diff --git a/preprocess_schemas.py b/preprocess_schemas.py
index 14d0464..a4fe2e9 100644
--- a/preprocess_schemas.py
+++ b/preprocess_schemas.py
@@ -412,6 +412,10 @@ def eval_prop_inclusion(name, data, op, base_required):
         is_required = False
     elif isinstance(marker, dict):
         val = marker.get(op)
+        if isinstance(val, dict):
+            # Handle transition-shaped marker: {"transition": {"from": "...", "to": "..."}}
+            transition = val.get("transition", {})
+            val = transition.get("to")
         if val == "omit" or val is None:
             include = False
         elif val == "required":
diff --git a/tests/test_codegen_pipeline.py b/tests/test_codegen_pipeline.py
index 955502b..fe4d863 100644
--- a/tests/test_codegen_pipeline.py
+++ b/tests/test_codegen_pipeline.py
@@ -227,6 +227,19 @@ def test_eval_prop_inclusion_applies_operation_overrides(self) -> None:
                 ["field"],
                 (False, True),
             ),
+            (
+                "transition-omit",
+                {
+                    "ucp_request": {
+                        "update": {
+                            "transition": {"from": "required", "to": "omit"}
+                        }
+                    }
+                },
+                "update",
+                ["field"],
+                (False, True),
+            ),
             (
                 "undeclared-operation",
                 {"ucp_request": {"update": "required"}},