accounted/CLAUDE.md

CLAUDE.md — erp-base

Project Overview

erp-base is a Swedish-focused accounting SaaS for sole traders (enskild firma) and limited companies (aktiebolag). It implements double-entry bookkeeping compliant with Swedish accounting law (Bokforingslagen), including VAT handling, tax reporting, and 7-year document retention.

Tech stack: Next.js 16 (App Router), React 19, TypeScript (strict), Supabase (PostgreSQL + RLS + magic link auth), Tailwind CSS 4 + shadcn/ui, Vercel hosting.

Integrations: Enable Banking (PSD2), Anthropic SDK, LangChain, OpenAI (embeddings), Resend (email), web-push (VAPID).

Path alias: @/* maps to the project root (tsconfig.json).

Language: All code, comments, and commit messages must be in English.

---

Commands

npm run dev          # Start development server
npm run build        # Production build
npm run lint         # ESLint
npm test             # Run all Vitest tests
npx vitest run <dir> # Run tests in a specific directory

---

Architecture

app/
  (auth)/                 Login, auth callback
  (onboarding)/           6-step setup wizard
  (dashboard)/            Authenticated routes (invoices, customers, transactions,
                          bookkeeping, reports, suppliers, supplier-invoices,
                          receipts, settings, calendar, help, import,
                          extensions, e/[sector]/[slug])
  (public)/               Public invoice action links (no auth)
  api/                    API routes organized by domain

components/
  ui/                     shadcn/ui primitives (button, card, dialog, table, etc.)
  bookkeeping/            Chart of accounts manager, account combobox, add/edit dialogs
  calendar/               Calendar views, deadline cards, payment summary, todo widgets
  chat/                   ChatWidget, ChatPanel, ChatInput, ChatMessage
  customers/              CustomerForm
  dashboard/              DashboardContent, DashboardNav, FSkattWarningCard
  extensions/             Extension marketplace UI (ExtensionCard, SectorCard,
                          ExtensionToggleButton, workspace components,
                          per-sector subdirectories)
  import/                 Bank file import workflow components
  invoices/               InvoiceReviewContent
  onboarding/             NewUserChecklist, setup step components
  reports/                Report views (including BankReconciliationView)
  settings/               CalendarFeedSettings
  suppliers/              Supplier-related components
  transactions/           Transaction list, categorization, booking components

extensions/               Sector-based extension hierarchy
  general/                General-purpose extensions (all businesses)
    ai-categorization/    AI-powered transaction categorization
    ai-chat/              Claude-based chat assistant (LangChain RAG)
    enable-banking/       PSD2 bank integration (opt-in, commented out in loader)
    example-logger/       Minimal reference extension (not loaded)
    invoice-inbox/        Supplier invoice intake via email/upload with AI extraction
    push-notifications/   Web push notification system
    receipt-ocr/          Receipt image OCR processing (includes components/pages)
  restaurant/             Restaurant & cafe sector
    food-cost/            Food cost percentage calculator
    earnings-per-liter/   Revenue per liter of alcohol
    pos-import/           POS Z-report import
    tip-tracking/         Tip tracking per shift/employee
  construction/           Construction & trades sector
    rot-calculator/       ROT tax deduction calculator
    project-cost/         Project cost tracking
  hotel/                  Hotel & lodging sector
    revpar/               Revenue Per Available Room
    occupancy/            Occupancy rate tracking
  tech/                   IT & consulting sector
    billable-hours/       Billable hours & utilization rate
    project-billing/      Project billing analysis
  ecommerce/              E-commerce sector
    shopify-import/       Shopify order import
    multichannel-revenue/ Multi-channel revenue analysis
  ne-bilaga/              NE tax form attachment generation (top-level)
  sru-export/             SRU file export (top-level)

