diff --git a/roadscore/prototype/launch_health.py b/roadscore/prototype/launch_health.py
new file mode 100644
index 0000000000..0dca264e1c
--- /dev/null
+++ b/roadscore/prototype/launch_health.py
@@ -0,0 +1,40 @@
+"""Keep preparation status truthful when supervised processes fail."""
+import json
+import time
+
+
+class LaunchFailure(RuntimeError):
+  def __init__(self, component, code, connection=False):
+    self.component, self.code, self.connection = component, code, connection
+    super().__init__(f'{component} exited with status {code}; see {component}.log')
+
+
+def check_children(children, *, remote, include_receiver=False, allow_clean_receiver=False):
+  names = ['semantic_planner', 'semantic_tunnel'] + (['receiver'] if include_receiver else [])
+  for name in names:
+    child = children.get(name)
+    if child is None:
+      continue
+    code = child.poll()
+    if code is not None and not (name == 'receiver' and code == 0 and allow_clean_receiver):
+      raise LaunchFailure(name, code, name == 'semantic_tunnel' or (name == 'receiver' and remote and code == 255))
+
+
+def describe_failure(error):
+  connection = isinstance(error, LaunchFailure) and error.connection
+  return {'readiness': 'DEGRADED', 'job_inflight': False,
+          'failure_kind': 'connection_lost' if connection else 'launch_failed',
+          'failure_component': getattr(error, 'component', 'launcher'),
+          'failure_exit_code': getattr(error, 'code', None),
+          'failure_cause': str(error)[-2000:], 'failure_time': time.time()}
+
+
+def write_failure(path, failure):
+  try:
+    state = json.loads(path.read_text())
+  except (OSError, ValueError):
+    state = {}
+  state.update(failure)
+  temporary = path.with_name(path.name + '.failure.tmp')
+  temporary.write_text(json.dumps(state))
+  temporary.replace(path)
diff --git a/roadscore/prototype/normal_onroad.py b/roadscore/prototype/normal_onroad.py
index 44c0c8f6d1..ee7ae7ce47 100644
--- a/roadscore/prototype/normal_onroad.py
+++ b/roadscore/prototype/normal_onroad.py
@@ -9,6 +9,7 @@ from clock_sync import measure
 from receiver_environment import assignments as receiver_assignments,resolve_compute
 from presentation_policy import select_launch
 from hook_launch import enabled as hook_enabled, start_planner
+from launch_health import check_children, describe_failure, write_failure
 from session_seed import select_session, seed_argument, seed_environment, remote_assignments
 R=Path(__file__).resolve().parents[1]
 native=Path('/TICI').exists()
@@ -74,10 +75,10 @@ if a.replay:
  from score_archive import latest
  try:score=latest(a.routeid)
  except FileNotFoundError:raise SystemExit('No stored RoadScore exists for this route. Generate a score first.')
-display=None;children=[];logs=[];launch_started=time.monotonic()
+display=None;children=[];named_children={};failure=None;logs=[];launch_started=time.monotonic()
 print(('Preparing stored score replay; no generation. ' if a.replay else ('Preparing ACE replay; first preparation may take 10–15 minutes. ' if a.composer=='ace' else 'Preparing RoadScore replay; cold preparation can take 2–3 minutes. '))+('Host speaker enabled.' if a.audible else 'Muted host capture.'),flush=True)
 def launch(cmd,name,**kw):
- f=(out/(name+'.log')).open('wb');logs.append(f);c=subprocess.Popen(cmd,stdout=f,stderr=f,env=env,cwd=rt,start_new_session=True,**kw);children.append(c);return c
+ f=(out/(name+'.log')).open('wb');logs.append(f);c=subprocess.Popen(cmd,stdout=f,stderr=f,env=env,cwd=rt,start_new_session=True,**kw);children.append(c);named_children[name]=c;return c
 try:
  if not native and Path('/usr/bin/caffeinate').exists():launch(['/usr/bin/caffeinate','-i'],'wake_assertion')
  if composition_policy=='hook-v2' and not a.transport_only:start_planner(launch,env,out,R,a.bench,native=native)
@@ -104,6 +105,7 @@ try:
   receiver=launch(receiver_command,'receiver',stdin=subprocess.PIPE)
