TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 10: refactor(gui_2): migrate L1052 shutdown save_ini to Result[T] (Phase 10 site 5)

Extracted _shutdown_save_ini_result(app) -> Result[None] helper above
the App.shutdown method.
ANTI-SLIMING: full Result[T] propagation (NO bare-except+pass). The
helper returns Result(data=None) on success or Result(data=None,
errors=[ErrorInfo]) on exception (logging NOT a drain per the user's
principle 2026-06-17).

The legacy shutdown method preserves its signature, calls the helper,
drains errors to self._startup_timeline_errors, and proceeds to
self.controller.shutdown().

Tests: 2 new tests verify both paths (success and OSError).

Audit: L1052 reclassified from INTERNAL_SILENT_SWALLOW (9 sites remaining,
was 10). New helper L1052 is INTERNAL_COMPLIANT.

tests/test_gui_2_result.py

@@ -1903,4 +1903,48 @@ def test_phase_10_l728_run_immapp_result_failure():
  assert "IM_ASSERT" in err.message
 
 
+def test_phase_10_l1052_shutdown_save_ini_result_success():
+ """
+ L1052 _shutdown_save_ini_result returns Result(data=None) on success.
+
+ The helper extracts the imgui.save_ini_settings_to_disk() try/except from
+ App.shutdown into a Result-returning helper. On success, returns
+ Result(data=None). The legacy shutdown method proceeds to
+ self.controller.shutdown().
+ """
+ from unittest.mock import MagicMock, patch
+ import src.gui_2 as gui2_mod
+ app = MagicMock()
+ app.runner_params = MagicMock()
+ app.runner_params.ini_filename = "manualslop_layout.ini"
+ with patch("src.gui_2.imgui.save_ini_settings_to_disk", return_value=None):
+  result = gui2_mod._shutdown_save_ini_result(app)
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data is None
+
+
+def test_phase_10_l1052_shutdown_save_ini_result_failure():
+ """
+ L1052 _shutdown_save_ini_result returns Result(data=None, errors=[ErrorInfo]) on failure.
+
+ When imgui.save_ini_settings_to_disk() raises (e.g., disk full, path
+ not writable), the helper converts to ErrorInfo. The legacy shutdown
+ method drains to self._startup_timeline_errors and proceeds to
+ self.controller.shutdown() (the original behavior preserved).
+ """
+ from unittest.mock import MagicMock, patch
+ import src.gui_2 as gui2_mod
+ app = MagicMock()
+ app.runner_params = MagicMock()
+ app.runner_params.ini_filename = "manualslop_layout.ini"
+ with patch("src.gui_2.imgui.save_ini_settings_to_disk", side_effect=OSError("disk full")):
+  result = gui2_mod._shutdown_save_ini_result(app)
+ assert not result.ok, f"Expected ok=False on failure, got data: {result.data}"
+ assert result.data is None
+ assert result.errors, "Expected at least one error on failure"
+ err = result.errors[0]
+ assert err.source == "gui_2._shutdown_save_ini_result"
+ assert "disk full" in err.message
+
+