diff --git a/mcp-server/src/legal_mcp/services/precedent_library.py b/mcp-server/src/legal_mcp/services/precedent_library.py
index 8e929e6..96813f5 100644
--- a/mcp-server/src/legal_mcp/services/precedent_library.py
+++ b/mcp-server/src/legal_mcp/services/precedent_library.py
@@ -116,6 +116,18 @@ async def ingest_precedent(
         raise FileNotFoundError(f"file not found: {src}")
     if not citation.strip():
         raise ValueError("citation is required")
+    # Citation guard at service level (catches both MCP and HTTP API paths).
+    # Appeals-committee decisions must go through ingest_internal_decision
+    # which records chair_name+district. The MCP wrapper has the same guard
+    # for an earlier, friendlier error message — but this is the source of
+    # truth. See TaskMaster #30(ב) and DB constraint case_law_external_arar_check.
+    _norm = citation.strip()
+    if _norm.startswith(("ערר ", "ערר(", "בל\"מ ", "בל\"מ(", "ARAR ")):
+        raise ValueError(
+            "ציטוט שמתחיל ב-'ערר' או 'בל\"מ' הוא החלטת ועדת ערר. "
+            "השתמש ב-internal_decision_upload (דורש chair_name + district), "
+            "לא ב-precedent_library_upload."
+        )
     if practice_area not in _VALID_PRACTICE_AREAS:
         raise ValueError(f"invalid practice_area: {practice_area!r}")
     if source_type not in _VALID_SOURCE_TYPES: