diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000000..41dfc484ff
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,17 @@
+<!-- Describe your PR here -->
+
+---
+
+## General Notes
+
+Thank you for contributing to `sentry-python`!
+
+Please add tests to validate your changes, and lint your code using `tox -e linters`.
+
+Running the test suite on your PR might require maintainer approval. Some tests (AWS Lambda) additionally require a maintainer to add a special label to run and will fail if the label is not present.
+
+#### For maintainers
+
+Sensitive test suites require maintainer review to ensure that tests do not compromise our secrets. This review must be repeated after any code revisions.
+
+Before running sensitive test suites, please carefully check the PR. Then, apply the `Trigger: tests using secrets` label. The label will be removed after any code changes to enforce our policy requiring maintainers to review all code revisions before running sensitive tests.
diff --git a/sentry_sdk/client.py b/sentry_sdk/client.py
index 8aad751470..846fc0a7b6 100644
--- a/sentry_sdk/client.py
+++ b/sentry_sdk/client.py
@@ -43,7 +43,10 @@
     from typing import Dict
     from typing import Optional
     from typing import Sequence
+    from typing import Type
+    from typing import Union
 
+    from sentry_sdk.integrations import Integration
     from sentry_sdk.scope import Scope
     from sentry_sdk._types import Event, Hint
     from sentry_sdk.session import Session
@@ -653,6 +656,22 @@ def capture_session(
         else:
             self.session_flusher.add_session(session)
 
+    def get_integration(
+        self, name_or_class  # type: Union[str, Type[Integration]]
+    ):
+        # type: (...) -> Any
+        """Returns the integration for this client by name or class.
+        If the client does not have that integration then `None` is returned.
+        """
+        if isinstance(name_or_class, str):
+            integration_name = name_or_class
+        elif name_or_class.identifier is not None:
+            integration_name = name_or_class.identifier
+        else:
+            raise ValueError("Integration has no name")
+
+        return self.integrations.get(integration_name)
+
     def close(
         self,
         timeout=None,  # type: Optional[float]
diff --git a/sentry_sdk/hub.py b/sentry_sdk/hub.py
index 2525dc56f1..032ccd09e7 100644
--- a/sentry_sdk/hub.py
+++ b/sentry_sdk/hub.py
@@ -3,7 +3,7 @@
 
 from contextlib import contextmanager
 
-from sentry_sdk._compat import datetime_utcnow, with_metaclass
+from sentry_sdk._compat import with_metaclass
 from sentry_sdk.consts import INSTRUMENTER
 from sentry_sdk.scope import Scope
 from sentry_sdk.client import Client
@@ -15,7 +15,6 @@
     BAGGAGE_HEADER_NAME,
     SENTRY_TRACE_HEADER_NAME,
 )
-from sentry_sdk.session import Session
 from sentry_sdk.tracing_utils import (
     has_tracing_enabled,
     normalize_incoming_data,
@@ -294,18 +293,9 @@ def get_integration(
         If the return value is not `None` the hub is guaranteed to have a
         client attached.
         """
-        if isinstance(name_or_class, str):
-            integration_name = name_or_class
-        elif name_or_class.identifier is not None:
-            integration_name = name_or_class.identifier
-        else:
-            raise ValueError("Integration has no name")
-
         client = self.client
         if client is not None:
-            rv = client.integrations.get(integration_name)
-            if rv is not None:
-                return rv
+            return client.get_integration(name_or_class)
 
     @property
     def client(self):
@@ -430,31 +420,9 @@ def add_breadcrumb(self, crumb=None, hint=None, **kwargs):
             logger.info("Dropped breadcrumb because no client bound")
             return
 
-        crumb = dict(crumb or ())  # type: Breadcrumb
-        crumb.update(kwargs)
-        if not crumb:
-            return
-
-        hint = dict(hint or ())  # type: Hint
-
-        if crumb.get("timestamp") is None:
-            crumb["timestamp"] = datetime_utcnow()
-        if crumb.get("type") is None:
-            crumb["type"] = "default"
-
-        if client.options["before_breadcrumb"] is not None:
-            new_crumb = client.options["before_breadcrumb"](crumb, hint)
-        else:
-            new_crumb = crumb
-
-        if new_crumb is not None:
-            scope._breadcrumbs.append(new_crumb)
-        else:
-            logger.info("before breadcrumb dropped breadcrumb (%s)", crumb)
+        kwargs["client"] = client
 
