fix: stop clearing feature cache on every Argo run — auto-invalidates via content hash

infra/k8s/argo/compile-and-train-template.yaml

@@ -393,11 +393,10 @@ spec:
             mkdir -p /workspace/output/hyperopt
 
             # Invalidate stale feature cache — the cache key now includes
-            # MBP-10 + trades dirs, so old caches (without trades/VPIN)
-            # won't match. But clean up the orphaned files to reclaim space.
-            echo "=== Clearing stale feature cache ==="
-            rm -f /workspace/.foxhunt_feature_cache/*.bin 2>/dev/null
-            echo "  Done (fresh features will be computed with VPIN enrichment)"
+            # Feature cache persists across runs — keyed by data file hashes,
+            # auto-invalidates when data changes. Do NOT clear it.
+            echo "=== Feature cache preserved (auto-invalidation via content hash) ==="
+            ls -lh /workspace/.foxhunt_feature_cache/*.bin 2>/dev/null || echo "  (empty — will be built on first run)"
 
             MODEL="{{workflow.parameters.model}}"
             case "$MODEL" in