tau2: ERROR+ log level; TAU2_DATA_DIR kills the data-dir banners

The startup noise (.env found note, data directory note) is itself
WARNING-level, so the WARNING filter passed it through. Level is now
ERROR and the data-dir warnings die at the source with the correct
TAU2_DATA_DIR.

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

evalharness/agent/envs/tau2_official.py

@@ -31,13 +31,18 @@ _TAU2_LOCAL_CANDIDATES = [
 
 
 def _silence_tau2_logs():
-    """tau2's loguru DEBUG dumps every full message to the terminal --
-    thousands of lines per run. Keep WARNING+ only."""
+    """tau2's loguru chatter: DEBUG dumps every full message, WARNING-level
+    banners fire at import (.env note, data-dir note, litellm cost-map
+    timeout). ERROR+ only -- the terminal stays ours."""
     try:
+        # kill the data-dir banner at the SOURCE (right directory set)
+        os.environ.setdefault(
+            'TAU2_DATA_DIR',
+            '/data1/sora/evalscope/tools/tau2-bench/data')
         from loguru import logger
 
         logger.remove()
-        logger.add(sys.stderr, level='WARNING')
+        logger.add(sys.stderr, level='ERROR')
     except Exception:
         pass