-        max_breadcrumbs = client.options["max_breadcrumbs"]  # type: int
-        while len(scope._breadcrumbs) > max_breadcrumbs:
-            scope._breadcrumbs.popleft()
+        scope.add_breadcrumb(crumb, hint, **kwargs)
 
     def start_span(self, span=None, instrumenter=INSTRUMENTER.SENTRY, **kwargs):
         # type: (Optional[Span], str, Any) -> Span
@@ -712,12 +680,9 @@ def start_session(
     ):
         # type: (...) -> None
         """Starts a new session."""
-        self.end_session()
         client, scope = self._stack[-1]
-        scope._session = Session(
-            release=client.options["release"] if client else None,
-            environment=client.options["environment"] if client else None,
-            user=scope._user,
+        scope.start_session(
+            client=client,
             session_mode=session_mode,
         )
 
@@ -725,13 +690,7 @@ def end_session(self):
         # type: (...) -> None
         """Ends the current session if there is one."""
         client, scope = self._stack[-1]
-        session = scope._session
-        self.scope._session = None
-
-        if session is not None:
-            session.close()
-            if client is not None:
-                client.capture_session(session)
+        scope.end_session(client=client)
 
     def stop_auto_session_tracking(self):
         # type: (...) -> None
@@ -740,9 +699,8 @@ def stop_auto_session_tracking(self):
         This temporarily session tracking for the current scope when called.
         To resume session tracking call `resume_auto_session_tracking`.
         """
-        self.end_session()
         client, scope = self._stack[-1]
-        scope._force_auto_session_tracking = False
+        scope.stop_auto_session_tracking(client=client)
 
     def resume_auto_session_tracking(self):
         # type: (...) -> None
@@ -750,8 +708,8 @@ def resume_auto_session_tracking(self):
         disabled earlier.  This requires that generally automatic session
         tracking is enabled.
         """
-        client, scope = self._stack[-1]
-        scope._force_auto_session_tracking = None
+        scope = self._stack[-1][1]
+        scope.resume_auto_session_tracking()
 
     def flush(
         self,
diff --git a/sentry_sdk/metrics.py b/sentry_sdk/metrics.py
index 0ffdcf6de5..69902ca1a7 100644
--- a/sentry_sdk/metrics.py
+++ b/sentry_sdk/metrics.py
@@ -375,20 +375,22 @@ def add(
 
     def to_json(self):
         # type: (...) -> Dict[str, Any]
-        rv = {}
+        rv = {}  # type: Any
         for (export_key, tags), (
             v_min,
             v_max,
             v_count,
             v_sum,
         ) in self._measurements.items():
-            rv[export_key] = {
-                "tags": _tags_to_dict(tags),
-                "min": v_min,
-                "max": v_max,
-                "count": v_count,
-                "sum": v_sum,
-            }
+            rv.setdefault(export_key, []).append(
+                {
+                    "tags": _tags_to_dict(tags),
+                    "min": v_min,
+                    "max": v_max,
+                    "count": v_count,
+                    "sum": v_sum,
+                }
+            )
         return rv
 
 
diff --git a/sentry_sdk/scope.py b/sentry_sdk/scope.py
index 5096eccce0..8e9724b4c5 100644
--- a/sentry_sdk/scope.py
+++ b/sentry_sdk/scope.py
@@ -5,7 +5,10 @@
 import uuid
 
 from sentry_sdk.attachments import Attachment
+from sentry_sdk._compat import datetime_utcnow
+from sentry_sdk.consts import FALSE_VALUES
 from sentry_sdk._functools import wraps
+from sentry_sdk.session import Session
 from sentry_sdk.tracing_utils import (
     Baggage,
     extract_sentrytrace_data,
@@ -20,9 +23,6 @@
 from sentry_sdk._types import TYPE_CHECKING
 from sentry_sdk.utils import logger, capture_internal_exceptions
 
