TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 5: refactor(gui_2): migrate L7208 render_beads_tab list to Result[T] (Phase 5)

Extract _render_beads_tab_list_result helper from the beads_client.BeadsClient
+ list_beads() try/except in render_beads_tab. Legacy wrapper drains errors
to app._last_request_errors per FR-BC-4 event-handler pattern.

[pre-audit] L7208 INTERNAL_BROAD_CATCH
[post-audit] V count: 4 -> 3 (L7208 removed)

src/gui_2.py

@@ -7112,10 +7112,13 @@ def render_beads_tab(app: App) -> None:
   imgui.text_wrapped("Beads mode requires Dolt and the Beads (bd) CLI tools.")
  
  if getattr(app, "ui_project_execution_mode", "native") == "beads":
-  try:
+  beads_result = _render_beads_tab_list_result(app)
-   from src import beads_client
+  if not beads_result.ok:
-   bclient = beads_client.BeadsClient(Path(app.active_project_root))
+   if not hasattr(app, '_last_request_errors'): app._last_request_errors = []
-   beads   = bclient.list_beads()
+   app._last_request_errors.append(("_render_beads_tab_list", beads_result.errors[0]))
+   imgui.text_colored(theme.get_color("status_error"), f"Error loading beads: {beads_result.errors[0].message}")
+  else:
+   beads = beads_result.data
    if not beads:
     imgui.text_disabled("No beads found.")
    else:
@@ -7129,8 +7132,6 @@ def render_beads_tab(app: App) -> None:
       imgui.text(str(b.id));     imgui.table_next_column()
       imgui.text(str(b.status)); imgui.table_next_column(); imgui.text(str(b.title))
      imgui.end_table()
-  except Exception as e:
-   imgui.text_colored(theme.get_color("status_error"), f"Error loading beads: {e}")
 
 def render_mma_focus_selector(app: App) -> None:
  """Renders the Focus Agent selector. Filters the discussion entries list to show
@@ -8043,6 +8044,33 @@ def _render_external_editor_panel_config_result(app: "App") -> Result[bool]:
    original=e,
   )])
 
+
+def _render_beads_tab_list_result(app: "App") -> Result[list]:
+ """Drain-aware variant of L7208 render_beads_tab BeadsClient list.
+
+ Extracts the beads_client.BeadsClient(...) + list_beads() try/except in
+ render_beads_tab into a Result-returning helper. On success, returns
+ Result(data=beads) where beads is the list of beads. On exception,
+ returns Result(data=[], errors=[ErrorInfo]).
+
+ The legacy wrapper drains errors to app._last_request_errors (per FR-BC-4
+ event-handler drain pattern; data plane attribute).
+
+ [C: src/gui_2.py:render_beads_tab (L7208 legacy wrapper)]
+ """
+ from src import beads_client
+ try:
+  bclient = beads_client.BeadsClient(Path(app.active_project_root))
+  beads   = bclient.list_beads()
+  return Result(data=beads)
+ except Exception as e:
+  return Result(data=[], errors=[ErrorInfo(
+   kind=ErrorKind.INTERNAL,
+   message=f"Render beads tab list failed: {e}",
+   source="gui_2._render_beads_tab_list_result",
+   original=e,
+  )])
+
 #endregion: Phase 5 Event Handler Result Helpers
 
 #endregion: MMA

tests/test_gui_2_result.py

@@ -1226,3 +1226,47 @@ def test_phase_5_l5920_render_external_editor_panel_config_result_failure():
  err = result.errors[0]
  assert err.source == "gui_2._render_external_editor_panel_config_result"
  assert "ext editor config blew up" in err.message
+
+
+def test_phase_5_l7208_render_beads_tab_list_result_success():
+ """
+ L7208 _render_beads_tab_list_result returns Result.ok=True on success.
+
+ The helper wraps the beads_client.BeadsClient(...) + list_beads() try/except in
+ render_beads_tab. On success, returns Result(data=beads) where beads is the
+ list of beads returned by list_beads().
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app.active_project_root = "/proj/foo"
+ mock_client = MagicMock()
+ mock_bead   = MagicMock()
+ mock_bead.id     = "bd-1"
+ mock_bead.status = "todo"
+ mock_bead.title  = "test"
+ mock_client.list_beads.return_value = [mock_bead]
+ with patch("src.beads_client.BeadsClient", return_value=mock_client):
+  result = gui_2._render_beads_tab_list_result(app)
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data == [mock_bead]
+
+
+def test_phase_5_l7208_render_beads_tab_list_result_failure():
+ """
+ L7208 _render_beads_tab_list_result returns Result.ok=False with ErrorInfo on failure.
+
+ When BeadsClient construction or list_beads() raises, the helper converts
+ the exception to ErrorInfo and returns Result(data=[], errors=[ErrorInfo]).
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ app.active_project_root = "/proj/foo"
+ with patch("src.beads_client.BeadsClient", side_effect=RuntimeError("dolt backend down")):
+  result = gui_2._render_beads_tab_list_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_beads_tab_list_result"
+ assert "dolt backend down" in err.message