TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 5: refactor(gui_2): migrate L1367 _apply_pending_patch to Result[T] (Phase 5)

Extract _apply_pending_patch_result helper from the apply_patch_to_file
try/except in App._apply_pending_patch. Legacy wrapper drains errors to
app._last_request_errors per FR-BC-4 event-handler pattern.

[pre-audit] L1367 INTERNAL_BROAD_CATCH
[post-audit] V count: 12 -> 11 (L1367 removed)

tests/test_gui_2_result.py

@@ -878,3 +878,48 @@ def test_phase_5_l1293_populate_auto_slices_file_read_result_failure():
  err = result.errors[0]
  assert err.source == "gui_2._populate_auto_slices_file_read_result"
  assert "no such file" in err.message
+
+
+def test_phase_5_l1367_apply_pending_patch_result_success():
+ """
+ L1367 _apply_pending_patch_result returns Result.ok=True on success.
+
+ The helper wraps the apply_patch_to_file try/except in App._apply_pending_patch.
+ On success (apply_patch_to_file returns (True, msg)), returns Result(data=True)
+ and sets app._show_patch_modal=False, app._pending_patch_text=None,
+ app._pending_patch_files=[], app._patch_error_message=None.
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app._pending_patch_text = "--- a/foo.py\n+++ b/foo.py\n@@ -1 +1 @@\n-old\n+new\n"
+ app.controller.current_project_dir = "/proj/foo"
+ with patch.object(gui_2, "apply_patch_to_file", return_value=(True, "patched")), \
+   patch.object(gui_2.imgui, "close_current_popup"):
+  result = gui_2._apply_pending_patch_result(app)
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data is True
+ assert app._show_patch_modal is False
+ assert app._patch_error_message is None
+
+
+def test_phase_5_l1367_apply_pending_patch_result_failure():
+ """
+ L1367 _apply_pending_patch_result returns Result.ok=False with ErrorInfo on failure.
+
+ When apply_patch_to_file returns (False, msg) or raises, the helper sets
+ app._patch_error_message to the error message and returns
+ Result(data=False, errors=[ErrorInfo]).
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app._pending_patch_text = "--- a/foo.py\n+++ b/foo.py\n"
+ app.controller.current_project_dir = "/proj/foo"
+ with patch.object(gui_2, "apply_patch_to_file", side_effect=RuntimeError("patch blew up")):
+  result = gui_2._apply_pending_patch_result(app)
+ assert not result.ok, f"Expected ok=False on failure, got data: {result.data}"
+ assert result.errors, "Expected at least one error on failure"
+ err = result.errors[0]
+ assert err.source == "gui_2._apply_pending_patch_result"
+ assert "patch blew up" in err.message