fix: sessions code fence, a2a tests & lint

src/strands/models/anthropic.py

@@ -414,7 +414,7 @@ async def structured_output(
         stop_reason, messages, _, _ = event["stop"]
 
         if stop_reason != "tool_use":
-            raise ValueError(f"Model returned stop_reason: {stop_reason} instead of \"tool_use\".")
+            raise ValueError(f'Model returned stop_reason: {stop_reason} instead of "tool_use".')
 
         content = messages["content"]
         output_response: dict[str, Any] | None = None

src/strands/models/bedrock.py

@@ -631,7 +631,7 @@ async def structured_output(
         stop_reason, messages, _, _ = event["stop"]
 
         if stop_reason != "tool_use":
-            raise ValueError(f"Model returned stop_reason: {stop_reason} instead of \"tool_use\".")
+            raise ValueError(f'Model returned stop_reason: {stop_reason} instead of "tool_use".')
 
         content = messages["content"]
         output_response: dict[str, Any] | None = None

src/strands/session/file_session_manager.py

@@ -23,6 +23,7 @@ class FileSessionManager(RepositorySessionManager, SessionRepository):
     """File-based session manager for local filesystem storage.
 
     Creates the following filesystem structure for the session storage:
+    ```bash
     /<sessions_dir>/
     └── session_<session_id>/
         ├── session.json                # Session metadata
@@ -32,7 +33,7 @@ class FileSessionManager(RepositorySessionManager, SessionRepository):
                 └── messages/
                     ├── message_<id1>.json
                     └── message_<id2>.json
-
+    ```
     """
 
     def __init__(self, session_id: str, storage_dir: Optional[str] = None, **kwargs: Any):

src/strands/session/s3_session_manager.py

@@ -24,6 +24,7 @@ class S3SessionManager(RepositorySessionManager, SessionRepository):
     """S3-based session manager for cloud storage.
 
     Creates the following filesystem structure for the session storage:
+    ```bash
     /<sessions_dir>/
     └── session_<session_id>/
         ├── session.json                # Session metadata
@@ -33,7 +34,7 @@ class S3SessionManager(RepositorySessionManager, SessionRepository):
                 └── messages/
                     ├── message_<id1>.json
                     └── message_<id2>.json
-
+    ```
     """
 
     def __init__(