lib/
  api/                    Zod validation schemas and utilities for API routes
    schemas.ts            Zod schemas for all API request bodies and query params
    validate.ts           validateBody() and validateQuery() helpers
  bookkeeping/            Core journal entry engine and all entry generators
    engine.ts             Draft/commit workflow, balance validation, voucher numbering
    invoice-entries.ts    Sales invoice journal entries (supports per-line VAT rates)
    transaction-entries.ts Bank transaction journal entries
    supplier-invoice-entries.ts Purchase invoice journal entries
    category-mapping.ts   Category-to-BAS-account mapping
    mapping-engine.ts     Rule-based auto-categorization (MCC codes, merchant patterns)
    vat-entries.ts        VAT line generation
    bas-reference.ts      BAS account catalog (~180 accounts with metadata, SRU codes)
    account-descriptions.ts Human-readable account name lookup
    validate-period-duration.ts Fiscal period duration validation (BFL 3 kap.)
    handlers/             Booking handler functions (supplier-invoice-handler.ts)
  core/
    bookkeeping/          Period service, storno reversal, year-end closing
    documents/            Document archive (upload, versioning, SHA-256 integrity)
    audit/                Audit trail service
    tax/                  Tax code service
  calendar/               Calendar utilities, ICS feed generation
  currency/               Riksbanken exchange rates
  deadlines/              Tax deadline tracking, status engine
  email/                  Email service (Resend), invoice/reminder templates
  events/                 Event bus (bus.ts, types.ts)
  extensions/             Extension system
    loader.ts             FIRST_PARTY_EXTENSIONS array, static imports
    registry.ts           Runtime extension registry
    types.ts              Extension, Sector, ExtensionDefinition, toggle types
    sectors.ts            Sector & extension metadata registry (pure data)
    hooks.ts              React hooks for extension state
    context-factory.ts    Extension context builder
    toggle-check.ts       Extension enable/disable logic
    validation.ts         Extension data validation
    workspace-registry.tsx Extension workspace component registry
    icon-resolver.tsx     Dynamic icon lookup for extensions
    use-account-totals.ts Hook for account balance queries
    use-extension-data.ts Hook for extension-specific data
  import/                 SIE parser, SIE import orchestrator, bank file parser
    bank-file/            Bank file parser with format modules
      formats/            camt053, generic-csv, handelsbanken, nordea, seb, swedbank
  invoices/               VAT rules, invoice matching, PDF template, reminder processor
  reconciliation/         Bank reconciliation engine (4-pass matching algorithm)
  reports/                Financial reports (trial-balance, income-statement,
                          balance-sheet, vat-declaration, sie-export,
                          supplier-ledger, supplier-reconciliation,
                          general-ledger, journal-register,
                          ar-ledger, ar-reconciliation, monthly-breakdown)
  supabase/               Client setup (client.ts = browser, server.ts = server/admin,
                          fetch-all.ts = pagination helper, middleware.ts)
  tax/                    Tax calculations, deadlines, Swedish holidays, expense warnings
  transactions/           Transaction processing, category suggestions
  init.ts                 Extension loader (idempotent, called by API routes)
  utils.ts                Shared utility functions

types/index.ts            Canonical type definitions (single source of truth)
types/chat.ts             Chat-specific type definitions
tests/helpers.ts          Mock factories and fixture builders
supabase/migrations/      SQL migration files
scripts/                  Utility scripts (clear-user-data.sql, copy-extensions.mjs,
                          move-extensions.js, setup-phase8.js)
dev_docs/                 Project documentation (BAS account guides, gap analysis,
                          Enable Banking docs, Bokio reference screenshots)
extensions.md             Extension system design document (architecture, data patterns,
                          sector model, workspace pattern, migration plan)

Key Relationships

• All journal entry creation routes through lib/bookkeeping/engine.ts. The entry generators (invoice-entries.ts, transaction-entries.ts, supplier-invoice-entries.ts) call createJournalEntry() from the engine.
• API routes that emit events must call ensureInitialized() (from lib/init.ts) at module level to load extensions.
• Event bus (lib/events/bus.ts) is a module-level singleton. Core services emit, extensions subscribe.
• Supabase clients: browser (lib/supabase/client.ts), server with user cookies (createClient() from lib/supabase/server.ts), and service role (createServiceClient()).
• Extension sector system: Extensions are organized by business sector (lib/extensions/sectors.ts). Users can browse/toggle extensions via the marketplace UI (app/(dashboard)/extensions/). Sector-specific extension workspaces are rendered at app/(dashboard)/e/[sector]/[slug]/.

