diff --git a/openpilot/starpilot/system/android_auto/current_car_ui.py b/openpilot/starpilot/system/android_auto/current_car_ui.py
index ff66a2ee7a..cf007109be 100644
--- a/openpilot/starpilot/system/android_auto/current_car_ui.py
+++ b/openpilot/starpilot/system/android_auto/current_car_ui.py
@@ -189,11 +189,14 @@ def run(frames_path: str, touch_path: str | None = None, control_path: str | Non
     gui_app._scale = 1.0
     gui_app._render_texture = None
     from openpilot.starpilot.system.android_auto.identity import certificate_days_left
-    from openpilot.starpilot.system.android_auto.projection_layout_runtime import load_projection_layout
+    from openpilot.starpilot.system.android_auto.projection_layout_runtime import ProjectionLayoutWatcher
     viewport = (geometry.logical_width, geometry.logical_height)
-    layout = ProjectionOnroad(viewport=viewport, customization=load_projection_layout(viewport),
-                              certificate_days=certificate_days_left())
+    watcher = ProjectionLayoutWatcher(viewport)
+    layout = ProjectionOnroad(viewport=viewport, customization=watcher.load(),
+                              certificate_days=certificate_days_left(), layout_watcher=watcher)
     resources.callback(layout.close)
+    watcher.start()
+    resources.callback(watcher.close)
     touch = TouchReceiver(touch_path or DEFAULT_TOUCH_SOCKET)
     resources.callback(touch.close)
     control = ProjectionControlSender(control_path or DEFAULT_CONTROL_SOCKET)
diff --git a/openpilot/starpilot/system/android_auto/projection_layout_runtime.py b/openpilot/starpilot/system/android_auto/projection_layout_runtime.py
index 2004c4c7a9..a44d15b8ac 100644
--- a/openpilot/starpilot/system/android_auto/projection_layout_runtime.py
+++ b/openpilot/starpilot/system/android_auto/projection_layout_runtime.py
@@ -1,4 +1,11 @@
-"""Read a saved projection layout once per connection, never in the frame loop."""
+"""Read the saved projection layout at connect, then again only after Galaxy saves it.
+
+Never read on the drawing thread: a background thread stats the file once a second,
+loads it only when it changed, and the renderer just takes the finished layout.
+"""
+import os
+import threading
+
 from openpilot.starpilot.saved_source import read_saved
 from openpilot.starpilot.system.android_auto.projection_layout import (
   DOCUMENT_KEY, MAX_BYTES, ProjectionLayoutSource, default_layout_for_viewport, decode_layout_for_viewport,
@@ -13,3 +20,74 @@ def load_projection_layout(viewport, source=None):
     return decode_layout_for_viewport(raw, viewport)
   except (ValueError, TypeError, UnicodeError, OverflowError, RecursionError):
     return default_layout_for_viewport(viewport)
+
+
+CHECK_SECONDS = 1.0
+
+
+class ProjectionLayoutWatcher:
+  """Loads the layout and, on its own thread, picks up each layout Galaxy saves."""
+
+  def __init__(self, viewport, source=None):
+    self.viewport = viewport
+    self.source = source or ProjectionLayoutSource()
+    self._stamp = None
+    self._lock = threading.Lock()
+    self._pending = None
+    self._stop = threading.Event()
+    self._thread = None
+
+  def start(self):
+    self._thread = threading.Thread(target=self._run, name='aa-layout-watch', daemon=True)
+    self._thread.start()
+
+  def close(self):
+    self._stop.set()
+    if self._thread is not None:
+      self._thread.join(timeout=2)
+
+  def _run(self):
+    while not self._stop.wait(CHECK_SECONDS):
+      try:
+        layout = self.poll()
+      except Exception:
+        continue  # a bad read must never stop live layout updates
+      if layout is not None:
+        with self._lock:
+          self._pending = layout
+
+  def take(self):
+    """For the drawing thread: the newest saved layout not yet applied, or None. No file access."""
+    with self._lock:
+      layout, self._pending = self._pending, None
+    return layout
+
+  def _current_stamp(self):
+    try:
+      info = os.stat(self.source.get_param_path(DOCUMENT_KEY), follow_symlinks=False)
+    except FileNotFoundError:
+      return None
+    return info.st_dev, info.st_ino, info.st_size, info.st_mtime_ns
+
+  def load(self):
+    self._stamp = self._current_stamp()
+    return load_projection_layout(self.viewport, self.source)
+
+  def poll(self):
+    """Background thread only: the new layout after a save, or None. An unreadable file is retried."""
+    try:
+      stamp = self._current_stamp()
+    except OSError:
+      return None
+    if stamp == self._stamp:
+      return None
+    raw, readable = read_saved(self.source, DOCUMENT_KEY, MAX_BYTES)
+    if not readable:
+      return None
+    self._stamp = stamp
+    if raw is None:
+      return default_layout_for_viewport(self.viewport)
+    try:
+      return decode_layout_for_viewport(raw, self.viewport)
+    except (ValueError, TypeError, UnicodeError, OverflowError, RecursionError):
+      return default_layout_for_viewport(self.viewport)
diff --git a/openpilot/starpilot/system/android_auto/projection_onroad.py b/openpilot/starpilot/system/android_auto/projection_onroad.py
index da9c5922a6..a91682a385 100644
--- a/openpilot/starpilot/system/android_auto/projection_onroad.py
+++ b/openpilot/starpilot/system/android_auto/projection_onroad.py
@@ -93,7 +93,8 @@ def native_dependencies():
 class ProjectionOnroad:
   """Separate renderer with projected actions; native UIState stays read-only."""
 
