Durable Actors for Python

Durable actors and typed clients, backed by the Rust runtime.

Quickstart · Reference · Runnable example

Quickstart

Requires Python 3.11+ and uv. The CLI, SDK, and native runtime are installed as Python packages.

Create a project anywhere. uv installs the SDK, CLI, and matching native runtime wheel from PyPI.

uvx --from 'durable-actors[cli]' durable-actors init my-actors
cd my-actors

Define src/actors.py. Every instance field must use persisted() or ephemeral(). Persisted fields are stored in SQLite, which the Rust runtime owns and replicates with Litestream; local development persists to the filesystem. Wrap persisted fields with emitted() to broadcast saved changes.

from durable_actors import Actor, emitted, persisted

class Counter(Actor):
    count: int = emitted(persisted(0))

    def increment(self, amount: int = 1) -> int:
        self.count += amount
        return self.count

uv run durable-actors dev

Call an actor

In another terminal in the same directory, generate the client:

uv run durable-actors generate

Save as client.py and run uv run client.py:

from generated import actors

counter = actors.Counter.get("one")
print(counter.increment())

Async actors and clients

Define AsyncActor methods and socket hooks with async def. Calls stay serialized across await unless marked @interleave. Generated async_actors clients work with either actor style:

from durable_actors import AsyncClient
from generated import async_actors

async with AsyncClient() as client:
    print(await async_actors.Counter.get("one", client).increment())

Await actor database and connection queries, and broadcast(); socket handle methods remain synchronous. Reuse AsyncClient for connection pooling. Close async connections and subscriptions with async with or aclose().

Use the client in another application

Copy the entire generated package, including its helper modules, into the application. From that application's root, install the client runtime:

uv add durable-actors

This installs the runtime dependencies automatically. The [codegen] extras are only needed to generate or regenerate clients, not to run them.

Subscribe to state

Callbacks receive complete typed snapshots on a background thread. Keep the process running while listening; the context manager closes the subscription.

from generated import actors

counter = actors.Counter.get("one")
with counter.subscribe(lambda state: print(state.count), on_error=print):
    counter.increment()
    input("Press Enter to stop.\n")