auto_dark_mode.py

#!/usr/bin/env python3

import asyncio
import iterm2

async def main(connection):
  async with iterm2.VariableMonitor(connection, iterm2.VariableScopes.APP, "effectiveTheme", None) as mon:
    while True:
      # Block until theme changes
      theme = await mon.async_get()

      # Themes have space-delimited attributes, one of which will be light or dark.
      parts = theme.split(" ")
      if "dark" in parts:
        preset = await iterm2.ColorPreset.async_get(connection, "Dark Background")
      else:
        preset = await iterm2.ColorPreset.async_get(connection, "Light Background")

      # Update the list of all profiles and iterate over them.
      profiles=await iterm2.PartialProfile.async_query(connection)
      for partial in profiles:
        # Fetch the full profile and then set the color preset in it.
        profile = await partial.async_get_full_profile()
      await profile.async_set_color_preset(preset)

iterm2.run_forever(main)