fix(tui): add preset count assertion and actor lookup exception test

Address reviewer feedback:
- Add exact preset count assertion (3 presets) to thinking_effort-only
  scenario to verify no extra presets are generated
- Add BDD scenario for actor lookup exception path to verify graceful
  fallback to default-only preset when get_actor() raises an exception
- Add step definition for plural 'presets' form to support count > 1
- Add step definition for actor service that raises on get_actor

ISSUES CLOSED: #9360

features/steps/tui_first_run_steps.py

@@ -536,7 +536,9 @@ def step_actor_service_with_temperature(context: object, actor: str) -> None:
     context._actor_service = mock_service
 
 
-@given('an actor service with a mock actor "{actor}" with thinking_effort and temperature arguments')
+@given(
+    'an actor service with a mock actor "{actor}" with thinking_effort and temperature arguments'
+)
 def step_actor_service_with_both(context: object, actor: str) -> None:
     from cleveragents.domain.models.core import Actor
 
@@ -580,6 +582,13 @@ def step_actor_service_with_no_args(context: object, actor: str) -> None:
     context._actor_service = mock_service
 
 
+@given("an actor service that raises an exception on get_actor")
+def step_actor_service_raises_exception(context: object) -> None:
+    mock_service = MagicMock()
+    mock_service.get_actor.side_effect = RuntimeError("Actor not found")
+    context._actor_service = mock_service
+
+
 @when('I call create_default_persona_for_actor with actor "{actor}" and actor_service')
 def step_create_persona_with_service(context: object, actor: str) -> None:
     from cleveragents.tui.first_run import create_default_persona_for_actor
@@ -595,12 +604,12 @@ def step_persona_has_preset(context: object, preset_name: str) -> None:
     assert persona is not None, "Expected persona 'default' in registry"
     preset_names = [p.name for p in persona.argument_presets]
     assert preset_name in preset_names, (
-        f"Expected preset '{preset_name}' in persona presets, "
-        f"got: {preset_names}"
+        f"Expected preset '{preset_name}' in persona presets, got: {preset_names}"
     )
 
 
-@then('the default persona should have exactly {count:d} preset')
+@then("the default persona should have exactly {count:d} preset")
+@then("the default persona should have exactly {count:d} presets")
 def step_persona_has_exact_presets(context: object, count: int) -> None:
     persona = context._registry.get("default")
     assert persona is not None, "Expected persona 'default' in registry"

features/tui_first_run.feature

@@ -207,6 +207,7 @@ Feature: TUI first-run experience with actor selection overlay
     And the default persona should have preset "default"
     And the default persona should have preset "think: high"
     And the default persona should have preset "think: max"
+    And the default persona should have exactly 3 presets
 
   Scenario: create_default_persona_for_actor auto-generates presets for actor with temperature
     Given an empty persona registry
@@ -242,3 +243,11 @@ Feature: TUI first-run experience with actor selection overlay
     Then the registry should contain a persona named "default"
     And the default persona should have preset "default"
     And the default persona should have exactly 1 preset
+
+  Scenario: create_default_persona_for_actor falls back to default preset when actor lookup fails
+    Given an empty persona registry
+    And an actor service that raises an exception on get_actor
+    When I call create_default_persona_for_actor with actor "anthropic/claude-4-sonnet" and actor_service
+    Then the registry should contain a persona named "default"
+    And the default persona should have preset "default"
+    And the default persona should have exactly 1 preset

src/cleveragents/tui/first_run.py

@@ -148,9 +148,7 @@ def create_default_persona_for_actor(
         presets = _auto_generate_presets(actor_service, actor)
     else:
         # Default to just the default preset
-        presets = [
-            PersonaPreset(name="default", display="default", overrides={})
-        ]
+        presets = [PersonaPreset(name="default", display="default", overrides={})]
 
     persona = Persona(
         name="default",