-  def __init__(self, *, dependencies=None, viewport=None, customization=None, certificate_days=None, native_focus=None):
+  def __init__(self, *, dependencies=None, viewport=None, customization=None, certificate_days=None, native_focus=None,
+               layout_watcher=None):
     viewport = FALLBACK_VIEWPORT if viewport is None else viewport
     self.width, self.height = viewport
     self.customization = customization
@@ -101,6 +102,7 @@ class ProjectionOnroad:
     self._certificate_notice_until_ns: int | None = None
     self._base_customization = None
     self._projection_customization = None
+    self.layout_watcher = layout_watcher
     self.native_focus = native_focus or (lambda: None)
     self.bookmark = lambda: False
     self.camera_stream = None  # the camera stream the last frame drew, or None
@@ -132,11 +134,7 @@ class ProjectionOnroad:
         self.onroad.pip_layer = self._pip_layer
       self.map = None
       self.map_feed = None
-      if self._map_placement() is not None and getattr(native, 'map_overlay', None) is not None:
-        self.map = native.map_overlay(fonts=self.fonts)
-        self._resources.callback(self.map.close)
-        self.map_feed = native.map_feed()
-        self.onroad.map_layer = self._map_layer
+      self._ensure_map()
       self.adapter = native.adapter(native.ui_state)
       self._state = None
       self.favorites = None
@@ -206,6 +204,28 @@ class ProjectionOnroad:
     finally:
       self.native.rl.rl_pop_matrix()
 
+  def _ensure_map(self):
+    """Build the map overlay the first time a layout turns it on; it stays for the connection."""
+    native = self.native
+    if self.map is None and self._map_placement() is not None and getattr(native, 'map_overlay', None) is not None:
+      self.map = native.map_overlay(fonts=self.fonts)
+      self._resources.callback(self.map.close)
+      self.map_feed = native.map_feed()
+      self.onroad.map_layer = self._map_layer
+
+  def apply_layout(self, customization):
+    """Switch to a newly saved Android Auto layout without reconnecting."""
+    self.customization = customization
+    self._base_customization = self._projection_customization = None
+    self.camera.large_ui_gamma_trial = bool((customization or {}).get('largeUiGammaTrial', False))
+    self._ensure_map()
+
+  def _check_layout(self):
+    # The watcher's own thread does all file work; this only takes a finished layout.
+    changed = self.layout_watcher.take() if self.layout_watcher is not None else None
+    if changed is not None:
+      self.apply_layout(changed)
+
   def _map_placement(self):
     """The enabled map overlay's placement from this connection's layout, or None."""
     if self.customization is None:
@@ -215,6 +235,7 @@ class ProjectionOnroad:
 
   def prepare(self):
     """Before the frame's render target is bound: offscreen map work happens here."""
+    self._check_layout()
     if self.favorites is not None:
       self.favorites.refresh()
       self.onroad.navigation_favorites.document = self.favorites.document
diff --git a/openpilot/starpilot/system/android_auto/tests/test_projection_layout_runtime.py b/openpilot/starpilot/system/android_auto/tests/test_projection_layout_runtime.py
index 1b8f4b029f..f79df60918 100644
--- a/openpilot/starpilot/system/android_auto/tests/test_projection_layout_runtime.py
+++ b/openpilot/starpilot/system/android_auto/tests/test_projection_layout_runtime.py
@@ -1,17 +1,19 @@
-"""Connection-scoped saved layout and real frozen-state replacement regressions."""
+"""Saved projection layout loading, live reload after a Galaxy save, and frozen-state replacement regressions."""
 import copy
 import fcntl
 import json
 import os
 from pathlib import Path
 import tempfile
+import threading
+import time
 from types import SimpleNamespace
 import unittest
 from unittest.mock import patch
 
 from openpilot.starpilot.system.android_auto.display_profile import record_screen, read_screen
 from openpilot.starpilot.system.android_auto.projection_layout import ProjectionLayoutSource, default_layout_for_viewport
-from openpilot.starpilot.system.android_auto.projection_layout_runtime import load_projection_layout
+from openpilot.starpilot.system.android_auto.projection_layout_runtime import ProjectionLayoutWatcher, load_projection_layout
 from openpilot.starpilot.system.android_auto.tests import test_projection_onroad_boundary as boundary
 projection = boundary.projection
 from openpilot.starpilot.ui.onroad_customization import default_document
@@ -88,6 +90,99 @@ class TestProjectionLayoutRuntime(unittest.TestCase):
       self.assertEqual(connection, original)
       self.assertEqual(load_projection_layout((2880, 1080), source), changed)
 