   deadline=time.monotonic()+(1560 if a.composer=='ace' else 420)
   while b'BRIDGE_READY' not in (out/'receiver.log').read_bytes():
+   check_children(named_children,remote=not native,include_receiver=True)
    if receiver.poll() is not None or time.monotonic()>deadline:raise RuntimeError('Bench receiver failed: '+(out/'receiver.log').read_text())
    time.sleep(.2)
   audio_host=None
@@ -112,12 +114,14 @@ try:
    audio_host=launch([str(R/'.analysis-venv/bin/python'),str(R/'prototype/host_audio.py'),'--bench',a.bench,'--out',str(out),'--clock',str(out/'clock_sync.json')]+(['--audible'] if a.audible else [])+(['--device',a.audio_device] if a.audio_device else []),'host_audio')
    deadline=time.monotonic()+20
    while not (out/'host_audio_ready').exists():
+    check_children(named_children,remote=not native,include_receiver=True)
     if audio_host.poll() is not None or time.monotonic()>deadline:raise RuntimeError('Host audio failed; see host_audio.log')
     time.sleep(.1)
   f=(out/'sender.log').open('wb');logs.append(f)
   sender=subprocess.Popen([str(py),str(R/'prototype/replay_bridge.py'),'send','--seconds',str(a.duration)],stdout=receiver.stdin,stderr=f,env=env,cwd=rt,start_new_session=True);children.append(sender);receiver.stdin.close()
   deadline=time.monotonic()+15
   while b'BRIDGE_SUBSCRIBED' not in (out/'sender.log').read_bytes():
+   check_children(named_children,remote=not native,include_receiver=True)
    if sender.poll() is not None or time.monotonic()>deadline:raise RuntimeError('Replay subscriber failed')
    time.sleep(.1)
  if a.replay:(out/'roadscore_status.json').write_text(json.dumps({'readiness':'READY','style':'Stored score','section':'ARCHIVED SCORE','compute':'none'}))
@@ -126,6 +130,7 @@ try:
  end_watch=ReplayEnd();end_reason='requested duration'
  state_path=Path('/tmp/replay_state_'+env.get('OPENPILOT_PREFIX','default')+'.json')
  while sender.poll() is None:
+  check_children(named_children,remote=not native,include_receiver=True,allow_clean_receiver=True)
   if receiver is not None and receiver.poll() not in (None,0):raise RuntimeError('RoadScore receiver failed; see receiver.log')
   if native and not a.replay:
    try:(out/'roadscore_status.json').write_text((R/'results/current/status.json').read_text())
@@ -163,12 +168,21 @@ try:
    if a.composer=='ace':subprocess.run(['scp',a.bench+':/data/roadscore/generated/ace_link.jsonl',str(out/'ace_link.jsonl')],stdout=subprocess.DEVNULL,stderr=subprocess.DEVNULL)
    from score_archive import archive
    archived=archive(a.routeid,out,a.start);print('Score archived:',archived,flush=True)
+except Exception as error:
+ try:
+  check_children(named_children,remote=not native,include_receiver=True,allow_clean_receiver=True)
+ except Exception as child_error:
+  error=child_error
+ failure=describe_failure(error)
+ write_failure(out/'roadscore_status.json',failure)
+ raise
 finally:
  for c in reversed(children):
   if c.poll() is None:
    os.killpg(c.pid,signal.SIGTERM)
    try:c.wait(timeout=10)
    except subprocess.TimeoutExpired:os.killpg(c.pid,signal.SIGKILL);c.wait()
+ if failure:write_failure(out/'roadscore_status.json',failure)
  if display:display.close()
  for f in logs:f.close()
  print('Replay processes stopped. Worker ownership remains with its supervisor.',flush=True)
diff --git a/roadscore/prototype/overlay_view.py b/roadscore/prototype/overlay_view.py
index b4e9a64596..f2a6ec25c6 100644
--- a/roadscore/prototype/overlay_view.py
+++ b/roadscore/prototype/overlay_view.py
@@ -61,7 +61,11 @@ def overlay_view(state):
     section = 'INTENT: ' + section
   elapsed = seconds(state.get('generation_elapsed_seconds'))
   note = ''
-  if state.get('holding_accepted_music'):
+  if state.get('failure_kind') in ('connection_lost', 'transport_unreachable'):
+    note = 'Connection lost'
+  elif state.get('failure_kind') == 'launch_failed':
