diff --git a/.env.template b/.env.template
index 48fe88a..4e8d34a 100644
--- a/.env.template
+++ b/.env.template
@@ -26,5 +26,10 @@ ELASTIC_BASE_URL=
 ELASTIC_USERNAME=
 ELASTIC_PASSWORD=
 PAGE_SIZE=1000
+
+# Fusion weights (result ranking)
+FUSION_VECTOR_WEIGHT=0.6
+FUSION_KS_WEIGHT=0.4
+
 GCS_BUCKET=
 GCS_PREFIX=
diff --git a/backend/agents.py b/backend/agents.py
index 155ce0a..aa5ddab 100644
--- a/backend/agents.py
+++ b/backend/agents.py
@@ -14,6 +14,13 @@
 from ks_search_tool import general_search, general_search_async, global_fuzzy_keyword_search
 from retrieval import get_retriever
 
+# Fusion weights configurable via environment variables
+VECTOR_WEIGHT = float(os.getenv("FUSION_VECTOR_WEIGHT", "0.6"))
+KS_WEIGHT = float(os.getenv("FUSION_KS_WEIGHT", "0.4"))
+
+# Defaults preserve existing behavior (vector=0.6, keyword search=0.4)
+if any(w < 0 for w in (VECTOR_WEIGHT, KS_WEIGHT)):
+    raise ValueError("Fusion weights must be non-negative")
 
 #  LLM (Gemini) client setup 
 try:
@@ -443,14 +450,14 @@ def fuse_results(state: AgentState) -> AgentState:
     for res in vector_results:
         if isinstance(res, dict):
             doc_id = res.get("id") or res.get("_id") or f"vec_{len(combined)}"
-            combined[doc_id] = {**res, "final_score": res.get("similarity", 0) * 0.6}
+            combined[doc_id] = {**res, "final_score": res.get("similarity", 0) * VECTOR_WEIGHT}
     for res in ks_results:
         if isinstance(res, dict):
             doc_id = res.get("_id") or res.get("id") or f"ks_{len(combined)}"
             if doc_id in combined:
-                combined[doc_id]["final_score"] += res.get("_score", 0) * 0.4
+                combined[doc_id]["final_score"] += res.get("_score", 0) * KS_WEIGHT
             else:
-                combined[doc_id] = {**res, "final_score": res.get("_score", 0) * 0.4}
+                combined[doc_id] = {**res, "final_score": res.get("_score", 0) * KS_WEIGHT}
     all_sorted = sorted(combined.values(), key=lambda x: x.get("final_score", 0), reverse=True)
     logger.info(
         "Results summary: KS=%d, Vector=%d, Combined=%d",