Fix quote style: Use single quotes to match project standard

Applied Ruff 0.13.3 formatting to correctly enforce single quote style
as specified in .ruff.toml. This matches the coding standard used across
all other Python samples in the repository.

- Ruff 0.14.4 had a bug ignoring quote-style = "single" setting
- Ruff 0.13.3 correctly respects the configuration
- All files now use single quotes consistently

Author: madankumarpichamuthu

samples/python/agents/helloworld_with_ratelimiter/__main__.py

@@ -14,7 +14,7 @@
 from ratelimiter_ext import RateLimitingExtension, TokenBucketLimiter
 
 
-if __name__ == "__main__":
+if __name__ == '__main__':
     # Initialize rate limiter for enforcement (always active)
     # Token bucket allows burst traffic up to 20 requests (10 * 2.0 multiplier)
     # then maintains steady 10 requests per minute
@@ -25,31 +25,31 @@
     rate_limit_extension = RateLimitingExtension()
     # --8<-- [start:AgentSkill]
     skill = AgentSkill(
-        id="hello_world",
-        name="Returns hello world",
-        description="just returns hello world",
-        tags=["hello world"],
-        examples=["hi", "hello world"],
+        id='hello_world',
+        name='Returns hello world',
+        description='just returns hello world',
+        tags=['hello world'],
+        examples=['hi', 'hello world'],
     )
     # --8<-- [end:AgentSkill]
 
     extended_skill = AgentSkill(
-        id="super_hello_world",
-        name="Returns a SUPER Hello World",
-        description="A more enthusiastic greeting, only for authenticated users.",
-        tags=["hello world", "super", "extended"],
-        examples=["super hi", "give me a super hello"],
+        id='super_hello_world',
+        name='Returns a SUPER Hello World',
+        description='A more enthusiastic greeting, only for authenticated users.',
+        tags=['hello world', 'super', 'extended'],
+        examples=['super hi', 'give me a super hello'],
     )
 
     # --8<-- [start:AgentCard]
     # This will be the public-facing agent card
     public_agent_card = AgentCard(
-        name="Hello World Agent with Rate Limiting",
-        description="Hello world agent demonstrating A2A rate limiting extension",
-        url="http://localhost:9999/",
-        version="1.0.0",
-        default_input_modes=["text"],
-        default_output_modes=["text"],
+        name='Hello World Agent with Rate Limiting',
+        description='Hello world agent demonstrating A2A rate limiting extension',
+        url='http://localhost:9999/',
+        version='1.0.0',
+        default_input_modes=['text'],
+        default_output_modes=['text'],
         capabilities=AgentCapabilities(streaming=True),
         skills=[skill],  # Only the basic skill for the public card
         supports_authenticated_extended_card=True,
@@ -60,13 +60,13 @@
     # It includes the additional 'extended_skill'
     specific_extended_agent_card = public_agent_card.model_copy(
         update={
-            "name": "Hello World Agent with Rate Limiting - Extended Edition",  # Different name for clarity
-            "description": "The full-featured rate-limited hello world agent for authenticated users.",
-            "version": "1.0.1",  # Could even be a different version
+            'name': 'Hello World Agent with Rate Limiting - Extended Edition',  # Different name for clarity
+            'description': 'The full-featured rate-limited hello world agent for authenticated users.',
+            'version': '1.0.1',  # Could even be a different version
             # Capabilities and other fields like url, default_input_modes,
             # default_output_modes, supports_authenticated_extended_card
             # are inherited from public_agent_card unless specified here.
-            "skills": [
+            'skills': [
                 skill,
                 extended_skill,
             ],  # Both skills for the extended card
@@ -98,4 +98,4 @@
     )
 
     # Bind to 0.0.0.0 to allow external connections in containerized environment
-    uvicorn.run(server.build(), host="0.0.0.0", port=9999)  # noqa: S104
+    uvicorn.run(server.build(), host='0.0.0.0', port=9999)  # noqa: S104

samples/python/agents/helloworld_with_ratelimiter/agent_executor.py

@@ -10,7 +10,7 @@ class HelloWorldAgent:
 
     async def invoke(self) -> str:
         """Invoke the agent to return a greeting."""
-        return "Hello World"
+        return 'Hello World'
 
 
 # --8<-- [end:HelloWorldAgent]
@@ -57,8 +57,8 @@ def _extract_client_key(self, context: RequestContext) -> str:
         Returns:
             Unique key for rate limiting this client
         """
-        remote_addr = getattr(context, "remote_addr", "unknown")
-        return f"ip:{remote_addr}"
+        remote_addr = getattr(context, 'remote_addr', 'unknown')
+        return f'ip:{remote_addr}'
 
     # --8<-- [start:HelloWorldAgentExecutor_execute]
     async def execute(
@@ -83,13 +83,15 @@ async def execute(
 
         # Step 2: ALWAYS check rate limits (enforcement)
         # Rate limit: 10 requests per minute
-        usage = self.rate_limiter.check_limit(key=client_key, limit=10, window=60)
+        usage = self.rate_limiter.check_limit(
+            key=client_key, limit=10, window=60
+        )
 
         # Step 3: If rate limited, return error
         if not usage.allowed:
             error_msg = (
-                f"Rate limit exceeded. {usage.remaining} requests remaining. "
-                f"Retry after {usage.retry_after:.1f} seconds."
+                f'Rate limit exceeded. {usage.remaining} requests remaining. '
+                f'Retry after {usage.retry_after:.1f} seconds.'
             )
             message = new_agent_text_message(error_msg)
 
@@ -113,9 +115,11 @@ async def execute(
     # --8<-- [end:HelloWorldAgentExecutor_execute]
 
     # --8<-- [start:HelloWorldAgentExecutor_cancel]
-    async def cancel(self, context: RequestContext, event_queue: EventQueue) -> None:
+    async def cancel(
+        self, context: RequestContext, event_queue: EventQueue
+    ) -> None:
         """Cancel the agent execution (not supported)."""
-        msg = "cancel not supported"
+        msg = 'cancel not supported'
         raise NotImplementedError(msg)
 
     # --8<-- [end:HelloWorldAgentExecutor_cancel]