---
phase: 09-storage-visualization
plan: 02
subsystem: services
tags: [csom, caml-query, file-metrics, sharepoint]

# Dependency graph
requires:
  - phase: 09-01
    provides: FileTypeMetric record, IStorageService.CollectFileTypeMetricsAsync signature
provides:
  - CollectFileTypeMetricsAsync implementation in StorageService
  - CSOM CamlQuery-based file enumeration grouped by extension
affects: [09-03, 09-04]

# Tech tracking
tech-stack:
  added: []
  patterns: [paginated CamlQuery with RowLimit for file enumeration]

key-files:
  created: []
  modified: [SharepointToolbox/Services/StorageService.cs]

key-decisions:
  - "Added System.IO using explicitly -- WPF project implicit usings do not include System.IO for Path.GetExtension"

patterns-established:
  - "CamlQuery pagination: RowLimit Paged=TRUE with ListItemCollectionPosition loop for batched file enumeration"
  - "Extension grouping: OrdinalIgnoreCase dictionary with ToLowerInvariant normalization for consistent extension keys"

requirements-completed: [VIZZ-02]

# Metrics
duration: 1min
completed: 2026-04-07
---

# Phase 09 Plan 02: CollectFileTypeMetricsAsync Summary

**CSOM CamlQuery-based file enumeration across all non-hidden document libraries, grouped by extension with paginated 500-item batches**

## Performance

- **Duration:** 1 min
- **Started:** 2026-04-07T13:23:20Z
- **Completed:** 2026-04-07T13:24:13Z
- **Tasks:** 1
- **Files modified:** 1

## Accomplishments
- Implemented CollectFileTypeMetricsAsync in StorageService resolving CS0535 interface compliance error
- CamlQuery with RecursiveAll scope and FSObjType=0 filter enumerates only files across all subfolders
- Paginated queries (500-item batches) avoid SharePoint list view threshold limits
- Extension-based grouping with case-insensitive dictionary produces sorted FileTypeMetric results

## Task Commits

Each task was committed atomically:

1. **Task 1: Implement CollectFileTypeMetricsAsync in StorageService** - `81e3dca` (feat)

**Plan metadata:** (pending)

## Files Created/Modified
- `SharepointToolbox/Services/StorageService.cs` - Added CollectFileTypeMetricsAsync method and System.IO using

## Decisions Made
- Added `using System.IO;` explicitly since WPF project implicit usings do not include it (Path.GetExtension not available without it)

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Added missing System.IO using directive**
- **Found during:** Task 1 (CollectFileTypeMetricsAsync implementation)
- **Issue:** `Path.GetExtension` not recognized -- WPF implicit usings exclude System.IO
- **Fix:** Added `using System.IO;` at top of StorageService.cs
- **Files modified:** SharepointToolbox/Services/StorageService.cs
- **Verification:** Build succeeds with 0 errors
- **Committed in:** 81e3dca (Task 1 commit)

---

**Total deviations:** 1 auto-fixed (1 blocking)
**Impact on plan:** Minor using directive addition required for compilation. No scope creep.

## Issues Encountered
None beyond the System.IO using directive (documented above as deviation).

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

## Next Phase Readiness
- StorageService now fully implements IStorageService (both CollectStorageAsync and CollectFileTypeMetricsAsync)
- Ready for Plan 09-03 (ViewModel integration) to wire CollectFileTypeMetricsAsync into the storage visualization UI
- FileTypeMetric results sorted by TotalSizeBytes descending, ready for chart data binding

---
*Phase: 09-storage-visualization*
*Completed: 2026-04-07*