fix(tui): apply ruff format and expand behave coverage for new TUI screens

- session_management.py: collapse three multi-line statements that
  ruff format would otherwise reformat (CI lint gate was failing on
  `ruff format --check`).
- features/tui_settings_session_screens.feature: add three scenarios
  that exercise the previously uncovered paths reported by
  diff_coverage on prior attempts:
  - SettingsScreen.get_settings() returns a settings dict
  - SessionManagementScreen renders sessions when visible+loaded
    (covers the render-loop body + _render_session_details
    non-None branch + the four detail lines)
  - TuiCommandRouter routes "/settings" to _settings_command
- features/steps/tui_settings_session_screens_steps.py:
  - Make `the selected_index should be {index:d}` look up whichever
    screen the scenario created (the step was always referencing
    `context.settings_screen`, which crashed in the
    SessionManagementScreen scenarios).
  - Reuse the existing TuiCommandRouter steps from
    tui_commands_coverage_steps.py for the /settings scenario.

The unit_tests / integration_tests CI gates on the prior run were
red on tests unrelated to this PR (CheckpointRepository and
actor_run_signature.robot, neither touched here); the targeted
behave run for this PR's feature file passes locally with all 12
scenarios green.

features/steps/tui_settings_session_screens_steps.py

@@ -2,6 +2,7 @@
 
 from behave import given, then, when
 
+from cleveragents.tui.commands import TuiCommandRouter
 from cleveragents.tui.screens.session_management import (
     SessionInfo,
     SessionManagementScreen,
@@ -110,8 +111,14 @@ def step_verify_settings_not_visible(context):
 
 @then("the selected_index should be {index:d}")
 def step_verify_selected_index(context, index):
-    """Verify the selected index."""
-    assert context.settings_screen.selected_index == index
+    """Verify the selected index on whichever screen was created in this scenario."""
+    screen = getattr(context, "session_screen", None) or getattr(
+        context, "settings_screen", None
+    )
+    assert screen is not None, "no screen widget created in this scenario"
+    assert screen.selected_index == index, (
+        f"expected selected_index={index}, got {screen.selected_index}"
+    )
 
 
 # ---------------------------------------------------------------------------
@@ -221,3 +228,51 @@ def step_verify_selected_session_none(context):
     """Verify get_selected_session returns None."""
     session = context.session_screen.get_selected_session()
     assert session is None
+
+
+@then(
+    'get_settings should return theme "{theme}", default_actor "{actor}", '
+    'safety_level "{level}"'
+)
+def step_verify_get_settings(context, theme, actor, level):
+    """Verify get_settings returns the expected settings dict."""
+    settings = context.settings_screen.get_settings()
+    assert settings == {
+        "theme": theme,
+        "default_actor": actor,
+        "safety_level": level,
+    }
+
+
+@then('the session screen rendered text should contain "{text}"')
+def step_verify_session_rendered_text_contains(context, text):
+    """Verify the rendered SessionManagementScreen text contains the given fragment."""
+    assert text in context.session_screen._text, (
+        f"expected {text!r} in rendered text, got: {context.session_screen._text!r}"
+    )
+
+
+# ---------------------------------------------------------------------------
+# TuiCommandRouter /settings route scenarios
+# ---------------------------------------------------------------------------
+class _FakePersonaRegistry:
+    """Minimal persona registry stub for /settings routing tests."""
+
+    def list_personas(self):
+        return []
+
+
+class _FakePersonaState:
+    """Minimal persona state stub for /settings routing tests."""
+
+    def get_active(self, session_id):
+        return None
+
+
+@given("a TuiCommandRouter for settings tests")
+def step_router_for_settings(context):
+    """Create a TuiCommandRouter with minimal stubs for the /settings route."""
+    context.router = TuiCommandRouter(
+        persona_registry=_FakePersonaRegistry(),  # type: ignore[arg-type]
+        persona_state=_FakePersonaState(),  # type: ignore[arg-type]
+    )

features/tui_settings_session_screens.feature

@@ -36,6 +36,13 @@ Feature: TUI Settings and Session Management Screens
     And the default_actor should be "admin"
     And the safety_level should be "high"
 
+  Scenario: SettingsScreen returns current settings as dict
+    Given a SettingsScreen widget
+    When I set the theme to "light"
+    And I set the default_actor to "admin"
+    And I set the safety_level to "high"
+    Then get_settings should return theme "light", default_actor "admin", safety_level "high"
+
   # ---------- SessionManagementScreen ----------
 
   Scenario: SessionManagementScreen initializes empty
@@ -67,3 +74,18 @@ Feature: TUI Settings and Session Management Screens
   Scenario: SessionManagementScreen returns None when no sessions
     Given a SessionManagementScreen widget
     Then get_selected_session should return None
+
+  Scenario: SessionManagementScreen renders sessions when visible
+    Given a SessionManagementScreen widget
+    When I show the session management screen
+    And I load 3 sessions
+    Then the session screen rendered text should contain "Session 1"
+    And the session screen rendered text should contain "10 msgs"
+    And the session screen rendered text should contain "[CURRENT]"
+
+  # ---------- TuiCommandRouter /settings route ----------
+
+  Scenario: TuiCommandRouter routes /settings to settings command
+    Given a TuiCommandRouter for settings tests
+    When I call handle with raw input "settings"
+    Then the handle result should be "Settings screen opened"

src/cleveragents/tui/screens/session_management.py

@@ -48,9 +48,7 @@ def _render_session_list(
     for i, session in enumerate(sessions):
         prefix = "❯ " if i == selected_index else "  "  # noqa: RUF001
         current = " [CURRENT]" if session.session_id == current_session_id else ""
-        lines.append(
-            f"{prefix}{session.name} ({session.message_count} msgs){current}"
-        )
+        lines.append(f"{prefix}{session.name} ({session.message_count} msgs){current}")
     return "\n".join(lines)
 
 
@@ -70,9 +68,7 @@ def _render_session_details(session: SessionInfo | None) -> str:
 
 def _render_status_bar() -> str:
     """Render the status bar at the bottom of the screen."""
-    return (
-        "j/k Nav │ enter Switch │ r Rename │ d Delete │ n New │ esc Close"
-    )
+    return "j/k Nav │ enter Switch │ r Rename │ d Delete │ n New │ esc Close"
 
 
 def _render_screen(
@@ -85,9 +81,7 @@ def _render_screen(
     selected_session = sessions[selected_index] if sessions else None
     session_details = _render_session_details(selected_session)
     status_bar = _render_status_bar()
-    return (
-        f"Session Management\n\n{session_list}\n\n{session_details}\n\n{status_bar}"
-    )
+    return f"Session Management\n\n{session_list}\n\n{session_details}\n\n{status_bar}"
 
 
 class SessionManagementScreen(_StaticBase):