diff --git a/opendbc_repo/opendbc/car/hyundai/g90_startup.py b/opendbc_repo/opendbc/car/hyundai/g90_startup.py
index 97282468ed..41b85d416e 100644
--- a/opendbc_repo/opendbc/car/hyundai/g90_startup.py
+++ b/opendbc_repo/opendbc/car/hyundai/g90_startup.py
@@ -2,10 +2,11 @@
 from copy import deepcopy
 import time
 
-from opendbc.car import Bus
+from opendbc.car import Bus, make_tester_present_msg
 from opendbc.car.hyundai.values import CAR, HyundaiFlags
 from opendbc.car.isotp_parallel_query import IsoTpParallelQuery
 from opendbc.can.parser import MAX_BAD_COUNTER
+from opendbc.car.hyundai.ev9_keeper import EV9Keeper as StartupKeeper
 from opendbc.car.hyundai.ecu_startup import HyundaiECUStartup, Outcome, stock_copy as stock_copy
 
 
@@ -16,8 +17,55 @@ def required(cp):
 
 
 class G90Startup(HyundaiECUStartup):
-  def __init__(self, cp, callbacks):
+  def __init__(self, cp, callbacks, *, clock=time.monotonic, keeper_factory=StartupKeeper):
     super().__init__(cp, callbacks, address=0x7d0, bus=0, label='G90')
+    self.clock = clock
+    self.keeper_factory = keeper_factory
+    self.keeper = None
+    self.handed_off = False
+
+  def prepare(self, *, admission):
+    result = super().prepare(admission=admission)
+    if required(self.cp) and self.outcome is Outcome.SENT_UNCONFIRMED:
+      self.keeper = self.keeper_factory(
+        lambda: self.callbacks[1]([make_tester_present_msg(self.address, self.bus, suppress_response=True)]), clock=self.clock)
+      try:
+        self.keeper.start()
+      except Exception:
+        if self.keeper.thread is not None and self.keeper.thread.ident is None:
+          self.keeper.event.set()
+          self.keeper.thread = None
+        self.close()
+        raise
+    return result
+
+  def check(self):
+    super().check()
+    keeper = getattr(self, 'keeper', None)
+    if keeper is not None and keeper.abort_reason is not None:
+      keeper.stop()
+      self.outcome = Outcome.ABORT_UNCERTAIN
+      raise RuntimeError('G90 startup diagnostic continuity failed')
+
+  def maintain(self, *, configured):
+    self.check()
+
+  def sent(self, frames, *, valid):
+    keeper = getattr(self, 'keeper', None)
+    if keeper is None or self.handed_off or not valid or self.closed or not self.published:
+      return
+    tester = make_tester_present_msg(self.address, self.bus, suppress_response=True)
+    if tester not in frames:
+      return
+    keeper.stop()
+    self.check()
+    self.handed_off = True
+
+  def close(self):
+    keeper = getattr(self, 'keeper', None)
+    if keeper is not None:
+      keeper.stop()
+    super().close()
 
