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.

src/gui_2.py

@@ -3392,10 +3392,10 @@ def render_persona_editor_window(app: App, is_embedded: bool = False) -> None:
   imgui.separator()
   if imgui.button("Save##pers", imgui.ImVec2(100, 0)):
    if app._editing_persona_name.strip():
-    try:
-     import copy; persona = models.Persona(name=app._editing_persona_name.strip(), system_prompt=app._editing_persona_system_prompt, tool_preset=app._editing_persona_tool_preset_id or None, bias_profile=app._editing_persona_bias_profile_id or None, context_preset=app._editing_persona_context_preset_id or None, aggregation_strategy=app._editing_persona_aggregation_strategy or None, preferred_models=copy.deepcopy(app._editing_persona_preferred_models_list))
-     app.controller._cb_save_persona(persona, getattr(app, '_editing_persona_scope', 'project')); app.ai_status = f"Saved: {persona.name}"
-    except Exception as e: app.ai_status = f"Error: {e}"
+    result = _render_persona_editor_save_result(app)
+    if not result.ok:
+     if not hasattr(app, '_last_request_errors'): app._last_request_errors = []
+     app._last_request_errors.append(("render_persona_editor.save", result.errors[0]))
    else: app.ai_status = "Name required"
   imgui.same_line(); 
   if imgui.button("Delete##pers", imgui.ImVec2(100, 0)):
@@ -7633,4 +7633,46 @@ def _handle_history_logic_result(app: "App") -> Result[bool]:
 
 #endregion: Phase 3 Render-Loop Result Helpers
 
+#region: Phase 4 Modal/Dialog Result Helpers (result_migration_gui_2_20260619)
+
+def _render_persona_editor_save_result(app: "App") -> Result[bool]:
+ """Drain-aware variant of L3398 render_persona_editor_window Save button try/except.
+
+ Extracts the models.Persona(...) construction + app.controller._cb_save_persona
+ try/except from the Save button handler in render_persona_editor_window into a
+ Result-returning helper. On success, sets app.ai_status to "Saved: <name>"
+ and returns Result(data=True). On failure (any exception in Persona
+ construction or _cb_save_persona), sets app.ai_status to an error message
+ and returns Result(data=False, errors=[ErrorInfo]).
+
+ The legacy wrapper drains errors to app._last_request_errors (per FR-BC-3
+ modal pattern: data plane attribute; the modal itself is the UI surface).
+
+ [C: src/gui_2.py:render_persona_editor_window (L3398 legacy wrapper)]
+ """
+ try:
+  import copy
+  persona = models.Persona(
+   name=app._editing_persona_name.strip(),
+   system_prompt=app._editing_persona_system_prompt,
+   tool_preset=app._editing_persona_tool_preset_id or None,
+   bias_profile=app._editing_persona_bias_profile_id or None,
+   context_preset=app._editing_persona_context_preset_id or None,
+   aggregation_strategy=app._editing_persona_aggregation_strategy or None,
+   preferred_models=copy.deepcopy(app._editing_persona_preferred_models_list),
+  )
+  app.controller._cb_save_persona(persona, getattr(app, '_editing_persona_scope', 'project'))
+  app.ai_status = f"Saved: {persona.name}"
+  return Result(data=True)
+ except Exception as e:
+  app.ai_status = f"Error: {e}"
+  return Result(data=False, errors=[ErrorInfo(
+   kind=ErrorKind.INTERNAL,
+   message=f"Persona save failed: {e}",
+   source="gui_2._render_persona_editor_save_result",
+   original=e,
+  )])
+
+#endregion: Phase 4 Modal/Dialog Result Helpers
+
 #endregion: MMA