+    note = 'Preparation stopped'
+  elif state.get('holding_accepted_music'):
     note = 'Holding accepted music'
   elif state.get('worker_failed'):
     note = 'Composer unavailable'
@@ -138,7 +142,9 @@ def draw_panel(rl, font, state, screen_width, screen_height, emphasis_font=None,
   subtitle = identity + (' / ' + section if section else '')
   title = 'RoadScore'
   if view['activity'] == 'DEGRADED':
-    subtitle = ('Music on hold' if state.get('holding_accepted_music') else
+    subtitle = ('Connection lost' if state.get('failure_kind') in ('connection_lost', 'transport_unreachable') else
+                'Preparation stopped' if state.get('failure_kind') == 'launch_failed' else
+                'Music on hold' if state.get('holding_accepted_music') else
                 'Composer unavailable' if state.get('worker_failed') else 'Reserve in use')
   elif view['event']:
     subtitle = view['event'].split(' / ')[0]
diff --git a/roadscore/tests/test_launch_health.py b/roadscore/tests/test_launch_health.py
new file mode 100644
index 0000000000..3cd87347e0
--- /dev/null
+++ b/roadscore/tests/test_launch_health.py
@@ -0,0 +1,56 @@
+import json
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import Mock
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / 'prototype'))
+from launch_health import LaunchFailure, check_children, describe_failure, write_failure
+from overlay_view import overlay_view
+
+
+class LaunchHealthTests(unittest.TestCase):
+  def test_dead_tunnel_detected_while_receiver_still_compiles(self):
+    children = {'receiver': Mock(poll=lambda: None), 'semantic_tunnel': Mock(poll=lambda: 255)}
+    with self.assertRaises(LaunchFailure) as caught:
+      check_children(children, remote=True, include_receiver=True)
+    status = describe_failure(caught.exception)
+    self.assertEqual(status['failure_kind'], 'connection_lost')
+    self.assertEqual(status['failure_component'], 'semantic_tunnel')
+    self.assertEqual(overlay_view(status)['note'], 'Connection lost')
+
+  def test_receiver_ssh_exit_distinct_from_remote_application_error(self):
+    for code, kind in [(255, 'connection_lost'), (1, 'launch_failed'), (0, 'launch_failed')]:
+      with self.subTest(code=code):
+        with self.assertRaises(LaunchFailure) as caught:
+          check_children({'receiver': Mock(poll=lambda: code)}, remote=True, include_receiver=True)
+        self.assertEqual(describe_failure(caught.exception)['failure_kind'], kind)
+    check_children({'receiver': Mock(poll=lambda: 0)}, remote=True, include_receiver=True, allow_clean_receiver=True)
+
+  def test_planner_failure_and_timeout_are_not_gpu_diagnoses(self):
+    for error in (LaunchFailure('semantic_planner', -9), TimeoutError('Receiver readiness deadline elapsed')):
+      status = describe_failure(error)
+      self.assertEqual(status['readiness'], 'DEGRADED')
+      self.assertNotIn('worker_failed', status)
+      self.assertIn('failure_cause', status)
+
+  def test_persisted_failure_replaces_preparing_without_losing_profile(self):
+    with tempfile.TemporaryDirectory() as root:
+      path = Path(root)/'roadscore_status.json'
+      path.write_text(json.dumps({'readiness': 'PREPARING', 'profile': 'prism', 'job_inflight': True}))
+      failure = describe_failure(LaunchFailure('receiver', 255, True))
+      write_failure(path, failure)
+      state = json.loads(path.read_text())
+      self.assertEqual(state['profile'], 'prism')
+      self.assertEqual(state['readiness'], 'DEGRADED')
+      self.assertFalse(state['job_inflight'])
+      self.assertNotIn('worker_failed', state)
+      self.assertEqual(state['failure_exit_code'], 255)
+      self.assertEqual(overlay_view(state)['note'], 'Connection lost')
+      path.write_text('{}')
+      write_failure(path, failure)
+      self.assertEqual(json.loads(path.read_text())['readiness'], 'DEGRADED')
+
+
+if __name__ == '__main__':
+  unittest.main()