   def _query(self, *args, **kwargs):
     return IsoTpParallelQuery(*args, **kwargs)
diff --git a/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity.py b/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity.py
new file mode 100644
index 0000000000..7d5410bed0
--- /dev/null
+++ b/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity.py
@@ -0,0 +1,153 @@
+from unittest.mock import patch
+
+import pytest
+
+from opendbc.car import gen_empty_fingerprint, make_tester_present_msg
+from opendbc.car.hyundai import g90_startup
+from opendbc.car.hyundai.ecu_startup import Outcome
+from opendbc.car.hyundai.ev9_keeper import EV9Keeper
+from opendbc.car.hyundai.g90_startup import G90Startup
+from opendbc.car.hyundai.interface import CarInterface
+from opendbc.car.hyundai.values import CAR
+
+
+class ManualKeeper(EV9Keeper):
+  def start(self):
+    self.tick()
+
+
+def prepared(*, aol=False, send_error=False, keeper_factory=ManualKeeper, holders=None):
+  now = [8.637416955]
+  sent = []
+  cp = CarInterface.get_params(CAR.GENESIS_G90, gen_empty_fingerprint(), [], alpha_long=True, is_release=False, docs=False)
+  assert cp.openpilotLongitudinalControl
+  if aol:
+    cp.safetyConfigs[0].safetyParam |= 0x400
+    cp.alternativeExperience = 32
+
+  def send(frames):
+    if send_error and make_tester_present_msg(0x7d0, 0, suppress_response=True) in frames:
+      raise OSError('Actual sender rejected tester')
+    sent.extend((now[0], frame) for frame in frames)
+
+  def query(can_send, can_recv, bus, addresses, requests, responses):
+    request = requests[0]
+
+    class Query:
+      def get_data(self, timeout):
+        can_send([(0x7d0, bytes([len(request)]) + request + bytes(7 - len(request)), 0)])
+        return {} if request == b"\x28\x83\x01" else {(0x7d0, None): b''}
+    return Query()
+
+  owner = G90Startup(cp, (list, send))
+  if holders is not None:
+    holders.append(owner)
+  owner.clock = lambda: now[0]
+  owner.keeper_factory = keeper_factory
+  with patch.object(g90_startup, 'IsoTpParallelQuery', side_effect=query), patch.object(g90_startup.time, 'sleep'):
+    owner.prepare(admission=lambda: True)
+  return owner, now, sent
+
+
+@pytest.mark.parametrize('aol', [False, True])
+def test_recorded_disable_to_first_controller_interval_has_continuous_tester(aol):
+  owner, now, sent = prepared(aol=aol)
+  tester = make_tester_present_msg(0x7d0, 0, suppress_response=True)
+  try:
+    assert any(frame == tester for _, frame in sent), 'No tester starts after successful ECU disable'
+    for second in range(1, 7):
+      now[0] = 8.637416955 + second
+      owner.keeper.tick()
+    now[0] = 15.046147807
+    times = [stamp for stamp, frame in sent if frame == tester]
+    assert len(times) == 7
+    assert max(right - left for left, right in zip(times, times[1:], strict=False)) <= 1.000001
+    assert now[0] - times[-1] < 1.0
+    assert owner.outcome is Outcome.SENT_UNCONFIRMED
+    assert all(frame == tester or frame[1][:3] == b"\x02\x10\x03" or frame[1][:4] == b"\x03\x28\x83\x01" for _, frame in sent)
+  finally:
+    owner.published = True
+    owner.close()
+
+
+@pytest.mark.parametrize('kind', ['invalid', 'empty', 'wrong_bus', 'wrong_payload', 'unpublished', 'valid'])
+def test_only_actual_valid_controller_tester_receipt_ends_continuity(kind):
+  owner, now, sent = prepared()
+  try:
+    tester = make_tester_present_msg(0x7d0, 0, suppress_response=True)
+    owner.published = kind != 'unpublished'
+    frames = [tester]
+    if kind == 'empty':
+      frames = []
+    elif kind == 'wrong_bus':
+      frames = [(tester[0], tester[1], 1)]
+    elif kind == 'wrong_payload':
+      frames = [(tester[0], b"\x02\x3e\x00" + bytes(5), tester[2])]
+    owner.sent(frames, valid=kind != 'invalid')
+    assert owner.handed_off == (kind == 'valid')
+    assert owner.keeper.event.is_set() == (kind == 'valid')
+    count = len(sent)
+    now[0] += 1.0
+    owner.keeper.tick()
+    assert len(sent) == count + (kind != 'valid')
+  finally:
+    owner.published = True
+    owner.close()
+
+
+@pytest.mark.parametrize('fault', ['deadline', 'clock_reversal', 'sender'])
+def test_failed_continuity_cannot_be_acknowledged_or_rearmed(fault):
+  owner, now, sent = prepared(send_error=fault == 'sender')
+  owner.published = True
+  try:
+    if fault == 'deadline':
+      now[0] += 60.0
+    elif fault == 'clock_reversal':
+      now[0] -= 1.0
+    owner.keeper.tick()
+    with pytest.raises(RuntimeError, match='diagnostic continuity failed'):
+      owner.maintain(configured=True)
+    assert owner.outcome is Outcome.ABORT_UNCERTAIN
+    assert not owner.handed_off
+    count = len(sent)
+    now[0] += 1.0
+    assert not owner.keeper.tick()
+    assert len(sent) == count
+  finally:
+    owner.close()
+
+
+def test_close_stops_tester_before_unpublished_stock_restoration():
+  owner, now, sent = prepared()
+  requests = []
+
+  def query(*args, **kwargs):
+    assert owner.keeper.event.is_set()
+    request = args[4][0]
+    requests.append(request)
+
+    class Query:
+      def get_data(self, timeout):
+        return {(0x7d0, None): b''}
+    return Query()
+
+  with patch.object(g90_startup, 'IsoTpParallelQuery', side_effect=query):
+    owner.close()
+  assert requests == [b"\x10\x03", b"\x28\x00\x01", b"\x10\x01"]
+  assert owner.closed and owner.restored
+  count = len(sent)
+  now[0] += 1.0
+  assert not owner.keeper.tick()
+  assert len(sent) == count
+
+
+def test_actual_thread_start_failure_restores_stock_and_preserves_original_error():
+  holders = []
+  with patch('threading.Thread.start', side_effect=OSError('thread launch failed')):
+    with pytest.raises(OSError, match='thread launch failed'):
+      prepared(keeper_factory=EV9Keeper, holders=holders)
+  owner = holders[0]
+  assert owner.closed and owner.restored
+  assert not owner.published
+  assert owner.keeper.event.is_set()
+  assert owner.keeper.thread is None
diff --git a/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity_native.py b/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity_native.py
new file mode 100644
index 0000000000..c9ba931dec
--- /dev/null
+++ b/opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity_native.py
@@ -0,0 +1,80 @@
+from types import SimpleNamespace
+from unittest.mock import patch
+
+import pytest
+
+from opendbc.car import Bus, make_tester_present_msg
+from opendbc.car.hyundai.tests.test_g90_continuity import prepared
+from opendbc.car.hyundai.interface import CarInterface
+from opendbc.car.hyundai.values import CAR, DBC
+from opendbc.safety.tests.common import CANPackerSafety
+from opendbc.safety.tests.test_hyundai import checksum
+from opendbc.safety.tests.libsafety import libsafety_py
+from openpilot.selfdrive.car.card import Car
+from openpilot.starpilot.vehicle_startup import VehicleStartupOwner
+
+
+@pytest.mark.parametrize('address,data', [(0x420, '501420c8b84b6a00'), (0x421, '000000ffe37f2db1')])
+@pytest.mark.parametrize('bus', [0, 2])
+def test_recorded_returned_stock_scc_keeps_native_relay_protection(address, data, bus):
+  safety = libsafety_py.libsafety
+  safety.set_alternative_experience(32)
+  assert safety.set_safety_hooks(8, 0xC04) == 0
+  safety.init_tests()
+  safety.set_alternative_experience(32)
+  packer = CANPackerSafety(DBC[CAR.GENESIS_G90][Bus.pt])
+  for name, values, fix in (
+    ('WHL_SPD11', {'WHL_SPD_AliveCounter_LSB': 0, 'WHL_SPD_AliveCounter_MSB': 0}, checksum),
+    ('TCS13', {'AliveCounterTCS': 0}, checksum),
+    ('MDPS12', {}, None),
+    ('CLU11', {'CF_Clu_AliveCnt1': 0}, None),
+    ('EMS16', {'CRUISE_LAMP_S': 0, 'AliveCounter': 0}, checksum),
+    ('BCM_PO_11', {'LDA_BTN': 0}, None),
+  ):
+    assert safety.safety_rx_hook(packer.make_can_msg_safety(name, 0, values, fix_checksum=fix)), name
+  safety.set_timer(1000)
+  safety.safety_tick()
+  assert safety.safety_config_valid()
+  assert not safety.get_relay_malfunction()
+  safety.safety_rx_hook(libsafety_py.make_CANPacket(address, bus, bytes.fromhex(data)))
+  assert bool(safety.get_relay_malfunction()) == (bus == 0)
+  assert not safety.get_controls_allowed()
+  assert safety.aol_get_permission_mask() == 0
+  if bus == 0:
+    tester = make_tester_present_msg(0x7d0, 0, suppress_response=True)
+    assert not safety.safety_tx_hook(libsafety_py.make_CANPacket(tester[0], tester[2], tester[1]))
+
+
+@pytest.mark.parametrize('receipt', ['valid', 'invalid', 'exception'])
+def test_current_card_publisher_transfers_continuity_only_after_success(receipt):
+  owner, now, sent = prepared()
+  owner.published = True
+  delivered = []
+  card = Car.__new__(Car)
+  card.CI = CarInterface(owner.cp)
+  card.CP = owner.cp
+  card.vehicle_startup = VehicleStartupOwner(owner)
+
+  def send(service, packet):
+    assert service == 'sendcan'
+    assert not owner.handed_off
+    if receipt == 'exception':
+      raise OSError('Actual publication failed')
+    delivered.append(packet)
+
+  try:
+    with patch.object(card, 'pm', SimpleNamespace(send=send), create=True), patch.object(card, 'volt_startup_keepalive', return_value=False):
+      frames = [make_tester_present_msg(0x7d0, 0, suppress_response=True)]
+      if receipt == 'exception':
+        with pytest.raises(OSError, match='publication failed'):
+          card.publish_sendcan(frames)
+      else:
+        card.publish_sendcan(frames, valid=receipt == 'valid')
+      assert bool(delivered) == (receipt != 'exception')
+      assert owner.handed_off == (receipt == 'valid')
+      count = len(sent)
+      now[0] += 1.0
+      owner.keeper.tick()
+      assert len(sent) == count + (receipt != 'valid')
+  finally:
+    owner.close()
diff --git a/prebuilt.json b/prebuilt.json
index b4353eccb2..01b7cc9754 100644
--- a/prebuilt.json
+++ b/prebuilt.json
@@ -1 +1 @@
-{"protected_inventory_sha256": "c319992bbe9280bf5904b8e8eb6a87d0f2d16d1a5a21482238b9d7e021ad06ff", "schema_version": 1}
+{"protected_inventory_sha256": "226a3f00d9020c539ae74d575cbc3fb3525405d370335ae84327401130bce1b7", "schema_version": 1}
diff --git a/tools/ci/run_vehicle_tests.py b/tools/ci/run_vehicle_tests.py
index 0e95e6b971..49b35660f9 100755
--- a/tools/ci/run_vehicle_tests.py
+++ b/tools/ci/run_vehicle_tests.py
@@ -33,6 +33,7 @@ DEBUG_SAFETY_CLASS_TARGETS = {
 
 
 RELEASE_TARGETS = (
+  "opendbc_repo/opendbc/car/hyundai/tests/test_g90_continuity.py",
   "opendbc_repo/opendbc/car/hyundai/tests/test_disable_response.py",
   "openpilot/starpilot/aol/tests/test_angle_stop_native_feedback.py",
   "openpilot/starpilot/aol/tests/test_angle_stop_fault_guards.py",