---
phase: 06-global-site-selection
plan: 02
subsystem: ui
tags: [wpf, mvvm, observable-collection, weak-reference-messenger, community-toolkit]

# Dependency graph
requires:
  - phase: 06-global-site-selection/06-01
    provides: GlobalSitesChangedMessage class in Core/Messages
provides:
  - GlobalSelectedSites ObservableCollection on MainWindowViewModel
  - OpenGlobalSitePickerCommand (disabled when no profile)
  - GlobalSitesSelectedLabel computed property for toolbar
  - WeakReferenceMessenger broadcast on GlobalSelectedSites change
  - Clear on tenant switch and session clear
affects:
  - 06-03 (toolbar XAML binds to these properties)
  - 06-04 (FeatureViewModelBase registers for GlobalSitesChangedMessage)

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Func<Window>? factory property for dialog opening (keeps Window refs out of VMs)"
    - "CollectionChanged subscription to broadcast messenger message and update computed label"
    - "ObservableCollection clear in OnSelectedProfileChanged for tenant-scoped state"

key-files:
  created: []
  modified:
    - SharepointToolbox/ViewModels/MainWindowViewModel.cs

key-decisions:
  - "Used using SharepointToolbox.Views.Dialogs in ViewModel for SitePickerDialog cast — acceptable given existing Window reference pattern in this VM"
  - "GlobalSitesSelectedLabel uses hardcoded string; plan 06-03 will replace with localized keys"
  - "CollectionChanged event subscribes in constructor to trigger both label update and messenger broadcast atomically"

patterns-established:
  - "OpenGlobalSitePickerDialog: same Func<Window>? factory pattern as OpenProfileManagementDialog"
  - "BroadcastGlobalSites(): single helper centralizes messenger send for GlobalSitesChangedMessage"

requirements-completed:
  - SITE-01

# Metrics
duration: 8min
completed: 2026-04-07
---

# Phase 06 Plan 02: MainWindowViewModel Global Site Selection Summary

**ObservableCollection<SiteInfo> GlobalSelectedSites with dialog command, computed label, messenger broadcast, and clear-on-tenant-switch added to MainWindowViewModel**

## Performance

- **Duration:** 8 min
- **Started:** 2026-04-07T10:10:00Z
- **Completed:** 2026-04-07T10:18:00Z
- **Tasks:** 1
- **Files modified:** 1

## Accomplishments
- Added GlobalSelectedSites and OpenGlobalSitePickerCommand to MainWindowViewModel — toolbar UI (06-03) can bind directly
- WeakReferenceMessenger broadcasts GlobalSitesChangedMessage on every collection change — all tab VMs receive live updates
- GlobalSelectedSites cleared on tenant switch and session clear, keeping site selection scoped to the current tenant

## Task Commits

Each task was committed atomically:

1. **Task 1: Add global site selection state, command, and broadcast to MainWindowViewModel** - `a10f03e` (feat)

**Plan metadata:** _(docs commit to follow)_

## Files Created/Modified
- `SharepointToolbox/ViewModels/MainWindowViewModel.cs` - Added OpenGlobalSitePickerDialog factory, GlobalSelectedSites, GlobalSitesSelectedLabel, OpenGlobalSitePickerCommand, ExecuteOpenGlobalSitePicker, BroadcastGlobalSites; clear on tenant switch and session clear

## Decisions Made
- Added `using SharepointToolbox.Views.Dialogs;` to MainWindowViewModel — acceptable because this VM already holds `Func<Window>?` factory properties that reference the View layer. The cast in `ExecuteOpenGlobalSitePicker` requires knowing the concrete dialog type.
- `GlobalSitesSelectedLabel` uses a hardcoded English string for now; plan 06-03 will replace it with a localized key from Strings.resx once toolbar XAML is added.

## Deviations from Plan

None - plan executed exactly as written.

(Note: `GlobalSitesChangedMessage.cs` was already present from plan 06-01 — no deviation needed.)

## Issues Encountered
None.

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- MainWindowViewModel now exposes all properties and commands needed for the toolbar XAML (plan 06-03)
- `OpenGlobalSitePickerDialog` factory property ready to be wired in MainWindow.xaml.cs (plan 06-03)
- GlobalSitesChangedMessage broadcasting is live; FeatureViewModelBase can register for it (plan 06-04)

---
*Phase: 06-global-site-selection*
*Completed: 2026-04-07*