---

Core Bookkeeping Engine

The bookkeeping engine (lib/bookkeeping/engine.ts) is the most critical system. All accounting flows route through it.

Journal Entry Lifecycle

1. createDraftEntry(userId, input) — Creates entry with status: 'draft', voucher_number: 0. Validates balance. Emits journal_entry.drafted.
2. commitEntry(userId, entryId) — Assigns voucher number via DB RPC (next_voucher_number, concurrent-safe). Sets status: 'posted'. DB trigger sets committed_at. Emits journal_entry.committed.
3. createJournalEntry(userId, input) — Convenience: draft + commit in one call. This is what all entry generators use.
4. reverseEntry(userId, entryId) — Storno reversal: swaps debit/credit, links via reverses_id/reversed_by_id. Original marked 'reversed'.

Entry Generators

Function	File	Purpose
createInvoiceJournalEntry()	invoice-entries.ts	Debit 1510, Credit 30xx + 26xx VAT (per-line VAT rates)
createInvoicePaymentJournalEntry()	invoice-entries.ts	Debit 1930, Credit 1510
createCreditNoteJournalEntry()	invoice-entries.ts	Reverses original invoice entry (per-rate lines)
createInvoiceCashEntry()	invoice-entries.ts	Cash method: revenue + VAT at payment (per-rate)
createTransactionJournalEntry()	transaction-entries.ts	Maps bank transactions via MappingResult
createSupplierInvoiceRegistrationEntry()	supplier-invoice-entries.ts	Debit expense + 2641, Credit 2440
createSupplierInvoicePaymentEntry()	supplier-invoice-entries.ts	Debit 2440, Credit 1930

Key BAS Accounts

Account	Description
1510	Accounts receivable
1930	Business bank account
2013	Private withdrawals (enskild firma)
2440	Accounts payable
2611 / 2621 / 2631	Output VAT 25% / 12% / 6%
2614	Output VAT reverse charge
2641	Input VAT (deductible)
2645	Calculated input VAT (EU reverse charge)
2893	Loan from shareholders (aktiebolag)
3001 / 3002 / 3003	Revenue by VAT rate (25% / 12% / 6%)
3305 / 3308	Export / EU service revenue
3960 / 7960	Exchange rate gains / losses

VAT Treatments

standard_25, reduced_12, reduced_6, reverse_charge, export, exempt

Per-Line VAT

Invoice items support individual vat_rate values, enabling mixed-rate invoices. The helper generatePerRateLines() in invoice-entries.ts groups items by VAT rate and creates separate revenue + VAT account lines per rate group. Available rates depend on customer type — use getAvailableVatRates(customerType, vatNumberValidated) from lib/invoices/vat-rules.ts.

Bank Reconciliation

The reconciliation engine (lib/reconciliation/bank-reconciliation.ts) matches bank transactions to journal entry lines on account 1930 using a 4-pass algorithm:

Pass	Method	Confidence	Match Criteria
1	auto_exact	0.95	Exact amount + exact date
2	auto_reference	0.90	Exact amount + reference/description match
3	auto_date_range	0.85	Exact amount + date within ±3 days
4	auto_fuzzy	0.75	Fuzzy amount (±0.01) + exact date

Manual linking (manual method) is also supported. Only SEK transactions are reconciled. Greedy assignment prevents double-matching.

---

Accounting Guard Rails

These rules exist for legal compliance and are enforced by database triggers. Never violate them.