-from sentry_sdk.consts import FALSE_VALUES
-
-
 if TYPE_CHECKING:
     from typing import Any
     from typing import Dict
@@ -36,6 +36,7 @@
 
     from sentry_sdk._types import (
         Breadcrumb,
+        BreadcrumbHint,
         Event,
         EventProcessor,
         ErrorProcessor,
@@ -46,7 +47,6 @@
 
     from sentry_sdk.profiler import Profile
     from sentry_sdk.tracing import Span
-    from sentry_sdk.session import Session
 
     F = TypeVar("F", bound=Callable[..., Any])
     T = TypeVar("T")
@@ -517,6 +517,97 @@ def add_attachment(
             )
         )
 
+    def add_breadcrumb(self, crumb=None, hint=None, **kwargs):
+        # type: (Optional[Breadcrumb], Optional[BreadcrumbHint], Any) -> None
+        """
+        Adds a breadcrumb.
+
+        :param crumb: Dictionary with the data as the sentry v7/v8 protocol expects.
+
+        :param hint: An optional value that can be used by `before_breadcrumb`
+            to customize the breadcrumbs that are emitted.
+        """
+        client = kwargs.pop("client", None)
+        if client is None:
+            return
+
+        before_breadcrumb = client.options.get("before_breadcrumb")
+        max_breadcrumbs = client.options.get("max_breadcrumbs")
+
+        crumb = dict(crumb or ())  # type: Breadcrumb
+        crumb.update(kwargs)
+        if not crumb:
+            return
+
+        hint = dict(hint or ())  # type: Hint
+
+        if crumb.get("timestamp") is None:
+            crumb["timestamp"] = datetime_utcnow()
+        if crumb.get("type") is None:
+            crumb["type"] = "default"
+
+        if before_breadcrumb is not None:
+            new_crumb = before_breadcrumb(crumb, hint)
+        else:
+            new_crumb = crumb
+
+        if new_crumb is not None:
+            self._breadcrumbs.append(new_crumb)
+        else:
+            logger.info("before breadcrumb dropped breadcrumb (%s)", crumb)
+
+        while len(self._breadcrumbs) > max_breadcrumbs:
+            self._breadcrumbs.popleft()
+
+    def start_session(self, *args, **kwargs):
+        # type: (*Any, **Any) -> None
+        """Starts a new session."""
+        client = kwargs.pop("client", None)
+        session_mode = kwargs.pop("session_mode", "application")
+
+        self.end_session(client=client)
+
+        self._session = Session(
+            release=client.options["release"] if client else None,
+            environment=client.options["environment"] if client else None,
+            user=self._user,
+            session_mode=session_mode,
+        )
+
+    def end_session(self, *args, **kwargs):
+        # type: (*Any, **Any) -> None
+        """Ends the current session if there is one."""
+        client = kwargs.pop("client", None)
+
+        session = self._session
+        self._session = None
+
+        if session is not None:
+            session.close()
+            if client is not None:
+                client.capture_session(session)
+
+    def stop_auto_session_tracking(self, *args, **kwargs):
+        # type: (*Any, **Any) -> None
+        """Stops automatic session tracking.
+
+        This temporarily session tracking for the current scope when called.
+        To resume session tracking call `resume_auto_session_tracking`.
+        """
+        client = kwargs.pop("client", None)
+
+        self.end_session(client=client)
+
+        self._force_auto_session_tracking = False
+
+    def resume_auto_session_tracking(self):
+        # type: (...) -> None
+        """Resumes automatic session tracking for the current scope if
+        disabled earlier.  This requires that generally automatic session
+        tracking is enabled.
+        """
+        self._force_auto_session_tracking = None
+
     def add_event_processor(
         self, func  # type: EventProcessor
     ):
diff --git a/tests/test_metrics.py b/tests/test_metrics.py
index 3decca31c2..3f8b6049d8 100644
--- a/tests/test_metrics.py
+++ b/tests/test_metrics.py
@@ -597,33 +597,37 @@ def test_metric_summaries(sentry_init, capture_envelopes):
     t = transaction.items[0].get_transaction_event()
 
