diff --git a/.coveragerc b/.coveragerc
index 0b5d5bf0ad4..7792266b114 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -6,3 +6,6 @@ omit = site-packages
 [report]
 exclude_also =
     if TYPE_CHECKING
+    assert False
+    : \.\.\.(\s*#.*)?$
+    ^ +\.\.\.$
diff --git a/.github/workflows/ci-cd.yml b/.github/workflows/ci-cd.yml
index 5d5d6fa8c62..a6a58cef9c2 100644
--- a/.github/workflows/ci-cd.yml
+++ b/.github/workflows/ci-cd.yml
@@ -45,7 +45,7 @@ jobs:
     - name: Setup Python
       uses: actions/setup-python@v5
       with:
-        python-version: 3.9
+        python-version: 3.11
     - name: Cache PyPI
       uses: actions/cache@v4.0.2
       with:
diff --git a/CHANGES/8634.misc.rst b/CHANGES/8634.misc.rst
new file mode 100644
index 00000000000..cf4c68d5119
--- /dev/null
+++ b/CHANGES/8634.misc.rst
@@ -0,0 +1 @@
+Minor improvements to various type annotations -- by :user:`Dreamsorcerer`.
diff --git a/aiohttp/client.py b/aiohttp/client.py
index c70ad65c59e..1d4ccc0814a 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -9,7 +9,7 @@
 import traceback
 import warnings
 from contextlib import suppress
-from types import SimpleNamespace, TracebackType
+from types import TracebackType
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -155,7 +155,7 @@
 
 
 class _RequestOptions(TypedDict, total=False):
-    params: Union[Mapping[str, str], None]
+    params: Union[Mapping[str, Union[str, int]], str, None]
     data: Any
     json: Any
     cookies: Union[LooseCookies, None]
@@ -175,7 +175,7 @@ class _RequestOptions(TypedDict, total=False):
     ssl: Union[SSLContext, bool, Fingerprint]
     server_hostname: Union[str, None]
     proxy_headers: Union[LooseHeaders, None]
-    trace_request_ctx: Union[SimpleNamespace, None]
+    trace_request_ctx: Union[Mapping[str, str], None]
     read_bufsize: Union[int, None]
     auto_decompress: Union[bool, None]
     max_line_size: Union[int, None]
@@ -422,11 +422,22 @@ def __del__(self, _warnings: Any = warnings) -> None:
                 context["source_traceback"] = self._source_traceback
             self._loop.call_exception_handler(context)
 
-    def request(
-        self, method: str, url: StrOrURL, **kwargs: Any
-    ) -> "_RequestContextManager":
-        """Perform HTTP request."""
-        return _RequestContextManager(self._request(method, url, **kwargs))
+    if sys.version_info >= (3, 11) and TYPE_CHECKING:
+
+        def request(
+            self,
+            method: str,
+            url: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> "_RequestContextManager": ...
+
+    else:
+
+        def request(
+            self, method: str, url: StrOrURL, **kwargs: Any
+        ) -> "_RequestContextManager":
+            """Perform HTTP request."""
+            return _RequestContextManager(self._request(method, url, **kwargs))
 
     def _build_url(self, str_or_url: StrOrURL) -> URL:
         url = URL(str_or_url)
@@ -466,7 +477,7 @@ async def _request(
         ssl: Union[SSLContext, bool, Fingerprint] = True,
         server_hostname: Optional[str] = None,
         proxy_headers: Optional[LooseHeaders] = None,
-        trace_request_ctx: Optional[SimpleNamespace] = None,
+        trace_request_ctx: Optional[Mapping[str, str]] = None,
         read_bufsize: Optional[int] = None,
         auto_decompress: Optional[bool] = None,
         max_line_size: Optional[int] = None,
diff --git a/aiohttp/client_exceptions.py b/aiohttp/client_exceptions.py
index f15a9ee3d3e..ff29b3d3ca9 100644
--- a/aiohttp/client_exceptions.py
+++ b/aiohttp/client_exceptions.py
@@ -100,7 +100,7 @@ def __str__(self) -> str:
         return "{}, message={!r}, url={!r}".format(
             self.status,
             self.message,
-            self.request_info.real_url,
+            str(self.request_info.real_url),
         )
 
     def __repr__(self) -> str:
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 37d14e107fd..2c10da4ff81 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -245,7 +245,8 @@ class ClientRequest:
         hdrs.ACCEPT_ENCODING: _gen_default_accept_encoding(),
     }
 
