3 files changed, 7 insertions, 6 deletions
diff --git a/synapse/handlers/account_data.py b/synapse/handlers/account_data.py
index d500b21809..67e789eef7 100644
--- a/synapse/handlers/account_data.py
+++ b/synapse/handlers/account_data.py
@@ -314,7 +314,7 @@ class AccountDataEventSource(EventSource[int, JsonDict]):
     def __init__(self, hs: "HomeServer"):
         self.store = hs.get_datastores().main
 
-    def get_current_key(self, direction: str = "f") -> int:
+    def get_current_key(self) -> int:
         return self.store.get_max_account_data_stream_id()
 
     async def get_new_events(
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index 6a4fed1156..04c61ae3dd 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -315,5 +315,5 @@ class ReceiptEventSource(EventSource[int, JsonDict]):
 
         return events, to_key
 
-    def get_current_key(self, direction: str = "f") -> int:
+    def get_current_key(self) -> int:
         return self.store.get_max_receipt_stream_id()
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 60a6d9cf3c..7ba7c4ff07 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -27,6 +27,7 @@ from typing_extensions import TypedDict
 
 import synapse.events.snapshot
 from synapse.api.constants import (
+    Direction,
     EventContentFields,
     EventTypes,
     GuestAccess,
@@ -1487,7 +1488,7 @@ class TimestampLookupHandler:
         requester: Requester,
         room_id: str,
         timestamp: int,
-        direction: str,
+        direction: Direction,
     ) -> Tuple[str, int]:
         """Find the closest event to the given timestamp in the given direction.
         If we can't find an event locally or the event we have locally is next to a gap,
@@ -1498,7 +1499,7 @@ class TimestampLookupHandler:
             room_id: Room to fetch the event from
             timestamp: The point in time (inclusive) we should navigate from in
                 the given direction to find the closest event.
-            direction: ["f"|"b"] to indicate whether we should navigate forward
+            direction: indicates whether we should navigate forward
                 or backward from the given timestamp to find the closest event.
 
         Returns:
@@ -1533,13 +1534,13 @@ class TimestampLookupHandler:
                 local_event_id, allow_none=False, allow_rejected=False
             )
 
-            if direction == "f":
+            if direction == Direction.FORWARDS:
                 # We only need to check for a backward gap if we're looking forwards
                 # to ensure there is nothing in between.
                 is_event_next_to_backward_gap = (
                     await self.store.is_event_next_to_backward_gap(local_event)
                 )
-            elif direction == "b":
+            elif direction == Direction.BACKWARDS:
                 # We only need to check for a forward gap if we're looking backwards
                 # to ensure there is nothing in between
                 is_event_next_to_forward_gap = (