5-state display mode: auto day/night, nightrider, screen off

New ScreenDisplayMode param (fixes ScreenDisaplayMode typo):
  0=auto-normal, 1=auto-nightrider, 2=normal, 3=screen-off, 4=nightrider

Nightrider mode: black background (no camera feed), path/lane lines
drawn as 2px outlines only. Auto mode uses NOAA solar position calc
in gpsd to switch between day/night based on GPS lat/lon and UTC time.
First calc on GPS fix, then every 30 seconds.

Button cycle onroad: 0→4, 1→2, 2→3, 3→4, 4→2 (never back to auto).
Offroad: any→3, 3→0. bench_cmd debugbutton simulates the button press.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

system/clearpilot/gpsd.py

@@ -14,11 +14,44 @@ import datetime
 from cereal import log
 import cereal.messaging as messaging
 from openpilot.common.gpio import gpio_init, gpio_set
+from openpilot.common.params import Params
 from openpilot.common.swaglog import cloudlog
 from openpilot.common.time import system_time_valid
 from openpilot.system.hardware.tici.pins import GPIO
 
 
+def is_daylight(lat: float, lon: float, utc_dt: datetime.datetime) -> bool:
+  """Return True if it's between sunrise and sunset at the given location.
+  Uses NOAA simplified solar position equations. Pure math, no external libs."""
+  n = utc_dt.timetuple().tm_yday
+  gamma = 2 * math.pi / 365 * (n - 1 + (utc_dt.hour - 12) / 24)
+  # Equation of time (minutes)
+  eqtime = 229.18 * (0.000075 + 0.001868 * math.cos(gamma)
+           - 0.032077 * math.sin(gamma)
+           - 0.014615 * math.cos(2 * gamma)
+           - 0.040849 * math.sin(2 * gamma))
+  # Solar declination (radians)
+  decl = (0.006918 - 0.399912 * math.cos(gamma)
+          + 0.070257 * math.sin(gamma)
+          - 0.006758 * math.cos(2 * gamma)
+          + 0.000907 * math.sin(2 * gamma)
+          - 0.002697 * math.cos(3 * gamma)
+          + 0.00148 * math.sin(3 * gamma))
+  lat_rad = math.radians(lat)
+  zenith = math.radians(90.833)
+  cos_ha = (math.cos(zenith) / (math.cos(lat_rad) * math.cos(decl))
+            - math.tan(lat_rad) * math.tan(decl))
+  if cos_ha < -1:
+    return True   # midnight sun
+  if cos_ha > 1:
+    return False  # polar night
+  ha = math.degrees(math.acos(cos_ha))
+  sunrise_min = 720 - 4 * (lon + ha) - eqtime
+  sunset_min = 720 - 4 * (lon - ha) - eqtime
+  now_min = utc_dt.hour * 60 + utc_dt.minute + utc_dt.second / 60
+  return sunrise_min <= now_min <= sunset_min
+
+
 def at_cmd(cmd: str) -> str:
   try:
     result = subprocess.check_output(
@@ -123,6 +156,9 @@ def main():
 
   pm = messaging.PubMaster(["gpsLocation"])
   clock_set = system_time_valid()
+  params_memory = Params("/dev/shm/params")
+  last_daylight_check = 0.0
+  daylight_computed = False
   print("gpsd: entering main loop", file=sys.stderr, flush=True)
 
   while True:
@@ -161,6 +197,30 @@ def main():
       gps.speedAccuracy = 1.0
       pm.send("gpsLocation", msg)
 
+      # CLEARPILOT: daylight calculation for auto display mode switching
+      if clock_set:
+        now_mono = time.monotonic()
+        interval = 1.0 if not daylight_computed else 30.0
+        if (now_mono - last_daylight_check) >= interval:
+          last_daylight_check = now_mono
+          utc_now = datetime.datetime.utcfromtimestamp(fix["timestamp_ms"] / 1000)
+          daylight = is_daylight(fix["latitude"], fix["longitude"], utc_now)
+          params_memory.put_bool("IsDaylight", daylight)
+
+          if not daylight_computed:
+            daylight_computed = True
+            cloudlog.warning("gpsd: initial daylight calc: %s", "day" if daylight else "night")
+            print(f"gpsd: initial daylight calc: {'day' if daylight else 'night'}", file=sys.stderr, flush=True)
+
+          # Auto-transition: only touch states 0 and 1
+          current_mode = params_memory.get_int("ScreenDisplayMode")
+          if current_mode == 0 and not daylight:
+            params_memory.put_int("ScreenDisplayMode", 1)
+            cloudlog.warning("gpsd: auto-switch to nightrider (sunset)")
+          elif current_mode == 1 and daylight:
+            params_memory.put_int("ScreenDisplayMode", 0)
+            cloudlog.warning("gpsd: auto-switch to normal (sunrise)")
+
     time.sleep(1.0)  # 1 Hz polling