diff --git a/ingestor/engines/active_read.py b/ingestor/engines/active_read.py
index 9748517..f42b4f7 100644
--- a/ingestor/engines/active_read.py
+++ b/ingestor/engines/active_read.py
@@ -40,7 +40,11 @@ class ActiveReadEngine(SientiaMonitoring):
         )
 
     async def read_now(
-        self, server_id: str, addr: str, names: list[dict] | None = None, server_cfg: dict | None = None
+        self,
+        server_id: str,
+        addr: str,
+        names: list[dict] | None = None,
+        server_cfg: dict | None = None,
     ) -> dict:
         """Read `addr` on `server_id` right now; persist via sink only if `names` given."""
         tags = {'pod_id': self.pod_id, 'server_name': server_id}
@@ -72,7 +76,9 @@ class ActiveReadEngine(SientiaMonitoring):
         source_str = self._format_ts(source_ts)
         persisted = bool(names)
         if persisted:
-            await self.sink.publish_reading(tag=addr, value=value, timestamp=source_str, names=names)
+            await self.sink.publish_reading(
+                tag=addr, value=value, timestamp=source_str, names=names
+            )
         return {
             'value': value,
             'opc_status_code': status_name,
@@ -96,7 +102,9 @@ class ActiveReadEngine(SientiaMonitoring):
         if source_ts is None:
             return
         lag = MonotonicClock.now_wall() - source_ts.replace(tzinfo=OPC_TIMEZONE).timestamp()
-        await self.emit_metric(metric_object=metrics.OPC_READ_LAG, method='set', value=lag, tags=tags)
+        await self.emit_metric(
+            metric_object=metrics.OPC_READ_LAG, method='set', value=lag, tags=tags
+        )
 
     async def scheduled_tick(self, slot: dict) -> None:
         """Sweep every server/tag in a parsed slot, reading tags due for an active read."""
diff --git a/ingestor/engines/write.py b/ingestor/engines/write.py
index 2f90d64..3b297d6 100644
--- a/ingestor/engines/write.py
+++ b/ingestor/engines/write.py
@@ -37,13 +37,24 @@ _VARIANT_TYPES = {
 # ponytail: same reconnect-worthy Bad*-status subset as laborious's
 # opc_repository.py (different repo, not importable here); keep in sync by
 # hand or promote to a shared lib if it drifts.
-_SESSION_BAD_NAMES = frozenset({
-    'BadSessionIdInvalid', 'BadSessionClosed', 'BadSessionNotActivated',
-    'BadSecureChannelIdInvalid', 'BadSecureChannelClosed', 'BadSecureChannelTokenUnknown',
-    'BadTcpSecureChannelUnknown', 'BadServerNotConnected', 'BadConnectionClosed',
-    'BadConnectionRejected', 'BadNotConnected', 'BadTimeout', 'BadRequestTimeout',
-    'BadTooManySessions',
-})
+_SESSION_BAD_NAMES = frozenset(
+    {
+        'BadSessionIdInvalid',
+        'BadSessionClosed',
+        'BadSessionNotActivated',
+        'BadSecureChannelIdInvalid',
+        'BadSecureChannelClosed',
+        'BadSecureChannelTokenUnknown',
+        'BadTcpSecureChannelUnknown',
+        'BadServerNotConnected',
+        'BadConnectionClosed',
+        'BadConnectionRejected',
+        'BadNotConnected',
+        'BadTimeout',
+        'BadRequestTimeout',
+        'BadTooManySessions',
+    }
+)
 
 
 @dataclass
@@ -174,7 +185,11 @@ class WriteEngine(SientiaMonitoring):
             metric_object=metrics.OPC_WRITE_STATUS_BY_MODEL,
             method='set',
             value=1,
-            tags={'pod_id': self.pod_id, 'model_id': cmd.get('model_id', 'unknown'), 'status': 'ok'},
+            tags={
+                'pod_id': self.pod_id,
+                'model_id': cmd.get('model_id', 'unknown'),
+                'status': 'ok',
+            },
         )
         result = WriteResult(ok=True, status='ok', opc_status_code='Good', message='')
         await self.sink.update_write_status(cmd, result)
diff --git a/ingestor/io/data_sink.py b/ingestor/io/data_sink.py
index eef8a50..290f0e4 100644
--- a/ingestor/io/data_sink.py
+++ b/ingestor/io/data_sink.py
@@ -57,7 +57,11 @@ class DataSink:
             f'UPDATE {schema}.{table} SET write_status = :status '  # noqa: S608
             'WHERE timestamp = :timestamp AND model_id = :model_id'
         )
-        params = {'status': result.status, 'timestamp': cmd['timestamp'], 'model_id': cmd['model_id']}
+        params = {
+            'status': result.status,
+            'timestamp': cmd['timestamp'],
+            'model_id': cmd['model_id'],
+        }
         # ponytail: sync engine call inside async def — same pattern sientia_do's own
         # Postgres activities use (e.g. export_data_to_postgres); no async pg driver here.
         with self.postgres.engine.begin() as connection:
diff --git a/tests/unit/engines/test_active_read.py b/tests/unit/engines/test_active_read.py
index d880a9e..2a7640b 100644
--- a/tests/unit/engines/test_active_read.py
+++ b/tests/unit/engines/test_active_read.py
@@ -74,7 +74,9 @@ async def test_read_now_persists_and_returns_fields_when_names_given():
     assert latency_call.kwargs['method'] == 'observe'
     assert latency_call.kwargs['value'] >= 0
     lag_call = next(
-        c for c in eng.emit_metric.await_args_list if c.kwargs['metric_object'] is metrics.OPC_READ_LAG
+        c
+        for c in eng.emit_metric.await_args_list
+        if c.kwargs['metric_object'] is metrics.OPC_READ_LAG
     )
     assert lag_call.kwargs['method'] == 'set'