Bug: breadcrumb-router-stale-selectedfolderpath-after-rebind #499

• Work Mode: full-bug

Summary

BreadcrumbBridgeRouter.BindRowsAsync clears _selectedRowId but does not clear
SelectedFolderPath. After a re-bind the UI shows no row highlighted while
EfcFormController.SelectedFolder still reports the previously selected folder. Because
BindFolderRows runs on every search keystroke, a confirm action taken at that moment can file mail
to a folder the user can no longer see selected.

Environment

• OS/version: Windows 11 Pro 10.0.26200
• Python version: n/a (C# / .NET Framework 4.8.1 WinForms VSTO add-in with Microsoft WebView2)
• Command/flags used: n/a - reached through the EfcViewer folder-list breadcrumb surface
• Data source or fixture: any folder set where a selection is made and then the search text changes

Steps to Reproduce

1. Open the EfcViewer folder list and type enough search text to show candidate folder rows.
2. Select a folder row, so SelectRow sets both _selectedRowId and SelectedFolderPath.
3. Type one more character in the search box. This reaches
   EfcFormController.BindFolderRows (QuickFiler/Controllers/EfcFormController.cs:873-883) and so
   BreadcrumbBridgeRouter.BindRowsAsync.
4. Observe that no row is highlighted in the re-rendered document.
5. Trigger a move or folder-open action.

Expected Behavior

After a re-bind clears the visible selection, the controller's SelectedFolder should agree with the
UI: either no folder is reported as the filing target, or the selection is visibly restored. The two
state fields _selectedRowId and SelectedFolderPath are written together in SelectRow and should
be cleared together.

Actual Behavior

Only _selectedRowId is cleared. SelectedFolderPath retains the previous value, so
EfcFormController.SelectedFolder keeps returning the old folder while the UI shows nothing
selected. A move performed at that point targets the stale folder.

Logs / Screenshots

• Attached minimal logs or screenshot
• Snippet: n/a - this is a silent state divergence with no error text.

Impact / Severity

• Blocker
• High
• Medium
• Low

Rationale: the consequence is mail filed to an unintended folder - a silent, user-visible data
placement error with no exception to signal it. Recorded by research as Medium-High; raised to High
here because BindFolderRows runs on every keystroke, so the divergent window is common rather than
rare, and the failure is silent.

Source

From: docs/features/potential/2026-08-08-breadcrumb-router-stale-selectedfolderpath-after-rebind.md