     assert t["_metrics_summary"] == {
-        "c:root-counter@none": {
-            "count": 1,
-            "min": 1.0,
-            "max": 1.0,
-            "sum": 1.0,
+        "c:root-counter@none": [
+            {
+                "count": 1,
+                "min": 1.0,
+                "max": 1.0,
+                "sum": 1.0,
+                "tags": {
+                    "transaction": "/foo",
+                    "release": "fun-release@1.0.0",
+                    "environment": "not-fun-env",
+                },
+            }
+        ]
+    }
+
+    assert t["spans"][0]["_metrics_summary"]["d:my-dist@none"] == [
+        {
+            "count": 10,
+            "min": 0.0,
+            "max": 9.0,
+            "sum": 45.0,
             "tags": {
-                "transaction": "/foo",
-                "release": "fun-release@1.0.0",
                 "environment": "not-fun-env",
+                "release": "fun-release@1.0.0",
+                "transaction": "/foo",
             },
         }
-    }
-
-    assert t["spans"][0]["_metrics_summary"]["d:my-dist@none"] == {
-        "count": 10,
-        "min": 0.0,
-        "max": 9.0,
-        "sum": 45.0,
-        "tags": {
-            "environment": "not-fun-env",
-            "release": "fun-release@1.0.0",
-            "transaction": "/foo",
-        },
-    }
+    ]
 
     assert t["spans"][0]["tags"] == {"a": "b"}
-    timer = t["spans"][0]["_metrics_summary"]["d:my-timer-metric@second"]
+    (timer,) = t["spans"][0]["_metrics_summary"]["d:my-timer-metric@second"]
     assert timer["count"] == 1
     assert timer["max"] == timer["min"] == timer["sum"]
     assert timer["sum"] > 0
@@ -697,6 +701,7 @@ def should_summarize_metric(key, tags):
         op="stuff", name="/foo", source=TRANSACTION_SOURCE_ROUTE
     ) as transaction:
         metrics.timing("foo", value=1.0, tags={"a": "b"}, timestamp=ts)
+        metrics.timing("foo", value=1.0, tags={"b": "c"}, timestamp=ts)
         metrics.timing("bar", value=1.0, tags={"a": "b"}, timestamp=ts)
 
     Hub.current.flush()
@@ -707,25 +712,40 @@ def should_summarize_metric(key, tags):
     assert envelope.items[0].headers["type"] == "statsd"
     m = parse_metrics(envelope.items[0].payload.get_bytes())
 
-    assert len(m) == 2
+    assert len(m) == 3
     assert m[0][1] == "bar@second"
     assert m[1][1] == "foo@second"
+    assert m[2][1] == "foo@second"
 
     # Measurement Attachment
     t = transaction.items[0].get_transaction_event()["_metrics_summary"]
     assert t == {
-        "d:foo@second": {
-            "tags": {
-                "a": "b",
-                "environment": "not-fun-env",
-                "release": "fun-release@1.0.0",
-                "transaction": "/foo",
+        "d:foo@second": [
+            {
+                "tags": {
+                    "a": "b",
+                    "environment": "not-fun-env",
+                    "release": "fun-release@1.0.0",
+                    "transaction": "/foo",
+                },
+                "min": 1.0,
+                "max": 1.0,
+                "count": 1,
+                "sum": 1.0,
             },
-            "min": 1.0,
-            "max": 1.0,
-            "count": 1,
-            "sum": 1.0,
-        }
+            {
+                "tags": {
+                    "b": "c",
+                    "environment": "not-fun-env",
+                    "release": "fun-release@1.0.0",
+                    "transaction": "/foo",
+                },
+                "min": 1.0,
+                "max": 1.0,
+                "count": 1,
+                "sum": 1.0,
+            },
+        ]
     }
 
 
diff --git a/tox.ini b/tox.ini
index 46477750e9..d93bc8ee1d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -241,7 +241,7 @@ deps =
     linters: werkzeug<2.3.0
 
     # Common
-    {py3.6,py3.7,py3.8,py3.9,py3.10,py3.11,py3.12}-common: pytest-asyncio
+    {py3.6,py3.7,py3.8,py3.9,py3.10,py3.11,py3.12}-common: pytest-asyncio<=0.21.1
     # See https://github.com/pytest-dev/pytest/issues/9621
     # and https://github.com/pytest-dev/pytest-forked/issues/67
     # for justification of the upper bound on pytest
@@ -252,6 +252,8 @@ deps =
     aiohttp-v3.8: aiohttp~=3.8.0
     aiohttp-latest: aiohttp
     aiohttp: pytest-aiohttp
+    aiohttp-v3.8: pytest-asyncio<=0.21.1
+    aiohttp-latest: pytest-asyncio<=0.21.1
 