-    body = b""
+    # Type of body depends on PAYLOAD_REGISTRY, which is dynamic.
+    body: Any = b""
     auth = None
     response = None
 
@@ -441,7 +442,7 @@ def update_headers(self, headers: Optional[LooseHeaders]) -> None:
 
         if headers:
             if isinstance(headers, (dict, MultiDictProxy, MultiDict)):
-                headers = headers.items()  # type: ignore[assignment]
+                headers = headers.items()
 
             for key, value in headers:  # type: ignore[misc]
                 # A special case for Host header
@@ -597,6 +598,10 @@ def update_proxy(
             raise ValueError("proxy_auth must be None or BasicAuth() tuple")
         self.proxy = proxy
         self.proxy_auth = proxy_auth
+        if proxy_headers is not None and not isinstance(
+            proxy_headers, (MultiDict, MultiDictProxy)
+        ):
+            proxy_headers = CIMultiDict(proxy_headers)
         self.proxy_headers = proxy_headers
 
     def keep_alive(self) -> bool:
@@ -632,10 +637,10 @@ async def write_bytes(
                 await self.body.write(writer)
             else:
                 if isinstance(self.body, (bytes, bytearray)):
-                    self.body = (self.body,)  # type: ignore[assignment]
+                    self.body = (self.body,)
 
                 for chunk in self.body:
-                    await writer.write(chunk)  # type: ignore[arg-type]
+                    await writer.write(chunk)
         except OSError as underlying_exc:
             reraised_exc = underlying_exc
 
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index cd89ea641d3..2e07395aece 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -23,6 +23,7 @@
     List,
     Literal,
     Optional,
+    Sequence,
     Set,
     Tuple,
     Type,
@@ -833,7 +834,7 @@ def clear_dns_cache(
             self._cached_hosts.clear()
 
     async def _resolve_host(
-        self, host: str, port: int, traces: Optional[List["Trace"]] = None
+        self, host: str, port: int, traces: Optional[Sequence["Trace"]] = None
     ) -> List[ResolveResult]:
         """Resolve host and return list of addresses."""
         if is_ip_address(host):
@@ -902,7 +903,7 @@ async def _resolve_host_with_throttle(
         key: Tuple[str, int],
         host: str,
         port: int,
-        traces: Optional[List["Trace"]],
+        traces: Optional[Sequence["Trace"]],
     ) -> List[ResolveResult]:
         """Resolve host with a dns events throttle."""
         if key in self._throttle_dns_events:
diff --git a/aiohttp/pytest_plugin.py b/aiohttp/pytest_plugin.py
index 6225fdf2be0..c862b409566 100644
--- a/aiohttp/pytest_plugin.py
+++ b/aiohttp/pytest_plugin.py
@@ -2,7 +2,17 @@
 import contextlib
 import inspect
 import warnings
-from typing import Any, Awaitable, Callable, Dict, Iterator, Optional, Type, Union
+from typing import (
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    Iterator,
+    Optional,
+    Protocol,
+    Type,
+    Union,
+)
 
 import pytest
 
@@ -24,9 +34,23 @@
 except ImportError:  # pragma: no cover
     uvloop = None  # type: ignore[assignment]
 
