docs(04-05): complete financial reports plan

Tasks completed: 2/2
- Financial report API routes (trial balance, income statement, balance sheet, drill-down)
- Comprehensive tests (16 passing — all 3 reports verified)

SUMMARY: .planning/phases/04-inventory-expenses-and-financial-reports/04-05-SUMMARY.md

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

.planning/phases/04-inventory-expenses-and-financial-reports/04-05-SUMMARY.md

@@ -0,0 +1,104 @@
+---
+phase: 04-inventory-expenses-and-financial-reports
+plan: 05
+subsystem: api, accounting
+tags: [financial-reports, trial-balance, income-statement, balance-sheet, journal-entries, prisma, drill-down]
+
+# Dependency graph
+requires:
+  - phase: 02-subscriber-and-billing-core
+    provides: JournalEntryService, Chart of Accounts, double-entry accounting foundation
+provides:
+  - FinancialReportService with getTrialBalance, getIncomeStatement, getBalanceSheet, getAccountEntries
+  - 4 API routes for financial reports and drill-down
+  - 16 passing integration tests verifying all 3 report types
+affects: [05-dashboard-and-polish]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "Financial reports derived entirely from POSTED journal entry lines — no stored balances"
+    - "Integer cents comparison (equalsInCents) for balanced verification"
+    - "Header account filtering via code.endsWith('000') convention"
+
+key-files:
+  created:
+    - src/app/api/reports/trial-balance/route.ts
+    - src/app/api/reports/income-statement/route.ts
+    - src/app/api/reports/balance-sheet/route.ts
+    - src/app/api/reports/accounts/[id]/entries/route.ts
+    - src/lib/__tests__/financial-report-service.test.ts
+  modified: []
+
+key-decisions:
+  - "FinancialReportService already existed from prior work — Task 1 focused on API routes"
+  - "Trial Balance delegates to JournalEntryService.getTrialBalance then enhances with accountType and totals"
+  - "Balance Sheet Net Income computed inline (revenue - expenses from beginning of time to asOfDate)"
+
+patterns-established:
+  - "Financial report API routes: GET with date query params, withPermission('read', 'Report')"
+  - "Drill-down route uses closure pattern for Next.js 15 Promise params"
+
+# Metrics
+duration: 10min
+completed: 2026-03-05
+---
+
+# Phase 4 Plan 05: Financial Reports Summary
+
+**Trial Balance, Income Statement, and Balance Sheet derived from JE history with drill-down, 4 API routes, and 16 passing tests**
+
+## Performance
+
+- **Duration:** 10 min
+- **Started:** 2026-03-05T04:25:30Z
+- **Completed:** 2026-03-05T04:35:30Z
+- **Tasks:** 2
+- **Files modified:** 6
+
+## Accomplishments
+- Financial report engine with 3 report types: Trial Balance (self-verifying debits = credits), Income Statement (revenue - expenses for date range), Balance Sheet (assets = liabilities + equity as of date)
+- Drill-down capability showing underlying JE lines per account with running balance
+- 4 API routes with proper ADMIN-only access control
+- 16 comprehensive integration tests proving all 3 reports balance correctly with known transaction data
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: FinancialReportService + API Routes** - `5366e8c` (feat)
+2. **Task 2: Financial report tests** - `1dd423c` (test)
+
+## Files Created/Modified
+- `src/lib/services/financial-report-service.ts` - Already existed: getTrialBalance, getIncomeStatement, getBalanceSheet, getAccountEntries
+- `src/app/api/reports/trial-balance/route.ts` - GET trial balance with optional asOfDate
+- `src/app/api/reports/income-statement/route.ts` - GET income statement with required startDate/endDate
+- `src/app/api/reports/balance-sheet/route.ts` - GET balance sheet with required asOfDate
+- `src/app/api/reports/accounts/[id]/entries/route.ts` - GET drill-down entries per account
+- `src/lib/__tests__/financial-report-service.test.ts` - 16 tests across Trial Balance, Income Statement, Balance Sheet, Drill-down, Edge Cases
+
+## Decisions Made
+- FinancialReportService already existed with all 4 methods — Task 1 created API routes only
+- Tests use vitest (not Jest) per project configuration — `npx vitest run` instead of `npx jest`
+- Future entry (April 2026) added to test data for date filtering verification across all report types
+- Empty tenant test uses isolated tenant with try/finally cleanup pattern
+
+## Deviations from Plan
+
+None - plan executed exactly as written. The FinancialReportService was already implemented, so Task 1 focused on API route creation.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- All 3 financial reports operational and tested
+- Capstone accounting capability complete: ISP owners can verify books balance, see profitability, and see financial position
+- Phase 4 has 04-02 and 04-04 remaining (inventory lifecycle and expense reports/exports)
+
+---
+*Phase: 04-inventory-expenses-and-financial-reports*
+*Completed: 2026-03-05*