CultLib/packages/cultmesh-py

cultmesh-py

cultmesh-py is the Python CultMesh runtime: a cache-backed local node, reactive and observed documents, the branded CultMesh facade, Verse and peer discovery clients, snapshot and observation fan-out, peer health monitoring, game sessions with prediction reconciliation, committed simulation facts, the local TCP/RUDP server, and a package daemon.

It depends on cultcache-py and cultnet-py, mirroring cultmesh-rs and @gamecult/cultmesh-ts. The Verse catalog, peer exchange, authority lease, stream negotiation, and simulation fact contracts are defined in cultnet_py.cultmesh_contracts and re-exported here.

This is the package a Python process embeds to serve a Verse — the Brokkr Blender add-on serves its editor mirror through CultMesh.serve_node(...) from inside Blender's own interpreter.

Example

from datetime import UTC, datetime, timedelta

from cultcache_py import define_database_entry_type
from cultnet_py import (
    CultNetClientAuthorityScope,
    CultNetFileShardReplicaCursorStore,
    CultNetRawClient,
    CultNetSchemaShardLogFetcher,
    CultNetSchemaShardSnapshotFetcher,
    CultNetShardDescriptor,
    CultNetShardReplicator,
    CultNetShardReplicatorOptions,
)
from cultmesh_py import (
    CultMesh,
    CultMeshAuthorityLease,
    CultMeshGameSessionOptions,
    CultMeshHmacAuthorityLeaseVerifier,
    CultMeshNodeOptions,
    CultMeshSnapshotFanout,
    peer_exchange_request,
)

note_doc = define_database_entry_type(
    "mesh.note",
    [("body", 0), ("name", 1), ("kind", 2)],
    name="name",
    indexes={"kind": "kind"},
)
node = CultMesh.start_node(
    "mesh.cc",
    runtime_id="python-runtime",
    options=CultMeshNodeOptions(enable_durable_shard_logs=True),
)
node.database.register_document(note_doc)
unsubscribe = node.database.watch_record(note_doc, "note:1", lambda change: print(change.change_kind))
unsubscribe_named = node.database.watch_by_name(note_doc, "intro", lambda change: print(change.record_key))
unsubscribe_kind = node.database.watch_by_index(note_doc, "kind", "guide", lambda change: print(change.record_key))
node.database.put(note_doc, "note:1", {"body": "hello", "name": "intro", "kind": "guide"})
live_note = node.database.get_required(note_doc, "note:1")
put_message = node.database.put_raw_message(
    note_doc,
    "note:2",
    {"body": "wire me", "name": "wire", "kind": "interop"},
    shard_id="interop",
    shard_epoch=1,
)
snapshot_response = node.database.build_snapshot_response(schema_ids=[note_doc.catalog_entry().schema_id])
snapshot_wire = node.database.create_snapshot_response(schema_ids=[note_doc.catalog_entry().schema_id])
delete_message = node.database.delete_raw_message(note_doc, "note:2", shard_id="interop", shard_epoch=1)
shard_log_response = node.database.build_shard_log_response(shard_id="interop", shard_epoch=1)
shard_log_wire = node.database.create_shard_log_response(shard_id="interop", shard_epoch=1)

station_stock_doc = define_database_entry_type(
    "aetheria.station_stock",
    [("missiles", 0), ("coolant", 1)],
    schema_id="gamecult.aetheria.station_stock.v1",
)
station_stock_ui_doc = define_database_entry_type(
    "aetheria.station_stock.ui",
    [("missiles", 0), ("coolant", 1)],
    schema_id="gamecult.aetheria.station_stock.v1",
)
node.database.register_document(station_stock_doc)
node.database.put(station_stock_ui_doc, "station:starbridge:stock", {"missiles": 24, "coolant": 80})
stock = node.database.get_required(station_stock_ui_doc, "station:starbridge:stock")

