UPDATE

rag/services/fertilization.py

@@ -54,6 +54,62 @@ def _find_section(sections: list[dict], section_type: str) -> dict | None:
     return None
 
 
+def _field_sources(llm_section: dict, fallback_section: dict, merged_section: dict) -> dict[str, str]:
+    sources: dict[str, str] = {}
+    for key, value in merged_section.items():
+        if key == "provenance":
+            continue
+        llm_value = llm_section.get(key)
+        fallback_value = fallback_section.get(key)
+        if key in llm_section and value == llm_value and value != fallback_value:
+            sources[key] = "llm"
+        elif key in fallback_section and value == fallback_value and value != llm_value:
+            sources[key] = "fallback"
+        elif key in llm_section and key in fallback_section and llm_value == fallback_value == value:
+            sources[key] = "shared"
+        elif key in llm_section and key in fallback_section:
+            sources[key] = "merged"
+        else:
+            sources[key] = "fallback" if key in fallback_section else "llm"
+    return sources
+
+
+def _attach_provenance(section_type: str, llm_section: dict, fallback_section: dict, merged_section: dict) -> dict:
+    merged = dict(merged_section)
+    field_sources = _field_sources(llm_section, fallback_section, merged)
+    merged["provenance"] = {
+        "sectionType": section_type,
+        "llmProvided": bool(llm_section),
+        "fallbackUsed": any(source != "llm" for source in field_sources.values()),
+        "fieldSources": field_sources,
+    }
+    return merged
+
+
+def _fallback_with_provenance(fallback: dict, reason: str) -> dict:
+    sections = []
+    for section in fallback.get("sections", []):
+        section_with_provenance = dict(section)
+        section_with_provenance["provenance"] = {
+            "sectionType": section.get("type"),
+            "llmProvided": False,
+            "fallbackUsed": True,
+            "fieldSources": {
+                key: "fallback"
+                for key in section.keys()
+                if key != "provenance"
+            },
+        }
+        sections.append(section_with_provenance)
+    return {
+        "sections": sections,
+        "mergeMetadata": {
+            "source": "fallback_only",
+            "reason": reason,
+        },
+    }
+
+
 def _build_fertilization_fallback(*, optimized_result: dict | None) -> dict:
     if optimized_result:
         recommended = optimized_result["recommended_strategy"]
@@ -134,11 +190,11 @@ def _merge_fertilization_response(
 ) -> dict:
     fallback = _build_fertilization_fallback(optimized_result=optimized_result)
     if not isinstance(parsed_result, dict):
-        return fallback
+        return _fallback_with_provenance(fallback, "invalid_llm_payload")
 
     sections = parsed_result.get("sections")
     if not isinstance(sections, list):
-        return fallback
+        return _fallback_with_provenance(fallback, "missing_sections")
 
     recommendation = _find_section(sections, "recommendation") or {}
     list_section = _find_section(sections, "list") or {}
@@ -169,7 +225,36 @@ def _merge_fertilization_response(
         "content": warning_section.get("content") or fallback_warning["content"],
     }
 
-    return {"sections": [merged_recommendation, merged_list, merged_warning]}
+    merged_recommendation = _attach_provenance(
+        "recommendation",
+        recommendation,
+        fallback_recommendation,
+        merged_recommendation,
+    )
+    merged_list = _attach_provenance(
+        "list",
+        list_section,
+        fallback_list,
+        merged_list,
+    )
+    merged_warning = _attach_provenance(
+        "warning",
+        warning_section,
+        fallback_warning,
+        merged_warning,
+    )
+
+    return {
+        "sections": [merged_recommendation, merged_list, merged_warning],
+        "mergeMetadata": {
+            "source": "llm_with_fallback_merge",
+            "llmSectionsDetected": [section.get("type") for section in sections if isinstance(section, dict)],
+            "fallbackSectionsApplied": [
+                item["type"]
+                for item in (fallback_recommendation, fallback_list, fallback_warning)
+            ],
+        },
+    }
 
 
 def get_fertilization_recommendation(