Session: invoice-number-sequences — 2026-10-08

Project: ledger-api · Branch: feat/invoice-numbers · Mode: default · Model: gpt-5-codex

Summary

Gap-free invoice numbers per legal entity and year, allocated from a Postgres row lock instead of a sequence, because sequences can skip numbers on rollback.

Conversation

Turn 1 — User

Accounting needs invoice numbers without gaps.

Turn 1 — Assistant

Postgres sequences are not gap-free. Use a numbering table per entity and year, SELECT … FOR UPDATE inside the invoice transaction.

Tools used in this turn:

• Write: ledger/numbering.py
• Write: migrations/versions/0007_numbering.py
• Bash: pytest tests/test_numbering.py -q — 5 passed

Connections

• [[ledger-api]]
• [[PostgreSQL]]
• [[RowLocks]]