Fix: read MODEL_REPO env var for classifier path

config.py

@@ -4,6 +4,7 @@ Includes label mappings, domain lists, question stems, and generation settings.
 """
 
 from dataclasses import dataclass, field
+import os
 
 
 # Bloom levels mapped to 3 classes.
@@ -300,8 +301,8 @@ class DeepModelConfig:
 class ProductConfig:
     """Configuration for the Dialectica application backend."""
 
-    # the fine-tuned classifier saved by Phase 4b
-    classifier_dir: str = "models/distilbert_bloom"
+    # DistilBERT classifier for Bloom-level classification
+    classifier_dir: str = os.environ.get("MODEL_REPO", "models/distilbert_bloom")
     # sentence embedding model for matching a question to a concept
     embed_model: str = "all-MiniLM-L6-v2"