GraphReFly Python

graphrefly is the Python host package for GraphReFly: a reactive graph runtime with a Python-owned facade over the native Rust engine.

Install it from PyPI:

pip install graphrefly

GraphReFly is alpha software, but the Python host/native binding closeout is now backed by the clean-slate conformance suite. The package requires Python 3.12+.

Quick Start

from graphrefly import Graph


with Graph("hello") as graph:
    count = graph.state(1, name="count")
    doubled = graph.derived([count], lambda value: value * 2, name="doubled")

    with doubled.subscribe(lambda msg: print(msg.kind, msg.value)):
        count.set(2)
        count.set(3)

    assert doubled.cache() == 6

The subscription receives the initial cached value and each later update. The graph owns the node topology; with Graph(...) closes facade resources when the scope exits.

Core Shape

from graphrefly import Graph


graph = Graph("demo")

source = graph.state(1, name="source")
plus_one = graph.derived([source], lambda value: value + 1, name="plus_one")
advanced = graph.node(
    [source],
    lambda ctx: ctx.emit(ctx.data(0) + 10),
    name="advanced",
)

with plus_one.subscribe(lambda msg: print(msg.kind, msg.value)):
    source.set(4)

assert plus_one.cache() == 5
assert advanced.cache() == 14
assert plus_one.status in {"settled", "resolved"}

Use Graph.derived(...) for value-level functions. Use Graph.node(...) when you need the callback-scoped Ctx surface for advanced graph behavior such as per-node state, raw wave data reads, invalidation hooks, pull demand, or deferred rewire.

Public Surface

The Python facade exports:

• Graph, Node[T], Ctx, PullContext, RewireNext
• Subscription, Retain, GraphReentryQueue
• DataMessage[T], ErrorMessage, ControlMessage, Message[T], GraphEvent
• SENTINEL for raw ctx.wave_data INVALIDATE/no-DATA projection
• checkpoint and restore helpers: GraphCheckpoint, RestoreRef, RestoreContext, RestoreDescriptor, RestoreRegistry, restore_ref, restore_registry, restore_graph
• async boundary helpers: AsyncRunner, from_awaitable, from_async_iter, async_node, asyncio_runner, trio_runner, anyio_runner
• network source adapters: HttpRequest, HttpResponse, HttpStreamHead, HttpStreamHeadEvent, HttpStreamChunkEvent, HttpStreamErrorEvent, HttpStreamCompleteEvent, HttpStreamDriverEvent, SseEvent, LocalHttpDriver, LocalHttpStreamDriver, from_http, from_sse
• wire bridge facades: wire_bridge, wire_bridge_protobuf, wire_edge_group, wire_bridge_ack_driver
• public exceptions under GraphReflyError

The private native extension is loaded as graphrefly._native; it is not the public API.

Boundary Notes

• The sync wave protocol runs in Rust. Python callbacks enter through the native dispatcher path; Python does not reimplement the wave core.
• Native graph handles are single-thread host objects in this foundation slice.
• None is valid Python DATA. Absence of DATA is separate and Node.cache() raises GraphReflyNoDataError when no DATA is present. Use Node.cache(default=...) or Node.has_value for non-exceptional absence handling.
• ctx.wave_data is the raw advanced dep input shape. Ergonomic helpers such as ctx.data() and ctx.has_data() are derived from that shape.
• Graph.close() and with Graph(...) are Python host lifetime scopes. They release facade-created subscriptions/observers and graph-owned retain roots; they do not emit protocol TEARDOWN or COMPLETE.
• Public Python exposes facade methods only; raw protocol ingress, arbitrary message construction/sending, and native handles remain hidden.

Async Runners

Async work enters only through explicit runner helpers. The core API does not own an asyncio loop, Trio nursery, AnyIO task group, background thread, portal, or hidden pump.

Install optional runtime adapters with:

pip install "graphrefly[async]"

import trio
from graphrefly import Graph, from_awaitable, trio_runner


async def fetch_value() -> int:
    return 42


async def main() -> None:
    graph = Graph("trio-demo")

    async with trio.open_nursery() as nursery:
        node = from_awaitable(
            graph,
            trio_runner(nursery),
            fetch_value,
            name="value",
        )
        with node.subscribe(lambda msg: print(msg.kind, msg.value)):
            await trio.lowlevel.checkpoint()

When a host runtime completes work away from the graph owner thread, keep re-entry explicit:

graph = Graph("queued-demo")
queue = graph.reentry_queue()
runner = queue.wrap_runner(host_owned_runner)
node = from_awaitable(graph, runner, fetch_value, name="queued")

with node.subscribe(lambda msg: None):
    queue.drain(max_items=None)

The queue accepts only GraphReFly-owned private completions; it is not a public callable enqueue or graph mutation channel.

from_http and from_sse follow the same boundary rule: callers provide both an explicit AsyncRunner and a host-owned driver. The package does not own an event loop or ship a default HTTP client in this slice; from_sse parses text/event-stream bytes from LocalHttpStreamDriver without hidden retry, reconnect, or Last-Event-ID management.

Documentation

• Python docs: https://py.graphrefly.dev/
• API reference: https://py.graphrefly.dev/api/
• Language-neutral spec: https://graphrefly.dev/spec/
• Repository: https://github.com/graphrefly/graphrefly-py

This repo owns the Python package docs: public docstrings, generated Python API reference, Starlight source pages, examples, PyPI install material, and package release notes, plus the package-local website/ site configuration. The package-local docs policy is docs/docs.jsonl.

Shared graphrefly.dev website architecture, shared concepts, protocol authority, and the public blog stay in ~/src/graphrefly under D563. Generated API output comes from docstrings through the griffe-backed Starlight generator; do not edit generated website/src/content/docs/api/ output by hand.

Local Development

This package expects sibling checkouts:

~/src/graphrefly-py
~/src/graphrefly-rs

Install and test:

uv sync --group dev --group docs
cd ../graphrefly-rs
mise exec -- bash -lc 'cd ../graphrefly-py && uv run maturin develop --release'
cd ../graphrefly-py
uv run pytest
uv run ruff check .
uv run mypy src
uv run python scripts/check_api_docs.py
cd website && pnpm docs:gen:check
cd website && pnpm build
python -c "import graphrefly; print(graphrefly.version())"

The Python repo validates Starlight and griffe-generated API output and deploys the package-local docs artifact to https://py.graphrefly.dev/. The shared ~/src/graphrefly website links to this route but does not copy generated Python API pages into the main graphrefly.dev artifact.

The Rust foundation can be checked directly from the sibling repo:

cd ~/src/graphrefly-rs
mise exec -- cargo test -p graphrefly-bindings-py