peers = CultMesh.create_peer_catalog()
response = peers.create_response(peer_exchange_request("pex-1", verse_id="local"))
lease_verifier = CultMeshHmacAuthorityLeaseVerifier({"odin": b"shared-lease-key"})
lease_catalog = CultMesh.create_authority_lease_catalog(
    signature_verifier=lease_verifier.verify,
    require_verified_signatures=True,
)
lease_valid_from = datetime.now(UTC)
lease = lease_verifier.issue(CultMeshAuthorityLease(
    lease_id="lease:python-runtime",
    verse_id="local",
    peer_id="python-runtime",
    roles=("shard-primary",),
    valid_from=lease_valid_from,
    expires_at=lease_valid_from + timedelta(minutes=5),
    shard_ids=("interop",),
    issuer_runtime_id="odin",
))
lease_catalog.upsert(lease)
session = CultMesh.create_game_session(
    node,
    CultMeshGameSessionOptions(
        client_authority_scopes=(
            CultNetClientAuthorityScope("python-runtime", schema_ids=(note_doc.catalog_entry().schema_id,), key_prefix="input:python"),
        ),
    ),
)
server = CultMesh.serve_node(
    node,
    peer_catalog=peers,
    observation_hub=session.observation_hub,
    port=3075,
    max_snapshot_documents=1000,
    max_snapshot_bytes=4 * 1024 * 1024,
)

Peer writes

Breaking (0.x): a served node refuses every peer document_put_raw and document_delete unless a write authority grants it, mirroring C# ICultNetRemoteWriteAuthority. Before this, any connected peer could overwrite or delete the node's documents. The refusal is a typed cultnet.error.v0 with code write_not_authorized and the record key in details; an authority that raises, or returns no decision, refuses too.

Known residual: ungranted peers can still distinguish registered from unregistered schemas by timing (the node resolves the schema before the gate so the authority sees the canonical id); the refusal itself is identical.

from cultmesh_py import CultMeshGrantAllWrites, CultMeshRemoteWriteDecision, CultMeshRemoteWriteRequest

class OwnKeysOnly:
    def decide(self, request: CultMeshRemoteWriteRequest) -> CultMeshRemoteWriteDecision:
        if request.record_key.startswith("input:python:"):
            return CultMeshRemoteWriteDecision.grant()
        return CultMeshRemoteWriteDecision.refuse("not your key")

server = CultMesh.serve_node(node, write_authority=OwnKeysOnly())

The request carries the peer (endpoint, transport), the operation, the canonical schema id the node resolved (never the alias the peer sent), the record key and the shard id and epoch as sent. session.serve(...) takes the same write_authority. A host that already authenticates its peers, or a test rig, opts in to CultMeshGrantAllWrites(); the daemon's equivalent is --allow-peer-writes. Without it the daemon is read-only to peers.

The same local server can be launched as a package daemon when another runtime or operator process needs a CultNet endpoint without embedding Python glue:

python -m cultmesh_py.daemon --runtime-id python-runtime --display-name "Python Runtime" --host 127.0.0.1 --port 3075 --cache-file mesh.cc --enable-durable-shard-logs --seed-interop-note --seed-shard-id interop --verse-id local --role shard-primary --ready-file mesh.ready.json

The ready file and stdout line are process readiness hints. The served state and capability truth still live on the framed CultNet/CultMesh endpoint. Use --register-interop-note to expose the package interop-note schema without seeding a note, or --seed-interop-note to register it and publish one local record for wire probes. Seeded records are committed through the raw mutation path, so peers can read them through both snapshot and shard-log catch-up. Add --verse-id and one or more --role values to publish the launched endpoint in its own Verse and peer catalogs for discovery clients. When the daemon is launched with --cache-file, --enable-durable-shard-logs, and --shard-log-file, a later daemon process can rehydrate and serve the persisted snapshot and shard log without reseeding.

