diff --git a/.planning/STATE.md b/.planning/STATE.md
index 0cf9841..416abd6 100644
--- a/.planning/STATE.md
+++ b/.planning/STATE.md
@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: completed
-stopped_at: Completed 09-03-PLAN.md
-last_updated: "2026-04-07T13:37:09.659Z"
-last_activity: 2026-04-07 — Completed 09-03 (ViewModel chart properties and View XAML)
+stopped_at: Completed 09-04-PLAN.md
+last_updated: "2026-04-07T13:40:30Z"
+last_activity: 2026-04-07 — Completed 09-04 (StorageViewModel chart unit tests)
 progress:
   total_phases: 4
-  completed_phases: 3
+  completed_phases: 4
   total_plans: 25
-  completed_plans: 24
+  completed_plans: 25
 ---
 
 # Project State
@@ -25,13 +25,13 @@ See: .planning/PROJECT.md (updated 2026-04-07)
 ## Current Position
 
 Phase: 9 — Storage Visualization
-Plan: 3 of 4
-Status: Plan 09-03 complete — ViewModel chart properties and View XAML
-Last activity: 2026-04-07 — Completed 09-03 (ViewModel chart properties and View XAML)
+Plan: 4 of 4
+Status: Plan 09-04 complete — StorageViewModel chart unit tests
+Last activity: 2026-04-07 — Completed 09-04 (StorageViewModel chart unit tests)
 
 ```
-v1.1 Progress: [██████████] 96%
-Phase 6 [x] → Phase 7 [x] → Phase 8 [x] → Phase 9 [~]
+v1.1 Progress: [██████████] 100%
+Phase 6 [x] → Phase 7 [x] → Phase 8 [x] → Phase 9 [x]
 ```
 
 ## Performance Metrics
@@ -65,6 +65,7 @@ Phase 6 [x] → Phase 7 [x] → Phase 8 [x] → Phase 9 [~]
 | Phase 09 P01 | 1 | 2 tasks | 3 files |
 | Phase 09 P02 | 1 | 1 tasks | 1 files |
 | Phase 09 P03 | 573 | 2 tasks | 5 files |
+| Phase 09 P04 | 146 | 1 tasks | 2 files |
 
 ## Accumulated Context
 
@@ -125,6 +126,6 @@ None.
 
 ## Session Continuity
 
-Last session: 2026-04-07T13:37:09.651Z
-Stopped at: Completed 09-03-PLAN.md
+Last session: 2026-04-07T13:40:30Z
+Stopped at: Completed 09-04-PLAN.md
 Resume file: None
diff --git a/.planning/phases/09-storage-visualization/09-04-SUMMARY.md b/.planning/phases/09-storage-visualization/09-04-SUMMARY.md
new file mode 100644
index 0000000..ecf463f
--- /dev/null
+++ b/.planning/phases/09-storage-visualization/09-04-SUMMARY.md
@@ -0,0 +1,71 @@
+---
+phase: 09-storage-visualization
+plan: 04
+subsystem: storage-visualization
+tags: [tests, unit-tests, charts, viewmodel, xunit]
+dependency_graph:
+  requires: [09-03]
+  provides: [chart-unit-tests]
+  affects: [SharepointToolbox.Tests]
+tech_stack:
+  added: []
+  patterns: [reflection-based-property-setting, moq-service-mocking]
+key_files:
+  created:
+    - SharepointToolbox.Tests/ViewModels/StorageViewModelChartTests.cs
+  modified:
+    - SharepointToolbox.Tests/SharepointToolbox.Tests.csproj
+decisions:
+  - "Used reflection to set FileTypeMetrics (private setter) instead of mocking full RunOperationAsync flow -- avoids sealed ClientContext dependency"
+  - "Added LiveChartsCore.SkiaSharpView.WPF 2.0.0-rc5.4 to test project to match main project version"
+  - "Asserted against DisplayLabel-uppercased 'OTHER' not raw 'Other' to match FileTypeMetric.DisplayLabel behavior"
+metrics:
+  duration: 146s
+  completed: "2026-04-07"
+---
+
+# Phase 09 Plan 04: StorageViewModel Chart Unit Tests Summary
+
+7 xUnit tests verifying chart series computation from FileTypeMetrics, donut/bar toggle via InnerRadius, top-10+Other aggregation, tenant switch cleanup, and empty data edge case -- all without SharePoint connection.
+
+## What Was Done
+
+### Task 1: Create StorageViewModel chart unit tests (TDD)
+
+Created `StorageViewModelChartTests.cs` with 7 tests:
+
+1. **After_setting_metrics_HasChartData_is_true_and_PieChartSeries_has_entries** -- Sets 5 metrics, asserts HasChartData=true and PieChartSeries count=5
+2. **After_setting_metrics_BarChartSeries_has_one_ColumnSeries_with_matching_values** -- Verifies single ColumnSeries with value count matching metric count
+3. **Toggle_IsDonutChart_changes_PieChartSeries_InnerRadius** -- Asserts InnerRadius=50 when donut, 0 when toggled off
+4. **More_than_10_metrics_produces_11_series_entries_with_Other** -- 15 metrics produce 10+1 "OTHER" entries in pie, bar, and x-axis labels
+5. **Ten_or_fewer_metrics_produces_no_Other_entry** -- 10 metrics produce exactly 10 entries, no "OTHER"
+6. **OnTenantSwitched_clears_FileTypeMetrics_and_HasChartData_is_false** -- TenantSwitchedMessage clears all chart state
+7. **Empty_metrics_yields_HasChartData_false_and_empty_series** -- Empty input produces empty series and false HasChartData
+
+**Approach:** Uses reflection to set `FileTypeMetrics` property (private setter triggers `UpdateChartSeries` internally), bypassing the need to mock sealed `ClientContext` for `RunOperationAsync`.
+
+**NuGet:** Added `LiveChartsCore.SkiaSharpView.WPF 2.0.0-rc5.4` to test project (matching main project version) for `PieSeries<T>`, `ColumnSeries<T>` type assertions.
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 1 - Bug] "Other" series name uses DisplayLabel not raw extension**
+- **Found during:** TDD RED phase
+- **Issue:** Test asserted `Name == "Other"` but FileTypeMetric("Other", ...).DisplayLabel returns "OTHER" (ToUpperInvariant)
+- **Fix:** Changed assertions to expect "OTHER"
+- **Files modified:** StorageViewModelChartTests.cs
+- **Commit:** 712b949
+
+## Verification
+
+- All 7 chart tests pass
+- Full suite: 210 passed, 22 skipped, 0 failed -- no regressions
+
+## Commits
+
+| Hash | Message |
+|------|---------|
+| 712b949 | test(09-04): add StorageViewModel chart unit tests |
+
+## Self-Check: PASSED