     # Ariadne
     ariadne-v0.20: ariadne~=0.20.0
@@ -265,17 +267,17 @@ deps =
     arq-v0.23: pydantic<2
     arq-latest: arq
     arq: fakeredis>=2.2.0,<2.8
-    arq: pytest-asyncio
+    arq: pytest-asyncio<=0.21.1
     arq: async-timeout
 
     # Asgi
-    asgi: pytest-asyncio
+    asgi: pytest-asyncio<=0.21.1
     asgi: async-asgi-testclient
 
     # Asyncpg
     asyncpg-v0.23: asyncpg~=0.23.0
     asyncpg-latest: asyncpg
-    asyncpg: pytest-asyncio
+    asyncpg: pytest-asyncio<=0.21.1
 
     # AWS Lambda
     aws_lambda: boto3
@@ -329,10 +331,10 @@ deps =
     django-v{1.8,1.11,2.0}: pytest-django<4.0
     django-v{2.2,3.0,3.2,4.0,4.1,4.2,5.0}: pytest-django
     django-v{4.0,4.1,4.2,5.0}: djangorestframework
-    django-v{4.0,4.1,4.2,5.0}: pytest-asyncio
+    django-v{4.0,4.1,4.2,5.0}: pytest-asyncio<=0.21.1
     django-v{4.0,4.1,4.2,5.0}: Werkzeug
     django-latest: djangorestframework
-    django-latest: pytest-asyncio
+    django-latest: pytest-asyncio<=0.21.1
     django-latest: pytest-django
     django-latest: Werkzeug
     django-latest: channels[daphne]
@@ -346,8 +348,7 @@ deps =
     django-v4.0: Django~=4.0.0
     django-v4.1: Django~=4.1.0
     django-v4.2: Django~=4.2.0
-    # TODO: change to final when available
-    django-v5.0: Django==5.0rc1
+    django-v5.0: Django~=5.0.0
     django-latest: Django
 
     # Falcon
@@ -360,7 +361,7 @@ deps =
     # FastAPI
     fastapi: httpx
     fastapi: anyio<4.0.0 # thats a dep of httpx
-    fastapi: pytest-asyncio
+    fastapi: pytest-asyncio<=0.21.1
     fastapi: python-multipart
     fastapi: requests
     fastapi-v{0.79}: fastapi~=0.79.0
@@ -407,7 +408,7 @@ deps =
     grpc: protobuf
     grpc: mypy-protobuf
     grpc: types-protobuf
-    grpc: pytest-asyncio
+    grpc: pytest-asyncio<=0.21.1
     grpc-v1.21: grpcio-tools~=1.21.0
     grpc-v1.30: grpcio-tools~=1.30.0
     grpc-v1.40: grpcio-tools~=1.40.0
@@ -466,7 +467,7 @@ deps =
 
     # Quart
     quart: quart-auth
-    quart: pytest-asyncio
+    quart: pytest-asyncio<=0.21.1
     quart-v0.16: blinker<1.6
     quart-v0.16: jinja2<3.1.0
     quart-v0.16: Werkzeug<2.1.0
@@ -478,7 +479,7 @@ deps =
 
     # Redis
     redis: fakeredis!=1.7.4
-    {py3.7,py3.8,py3.9,py3.10,py3.11}-redis: pytest-asyncio
+    {py3.7,py3.8,py3.9,py3.10,py3.11}-redis: pytest-asyncio<=0.21.1
     redis-v3: redis~=3.0
     redis-v4: redis~=4.0
     redis-v5: redis~=5.0
@@ -520,7 +521,7 @@ deps =
     sanic-latest: sanic
 
     # Starlette
-    starlette: pytest-asyncio
+    starlette: pytest-asyncio<=0.21.1
     starlette: python-multipart
     starlette: requests
     starlette: httpx
@@ -534,7 +535,7 @@ deps =
     starlette-latest: starlette
 
     # Starlite
-    starlite: pytest-asyncio
+    starlite: pytest-asyncio<=0.21.1
     starlite: python-multipart
     starlite: requests
     starlite: cryptography