diff --git a/docs/ROADMAP.md b/docs/ROADMAP.md
index 467da9f..8d71653 100644
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -175,7 +175,7 @@ turning Sentinel into a noisy rules dump.
   event type, match fields, expected false positives, and drill coverage.
 - ✅ Require a fixture or safe red-team drill for every built-in SID, including
   event-only and correlation SIDs.
-- Add compatibility tests for rule JSON/event schema evolution.
+- ✅ Add compatibility tests for rule JSON/event schema evolution.
 - ✅ Extend triage so false-positive suggestions are tied to SID/classtype and can
   emit TOML snippets for allowlists, correlation windows, or severity overrides.
 - ✅ Add post-alert enrichment consistently across detections:
diff --git a/tests/test_rule_compat.py b/tests/test_rule_compat.py
new file mode 100644
index 0000000..793341d
--- /dev/null
+++ b/tests/test_rule_compat.py
@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+"""Compatibility tests for rule event JSON evolution."""
+import unittest
+
+from enodia_sentinel import ruleops
+from enodia_sentinel.config import Config
+
+
+class TestRuleEventCompatibility(unittest.TestCase):
+    def setUp(self):
+        self.cfg = Config()
+
+    def _sids(self, event):
+        return {a.sid for a in ruleops.test_event(self.cfg, event)}
+
+    def test_exec_event_accepts_type_alias(self):
+        event = {
+            "type": "execve",
+            "pid": "4242",
+            "ppid": "1",
+            "uid": "1000",
+            "parent_comm": "nginx",
+            "filename": "/usr/bin/sh",
+            "argv": ["-c", "id"],
+        }
+        self.assertIn(100003, self._sids(event))
+
+    def test_exec_event_kind_can_be_inferred_from_fields(self):
+        event = {
+            "pid": 4242,
+            "ppid": 1,
+            "uid": 1000,
+            "parent_comm": "bash",
+            "filename": "/tmp/payload",
+            "argv": [],
+        }
+        self.assertIn(100001, self._sids(event))
+
+    def test_syscall_event_accepts_type_alias_and_numeric_strings(self):
+        event = {
+            "type": "sys",
+            "pid": "4242",
+            "ppid": "1",
+            "uid": "1000",
+            "comm": "loader",
+            "syscall": "mprotect",
+            "args": ["0x1000", "0x1000", "0x6"],
+        }
+        self.assertIn(100060, self._sids(event))
+
+    def test_syscall_event_kind_can_be_inferred_from_fields(self):
+        event = {
+            "pid": 4242,
+            "ppid": 1,
+            "uid": 1000,
+            "comm": "loader",
+            "syscall": "memfd_create",
+        }
+        self.assertIn(100062, self._sids(event))
+
+    def test_syscall_arg_fields_override_args_array(self):
+        event = {
+            "event": "syscall",
+            "pid": 4242,
+            "ppid": 1,
+            "uid": 1000,
+            "comm": "loader",
+            "syscall": "mmap",
+            "args": [0, 4096, 0],
+            "arg2": "0x6",
+        }
+        self.assertIn(100061, self._sids(event))
+
+    def test_unknown_event_shape_still_errors(self):
+        with self.assertRaisesRegex(
+            ValueError, "event JSON must be an exec or syscall event"
+        ):
+            ruleops.test_event(self.cfg, {"pid": 4242})
+
+
+if __name__ == "__main__":
+    unittest.main()