-AiohttpClient = Callable[[Union[Application, BaseTestServer]], Awaitable[TestClient]]
 AiohttpRawServer = Callable[[Application], Awaitable[RawTestServer]]
-AiohttpServer = Callable[[Application], Awaitable[TestServer]]
+
+
+class AiohttpClient(Protocol):
+    def __call__(
+        self,
+        __param: Union[Application, BaseTestServer],
+        *,
+        server_kwargs: Optional[Dict[str, Any]] = None,
+        **kwargs: Any
+    ) -> Awaitable[TestClient]: ...
+
+
+class AiohttpServer(Protocol):
+    def __call__(
+        self, app: Application, *, port: Optional[int] = None, **kwargs: Any
+    ) -> Awaitable[TestServer]: ...
 
 
 def pytest_addoption(parser):  # type: ignore[no-untyped-def]
@@ -262,7 +286,9 @@ def aiohttp_server(loop: asyncio.AbstractEventLoop) -> Iterator[AiohttpServer]:
     """
     servers = []
 
-    async def go(app, *, port=None, **kwargs):  # type: ignore[no-untyped-def]
+    async def go(
+        app: Application, *, port: Optional[int] = None, **kwargs: Any
+    ) -> TestServer:
         server = TestServer(app, port=port)
         await server.start_server(loop=loop, **kwargs)
         servers.append(server)
diff --git a/aiohttp/test_utils.py b/aiohttp/test_utils.py
index a36e8599689..97c1469dd2a 100644
--- a/aiohttp/test_utils.py
+++ b/aiohttp/test_utils.py
@@ -11,17 +11,7 @@
 import warnings
 from abc import ABC, abstractmethod
 from types import TracebackType
-from typing import (
-    TYPE_CHECKING,
-    Any,
-    Callable,
-    Iterator,
-    List,
-    Optional,
-    Type,
-    Union,
-    cast,
-)
+from typing import TYPE_CHECKING, Any, Callable, Iterator, List, Optional, Type, cast
 from unittest import IsolatedAsyncioTestCase, mock
 
 from aiosignal import Signal
@@ -29,7 +19,11 @@
 from yarl import URL
 
 import aiohttp
-from aiohttp.client import _RequestContextManager, _WSRequestContextManager
+from aiohttp.client import (
+    _RequestContextManager,
+    _RequestOptions,
+    _WSRequestContextManager,
+)
 
 from . import ClientSession, hdrs
 from .abc import AbstractCookieJar
@@ -55,6 +49,9 @@
 else:
     SSLContext = None
 
+if sys.version_info >= (3, 11) and TYPE_CHECKING:
+    from typing import Unpack
+
 REUSE_ADDRESS = os.name == "posix" and sys.platform != "cygwin"
 
 
@@ -90,7 +87,7 @@ class BaseTestServer(ABC):
     def __init__(
         self,
         *,
-        scheme: Union[str, object] = sentinel,
+        scheme: str = "",
         loop: Optional[asyncio.AbstractEventLoop] = None,
         host: str = "127.0.0.1",
         port: Optional[int] = None,
@@ -135,12 +132,8 @@ async def start_server(
         sockets = server.sockets  # type: ignore[attr-defined]
         assert sockets is not None
         self.port = sockets[0].getsockname()[1]
-        if self.scheme is sentinel:
-            if self._ssl:
-                scheme = "https"
-            else:
-                scheme = "http"
-            self.scheme = scheme
+        if not self.scheme:
+            self.scheme = "https" if self._ssl else "http"
         self._root = URL(f"{self.scheme}://{self.host}:{self.port}")
 
     @abstractmethod  # pragma: no cover
@@ -222,7 +215,7 @@ def __init__(
         self,
         app: Application,
         *,
-        scheme: Union[str, object] = sentinel,
+        scheme: str = "",
         host: str = "127.0.0.1",
         port: Optional[int] = None,
         **kwargs: Any,
@@ -239,7 +232,7 @@ def __init__(
         self,
         handler: _RequestHandler,
         *,
-        scheme: Union[str, object] = sentinel,
+        scheme: str = "",
         host: str = "127.0.0.1",
         port: Optional[int] = None,
         **kwargs: Any,
@@ -324,45 +317,101 @@ async def _request(
         self._responses.append(resp)
         return resp
 