1. Committed entries are immutable. Once status: 'posted', an entry cannot be edited or deleted. Enforced by DB trigger enforce_journal_entry_immutability.
2. Never delete posted entries. Use reverseEntry() (storno) to cancel. The reversal creates a new entry with swapped debit/credit and bidirectional linking.
3. Every entry must balance. sum(debits) === sum(credits), both must be > 0. Checked by validateBalance() before insert.
4. Voucher numbers are sequential. Assigned via DB RPC next_voucher_number (concurrent-safe). Never set manually.
5. Period lock enforcement. DB trigger enforce_period_lock blocks writes to closed/locked fiscal periods. Check period status before creating entries.
6. 7-year document retention. DB triggers prevent deletion of documents linked to posted entries. retention_expires_at is auto-calculated as period_end + 7 years.
7. Storno, never edit. To correct an error: reverse the wrong entry, then create a new correct one. Use correctEntry() from lib/core/bookkeeping/storno-service.ts for atomic correction.
8. Use Math.round(x * 100) / 100 for all monetary calculations. Never use toFixed() (returns strings, has rounding edge cases).
9. Always use engine functions. Never insert directly into journal_entries or journal_entry_lines tables. Always go through lib/bookkeeping/engine.ts.
10. Account numbers are strings. BAS account numbers like '1930' are always strings, never numbers.

---

Extension Development

Extensions are first-party plugins organized by business sector in the /extensions/ directory, loaded statically at startup.

Sector System

Extensions are grouped into sectors defined in lib/extensions/sectors.ts. Each sector targets a specific industry (restaurant, construction, hotel, tech, ecommerce) or serves all businesses (general). The sector registry provides metadata used by the extension marketplace UI.

Key types (from lib/extensions/types.ts):

• SectorSlug — 'general' | 'restaurant' | 'construction' | 'hotel' | 'tech' | 'ecommerce'
• ExtensionDefinition — Marketplace metadata (slug, name, sector, category, icon, dataPattern, description)
• ExtensionCategory — 'import' | 'operations' | 'reports' | 'accounting'
• ExtensionDataPattern — 'core' | 'manual' | 'both' (how extension accesses data)
• ExtensionToggle — Per-user enable/disable state for extensions

Creating a New Extension

1. Create extensions/<sector>/<name>/index.ts
2. Export an object implementing the Extension interface from lib/extensions/types.ts
3. Add a static import to the FIRST_PARTY_EXTENSIONS array in lib/extensions/loader.ts
4. Add metadata to the appropriate sector in lib/extensions/sectors.ts
5. Extensions cannot use dynamic imports (Next.js bundling constraint)

Currently Loaded Extensions (FIRST_PARTY_EXTENSIONS)

receiptOcrExtension        @/extensions/general/receipt-ocr
aiCategorizationExtension  @/extensions/general/ai-categorization
pushNotificationsExtension @/extensions/general/push-notifications
sruExportExtension         @/extensions/sru-export
neBilagaExtension          @/extensions/ne-bilaga
aiChatExtension            @/extensions/general/ai-chat
invoiceInboxExtension      @/extensions/general/invoice-inbox
# enableBankingExtension   @/extensions/general/enable-banking  (commented out, opt-in)

Extension Interface

interface Extension {
  id: string              // Unique identifier (e.g. 'receipt-ocr')
  name: string            // Display name
  version: string         // Semver

  // Surfaces (all optional)
  routes?: RouteDefinition[]
  apiRoutes?: ApiRouteDefinition[]
  sidebarItems?: SidebarItem[]
  eventHandlers?: ExtensionEventHandler[]
  mappingRuleTypes?: MappingRuleTypeDefinition[]
  reportTypes?: ReportDefinition[]
  settingsPanel?: SettingsPanelDefinition
  taxCodes?: TaxCodeDefinition[]
  dimensionTypes?: DimensionDefinition[]

  // Lifecycle hooks
  onInstall?(ctx: ExtensionContext): Promise<void>
  onUninstall?(ctx: ExtensionContext): Promise<void>
}

Minimal Example

See extensions/general/example-logger/index.ts:

import type { Extension } from '@/lib/extensions/types'
import type { EventPayload } from '@/lib/events/types'

export const myExtension: Extension = {
  id: 'my-extension',
  name: 'My Extension',
  version: '0.1.0',
  eventHandlers: [
    {
      eventType: 'journal_entry.committed',
      handler: async (payload: EventPayload<'journal_entry.committed'>) => {
        // React to committed journal entries
      },
    },
  ],
}

Available Event Types

All defined in lib/events/types.ts:

Event	Payload
journal_entry.drafted	{ entry, userId }
journal_entry.committed	{ entry, userId }
journal_entry.corrected	{ original, storno, corrected, userId }
document.uploaded	{ document, userId }
invoice.created	{ invoice, userId }
invoice.sent	{ invoice, userId }
invoice.paid	{ invoice, transaction, kursdifferens?, userId }
invoice.overdue	{ invoice, days, userId }
credit_note.created	{ creditNote, userId }
transaction.synced	{ transactions[], userId }
transaction.categorized	{ transaction, account, taxCode, userId }
transaction.reconciled	{ transaction, journalEntryId, method, userId }
bank.statement_received	{ statement, userId }
bank.payment_notification	{ notification, userId }
period.locked	{ period, userId }
period.year_closed	{ period, userId }
customer.created	{ customer, userId }
customer.pseudonymized	{ customerId, userId }
receipt.extracted	{ receipt, documentId, confidence, userId }
receipt.matched	{ receipt, transaction, confidence, autoMatched, userId }
receipt.confirmed	{ receipt, businessTotal, privateTotal, userId }
supplier_invoice.received	{ inboxItem, userId }
supplier_invoice.extracted	{ inboxItem, confidence, userId }
supplier_invoice.confirmed	{ inboxItem, supplierInvoice, userId }
audit.security_event	{ event, userId }

Event Bus Behavior

• Handlers run concurrently via Promise.allSettled — a failing handler never crashes the emitter
• Module-level singleton, persists across requests in the same process
• One-way: core services emit, extensions subscribe
• Call eventBus.clear() in tests to reset state

---

Testing Guidelines

Scope

Test business logic in lib/ and API routes in app/api/. No component tests, no E2E tests.

Framework

Vitest 4 with globals: true and environment: 'node'. Config in vitest.config.ts.

Test Location

Colocated __tests__/ directories alongside source files in lib/.

Test Helpers (tests/helpers.ts)

Supabase mock:

const { supabase, mockResult } = createMockSupabase()
mockResult({ data: makeTransaction(), error: null })
// supabase.from('x').select('*').eq('id', '1') resolves to the mocked result

Fixture factories (all accept Partial<T> overrides):

• makeReceipt() — Receipt with default merchant, amounts, dates
• makeTransaction() — Transaction with default category, amount
• makeFiscalPeriod() — FiscalPeriod with default date range
• makeJournalEntry() — Posted JournalEntry with voucher number
• makeJournalEntryLine() — Line with account number, zero amounts
• makeDocumentAttachment() — Document with hash, storage path
• makeTaxCode() — TaxCode with default output VAT 25%
• makeInvoice() — Invoice with default customer, amounts, dates
• makeCustomer() — Customer with default name, address
• makeSupplier() — Supplier with default details
• makeSupplierInvoice() — Supplier invoice with default amounts
• makeCompanySettings() — Company settings with defaults
• makeInvoiceInboxItem() — Invoice inbox item for supplier invoice intake
• makeExtensionToggle() — Extension toggle state

Patterns

• Always mock @/lib/supabase/server to avoid real DB calls
• Use vi.clearAllMocks() and eventBus.clear() in beforeEach
• Test balance validation edge cases (floating point precision, zero amounts)
• Test error paths (missing fiscal period, unbalanced entries)
• Verify events are emitted correctly

API Route Tests

• Colocated __tests__/ directories alongside route files (e.g., app/api/invoices/__tests__/route.test.ts)
• Mock @/lib/supabase/server, @/lib/init, and lib functions — do NOT re-test lib business logic
• Use createMockRequest(), parseJsonResponse(), createMockRouteParams() from tests/helpers.ts
• Use createQueuedMockSupabase() for routes with multiple sequential Supabase calls
• Test: auth (401), validation (400), not found (404), errors (500), happy path, non-blocking journal entry failures

