Remote domain configuration via admin domains API

ApiDomain carries the remote block (sync token write-only, never
echoed); create/patch accept it, validated with the combined config
(auth host mandatory for remote domains). db.update_domain replaces
remote wholesale like the other domain fields.

tests/test_remote.py

@@ -0,0 +1,198 @@
+"""Tests for remote (satellite) domains: config, replica application, feed."""
+
+import asyncio
+import os
+import secrets
+from datetime import UTC, datetime
+from uuid import UUID
+
+import pytest
+
+import paskia.db.operations as ops_db
+from paskia import domains, satellite, syncfeed
+from paskia.db.structs import (
+    Config,
+    Credential,
+    DomainConfig,
+    OriginEntry,
+    RemoteConfig,
+    Session,
+    User,
+)
+from paskia.db.structs import DB
+from paskia.util.crypto import hash_secret
+
+from .conftest import TEST_RP_ID
+
+REMOTE_URL = "http://remote.test"
+
+
+def _remote_domain_config(**kw) -> Config:
+    return Config(
+        domains={
+            TEST_RP_ID: DomainConfig(origins={f"**.{TEST_RP_ID}": True}),
+            "example.com": DomainConfig(
+                origins={
+                    "**.example.com": True,
+                    "auth.example.com": OriginEntry(auth_host=True),
+                },
+                remote=RemoteConfig(url=REMOTE_URL, token="t", **kw),
+            ),
+        }
+    )
+
+
+def test_remote_domain_valid():
+    domains.validate_config(_remote_domain_config())
+
+
+def test_remote_domain_requires_auth_host():
+    config = _remote_domain_config()
+    config.domains["example.com"].origins = {"**.example.com": True}
+    with pytest.raises(ValueError, match="auth host"):
+        domains.validate_config(config)
+
+
+def test_remote_domain_requires_http_url():
+    config = _remote_domain_config()
+    config.domains["example.com"].remote.url = "ftp://x"
+    with pytest.raises(ValueError, match="http"):
+        domains.validate_config(config)
+
+
+def test_sanitize_preserves_remote():
+    config, warnings = domains.sanitize_config(_remote_domain_config())
+    assert not warnings
+    assert config.domains["example.com"].remote.url == REMOTE_URL
+
+
+def test_apply_upsert_and_delete():
+    replica = DB()
+    user = User.create(display_name="U", role=UUID(int=1))
+    user.uuid = UUID(int=2)
+    satellite._apply(
+        replica, "users", str(user.uuid), "upsert", _builtins(user)
+    )
+    assert replica.users[user.uuid].display_name == "U"
+    satellite._apply(replica, "users", str(user.uuid), "delete", None)
+    assert not replica.users
+
+
+def _builtins(obj):
+    import msgspec
+
+    return msgspec.to_builtins(obj)
+
+
+def test_apply_session_roundtrip():
+    """Sessions keep their string key and datetime/UUID fields."""
+    replica = DB()
+    session = Session.create(
+        user=UUID(int=1),
+        credential=UUID(int=2),
+        key=hash_secret("cookie", "sekret"),
+        host="app2.example.com",
+        ip="127.0.0.1",
+        user_agent="ua",
+        validated=datetime.now(UTC),
+        rp_id="example.com",
+    )
+    satellite._apply(replica, "sessions", session.key, "upsert", _builtins(session))
+    stored = replica.sessions[session.key]
+    assert stored.host == "app2.example.com"
+    assert stored.validated == session.validated
+    assert stored.user_uuid == UUID(int=1)
+
+
+def test_apply_credential_bytes_roundtrip():
+    """credential_id/public_key are bytes over the wire (base64 in JSON)."""
+    replica = DB()
+    cred = Credential.create(
+        credential_id=os.urandom(32),
+        user=UUID(int=1),
+        aaguid=UUID(int=0),
+        public_key=os.urandom(64),
+        sign_count=3,
+        rp_id="example.com",
+    )
+    cred.uuid = UUID(int=9)
+    # Simulate the full wire path: builtins -> JSON -> builtins
+    import msgspec
+
+    wire = msgspec.json.decode(msgspec.json.encode(_builtins(cred)))
+    satellite._apply(replica, "credentials", str(cred.uuid), "upsert", wire)
+    stored = replica.credentials[cred.uuid]
+    assert stored.credential_id == cred.credential_id
+    assert stored.public_key == cred.public_key
+    assert stored.sign_count == 3
+
+
+def test_feed_emit_and_replay():
+    feed = syncfeed.SyncFeed()
+    user = User.create(display_name="A", role=UUID(int=1))
+    feed.emit("users", "k1", user)
+    feed.emit("users", "k1", None)
+    assert feed.seq == 2
+    assert feed.replay_since(0)[0]["op"] == "upsert"
+    assert feed.replay_since(1)[0]["op"] == "delete"
+    assert feed.replay_since(2) == []
+    assert feed.replay_since(99) is None
+
+
+def test_feed_ring_overflow_replay_none():
+    feed = syncfeed.SyncFeed()
+    feed.events = __import__("collections").deque(maxlen=3)
+    for i in range(5):
+        feed.emit("users", f"k{i}", None)
+    assert feed.replay_since(0) is None  # fell off the ring
+    assert [e["seq"] for e in feed.replay_since(4)] == [5]
+    assert feed.replay_since(5) == []
+
+
+@pytest.mark.asyncio
+async def test_operations_emit_events(test_db):
+    """Writes through db.operations land on the sync feed."""
+    syncfeed.feed.events.clear()
+    syncfeed.feed.seq = 0
+    user = next(iter(test_db.users.values()))
+    ops_db.update_user_display_name(user.uuid, "Renamed")
+    tables = {e["table"] for e in syncfeed.feed.events}
+    assert "users" in tables
+    key = syncfeed.feed.events[-1]["key"]
+    assert syncfeed.feed.events[-1]["fields"]["display_name"] == "Renamed"
+    assert key == str(user.uuid)
+
+
+@pytest.mark.asyncio
+async def test_replica_refresh_and_evict():
+    replica = satellite.RemoteReplica(RemoteConfig(url=REMOTE_URL, token="t"))
+    token = secrets.token_urlsafe(12)
+    session = Session.create(
+        user=UUID(int=1),
+        credential=UUID(int=2),
+        key=hash_secret("cookie", token),
+        host="app2.example.com",
+        ip="1.1.1.1",
+        user_agent="ua",
+        validated=datetime(2020, 1, 1, tzinfo=UTC),
+    )
+    replica.db.sessions[session.key] = session
+
+    now = datetime.now(UTC)
+    replica.refresh_session(session.key, now, "2.2.2.2", "new-ua")
+    assert replica.db.sessions[session.key].validated == now
+    queued = replica._pending_refresh[session.key]
+    assert queued["type"] == "session_refresh"
+    assert queued["ip"] == "2.2.2.2"
+
+    replica.evict_session(token)
+    assert not replica.db.sessions
+
+
+def test_availability_gate():
+    replica = satellite.RemoteReplica(
+        RemoteConfig(url=REMOTE_URL, token="t", cache_ttl=60)
+    )
+    assert not replica.available()  # never synced
+    replica.last_contact = __import__("time").monotonic()
+    assert replica.available()