-    def request(
-        self, method: str, path: StrOrURL, **kwargs: Any
-    ) -> _RequestContextManager:
-        """Routes a request to tested http server.
+    if sys.version_info >= (3, 11) and TYPE_CHECKING:
+
+        def request(
+            self, method: str, path: StrOrURL, **kwargs: Unpack[_RequestOptions]
+        ) -> _RequestContextManager: ...
+
+        def get(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def options(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def head(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def post(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def put(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def patch(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
+
+        def delete(
+            self,
+            path: StrOrURL,
+            **kwargs: Unpack[_RequestOptions],
+        ) -> _RequestContextManager: ...
 
-        The interface is identical to aiohttp.ClientSession.request,
-        except the loop kwarg is overridden by the instance used by the
-        test server.
+    else:
 
-        """
-        return _RequestContextManager(self._request(method, path, **kwargs))
+        def request(
+            self, method: str, path: StrOrURL, **kwargs: Any
+        ) -> _RequestContextManager:
+            """Routes a request to tested http server.
 
-    def get(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP GET request."""
-        return _RequestContextManager(self._request(hdrs.METH_GET, path, **kwargs))
+            The interface is identical to aiohttp.ClientSession.request,
+            except the loop kwarg is overridden by the instance used by the
+            test server.
 
-    def post(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP POST request."""
-        return _RequestContextManager(self._request(hdrs.METH_POST, path, **kwargs))
+            """
+            return _RequestContextManager(self._request(method, path, **kwargs))
 
-    def options(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP OPTIONS request."""
-        return _RequestContextManager(self._request(hdrs.METH_OPTIONS, path, **kwargs))
+        def get(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP GET request."""
+            return _RequestContextManager(self._request(hdrs.METH_GET, path, **kwargs))
 
-    def head(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP HEAD request."""
-        return _RequestContextManager(self._request(hdrs.METH_HEAD, path, **kwargs))
+        def post(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP POST request."""
+            return _RequestContextManager(self._request(hdrs.METH_POST, path, **kwargs))
 
-    def put(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP PUT request."""
-        return _RequestContextManager(self._request(hdrs.METH_PUT, path, **kwargs))
+        def options(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP OPTIONS request."""
+            return _RequestContextManager(
+                self._request(hdrs.METH_OPTIONS, path, **kwargs)
+            )
+
+        def head(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP HEAD request."""
+            return _RequestContextManager(self._request(hdrs.METH_HEAD, path, **kwargs))
 
-    def patch(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP PATCH request."""
-        return _RequestContextManager(self._request(hdrs.METH_PATCH, path, **kwargs))
+        def put(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP PUT request."""
+            return _RequestContextManager(self._request(hdrs.METH_PUT, path, **kwargs))
 
-    def delete(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
-        """Perform an HTTP PATCH request."""
-        return _RequestContextManager(self._request(hdrs.METH_DELETE, path, **kwargs))
+        def patch(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP PATCH request."""
+            return _RequestContextManager(
+                self._request(hdrs.METH_PATCH, path, **kwargs)
+            )
+
+        def delete(self, path: StrOrURL, **kwargs: Any) -> _RequestContextManager:
+            """Perform an HTTP PATCH request."""
+            return _RequestContextManager(
+                self._request(hdrs.METH_DELETE, path, **kwargs)
+            )
 
     def ws_connect(self, path: StrOrURL, **kwargs: Any) -> _WSRequestContextManager:
         """Initiate websocket connection.
diff --git a/aiohttp/tracing.py b/aiohttp/tracing.py
index 66007cbeb2c..012ed7bdaf6 100644
--- a/aiohttp/tracing.py
+++ b/aiohttp/tracing.py
@@ -1,5 +1,5 @@
 from types import SimpleNamespace
-from typing import TYPE_CHECKING, Awaitable, Optional, Protocol, Type, TypeVar
+from typing import TYPE_CHECKING, Awaitable, Mapping, Optional, Protocol, Type, TypeVar
 
