TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 5: refactor(gui_2): migrate L3163 render_tool_preset_manager_content bias_save to Result[T] (Phase 5)

Extract _render_tool_preset_bias_save_result helper from the BiasProfile
save try/except in render_tool_preset_manager_content. The imgui.button
callback drains errors to app._last_request_errors per FR-BC-4
event-handler pattern.

[pre-audit] L3163 INTERNAL_BROAD_CATCH
[post-audit] V count: 9 -> 8 (L3163 removed)

src/gui_2.py

@@ -3116,10 +3116,10 @@ def render_tool_preset_manager_content(app: App, is_embedded: bool = False) -> N
          imgui.end_child()
        
        if imgui.button("Save Profile", imgui.ImVec2(-1, 0)):
-        try:
-         p = models.BiasProfile(name=app._editing_bias_profile_name, tool_weights=app._editing_bias_profile_tool_weights, category_multipliers=app._editing_bias_profile_category_multipliers)
-         app.controller._cb_save_bias_profile(p, app._editing_tool_preset_scope); app.ai_status = f"Saved: {p.name}"
-        except Exception as e: app.ai_status = f"Error: {e}"
+        bias_save_result = _render_tool_preset_bias_save_result(app)
+        if not bias_save_result.ok:
+         if not hasattr(app, '_last_request_errors'): app._last_request_errors = []
+         app._last_request_errors.append(("_render_tool_preset_bias_save", bias_save_result.errors[0]))
        imgui.end_child()
       imgui.end_table()
      imgui.end_child()
@@ -7895,6 +7895,42 @@ def request_patch_from_tier4_result(app: "App", error: str, file_context: str) -
    original=e,
   )])
 
+
+def _render_tool_preset_bias_save_result(app: "App") -> Result[bool]:
+ """Drain-aware variant of L3163 render_tool_preset_manager_content Save Profile button.
+
+ Extracts the BiasProfile save try/except from
+ render_tool_preset_manager_content into a Result-returning helper. On
+ success (BiasProfile construction + _cb_save_bias_profile), sets
+ app.ai_status to "Saved: <name>" and returns Result(data=True). On
+ failure (BiasProfile construction or _cb_save_bias_profile raises), sets
+ app.ai_status to an error message and returns
+ Result(data=False, errors=[ErrorInfo]).
+
+ The legacy wrapper (the imgui.button callback) drains errors to
+ app._last_request_errors (per FR-BC-4 event-handler drain pattern;
+ data plane attribute).
+
+ [C: src/gui_2.py:render_tool_preset_manager_content (L3163 legacy wrapper)]
+ """
+ try:
+  p = models.BiasProfile(
+   name=app._editing_bias_profile_name,
+   tool_weights=app._editing_bias_profile_tool_weights,
+   category_multipliers=app._editing_bias_profile_category_multipliers,
+  )
+  app.controller._cb_save_bias_profile(p, app._editing_tool_preset_scope)
+  app.ai_status = f"Saved: {p.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"Bias profile save failed: {e}",
+   source="gui_2._render_tool_preset_bias_save_result",
+   original=e,
+  )])
+
 #endregion: Phase 5 Event Handler Result Helpers
 
 #endregion: MMA