+  def test_watcher_reports_each_save_once_and_skips_reads_otherwise(self):
+    with tempfile.TemporaryDirectory() as directory:
+      source = ProjectionLayoutSource(Path(directory) / 'layouts/document.json')
+      source.prepare()
+      viewport = (2880, 1080)
+      original = default_layout_for_viewport(viewport)
+      source.path.write_text(json.dumps(original))
+      watcher = ProjectionLayoutWatcher(viewport, source)
+      self.assertEqual(watcher.load(), original)
+      with patch('openpilot.starpilot.system.android_auto.projection_layout_runtime.read_saved',
+                 side_effect=AssertionError('unchanged file reread')):
+        self.assertIsNone(watcher.poll())
+      changed = copy.deepcopy(original)
+      changed['widgets']['current_speed']['x'] += 60
+      temporary = source.path.with_suffix('.tmp')
+      temporary.write_text(json.dumps(changed))
+      os.replace(temporary, source.path)  # Galaxy saves by atomic replace
+      self.assertEqual(watcher.poll(), changed)
+      self.assertIsNone(watcher.poll())
+      source.path.write_bytes(b'x' * 16385)  # unreadable: keep the current layout and retry
+      self.assertIsNone(watcher.poll())
+      self.assertIsNone(watcher.poll())
+      source.path.write_text(json.dumps(original))
+      self.assertEqual(watcher.poll(), original)
+      source.path.unlink()
+      self.assertEqual(watcher.poll(), default_layout_for_viewport(viewport))
+      self.assertIsNone(watcher.poll())
+
+  def test_background_thread_hands_over_saved_layouts_without_drawing_thread_reads(self):
+    with tempfile.TemporaryDirectory() as directory:
+      source = ProjectionLayoutSource(Path(directory) / 'layouts/document.json')
+      source.prepare()
+      viewport = (2880, 1080)
+      original = default_layout_for_viewport(viewport)
+      source.path.write_text(json.dumps(original))
+      watcher = ProjectionLayoutWatcher(viewport, source)
+      watcher.load()
+      polled = threading.Event()
+      poll = watcher.poll
+      def observed_poll():
+        try:
+          return poll()
+        finally:
+          polled.set()
+      watcher.poll = observed_poll
+      with patch('openpilot.starpilot.system.android_auto.projection_layout_runtime.CHECK_SECONDS', 0.01):
+        watcher.start()
+        try:
+          changed = copy.deepcopy(original)
+          changed['widgets']['current_speed']['x'] += 60
+          temporary = source.path.with_suffix('.tmp')
+          temporary.write_text(json.dumps(changed))
+          os.replace(temporary, source.path)
+          deadline = time.monotonic() + 2
+          taken = None
+          while taken is None and time.monotonic() < deadline:
+            taken = watcher.take()
+            polled.wait(0.05)
+          self.assertEqual(taken, changed)
+          self.assertIsNone(watcher.take(), 'each save is handed over once')
+        finally:
+          watcher.close()
+      self.assertFalse(watcher._thread.is_alive())
+
+  def test_take_never_touches_files(self):
+    watcher = ProjectionLayoutWatcher((2880, 1080), ProjectionLayoutSource('/nonexistent/document.json'))
+    with patch('openpilot.starpilot.system.android_auto.projection_layout_runtime.os.stat', side_effect=AssertionError('stat')), \
+         patch('openpilot.starpilot.system.android_auto.projection_layout_runtime.read_saved', side_effect=AssertionError('read')):
+      self.assertIsNone(watcher.take())
+
+  def test_renderer_applies_a_handed_over_layout(self):
+    from openpilot.starpilot.system.android_auto.tests.test_projection_map import FakeFeed, FakeMap
+    native, _ = boundary.TestProjectionOnroad().dependencies()
+    native.map_overlay, native.map_feed = FakeMap, FakeFeed
+    layout = default_layout_for_viewport((2880, 1080))
+    saved = copy.deepcopy(layout)
+    saved['widgets']['nav_map'].update(enabled=True, x=100, y=200, width=640, height=480, opacity=45)
+    saved['largeUiGammaTrial'] = True
+    pending = [None, saved]
+    view = projection.ProjectionOnroad(dependencies=native, viewport=(2880, 1080), customization=layout,
+                                       layout_watcher=SimpleNamespace(take=lambda: pending.pop(0) if pending else None))
+    self.addCleanup(view.close)
+    self.assertIsNone(view.map)
+    view._projection_customization = view._base_customization = object()
+    view.prepare()
+    self.assertIs(view.customization, layout)
+    view.prepare()
+    self.assertIs(view.customization, saved)
+    self.assertIsNone(view._projection_customization, 'the cached projected layout is rebuilt')
+    self.assertIs(view.camera.large_ui_gamma_trial, True)
+    self.assertIsInstance(view.map, FakeMap, 'turning the map on in Galaxy builds it without reconnecting')
+    self.assertEqual(view.onroad.map_layer, view._map_layer)
+
   def test_screen_writer_lock_contention_preserves_previous_receipt(self):
     with tempfile.TemporaryDirectory() as directory:
       path = Path(directory) / 'screen.json'