Test coverage and headless nvim bug fixes

server/src/handlers/graph.rs

@@ -147,7 +147,16 @@ impl McpTool for CreateRelationsHandler {
     }
 
     async fn execute(&self, args: Value, state: Arc<MemoryState>) -> Result<String, String> {
-        let req: CreateRelationsTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
+        let req: CreateRelationsTool = match serde_json::from_value(args.clone()) {
+            Ok(r) => r,
+            Err(e) => {
+                let err_msg = e.to_string();
+                if err_msg.contains("missing field `from`") || err_msg.contains("missing field `to`") || err_msg.contains("missing field `relation_type`") {
+                    return Err(format!("Schema error: {}. Note that the relation schema strictly uses 'from', 'to', and 'relation_type' (not 'source', 'target', or 'relationType'). Please correct your tool call arguments.", err_msg));
+                }
+                return Err(err_msg);
+            }
+        };
         let mut missing_nodes = std::collections::HashSet::new();
         state.modify_graph(|g| {
             for relation in req.relations {
@@ -682,6 +691,16 @@ mod tests {
         });
         let res = handler.execute(args, state.clone()).await.unwrap();
         assert_eq!(res, "Relations created");
+        
+        // Test semantic LLM schema feedback (User request)
+        let bad_args = json!({
+            "relations": [
+                {"source": "A", "target": "B", "relationType": "knows"}
+            ]
+        });
+        let err_res = handler.execute(bad_args, state.clone()).await.unwrap_err();
+        assert!(err_res.contains("Schema error:"));
+        assert!(err_res.contains("strictly uses 'from', 'to', and 'relation_type'"));
     }
 
     #[tokio::test]