docs(13-02): complete User Directory ViewModel plan

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/phases/13-user-directory-viewmodel/13-RESEARCH.md

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+# Phase 13 Research: User Directory ViewModel
+
+## What Exists
+
+### GraphUserDirectoryService (Phase 10)
+- `GetUsersAsync(clientId, progress?, ct)` → `IReadOnlyList<GraphDirectoryUser>`
+- Filter: `accountEnabled eq true and userType eq 'Member'` (members only)
+- Select: displayName, userPrincipalName, mail, department, jobTitle
+- Uses `PageIterator<User, UserCollectionResponse>` for transparent pagination
+- Reports progress via `IProgress<int>` (running count)
+- Honors cancellation in page callback
+
+### GraphDirectoryUser Model
+```csharp
+public record GraphDirectoryUser(
+    string DisplayName, string UserPrincipalName,
+    string? Mail, string? Department, string? JobTitle);
+```
+**GAP**: No `UserType` property — needed for SC3 member/guest in-memory filtering.
+
+### UserAccessAuditViewModel (Phase 7)
+- Inherits `FeatureViewModelBase` (IsRunning, StatusMessage, ProgressValue, RunCommand, CancelCommand)
+- People-picker search: `SearchQuery` → debounce → `IGraphUserSearchService.SearchUsersAsync` → `SearchResults`
+- User selection: `SelectedUsers` (ObservableCollection<GraphUserResult>) → `RunOperationAsync` → audit
+- Results: `Results` (ObservableCollection<UserAccessEntry>) + `ResultsView` (ICollectionView with grouping/filtering)
+- Two constructors: full (DI) and test (omits export services)
+- `_currentProfile` tracks active tenant (via TenantSwitchedMessage)
+- `OnTenantSwitched` clears all state
+
+### ICollectionView Pattern (existing in same ViewModel)
+```csharp
+var cvs = new CollectionViewSource { Source = Results };
+ResultsView = cvs.View;
+ResultsView.GroupDescriptions.Add(new PropertyGroupDescription(...));
+ResultsView.Filter = FilterPredicate;
+// On filter change: ResultsView.Refresh();
+```
+
+### DI Registration
+- `IGraphUserDirectoryService` registered as Transient
+- `UserAccessAuditViewModel` registered as Transient
+- Currently NOT injected into UserAccessAuditViewModel
+
+## Gaps to Fill
+
+1. **GraphDirectoryUser needs UserType** — add `string? UserType` to record + update MapUser + select
+2. **Service needs guest inclusion** — add `bool includeGuests` parameter; when true, drop userType filter
+3. **ViewModel needs IGraphUserDirectoryService** — add to both constructors
+4. **ViewModel needs browse mode** — mode toggle, directory collection, load command, cancel, filter, sort
+5. **DI registration** — add IGraphUserDirectoryService to UserAccessAuditViewModel constructor resolution
+
+## Plan Breakdown
+
+1. **13-01** (Wave 1): Extend GraphDirectoryUser + GraphUserDirectoryService
+   - Add UserType to model
+   - Add userType to select fields
+   - Add `includeGuests` parameter (default false for backward compat)
+   - Update MapUser
+   - Update tests
+
+2. **13-02** (Wave 2): UserAccessAuditViewModel directory browse mode
+   - Inject IGraphUserDirectoryService
+   - Add AuditMode enum (Search/Browse) + IsBrowseMode toggle
+   - Add DirectoryUsers collection + DirectoryUsersView (ICollectionView)
+   - Add LoadDirectoryCommand with own CTS, progress reporting
+   - Add CancelDirectoryLoadCommand
+   - Add IncludeGuests toggle + in-memory filter by UserType
+   - Add DirectoryFilterText + filter predicate (DisplayName, UPN, Department, JobTitle)
+   - Add SortDescription defaults (DisplayName ascending)
+   - Add DirectoryLoadStatus string for "Loading... X users" display
+   - Update OnTenantSwitched to clear directory state
+   - Update DI in App.xaml.cs
+   - Comprehensive tests