TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 4: refactor(gui_2): migrate L3718 render_ast_inspector_modal outline to Result[T] (Phase 4)

Adds _render_ast_inspector_outline_result(app, f_path) -> Result[str] helper that wraps
the mcp_client.configure + outline fetch try/except in render_ast_inspector_modal.
The data field carries the outline string so the legacy wrapper can iterate it
without an additional instance attribute. Errors drain to app._last_request_errors
(per FR-BC-3 modal pattern; data plane attribute).

Audit: BROAD_CATCH count 16 -> 15, COMPLIANT count 21 -> 22. Migration
target count drops by 1. Tests: 2/2 pass.

tests/test_gui_2_result.py

@@ -658,3 +658,43 @@ def test_phase_4_l3398_render_persona_editor_save_result_failure():
  assert err.source == "gui_2._render_persona_editor_save_result"
  assert "validation failed" in err.message
  assert "Error:" in app.ai_status
+
+
+def test_phase_4_l3718_render_ast_inspector_outline_result_success():
+ """
+ L3718 _render_ast_inspector_outline_result returns Result.ok=True on success.
+
+ The helper wraps the mcp_client.{py,ts_c,ts_cpp}_get_code_outline try/except
+ in render_ast_inspector_modal. On success, returns Result(data=outline)
+ where outline is the string from the appropriate outline function.
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app.controller.active_project_path = "/proj/foo"
+ with patch.object(gui_2.mcp_client, "configure") as _cfg, \
+   patch.object(gui_2.mcp_client, "py_get_code_outline", return_value="[def] foo (Lines 1-10)") as _outline:
+  result = gui_2._render_ast_inspector_outline_result(app, "/proj/foo/src/bar.py")
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data == "[def] foo (Lines 1-10)"
+
+
+def test_phase_4_l3718_render_ast_inspector_outline_result_failure():
+ """
+ L3718 _render_ast_inspector_outline_result returns Result.ok=False on failure.
+
+ When mcp_client configure or outline fetch raises, the helper returns
+ Result(data="", 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.controller.active_project_path = "/proj/foo"
+ with patch.object(gui_2.mcp_client, "configure", side_effect=RuntimeError("configure failed")):
+  result = gui_2._render_ast_inspector_outline_result(app, "/proj/foo/src/bar.py")
+ 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_ast_inspector_outline_result"
+ assert "Error fetching outline" in result.data