Reference Tests

• lib/api/__tests__/schemas.test.ts — Zod schema validation
• lib/api/__tests__/validate.test.ts — Body/query validation helpers
• lib/bookkeeping/__tests__/engine.test.ts — Balance validation
• lib/bookkeeping/__tests__/invoice-entries.test.ts — Per-line VAT, mixed-rate invoices, credit notes
• lib/core/bookkeeping/__tests__/storno-service.test.ts — Complex mock queues
• lib/core/documents/__tests__/document-service.test.ts — Storage mocking
• lib/events/__tests__/bus.test.ts — Event bus behavior
• lib/extensions/__tests__/registry.test.ts — Extension registration
• lib/import/__tests__/sie-parser.test.ts — SIE file parsing
• lib/import/bank-file/__tests__/parser.test.ts — Bank file format parsing
• lib/reconciliation/__tests__/bank-reconciliation.test.ts — Reconciliation matching algorithm
• lib/reports/__tests__/vat-declaration.test.ts — VAT declaration report
• lib/tax/__tests__/deadline-config.test.ts — Tax deadline configuration
• lib/transactions/__tests__/ingest.test.ts — Transaction ingestion and dedup

---

Database & Migrations

Location

supabase/migrations/ — currently 39 files numbered 20240101000001 through 20240101000038 (note: two files share number 000033).

Naming Convention

YYYYMMDD00NNNN_descriptive_name.sql — next migration: 20240101000039_*.sql

Migration Rules

1. Always enable RLS on new tables: ALTER TABLE public.tablename ENABLE ROW LEVEL SECURITY;
2. Always create RLS policies using auth.uid() = user_id:

   CREATE POLICY "tablename_select" ON public.tablename FOR SELECT USING (auth.uid() = user_id);
   CREATE POLICY "tablename_insert" ON public.tablename FOR INSERT WITH CHECK (auth.uid() = user_id);
   CREATE POLICY "tablename_update" ON public.tablename FOR UPDATE USING (auth.uid() = user_id);
   

3. Always add updated_at trigger:

   CREATE TRIGGER tablename_updated_at BEFORE UPDATE ON public.tablename
     FOR EACH ROW EXECUTE FUNCTION public.update_updated_at_column();
   

4. UUID primary keys: id UUID PRIMARY KEY DEFAULT uuid_generate_v4()
5. User ownership: user_id UUID REFERENCES auth.users ON DELETE CASCADE NOT NULL
6. Never modify existing migrations — create new ones instead
7. Never modify enforcement triggers (migration 20240101000017) — these are legally required
8. Never hardcode IDs in data migrations — use subqueries or variables
9. Apply via Supabase MCP tool: mcp__plugin_supabase_supabase__apply_migration
10. Test on a branch database before applying to production (use create_branch MCP tool)

Key Enforcement Triggers (migration 017)

• enforce_journal_entry_immutability — Blocks edits/deletes on posted/reversed entries
• enforce_journal_entry_line_immutability — Blocks line modifications on committed entries
• enforce_period_lock — Blocks writes to closed/locked fiscal periods
• block_document_deletion — Prevents deletion of documents linked to committed entries
• enforce_retention_journal_entries — 7-year retention enforcement
• set_committed_at — Auto-sets timestamp on draft-to-posted transition
• calculate_retention_expiry — Auto-sets retention_expires_at = period_end + 7 years

Recent Migrations

• Migration 030 (bank_reconciliation) — Adds reconciliation_method column to transactions (CHECK constraint for method types), indexes for unmatched transaction lookup, and RPC get_unlinked_1930_lines() for finding unreconciled GL lines.
• Migration 031 (invoice_document_type) — Adds document_type column to invoices (CHECK: invoice/proforma/delivery_note, default 'invoice') and converted_from_id FK for tracking proforma-to-invoice conversions.
• Migration 032 (add_accounting_method) — Adds accounting_method column to company_settings (CHECK: accrual/cash, default 'accrual') to support kontantmetoden vs faktureringsmetoden.
• Migration 033 (ai_chat_schema) — AI chat conversation and message storage.
• Migration 033 (invoice_inbox) — Invoice inbox table for supplier invoice intake. (Note: shares number with ai_chat_schema.)
• Migration 034 (fix_extension_data_trigger) — Fixes extension data trigger.
• Migration 035 (fix_push_notifications) — Push notifications schema fix.
• Migration 036 (fix_enable_banking) — Enable Banking schema fix.
• Migration 037 (extension_toggles) — Extension toggle table for per-user enable/disable.
• Migration 038 (fix_match_documents_search_path) — Fixes search path for document matching function.

