parse_client: Migrate has_request_variables to typed_endpoint.

Refactor `parse_client` view to use `typed_endpoint decorator`
instead of `has_request_variables`. This change improves code consistency
and enhances codebase comprehension.

zerver/middleware.py

@@ -22,7 +22,7 @@ from django.utils.translation import gettext as _
 from django_scim.middleware import SCIMAuthCheckMiddleware
 from django_scim.settings import scim_settings
 from sentry_sdk import set_tag
-from typing_extensions import Concatenate, ParamSpec, override
+from typing_extensions import Annotated, Concatenate, ParamSpec, override
 
 from zerver.lib.cache import get_remote_cache_requests, get_remote_cache_time
 from zerver.lib.db import reset_queries
@@ -32,7 +32,7 @@ from zerver.lib.html_to_text import get_content_description
 from zerver.lib.markdown import get_markdown_requests, get_markdown_time
 from zerver.lib.per_request_cache import flush_per_request_caches
 from zerver.lib.rate_limiter import RateLimitResult
-from zerver.lib.request import REQ, RequestNotes, has_request_variables
+from zerver.lib.request import RequestNotes
 from zerver.lib.response import (
     AsynchronousResponse,
     json_response,
@@ -40,6 +40,7 @@ from zerver.lib.response import (
     json_unauthorized,
 )
 from zerver.lib.subdomains import get_subdomain
+from zerver.lib.typed_endpoint import INTENTIONALLY_UNDOCUMENTED, ApiParamConfig, typed_endpoint
 from zerver.lib.user_agent import parse_user_agent
 from zerver.models import Realm
 from zerver.models.realms import get_realm
@@ -226,15 +227,18 @@ def write_log_line(
         logger.info("status=%3d, data=%s, uid=%s", status_code, error_data, requester_for_logs)
 
 
-# We take advantage of `has_request_variables` being called multiple times
+# We take advantage of `typed_endpoint` being called multiple times
 # when processing a request in order to process any `client` parameter that
 # may have been sent in the request content.
-@has_request_variables
+@typed_endpoint
 def parse_client(
     request: HttpRequest,
     # As `client` is a common element to all API endpoints, we choose
     # not to document on every endpoint's individual parameters.
-    req_client: Optional[str] = REQ("client", default=None, intentionally_undocumented=True),
+    *,
+    req_client: Annotated[
+        Optional[str], ApiParamConfig("client", documentation_status=INTENTIONALLY_UNDOCUMENTED)
+    ] = None,
 ) -> Tuple[str, Optional[str]]:
     # If the API request specified a client in the request content,
     # that has priority. Otherwise, extract the client from the