pactix 0.1.0

Transactional outbox and inbox primitives for PostgreSQL, on SQLAlchemy.

pactix

pactix is a Python library for transactional outbox and inbox workflows on PostgreSQL, built on SQLAlchemy (async).

Use it when a service needs to commit business data and outgoing events in the same transaction, store incoming messages before handler execution, and retry failed work safely across multiple workers.

Features

• Deduplication by source + message_id on the inbox side
• FIFO within the same event_type + ordering_key
• Optional unordered inbox processing with a stale-event filter contract
• Retry scheduling and lease-based recovery for stuck workers
• Transport-agnostic core protocols
• Built-in helpers for common hooks, stale-event filters, and closure-based adapters
• Optional Kafka adapters behind the kafka extra
• Optional HTTP adapters behind the http extra

If a publisher or handler may run more than once, that is normal. Business effects still need idempotent application logic.

Installation

pip install pactix                 # core (sqlalchemy + asyncpg)
pip install "pactix[kafka]"        # + Kafka transport (aiokafka)
pip install "pactix[http]"         # + HTTP transport (httpx + starlette)
pip install "pactix[migrations]"   # + Alembic for running the migrations

Database setup

pactix does not run migrations for you. Either run the bundled Alembic migrations (src/pactix/db/migrations, see alembic.ini) or copy the table definitions in pactix.db.tables into your own migration system. The library expects two tables: outbox_message and inbox_message.

Documentation

• Core workflows — append, publish, save, and process flows
• Helper adapters — closures, ProcessAll, StaticIdempotency, filters
• Kafka transport
• HTTP transport
• Operations, migrations, and workers

See examples/worker_loop.py for a runnable worker-loop sketch.

Development

make install   # uv sync with all extras
make check     # format + lint + mypy + test

Database-backed tests use testcontainers and require Docker.