diff --git a/object_model_parity.py b/object_model_parity.py
index 7a8de66..f4c31b6 100644
--- a/object_model_parity.py
+++ b/object_model_parity.py
@@ -26,6 +26,18 @@
           else Path(__file__).resolve().parent.parent
           / "PyMEOS" / "pymeos" / "factory.py")
 
+
+def _oracle_id(path: Path) -> str:
+    """The oracle named by its place INSIDE PyMEOS, never by this machine.
+
+    Where the file sits on a given disk is a property of the checkout, not of
+    the audit, so recording it makes the artefact differ between two machines
+    that read the very same oracle -- and a consumer that regenerates the file
+    to check for drift then sees drift that is not there.
+    """
+    parts = path.resolve().parts
+    return "/".join(parts[-2:]) if len(parts) >= 2 else path.name
+
 _SUBTYPE = {"INSTANT": "TINSTANT", "SEQUENCE": "TSEQUENCE",
             "SEQUENCE_SET": "TSEQUENCESET"}
 _TEMPORAL_RE = re.compile(
@@ -76,7 +88,7 @@ def add(kind, detail, status, ref=None):
     if oracle is None:
         return {
             "status": "oracle-unavailable",
-            "oraclePath": str(PYMEOS),
+            "oraclePath": _oracle_id(PYMEOS),
             "note": "PyMEOS factory.py not found; reporting curated "
                     "corrections only — no fabricated parity verdict.",
             "total": len(work), "aligned": 0,
@@ -137,7 +149,7 @@ def add(kind, detail, status, ref=None):
     needs = [w for w in work if w["status"] == "needs-correction"]
     return {
         "status": "audited",
-        "oraclePath": str(PYMEOS),
+        "oraclePath": _oracle_id(PYMEOS),
         "total": len(work),
         "aligned": aligned_concrete,
         "divergences": len(work),
diff --git a/tests/test_object_model_parity.py b/tests/test_object_model_parity.py
index c5120f1..14656e4 100644
--- a/tests/test_object_model_parity.py
+++ b/tests/test_object_model_parity.py
@@ -17,7 +17,8 @@
 sys.path.insert(0, str(ROOT))
 
 from parser.object_model import attach_object_model
-from object_model_parity import build_parity, _parse_oracle, PYMEOS
+from object_model_parity import (build_parity, _parse_oracle, _oracle_id,
+                                 PYMEOS)
 
 MODEL = ROOT / "meta" / "object-model.json"
 _CATALOG = ROOT / "output" / "meos-idl.json"
@@ -58,6 +59,21 @@ def test_audited_against_fake_oracle(self):
         self.assertEqual(rep["knownCorrections"] + rep["needsCorrection"],
                          rep["divergences"])
 
+    def test_oracle_is_named_by_its_place_not_by_this_machine(self):
+        """Two checkouts of the same oracle must yield the same artefact.
+
+        The consumer regenerates this file to detect drift, so an oracle path
+        carrying the checkout's location reports drift between any two machines
+        reading the very same oracle -- and the drift gate can then never go
+        green.
+        """
+        a = _oracle_id(Path("/home/someone/src/PyMEOS/pymeos/factory.py"))
+        b = _oracle_id(Path("/opt/build-7f3/PyMEOS/pymeos/factory.py"))
+        self.assertEqual(a, b)
+        self.assertEqual(a, "pymeos/factory.py")
+        self.assertNotIn("/home", a)
+        self.assertFalse(Path(a).is_absolute())
+
     def test_every_divergence_has_a_correction(self):
         oracle = _parse_oracle(PYMEOS)
         if oracle is None: