fix: canonicalize numeric legacy timestamps

hub_core/runtime/migration.py

@@ -60,6 +60,8 @@ def _datetime(value: Any, default: datetime | None = None) -> datetime:
         return value if value.tzinfo else value.replace(tzinfo=timezone.utc)
     if isinstance(value, str) and value:
         return datetime.fromisoformat(value.replace("Z", "+00:00"))
+    if isinstance(value, (int, float)) and not isinstance(value, bool):
+        return datetime.fromtimestamp(value, tz=timezone.utc)
     return default or _now()
 
 

tests/test_migration.py

@@ -52,6 +52,22 @@ def test_validation_rejects_secret_material_and_digest_drift():
     assert any("bundleSha256" in error for error in report["errors"])
 
 
+def test_numeric_legacy_timestamps_have_deterministic_content_hashes():
+    numeric = bundle()
+    numeric["records"]["interactionEvents"][0]["metadata"]["recordedAt"] = 1
+    numeric["bundleSha256"] = bundle_digest(numeric)
+    textual = bundle()
+    textual["records"]["interactionEvents"][0]["metadata"]["recordedAt"] = (
+        "1970-01-01T00:00:01Z"
+    )
+    textual["bundleSha256"] = bundle_digest(textual)
+
+    assert (
+        validate_bundle(numeric)["contentHashes"]["interactionEvents"]
+        == validate_bundle(textual)["contentHashes"]["interactionEvents"]
+    )
+
+
 def test_import_is_idempotent_and_exports_all_seven_collections(tmp_path):
     async def run():
         store = await make_store(tmp_path)