CultMeshPeerHealthMonitor probes peer-card endpoints with cultnet.hello.v0 and preserves the runtime id, display name, document types, message versions, and mutation contracts reported by the peer.

client = CultMesh.create_verse_discovery_client("127.0.0.1", 3075)
verses = client.fetch_verses(transport_version="cultmesh.v0")
mesh_peers = client.fetch_peers(verse_id="python-interop", roles=["read-replica"])
client.sync_peer_catalog(peers, verse_id="python-interop", roles=["read-replica"])
client.fanout_peer_catalog(peers, verse_id="python-interop", roles=["read-replica"])
replica_notes = client.sync_documents(
    node.database,
    peers,
    verse_id="python-interop",
    roles=["read-replica"],
    documents=[(note_doc, "note:remote")],
)
snapshot_fanout = CultMeshSnapshotFanout(
    client,
    node.database,
    peers,
    verse_id="python-interop",
    roles=["read-replica"],
    documents=[(note_doc, "note:remote")],
    on_document=lambda note: print(note),
)
snapshot_fanout.sync_once()

raw_client = CultNetRawClient("127.0.0.1", 3075)
synced_note = node.database.sync_document(raw_client, note_doc, "note:remote")
synced_stock = CultMesh.sync_document(
    node,
    raw_client,
    station_stock_ui_doc,
    "station:starbridge:stock",
)
with CultMesh.subscribe_document(
    node,
    raw_client,
    station_stock_ui_doc,
    "station:starbridge:stock",
) as stock_subscription:
    stock = stock_subscription.sync_initial()
    next_change = stock_subscription.read_next_change()
node.database.sync_shard_log(raw_client, shard_id="interop", shard_epoch=1)
replicator = CultNetShardReplicator(
    node.database,
    CultNetShardReplicatorOptions(
        fetcher=CultNetSchemaShardLogFetcher(),
        snapshot_fetcher=CultNetSchemaShardSnapshotFetcher(),
        cursor_store=CultNetFileShardReplicaCursorStore("mesh.replica-cursors.msgpack"),
        poll_interval_seconds=1.0,
        on_error=lambda error: print(error),
    ),
)
replica_shard = CultNetShardDescriptor(
    shard_id="interop",
    owner_runtime_id="primary-runtime",
    epoch=1,
    schema_ids=(note_doc.catalog_entry().schema_id,),
    primary_endpoints=("cultnet://127.0.0.1:3075",),
)
replicator.pull_once(replica_shard)
replicator.start([replica_shard])
replicator.stop()
server.stop()

streams = CultMesh.create_stream_catalog()

facts = CultMesh.create_simulation_fact_committer(node)
committed = facts.commit({
    "shardId": "arena",
    "shardEpoch": 4,
    "frame": 100,
    "subjectId": "bob",
    "claimKind": "hit",
    "claimHash": "accepted-claim-hash",
    "witnessCount": 2,
    "supportWeight": 2.0,
    "totalWeight": 2.0,
    "confidence": 1.0,
    "hasQuorum": True,
})
prediction = session.predict(note_doc, "input:python:move", {"body": "predicted input"})
unsubscribe()

Authority route verification

cultmesh_py.authority ports the C# reference (src/GameCult.Mesh/CultMeshAuthorityProof.cs): AuthorityTrustPolicy.validate judges an Odin-signed ECDSA P-256 route (channel protection, trusted root, validity window, IEEE P1363 signature over the canonical bytes) and verify_session_proof checks the provider nonce proof. Refusals raise AuthorityRouteRefusal with the C# message text. It needs cryptography. tests/test_authority_route_vectors.py judges contracts/cultmesh/authority-route-vectors*.json.

Verify

cultmesh_py.verify checks the public exports and py.typed markers of all three Python packages, smokes a local node over the wire, checks the served capability truth, and runs the benchmark for sanity:

python -m cultmesh_py.verify --json

Tests

$env:PYTHONPATH="$PWD\packages\cultcache-py\src;$PWD\packages\cultnet-py\src;$PWD\packages\cultmesh-py\src"
python -m unittest discover -s packages\cultmesh-py\tests

packages\cultnet-ts\test\interop\cultnet-interop.test.ts verifies the public CultMeshDiscoveryClient can fetch typed Verse and peer descriptors from the live Python peer. See docs/python-runtime-parity.md for the evidence map across the three Python packages.