docs(04-02): complete asset management plan — Phase 4 complete

Tasks completed: 2/2
- AssetService with assign, return, dispose, history
- 11 integration tests all passing

SUMMARY: .planning/phases/04-inventory-expenses-and-financial-reports/04-02-SUMMARY.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/phases/04-inventory-expenses-and-financial-reports/04-02-SUMMARY.md

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+---
+phase: 04-inventory-expenses-and-financial-reports
+plan: 02
+subsystem: inventory
+tags: [asset-management, serialized-tracking, disposal, write-off, journal-entry, location-history]
+
+# Dependency graph
+requires:
+  - phase: 04-01
+    provides: InventoryService.recordMovement, InventoryItem/StockMovement models, COA accounts 1200/2010
+  - phase: 02-02
+    provides: JournalEntryService.createEntry for disposal write-off JE
+provides:
+  - AssetService with assignToSubscriber, assignToTechnician, returnAsset, disposeAsset, getAssetHistory
+  - API routes for assign, return, dispose, and history
+  - Admin-only disposal with write-off JE (DR 5030, CR 1200)
+  - Chronological location history with resolved names
+affects: []
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "Asset lifecycle builds on immutable movement ledger (no new models)"
+    - "Role-based authorization at service layer (userRoles parameter)"
+    - "Location name resolution via batch query + map lookup"
+
+key-files:
+  created:
+    - src/lib/services/asset-service.ts
+    - src/lib/__tests__/asset-service.test.ts
+    - src/app/api/inventory/items/[id]/assign/route.ts
+    - src/app/api/inventory/items/[id]/return/route.ts
+    - src/app/api/inventory/items/[id]/dispose/route.ts
+    - src/app/api/inventory/items/[id]/history/route.ts
+  modified: []
+
+key-decisions:
+  - "AssetService delegates all movement recording to InventoryService.recordMovement — no direct StockMovement writes"
+  - "Disposal JE created separately before movement record — InventoryService only auto-creates JEs for RECEIVED"
+  - "getCurrentLocation derives from latest movement's to-fields (null for DISPOSED)"
+  - "returnAsset always returns to main-warehouse — single warehouse model sufficient for ISP scale"
+  - "History name resolution uses batch queries (subscribers + users) then Map lookup — avoids N+1"
+
+patterns-established:
+  - "Service-layer role check via userRoles array parameter (not CASL) for admin-only operations"
+
+# Metrics
+duration: 8min
+completed: 2026-03-05
+---
+
+# Phase 4 Plan 2: Asset Management Summary
+
+**Asset lifecycle on immutable movement ledger — assign to subscriber/technician, return with condition, admin-only disposal with write-off JE (DR 5030, CR 1200), chronological location history**
+
+## Performance
+
+- **Duration:** 8 min
+- **Started:** 2026-03-05T05:03:22Z
+- **Completed:** 2026-03-05T05:11:00Z
+- **Tasks:** 2
+- **Files created:** 6
+
+## Accomplishments
+- AssetService with full lifecycle: assign, return, dispose, history
+- Admin-only disposal creates write-off JE (DR 5030 Equipment Expense, CR 1200 Equipment Inventory)
+- Chronological location history with resolved subscriber/technician/warehouse names
+- 11 integration tests all passing covering assignment, return, disposal auth, history, and full lifecycle
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: AssetService and API routes** - `eb29d6e` (feat)
+2. **Task 2: Asset service tests** - `0f73362` (test)
+
+## Files Created/Modified
+- `src/lib/services/asset-service.ts` - AssetService: assignToSubscriber, assignToTechnician, returnAsset, disposeAsset, getAssetHistory, getCurrentLocation
+- `src/app/api/inventory/items/[id]/assign/route.ts` - POST assign (SUBSCRIBER or TECHNICIAN)
+- `src/app/api/inventory/items/[id]/return/route.ts` - POST return with condition
+- `src/app/api/inventory/items/[id]/dispose/route.ts` - POST dispose (admin only, 403 for non-admin)
+- `src/app/api/inventory/items/[id]/history/route.ts` - GET chronological timeline
+- `src/lib/__tests__/asset-service.test.ts` - 11 integration tests
+
+## Decisions Made
+- AssetService delegates all movement recording to InventoryService.recordMovement — no direct StockMovement writes
+- Disposal JE created separately before movement record — InventoryService only auto-creates JEs for RECEIVED movements
+- getCurrentLocation derives from latest movement's toLocationType/toLocationId (null for DISPOSED)
+- returnAsset always returns to "main-warehouse" — single warehouse model sufficient for ISP scale
+- History name resolution uses batch queries then Map lookup — avoids N+1 query pattern
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None.
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Phase 4 now complete (all 5 plans: 04-01 Inventory, 04-02 Asset Management, 04-03 Expenses, 04-05 Financial Reports)
+- Ready for Phase 5
+
+---
+*Phase: 04-inventory-expenses-and-financial-reports*
+*Completed: 2026-03-05*