 import attr
 from aiosignal import Signal
@@ -101,7 +101,7 @@ def __init__(
         self._trace_config_ctx_factory = trace_config_ctx_factory
 
     def trace_config_ctx(
-        self, trace_request_ctx: Optional[SimpleNamespace] = None
+        self, trace_request_ctx: Optional[Mapping[str, str]] = None
     ) -> SimpleNamespace:
         """Return a new trace_config_ctx instance"""
         return self._trace_config_ctx_factory(trace_request_ctx=trace_request_ctx)
diff --git a/aiohttp/typedefs.py b/aiohttp/typedefs.py
index 80dd26e80bd..9fb21c15f83 100644
--- a/aiohttp/typedefs.py
+++ b/aiohttp/typedefs.py
@@ -35,7 +35,13 @@
 Byteish = Union[bytes, bytearray, memoryview]
 JSONEncoder = Callable[[Any], str]
 JSONDecoder = Callable[[str], Any]
-LooseHeaders = Union[Mapping[Union[str, istr], str], _CIMultiDict, _CIMultiDictProxy]
+LooseHeaders = Union[
+    Mapping[str, str],
+    Mapping[istr, str],
+    _CIMultiDict,
+    _CIMultiDictProxy,
+    Iterable[Tuple[Union[str, istr], str]],
+]
 RawHeaders = Tuple[Tuple[bytes, bytes], ...]
 StrOrURL = Union[str, URL]
 
diff --git a/aiohttp/web_request.py b/aiohttp/web_request.py
index d059a166884..28d9ef3d10b 100644
--- a/aiohttp/web_request.py
+++ b/aiohttp/web_request.py
@@ -239,7 +239,8 @@ def clone(
             # a copy semantic
             dct["headers"] = CIMultiDictProxy(CIMultiDict(headers))
             dct["raw_headers"] = tuple(
-                (k.encode("utf-8"), v.encode("utf-8")) for k, v in headers.items()
+                (k.encode("utf-8"), v.encode("utf-8"))
+                for k, v in dct["headers"].items()
             )
 
         message = self._message._replace(**dct)
diff --git a/requirements/lint.in b/requirements/lint.in
index 98910e21f0e..0d46809a083 100644
--- a/requirements/lint.in
+++ b/requirements/lint.in
@@ -1,8 +1,11 @@
 aiodns
 aioredis
+freezegun
 mypy; implementation_name == "cpython"
 pre-commit
 pytest
+pytest-mock
 python-on-whales
 slotscheck
+trustme
 uvloop; platform_system != "Windows"
diff --git a/requirements/lint.txt b/requirements/lint.txt
index 85b96964c05..97809fe3dde 100644
--- a/requirements/lint.txt
+++ b/requirements/lint.txt
@@ -30,6 +30,8 @@ exceptiongroup==1.1.2
     # via pytest
 filelock==3.12.2
     # via virtualenv
+freezegun==1.5.1
+    # via -r requirements/lint.in
 identify==2.5.26
     # via pre-commit
 idna==3.7
@@ -66,6 +68,8 @@ pygments==2.17.2
     # via rich
 pytest==8.3.2
     # via -r requirements/lint.in
+pytest-mock==3.14.0
+    # via -r requirements/lint.in
 python-on-whales==0.72.0
     # via -r requirements/lint.in
 pyyaml==6.0.1
@@ -85,6 +89,8 @@ tomli==2.0.1
     #   slotscheck
 tqdm==4.66.2
     # via python-on-whales
+trustme==1.1.0
+    # via -r requirements/lint.in
 typer==0.12.3
     # via python-on-whales
 typing-extensions==4.11.0