py
+++ b/src/app_controller.py
@@ -951,6 +951,7 @@ class AppController:
   self.prior_mma_dashboard_state = {}
   self.diagnostic_log: List[Dict[str, Any]] = []
   self.ui_active_tool_preset: str | None = None
+  self.ui_active_bias_profile: str | None = None
   self.available_models: List[str] = []
   self.all_available_models: Dict[str, List[str]] = {}
   self.proposed_tracks: List[Dict[str, Any]] = []
@@ -2782,6 +2783,17 @@ class AppController:
   self.tool_preset_manager.project_root = Path(self.active_project_root)
   self.tool_presets = self.tool_preset_manager.load_all_presets()
   self.bias_profiles = self.tool_preset_manager.load_all_bias_profiles()
+  self.personas = self.persona_manager.load_all()
+  if self.ui_active_persona and self.ui_active_persona not in self.personas:
+   self.ui_active_persona = ""
+  if self.ui_active_tool_preset and self.ui_active_tool_preset not in self.tool_presets:
+   self.ui_active_tool_preset = None
+  if self.ui_active_bias_profile and self.ui_active_bias_profile not in self.bias_profiles:
+   self.ui_active_bias_profile = None
+  if self.ui_project_preset_name and self.ui_project_preset_name not in self.presets:
+   self.ui_project_preset_name = None
+  ai_client.set_tool_preset(self.ui_active_tool_preset)
+  ai_client.set_bias_profile(self.ui_active_bias_profile)
   raw_presets = proj.get("view_presets", [])
   if isinstance(raw_presets, dict):
    self.view_presets = [models.NamedViewPreset.from_dict({"name": name, **data}) for name, data in raw_presets.items()]
diff --git a/tests/test_project_switch_persona_preset.py b/tests/test_project_switch_persona_preset.py
new file mode 100644
index 00000000..6a93e095
--- /dev/null
+++ b/tests/test_project_switch_persona_preset.py
@@ -0,0 +1,139 @@
+import os
+import json
+import pytest
+import tempfile
+import shutil
+from pathlib import Path
+from src.app_controller import AppController
+from src import models
+from src.personas import PersonaManager
+from src import presets, tool_presets
+from src import project_manager
+
+
+def _setup_two_projects(tmp_path):
+    project_a_dir = tmp_path / "project_a"
+    project_a_dir.mkdir()
+    project_a_path = project_a_dir / "project.toml"
+    project_a_path.write_text('[project]\nname = "project_a"\nactive_preset = "PresetA"\n')
+
+    project_b_dir = tmp_path / "project_b"
+    project_b_dir.mkdir()
+    project_b_path = project_b_dir / "project.toml"
+    project_b_path.write_text('[project]\nname = "project_b"\n')
+
+    (project_a_dir / "project_personas.toml").write_text(
+        '[personas."PersonaA"]\nsystem_prompt = "Project A persona"\npreferred_models = []\n'
+    )
+    (project_b_dir / "project_personas.toml").write_text(
+        '[personas."PersonaB"]\nsystem_prompt = "Project B persona"\npreferred_models = []\n'
+    )
+    (project_a_dir / "project_presets.toml").write_text(
+        '[presets."PresetA"]\nsystem_prompt = "Project A preset"\n'
+    )
+    (project_b_dir / "project_presets.toml").write_text(
+        '[presets."PresetB"]\nsystem_prompt = "Project B preset"\n'
+    )
+
+    return project_a_path, project_b_path
+
+
+def test_switch_project_resets_invalid_persona(tmp_path, monkeypatch):
+    project_a_path, project_b_path = _setup_two_projects(tmp_path)
+
+    ctrl = AppController()
+    monkeypatch.setattr(ctrl, "_rebuild_rag_index", lambda: None)
+    monkeypatch.setattr(ctrl, "_flush_to_project", lambda: None)
+
+    ctrl.active_project_path = str(project_a_path)
+    ctrl.project = project_manager.load_project(str(project_a_path))
+    ctrl.preset_manager = presets.PresetManager(Path(project_a_path).parent)
