diff --git a/src/specify_cli/workflows/overlays/schema.py b/src/specify_cli/workflows/overlays/schema.py
index 0a018b7af0..969bbd94a9 100644
--- a/src/specify_cli/workflows/overlays/schema.py
+++ b/src/specify_cli/workflows/overlays/schema.py
@@ -60,7 +60,13 @@ def _validate_safe_id(
 
 def _parse_edit(edit_raw: dict[str, Any], idx: int) -> tuple[OverlayEdit | None, str | None]:
     """Parse a single edit dict into an OverlayEdit or an error string."""
-    shorthand_keys = [key for key in _SHORTHAND_OPERATION_KEYS if key in edit_raw]
+    # Iterate ``edit_raw`` rather than ``_SHORTHAND_OPERATION_KEYS``: the latter
+    # is a frozenset, whose iteration order varies between processes with
+    # string-hash randomization, so the error messages built from this list
+    # named the offending keys in a different order on every run for the very
+    # same overlay file. Dict keys are always hashable, so the membership test
+    # is safe in this direction too.
+    shorthand_keys = [key for key in edit_raw if key in _SHORTHAND_OPERATION_KEYS]
     has_operation = "operation" in edit_raw
 
     operation: str | None = None
diff --git a/tests/workflows/test_overlay_schema.py b/tests/workflows/test_overlay_schema.py
index 77e0432eca..a91efb0a36 100644
--- a/tests/workflows/test_overlay_schema.py
+++ b/tests/workflows/test_overlay_schema.py
@@ -124,6 +124,57 @@ def test_multiple_operation_fields_rejected(self):
         assert overlay is None
         assert any("multiple" in e.lower() for e in errors), errors
 
+    @pytest.mark.parametrize(
+        "first,second",
+        [("remove", "insert_after"), ("insert_after", "remove")],
+        ids=["remove-first", "insert_after-first"],
+    )
+    def test_multiple_operation_keys_reported_in_declaration_order(
+        self, first, second
+    ):
+        """The message must name the keys in the order the user wrote them.
+
+        Collecting the keys by iterating the ``_SHORTHAND_OPERATION_KEYS``
+        frozenset made the order depend on per-process string-hash
+        randomization, so the same overlay file produced a different message on
+        every run. Whatever fixed order a frozenset happens to have in a given
+        process, one of these two parametrizations contradicts it -- so this
+        pair fails deterministically without the fix, in every process.
+        """
+        overlay, errors = validate_overlay_yaml(
+            {
+                "id": "ov",
+                "extends": "wf",
+                "edits": [{first: "a", second: "a"}],
+            }
+        )
+        assert overlay is None
+        assert errors == [
+            f"Edit at index 0 has multiple operation keys: {first!r}, {second!r}."
+        ]
+
+    @pytest.mark.parametrize(
+        "first,second",
+        [("remove", "insert_after"), ("insert_after", "remove")],
+        ids=["remove-first", "insert_after-first"],
+    )
+    def test_shorthand_mixed_with_operation_names_first_declared_key(
+        self, first, second
+    ):
+        """``shorthand_keys[0]`` must be the first key the user declared."""
+        overlay, errors = validate_overlay_yaml(
+            {
+                "id": "ov",
+                "extends": "wf",
+                "edits": [{first: "a", second: "a", "operation": "replace"}],
+            }
+        )
+        assert overlay is None
+        assert errors == [
+            f"Edit at index 0 mixes shorthand operation key ({first!r}) "
+            f"with explicit 'operation' field."
+        ]
+
     def test_invalid_operation_field_rejected(self):
         overlay, errors = validate_overlay_yaml(
             {