fix: add retry adapter to requests.Session in batch_validate.py

Stale keep-alive connections in the pool can cause silent hangs when the
server closes an idle connection between trace validations. The retry
adapter (3 retries, 0.5s backoff) handles connection resets on POST
requests automatically, preventing delays mid-batch.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Bharatram-altimate-ai

packages/altimate-code/src/skills/validate/batch_validate.py

@@ -27,6 +27,8 @@
 from pathlib import Path
 
 import requests
+from requests.adapters import HTTPAdapter
+from urllib3.util.retry import Retry
 from dotenv import load_dotenv
 
 # ---------------------------------------------------------------------------
@@ -206,7 +208,13 @@ def fetch_traces_by_session_id(session_id):
 # ---------------------------------------------------------------------------
 
 # Session reuses TCP connection and SSL handshake across all traces.
+# Retry adapter handles stale keep-alive connections being reset mid-batch.
 _SESSION = requests.Session()
+_adapter = HTTPAdapter(
+    max_retries=Retry(total=3, allowed_methods=["POST"], backoff_factor=0.5)
+)
+_SESSION.mount("https://", _adapter)
+_SESSION.mount("http://", _adapter)
 
 
 def validate_trace(trace_id):