+    ctrl.tool_preset_manager = tool_presets.ToolPresetManager(Path(project_a_path).parent)
+    ctrl.persona_manager = PersonaManager(Path(project_a_path).parent)
+    ctrl._refresh_from_project()
+
+    assert "PersonaA" in ctrl.personas
+    assert "PersonaB" not in ctrl.personas
+    ctrl.ui_active_persona = "PersonaA"
+
+    ctrl._switch_project(str(project_b_path))
+
+    assert "PersonaA" not in ctrl.personas
+    assert "PersonaB" in ctrl.personas
+    assert ctrl.ui_active_persona == ""
+
+
+def test_switch_project_resets_invalid_preset(tmp_path, monkeypatch):
+    project_a_path, project_b_path = _setup_two_projects(tmp_path)
+
+    ctrl = AppController()
+    monkeypatch.setattr(ctrl, "_rebuild_rag_index", lambda: None)
+    monkeypatch.setattr(ctrl, "_flush_to_project", lambda: None)
+
+    ctrl.active_project_path = str(project_a_path)
+    ctrl.project = project_manager.load_project(str(project_a_path))
+    ctrl.preset_manager = presets.PresetManager(Path(project_a_path).parent)
+    ctrl.tool_preset_manager = tool_presets.ToolPresetManager(Path(project_a_path).parent)
+    ctrl.persona_manager = PersonaManager(Path(project_a_path).parent)
+    ctrl._refresh_from_project()
+
+    assert ctrl.ui_project_preset_name == "PresetA"
+
+    ctrl._switch_project(str(project_b_path))
+
+    assert "PresetA" not in ctrl.presets
+    assert "PresetB" in ctrl.presets
+    assert ctrl.ui_project_preset_name is None
+
+
+def test_switch_project_resets_invalid_tool_preset(tmp_path, monkeypatch):
+    project_a_path, project_b_path = _setup_two_projects(tmp_path)
+
+    (Path(project_a_path).parent / "project_tool_presets.toml").write_text(
+        '[presets."ToolA"]\ndescription = "A"\n[presets.tools."run_powershell"]\nweight = 1\n'
+    )
+    (Path(project_b_path).parent / "project_tool_presets.toml").write_text(
+        '[presets."ToolB"]\ndescription = "B"\n[presets.tools."run_powershell"]\nweight = 1\n'
+    )
+
+    ctrl = AppController()
+    monkeypatch.setattr(ctrl, "_rebuild_rag_index", lambda: None)
+    monkeypatch.setattr(ctrl, "_flush_to_project", lambda: None)
+
+    ctrl.active_project_path = str(project_a_path)
+    ctrl.project = project_manager.load_project(str(project_a_path))
+    ctrl.preset_manager = presets.PresetManager(Path(project_a_path).parent)
+    ctrl.tool_preset_manager = tool_presets.ToolPresetManager(Path(project_a_path).parent)
+    ctrl.persona_manager = PersonaManager(Path(project_a_path).parent)
+    ctrl._refresh_from_project()
+
+    ctrl.ui_active_tool_preset = "ToolA"
+    assert "ToolA" in ctrl.tool_presets
+
+    ctrl._switch_project(str(project_b_path))
+
+    assert "ToolA" not in ctrl.tool_presets
+    assert "ToolB" in ctrl.tool_presets
+    assert ctrl.ui_active_tool_preset is None
+
+
+def test_switch_project_preserves_global_preset(tmp_path, monkeypatch):
+    project_a_path, project_b_path = _setup_two_projects(tmp_path)
+
+    ctrl = AppController()
+    monkeypatch.setattr(ctrl, "_rebuild_rag_index", lambda: None)
+    monkeypatch.setattr(ctrl, "_flush_to_project", lambda: None)
+
+    ctrl.active_project_path = str(project_a_path)
+    ctrl.project = project_manager.load_project(str(project_a_path))
+    ctrl.preset_manager = presets.PresetManager(Path(project_a_path).parent)
+    ctrl.tool_preset_manager = tool_presets.ToolPresetManager(Path(project_a_path).parent)
+    ctrl.persona_manager = PersonaManager(Path(project_a_path).parent)
+    ctrl._refresh_from_project()
+
+    ctrl.ui_global_preset_name = "GlobalPresetA"
+    original_global = ctrl.ui_global_preset_name
+
+    ctrl._switch_project(str(project_b_path))
+
+    assert ctrl.ui_global_preset_name == original_global