---

Type System

• All shared types live in types/index.ts — this is the single source of truth
• Import via import type { TypeName } from '@/types'
• When adding new domain types, add them to types/index.ts
• Event types are the exception — they live in lib/events/types.ts (since they reference domain types)

---

API Route Patterns

Standard pattern for new API routes:

import { createClient } from '@/lib/supabase/server'
import { NextResponse } from 'next/server'
import { ensureInitialized } from '@/lib/init'
import { validateBody } from '@/lib/api/validate'
import { CreateInvoiceSchema } from '@/lib/api/schemas'

ensureInitialized()  // Module-level — loads extensions for event emission

export async function POST(request: Request) {
  const supabase = await createClient()
  const { data: { user } } = await supabase.auth.getUser()

  if (!user) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  // Validate request body with Zod schema
  const result = await validateBody(request, CreateInvoiceSchema)
  if (!result.success) return result.response
  const { data } = result

  // Business logic using validated `data`...
  // Always filter by user_id (defense in depth alongside RLS)
  // Wrap journal entry creation in try/catch (non-blocking side effect)
  // Emit events after successful operations

  return NextResponse.json({ data: result })
}

Key conventions:

• Call ensureInitialized() at module level in any route that emits events
• Validate all input with validateBody() / validateQuery() from lib/api/validate.ts using schemas from lib/api/schemas.ts
• Dynamic route params use { params }: { params: Promise<{ id: string }> } (Next.js 16)
• Response shapes: { data } for success, { error } for failures
• Journal entry creation is non-blocking: catch errors and continue

---

Skills Usage

• Always use the /frontend-design skill when creating new UI pages or significant components. This ensures consistent use of shadcn/ui, Tailwind CSS 4, and the existing component library.
• Use the langchain skill when building or modifying AI features (ai-chat, ai-categorization extensions).
• Use vercel:deploy for deployment tasks.

---

Git Conventions

Use conventional commits:

feat: add supplier invoice payment tracking
fix: correct VAT calculation for reduced 12% rate
refactor: extract VAT line generation into vat-entries.ts
test: add balance validation edge cases
docs: update CLAUDE.md with extension guide

• Atomic commits — one logical change per commit
• Branch from main for new work

---

Deployment

Hosted on Vercel with cron jobs defined in vercel.json:

Cron Job	Schedule
/api/extensions/enable-banking/sync/cron	Daily 05:00
/api/deadlines/status/cron	Daily 06:00
/api/invoices/reminders/cron	Daily 08:00
/api/extensions/push-notifications/cron	Daily 09:00
/api/tax-deadlines/cron	Yearly, January 2nd at 00:00
/api/documents/verify/cron	Weekly, Sunday 03:00

Required Environment Variables

NEXT_PUBLIC_SUPABASE_URL          # Supabase project URL
NEXT_PUBLIC_SUPABASE_ANON_KEY     # Supabase anonymous key
SUPABASE_SERVICE_ROLE_KEY         # Supabase service role key
RESEND_API_KEY                    # Resend email service API key
RESEND_FROM_EMAIL                 # Sender email for transactional mail
RESEND_WEBHOOK_SECRET             # Webhook auth for Resend
ENABLE_BANKING_APP_ID             # Enable Banking app ID
ENABLE_BANKING_PRIVATE_KEY        # Enable Banking private key (base64-encoded)
ENABLE_BANKING_SANDBOX            # Enable Banking sandbox mode flag
ANTHROPIC_API_KEY                 # Claude API key (ai-chat)
OPENAI_API_KEY                    # OpenAI API key (embeddings)
NEXT_PUBLIC_APP_URL               # App base URL
CRON_SECRET                       # Auth secret for Vercel cron jobs
NEXT_PUBLIC_VAPID_PUBLIC_KEY      # Web push public key
VAPID_PRIVATE_KEY                 # Web push private key
VAPID_SUBJECT                     # VAPID subject (mailto: URI) for web push

Other

We should never create a nul file