Devstral Small 2: serve.sh, baseline.py without thinking args, repair rate, activation error message fix, stop rule in chain (run base 21000)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014aUaQeLnwbb1zTpN7kHeat

harness/proxy.py

@@ -43,8 +43,8 @@ def activation_messages(text, is_error=False):
         return []
     msgs = (obj.get("activation") or {}).get("messages") or obj.get("messages") or []
     out = [str(m.get("message", ""))[:300] for m in msgs if isinstance(m, dict) and m.get("severity") == "E"]
-    if not out and is_error:
-        out = [str(obj.get("message") or text)[:300]]
+    if not out and (is_error or obj.get("success") is False):
+        out = [str(obj.get("error") or obj.get("message") or text)[:300]]  # {"success":false,"error":...} of a failed write
     return out