--- a/mercurial/httppeer.py	Mon Dec 16 02:41:24 2024 -0500
+++ b/mercurial/httppeer.py	Mon Dec 16 03:04:44 2024 -0500
@@ -13,6 +13,7 @@
 import os
 import socket
 import struct
+import typing
 
 from concurrent import futures
 from .i18n import _
@@ -28,6 +29,11 @@
 )
 from .utils import urlutil
 
+if typing.TYPE_CHECKING:
+    from typing import (
+        Set,
+    )
+
 httplib = util.httplib
 urlerr = util.urlerr
 urlreq = util.urlreq
@@ -439,7 +445,7 @@
 
     # Begin of ipeercapabilities interface.
 
-    def capabilities(self):
+    def capabilities(self) -> Set[bytes]:
         return self._caps
 
     # End of ipeercapabilities interface.

--- a/mercurial/interfaces/repository.py	Mon Dec 16 02:41:24 2024 -0500
+++ b/mercurial/interfaces/repository.py	Mon Dec 16 03:04:44 2024 -0500
@@ -205,7 +205,7 @@
         """
 
     @abc.abstractmethod
-    def capabilities(self):
+    def capabilities(self) -> Set[bytes]:
         """Obtain capabilities of the peer.
 
         Returns a set of string capabilities.

--- a/mercurial/localrepo.py	Mon Dec 16 02:41:24 2024 -0500
+++ b/mercurial/localrepo.py	Mon Dec 16 03:04:44 2024 -0500
@@ -20,6 +20,7 @@
 from concurrent import futures
 from typing import (
     Optional,
+    Set,
 )
 
 from .i18n import _
@@ -341,7 +342,7 @@
 
     # Begin of ipeercapabilities interface.
 
-    def capabilities(self):
+    def capabilities(self) -> Set[bytes]:
         return self._caps
 
     # End of ipeercapabilities interface.

--- a/mercurial/sshpeer.py	Mon Dec 16 02:41:24 2024 -0500
+++ b/mercurial/sshpeer.py	Mon Dec 16 03:04:44 2024 -0500
@@ -8,6 +8,7 @@
 from __future__ import annotations
 
 import re
+import typing
 import uuid
 
 from .i18n import _
@@ -25,6 +26,11 @@
     urlutil,
 )
 
+if typing.TYPE_CHECKING:
+    from typing import (
+        Set,
+    )
+
 
 def _serverquote(s):
     """quote a string for the remote shell ... which we assume is sh"""
@@ -441,7 +447,7 @@
 
     # Begin of ipeercapabilities interface.
 
-    def capabilities(self):
+    def capabilities(self) -> Set[bytes]:
         return self._caps
 
     # End of ipeercapabilities interface.

--- a/tests/test-wireproto.py	Mon Dec 16 02:41:24 2024 -0500
+++ b/tests/test-wireproto.py	Mon Dec 16 03:04:44 2024 -0500
@@ -1,5 +1,9 @@
 import sys
 
+from typing import (
+    Set,
+)
+
 from mercurial import (
     error,
     pycompat,
@@ -55,8 +59,8 @@
     def close(self):
         pass
 
-    def capabilities(self):
-        return [b'batch']
+    def capabilities(self) -> Set[bytes]:
+        return {b'batch'}
 
     def _call(self, cmd, **args):
         args = pycompat.byteskwargs(args)