Clean up stale config, fix DummyResponse headers, and harden shutdown

- Remove mypy.ini sections referencing deleted files (proxyagent_twisted,
  twisted_test_helpers, asyncio_test_helpers, test_httpproxy_*)
- Use CIMultiDict for DummyResponse.headers so .getall() works if tests
  ever exercise the retry/5xx code path
- Wrap individual pushkin.close() calls in try/except during shutdown so
  one failure doesn't prevent cleanup of remaining pushkins

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sandhose

mypy.ini

@@ -23,20 +23,5 @@ disallow_untyped_defs = False
 [mypy-sygnal.sygnal]
 disallow_untyped_defs = False
 
-[mypy-tests.asyncio_test_helpers]
-disallow_untyped_defs = False
-
-[mypy-tests.test_httpproxy_asyncio]
-disallow_untyped_defs = False
-
-[mypy-tests.test_httpproxy_twisted]
-disallow_untyped_defs = False
-
 [mypy-tests.testutils]
 disallow_untyped_defs = False
-
-[mypy-tests.twisted_test_helpers]
-disallow_untyped_defs = False
-
-[mypy-sygnal.helper.proxy.proxyagent_twisted]
-ignore_errors = True

sygnal/sygnal.py

@@ -194,8 +194,11 @@ async def _start(self) -> None:
         try:
             await asyncio.Event().wait()
         finally:
-            for pushkin in self.pushkins.values():
-                await pushkin.close()
+            for name, pushkin in self.pushkins.items():
+                try:
+                    await pushkin.close()
+                except Exception:
+                    logger.exception("Error closing pushkin %s", name)
             await runner.cleanup()
 
     def run(self) -> None:

tests/testutils.py

@@ -11,6 +11,7 @@
 from typing import Any, Dict, List, Union
 
 import pytest_asyncio
+from multidict import CIMultiDict
 
 from sygnal.http import create_app
 from sygnal.sygnal import CONFIG_DEFAULTS, Sygnal, merge_left_with_defaults
@@ -265,7 +266,7 @@ async def _multi_requests(
 class DummyResponse:
     def __init__(self, code):
         self.status = code
-        self.headers: Dict[str, str] = {}
+        self.headers: CIMultiDict[str] = CIMultiDict()
 
 
 def make_async_magic_mock(ret_val):