diff --git a/scripts/check_layer_conformance.py b/scripts/check_layer_conformance.py
index 1e8b691..b39daf4 100644
--- a/scripts/check_layer_conformance.py
+++ b/scripts/check_layer_conformance.py
@@ -30,10 +30,14 @@ sys.path.insert(0, str(ROOT / "src"))
 
 from user_engine.layer_yaml import load_mapping, load_mapping_text  # noqa: E402
 
-# The standard text this checker was built and validated against. The version
-# belongs to the run, not to the declaration (GH-DEC-2026-020 §4, A12 r2); it is
-# printed on every run. Bump it when the checker is re-validated.
-VALIDATED_AGAINST = "net-kingdom/canon/standards/security-layer-model_v0.7.md"
+# What every run checks against, printed on every run (GH-DEC-2026-020 §4,
+# GH-DEC-2026-021 §2). The accepted text is v0.7 at net-kingdom@66dc491; the
+# decision records whose rulings this checker enforces beyond v0.7 are named with it.
+VALIDATED_AGAINST = (
+    "net-kingdom/canon/standards/security-layer-model_v0.7.md (net-kingdom@66dc491) "
+    "as amended by GH-DEC-2026-017, GH-DEC-2026-020 and GH-DEC-2026-021 "
+    "(A9-A13, A12 r3; gate-house@39d9287)"
+)
 
 # What every run ranges over. Stance, claims and classification maps
 # (pep-stance.yaml) are not declarations and are not checked for versions
@@ -45,9 +49,15 @@ SCOPE = (
 
 # A12 r2: no standard or companion version in any key or value of the
 # declaration. Comments are not parsed; schema_version is not reached.
-VERSION_KEY = re.compile(r"(?:^|_)version$", re.IGNORECASE)
-VERSION_VALUE = re.compile(r"(?:^|[_\-/\s])v?\d+\.\d+(?:\.\d+)*(?:\.md)?(?=$|[\s/])|_v\d+", re.IGNORECASE)
+# Detector converged on the estate reference, ops-warden's (GH-DEC-2026-021 §3):
+# a version token (`v?N.N`) in an identity-bearing value (`standard:`,
+# `companion:`) is a pin (A12 r3); keys naming neither, e.g. `intent_version`,
+# are not reached.
+VERSION_KEY = re.compile(r"(standard|companion).*version|version.*(standard|companion)", re.I)
+VERSION_VALUE = re.compile(r"[_\-.]v\d+(\.\d+)*(\.md)?\b|@v?\d+\.\d+", re.I)
 UNREACHED_KEYS = {"schema_version"}
+IDENTITY_KEYS = {"standard", "companion"}
+IDENTITY_VERSION = re.compile(r"\bv?\d+\.\d+", re.I)
 
 TOOLING_IMPORTS = {
     "hvac": "OpenBao / Vault client",
@@ -81,7 +91,9 @@ def fold(value: object) -> str:
     )
 
 
-def find_versions(node: object, where: str, path: str = "") -> list[str]:
+def find_versions(
+    node: object, where: str, path: str = "", identity: bool = False
+) -> list[str]:
     """Every key or value in a declaration that carries a version (A12 r2)."""
     found: list[str] = []
     if isinstance(node, dict):
@@ -92,12 +104,14 @@ def find_versions(node: object, where: str, path: str = "") -> list[str]:
             if VERSION_KEY.search(str(key)):
                 found.append(f"{where}: key '{here}'")
                 continue
-            found.extend(find_versions(value, where, here))
+            found.extend(find_versions(value, where, here, str(key).lower() in IDENTITY_KEYS))
     elif isinstance(node, list):
         for index, item in enumerate(node):
-            found.extend(find_versions(item, where, f"{path}[{index}]"))
+            found.extend(find_versions(item, where, f"{path}[{index}]", identity))
     elif isinstance(node, str) and VERSION_VALUE.search(node):
         found.append(f"{where}: value of '{path}' = {node!r}")
+    elif isinstance(node, str) and identity and IDENTITY_VERSION.search(node):
+        found.append(f"{where}: identity-bearing value of '{path}' = {node!r}")
     return found
 
 
@@ -106,7 +120,7 @@ def reject_versions(data: dict, where: str) -> None:
     if found:
         print(
             "FAIL: a layer declaration MUST NOT carry a standard or companion "
-            "version in any key or value (GH-DEC-2026-017 §5, GH-DEC-2026-020, A12 r2)",
+            "version in any key or value (GH-DEC-2026-017 §5, GH-DEC-2026-020, GH-DEC-2026-021, A12 r3)",
             file=sys.stderr,
         )
         for item in found:
diff --git a/tests/test_layer_conformance.py b/tests/test_layer_conformance.py
index 25425c0..eea3cdc 100644
--- a/tests/test_layer_conformance.py
+++ b/tests/test_layer_conformance.py
@@ -81,6 +81,15 @@ class LayerDeclarationTests(unittest.TestCase):
         # pep-stance.yaml keeps its version fields (GH-DEC-2026-020 §3).
         self.assertTrue(module.find_versions(load_mapping(STANCE_FILE), "stance"))
 
+    def test_version_scan_matches_estate_reference_detector(self):
+        # GH-DEC-2026-021 §3 (A12 r3): a version token in an identity-bearing
+        # value is a pin; a key naming neither standard nor companion is not.
+        module = _checker()
+        self.assertTrue(module.find_versions({"standard": "security-layer-model 0.7"}, "x"))
+        self.assertTrue(module.find_versions({"companion": ["SECURITY-COMPANION v0.2"]}, "x"))
+        self.assertEqual(module.find_versions({"intent_version": "0.3"}, "x"), [])
+        self.assertEqual(module.find_versions({"note": "revised 0.7 wording"}, "x"), [])
+
     def test_every_run_prints_version_and_scope(self):
         module = _checker()
         for argv in ([], ["--report"]):