TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 4: refactor(gui_2): migrate L3398 render_persona_editor_window to Result[T] (Phase 4)

Adds _render_persona_editor_save_result(app) -> Result[bool] helper that wraps
the models.Persona(...) construction + _cb_save_persona try/except in
render_persona_editor_window Save button. The legacy wrapper drains errors
to app._last_request_errors (per FR-BC-3 modal pattern; data plane attribute).

Audit: BROAD_CATCH count 17 -> 16, COMPLIANT count 20 -> 21. Migration
target count drops by 1. Tests: 2/2 pass.

tests/test_gui_2_result.py

@@ -604,4 +604,57 @@ def test_phase_3_l4848_render_warmup_status_indicator_result_failure():
  assert result.errors, "Expected at least one error on failure"
  err = result.errors[0]
  assert err.source == "gui_2._render_warmup_status_indicator_result"
- assert "warmup backend down" in err.message
+def test_phase_4_l3398_render_persona_editor_save_result_success():
+ """
+ L3398 _render_persona_editor_save_result returns Result.ok=True on success.
+
+ The helper wraps the Save button try/except in render_persona_editor_window
+ (Persona creation: models.Persona(...) + _cb_save_persona). On success,
+ sets app.ai_status to "Saved: <name>" and returns Result(data=True).
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app._editing_persona_name            = "test_persona"
+ app._editing_persona_system_prompt   = "you are a helper"
+ app._editing_persona_tool_preset_id  = ""
+ app._editing_persona_bias_profile_id = ""
+ app._editing_persona_context_preset_id = ""
+ app._editing_persona_aggregation_strategy = ""
+ app._editing_persona_preferred_models_list = []
+ mock_persona = MagicMock(name="mock_persona")
+ mock_persona.name = "test_persona"
+ with patch.object(gui_2.models, "Persona", return_value=mock_persona):
+  result = gui_2._render_persona_editor_save_result(app)
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data is True
+ assert "Saved: test_persona" in app.ai_status
+
+
+def test_phase_4_l3398_render_persona_editor_save_result_failure():
+ """
+ L3398 _render_persona_editor_save_result returns Result.ok=False on failure.
+
+ When Persona construction or _cb_save_persona raises, the helper sets
+ app.ai_status to an error message and returns Result(data=False,
+ errors=[ErrorInfo]). The legacy wrapper should drain to
+ app._last_request_errors (per FR-BC-3 modal pattern).
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app._editing_persona_name            = "test_persona"
+ app._editing_persona_system_prompt   = "you are a helper"
+ app._editing_persona_tool_preset_id  = ""
+ app._editing_persona_bias_profile_id = ""
+ app._editing_persona_context_preset_id = ""
+ app._editing_persona_aggregation_strategy = ""
+ app._editing_persona_preferred_models_list = []
+ with patch.object(gui_2.models, "Persona", side_effect=RuntimeError("validation failed")):
+  result = gui_2._render_persona_editor_save_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._render_persona_editor_save_result"
+ assert "validation failed" in err.message
+ assert "Error:" in app.ai_status