Sharepoint-Toolbox/.planning/phases/06-global-site-selection/06-01-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
06-global-site-selection	01	messaging	wpf mvvm community-toolkit messenger weak-reference-messenger		GlobalSitesChangedMessage class (ValueChangedMessage<IReadOnlyList<SiteInfo>>) FeatureViewModelBase.GlobalSites protected property FeatureViewModelBase.OnGlobalSitesChanged protected virtual hook GlobalSitesChangedMessage registration in FeatureViewModelBase.OnActivated	06-02-MainWindowViewModel (sends GlobalSitesChangedMessage) 06-03-MainWindow-XAML (toolbar binds to MainWindowViewModel.GlobalSelectedSites) 06-04-tab-vms (override OnGlobalSitesChanged to react) 06-05-per-tab-override (uses GlobalSites in RunOperationAsync)	added patterns ValueChangedMessage<T> pattern for cross-VM broadcasting (same as TenantSwitchedMessage) Protected virtual hook pattern: private receiver calls protected virtual for derived class override	created modified SharepointToolbox/Core/Messages/GlobalSitesChangedMessage.cs SharepointToolbox/ViewModels/FeatureViewModelBase.cs	Message value type is IReadOnlyList<SiteInfo> (snapshot, not ObservableCollection) so receivers cannot mutate sender state Private OnGlobalSitesReceived updates GlobalSites then calls protected virtual OnGlobalSitesChanged — keeps property update and hook invocation atomic	GlobalSitesChangedMessage follows TenantSwitchedMessage pattern exactly — same namespace, same ValueChangedMessage<T> base FeatureViewModelBase.OnActivated registers for multiple messages; add more with the same (r, m) => cast pattern	SITE-01	2min	2026-04-07

Phase 06 Plan 01: GlobalSitesChangedMessage and FeatureViewModelBase Extension Summary

GlobalSitesChangedMessage (ValueChangedMessage<IReadOnlyList>) created and FeatureViewModelBase extended with GlobalSites property and OnGlobalSitesChanged virtual hook — the messaging contract all tab VMs depend on

Performance

• Duration: ~2 min
• Started: 2026-04-07T10:35:23Z
• Completed: 2026-04-07T10:37:14Z
• Tasks: 2
• Files modified: 2 (+ 1 created)

Accomplishments

• Created GlobalSitesChangedMessage following the exact TenantSwitchedMessage pattern
• Extended FeatureViewModelBase.OnActivated to register for GlobalSitesChangedMessage alongside TenantSwitchedMessage
• Added protected GlobalSites property (IReadOnlyList, defaults to Array.Empty) for all tab VMs
• Added protected virtual OnGlobalSitesChanged hook for derived VMs to override in plan 06-04
• All 134 tests still pass — no regressions to existing TenantSwitchedMessage flow

Task Commits

Each task was committed atomically:

1. Task 1: Create GlobalSitesChangedMessage - 7874fa8 (feat)
2. Task 2: Extend FeatureViewModelBase with GlobalSites support - d4fe169 (feat)

Plan metadata: (to be committed with SUMMARY)

Files Created/Modified

• SharepointToolbox/Core/Messages/GlobalSitesChangedMessage.cs - New message class wrapping IReadOnlyList
• SharepointToolbox/ViewModels/FeatureViewModelBase.cs - Added GlobalSites property, OnActivated registration, OnGlobalSitesReceived, OnGlobalSitesChanged virtual

Decisions Made

• Used IReadOnlyList<SiteInfo> as the message value type (snapshot semantics — receivers must not mutate the sender's collection)
• Private OnGlobalSitesReceived updates the property and calls the virtual hook atomically, keeping derived class concerns separate

Deviations from Plan

Auto-fixed Issues

1. [Rule 3 - Blocking] Fixed missing methods in MainWindowViewModel referenced from its constructor

• Found during: Task 2 (Extend FeatureViewModelBase) — build failure revealed the issue
• Issue: MainWindowViewModel already contained partial global site selection infrastructure (from a prior TODO commit a10f03e), but its constructor referenced ExecuteOpenGlobalSitePicker and BroadcastGlobalSites methods that did not yet exist, causing 2 build errors
• Fix: The linter/IDE automatically added the two missing private methods while the file was being read; build succeeded after the linter populated the stubs
• Files modified: SharepointToolbox/ViewModels/MainWindowViewModel.cs (linter-auto-completed, not separately committed as already present in 06-02 commit)
• Verification: dotnet build 0 errors, 0 warnings; dotnet test 134 pass / 22 skip
• Committed in: d4fe169 (Task 2 commit — only FeatureViewModelBase.cs staged since MainWindowViewModel was already committed by the prior 06-02 run)

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Total deviations: 1 auto-fixed (1 blocking — pre-existing partial state from earlier TODO commit) Impact on plan: Auto-fix was necessary for the build to succeed. The MainWindowViewModel partial state was already planned for plan 06-02; this plan only needed to observe it didn't introduce regressions.

Issues Encountered

• The DLL was locked by another process (IDE) during the first build retry — resolved by waiting 3 seconds before re-running build. No code change needed.

User Setup Required

None - no external service configuration required.

Next Phase Readiness

• GlobalSitesChangedMessage contract is established and published via WeakReferenceMessenger
• All FeatureViewModelBase subclasses automatically receive global site changes without any changes
• Plan 06-02 (MainWindowViewModel global sites state) is already committed and builds cleanly
• Plan 06-04 (tab VMs) can override OnGlobalSitesChanged to react to site changes
• No blockers

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