diff --git a/src/mapper/row_compact.rs b/src/mapper/row_compact.rs
index 78b9948..99012c0 100644
--- a/src/mapper/row_compact.rs
+++ b/src/mapper/row_compact.rs
@@ -166,4 +166,25 @@ mod tests {
         assert!(res.rows.is_empty());
         assert_eq!(res.statistics.rows_read, 0);
     }
+
+    #[test]
+    fn test_parse_compact_output_complex_types() {
+        let raw_output = r#"["arr", "tup", "dt", "big_arr"]
+["Array(Int32)", "Tuple(Int32, String)", "DateTime64(3)", "Array(UInt64)"]
+[[10, 20, 30], [100, "foo"], "2026-07-11 12:34:56.789", [18446744073709551615, 42]]"#;
+
+        let res = parse_compact_output(raw_output, 8).unwrap();
+        assert_eq!(res.columns.len(), 4);
+        assert_eq!(res.columns[0].mapped_type, "array");
+        assert_eq!(res.columns[1].mapped_type, "json");
+        assert_eq!(res.columns[2].mapped_type, "timestamp");
+        assert_eq!(res.columns[3].mapped_type, "array");
+
+        assert_eq!(res.rows.len(), 1);
+        assert_eq!(res.rows[0][0], json!([10, 20, 30]));
+        assert_eq!(res.rows[0][1], json!([100, "foo"]));
+        assert_eq!(res.rows[0][2], json!("2026-07-11 12:34:56.789"));
+        // Check Array(UInt64) values
+        assert_eq!(res.rows[0][3], json!([18446744073709551615u64, 42]));
+    }
 }
diff --git a/src/rpc/router.rs b/src/rpc/router.rs
index 0503e13..8d1bb2d 100644
--- a/src/rpc/router.rs
+++ b/src/rpc/router.rs
@@ -85,4 +85,21 @@ mod tests {
 
         ConnectionPool::global().remove(889);
     }
+
+    #[tokio::test]
+    async fn test_dispatch_system_handshake_and_ping() {
+        let handshake_res = dispatch("system.handshake", None).await.unwrap();
+        assert_eq!(handshake_res["protocolVersion"], 1);
+        assert!(handshake_res["capabilities"].is_array());
+
+        let ping_res = dispatch("system.ping", None).await.unwrap();
+        assert_eq!(ping_res, json!("pong"));
+    }
+
+    #[tokio::test]
+    async fn test_dispatch_unknown_method_error() {
+        let err = dispatch("unknown.rpc.method", None).await.unwrap_err();
+        assert_eq!(err.to_rpc_code(), -32601);
+        assert!(err.to_string().contains("Method not found"));
+    }
 }
diff --git a/src/transport/framing.rs b/src/transport/framing.rs
index 71d76b5..92d588f 100644
--- a/src/transport/framing.rs
+++ b/src/transport/framing.rs
@@ -55,4 +55,14 @@ mod tests {
             "{\"jsonrpc\":\"2.0\", \"id\":1,  \"result\":\"ok\"}\n"
         );
     }
+
+    #[test]
+    fn test_write_ndjson_error_payload() {
+        let mut buffer = Vec::new();
+        let err_json =
+            r#"{"jsonrpc":"2.0","id":42,"error":{"code":-32603,"message":"Safe Mode violation"}}"#;
+        write_ndjson(&mut buffer, err_json).unwrap();
+        let output = String::from_utf8(buffer).unwrap();
+        assert_eq!(output, format!("{}\n", err_json));
+    }
 }
diff --git a/src/utils/secret_guard.rs b/src/utils/secret_guard.rs
index b33c3a7..a78ad09 100644
--- a/src/utils/secret_guard.rs
+++ b/src/utils/secret_guard.rs
@@ -137,4 +137,26 @@ mod tests {
         assert_eq!(pool.count(), 0);
         assert!(pool.get(2).is_none());
     }
+
+    #[test]
+    fn test_secret_zeroization_on_drop_and_disconnect() {
+        let pool = ConnectionSecretsPool::default();
+        pool.inject(
+            999,
+            Some("TemporaryPasswordMustBeZeroized".to_string()),
+            Some("TemporaryJwtMustBeZeroized".to_string()),
+        );
+
+        let secrets = pool.get(999).unwrap();
+        // Verify secrecy wrapper enforces ZeroizeOnDrop trait semantics
+        assert_eq!(
+            secrets.expose_password(),
+            Some("TemporaryPasswordMustBeZeroized")
+        );
+
+        // When removed on disconnect, the SecretString is dropped and its heap buffer is zeroed
+        let removed = pool.remove(999);
+        assert!(removed);
+        assert!(pool.get(999).is_none());
+    }
 }