Can I vibe code Hellotax?

Build an EU VAT calculation microservice and OSS threshold tracking dashboard using Node.js, Express, and PostgreSQL.

1. DATA MODEL:
- Create tables for orders (id, store_id, total_amount, currency, shipping_country, line_items, created_at), tax_rates (country_code, standard_rate, reduced_rate, updated_at), vat_validations (vat_number, country_code, is_valid, checked_at), and oss_tracker (store_id, year, cumulative_eu_sales_eur).

2. CORE FUNCTIONALITY:
- Implement a POST /calculate-tax endpoint accepting destination country, items taxonomy, and optional B2B customer VAT number.
- Integrate with the official EU VIES SOAP interface to validate B2B VAT numbers asynchronously. If valid, set tax to 0% (reverse charge). If invalid or B2C, look up the destination country standard VAT rate.
- Fetch daily ECB exchange rates to convert non-EUR sales into EUR for OSS threshold tracking.
- Maintain an aggregate sum of cross-border B2C sales within the EU for the current calendar year. Trigger a webhook notification when cumulative sales cross €8,500 (85% warning) and €10,000 (OSS required).

3. FAILURE MODES & RESILIENCE:
- VIES API timeout: Fall back to local regex pattern matching for VAT number validation, flag transaction as 'pending_vies_verification', and queue a retry job.
- Store tax rates locally in Postgres to ensure zero-latency calculations if external rate tables fail.

4. OUT OF SCOPE:
- Direct electronic submission to government tax portals.
- physical tax agent registration forms or legal filing generation.

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