fix: api-catalog.json -> api-catalog as per RFC

Signed-off-by: Shingo OKAWA <[email protected]>

Author: ognis1205

examples/apicatalog/test_client.py

@@ -15,7 +15,7 @@
 
 
 async def fetch_api_catalog(base_url: str):
-    url = f'{base_url.rstrip("/")}/.well-known/api-catalog.json'
+    url = f'{base_url.rstrip("/")}/.well-known/api-catalog'
     async with httpx.AsyncClient() as client:
         response = await client.get(url)
         response.raise_for_status()

src/a2a/server/apps/jsonrpc/starlette_app.py

@@ -255,7 +255,7 @@ class StarletteBuilder:
     This class enables mounting multiple A2AStarletteRouteBuilder instances under
     specific paths and generates a complete Starlette application that serves them.
     It also collects AgentLinkContext entries and exposes them as an AgentCatalog
-    document at the standard path /.well-known/api-catalog.json.
+    document at the standard path /.well-known/api-catalog.
     """
 
     def __init__(self) -> None:
@@ -268,7 +268,7 @@ def __init__(self) -> None:
             _mounts: A list of Starlette Mount objects representing route groups
               mounted at specific paths.
             _catalog_links: A list of AgentLinkContext instances used to generate
-              the Agent Catalog served at /.well-known/api-catalog.json.
+              the Agent Catalog served at /.well-known/api-catalog.
         """
         self._mounts: list[Mount] = []
         self._catalog_links: list[AgentLinkContext] = []
@@ -345,7 +345,7 @@ def mount(
     def build(self, **kwargs: Any) -> Starlette:
         """Builds and returns a Starlette application."""
         catalog_route = Route(
-            '/.well-known/api-catalog.json',
+            '/.well-known/api-catalog',
             endpoint=self._handle_get_api_catalog,
             methods=['GET'],
             name='api_catalog',