Critical (P0 — required before production billing)

Gap	Impact	Solution
No PDF generation	Can’t send professional invoices	Implement via pdfmake lazy-loaded in api/lib/pdf-invoice.ts
No mark_invoice_paid action	payment_status never updates to paid	Add action + paid_at, solana_tx_sig columns
No invoice email delivery	Invoices only visible in admin UI	Trigger email on finalize_invoice via existing MS Graph
billing_period NULL on old entries	Invoices may miss pre-035 fees	Migration 038: backfill from DATE_TRUNC('month', created_at)
Distribution model not implemented	Settlement statements, rebates don’t exist	Migrations 042–044 + new API actions