🌙 Night Ember

Night Ember is a portable night-light application for Windows. It applies a warm color temperature directly through each display's gamma ramp and runs quietly in the system tray.

Features

• Adjustable warmth from 6500 K down to 1200 K
• Adjustable brightness from 100% (no dimming) down to 50%, using software dimming
• Manual, sunset-to-sunrise, and custom-hour schedules
• Offline sunrise and sunset estimates with no location permission or network access
• Smooth, configurable transitions
• Multi-monitor support
• Automatic recovery after display changes, unlock, or resume
• Gamma drift detection when another program resets a display
• Tray toggle, settings window, and optional sign-in startup
• Settings and tray-menu styling that follows the Windows light or dark app theme
• Single-instance behavior
• A cleanup watchdog that restores neutral gamma after an unexpected process exit
• Portable settings stored beside the executable

Use

1. Turn off Windows Night Light and other gamma-adjustment tools so they do not compete with Night Ember.
2. Run NightEmber.exe.
3. Adjust the settings and select Save.
4. Use the crescent moon in the system tray to toggle the effect, reopen settings, or exit.

Warmth and brightness changes are previewed immediately and remain active while the settings window is open. Select Save to keep them; select Cancel or close the window to restore the active saved state. Using the tray toggle while the window is open ends the preview and applies a manual override.

Closing the settings window leaves Night Ember running in the tray. Choose Exit from the tray menu to stop the application and restore neutral display gamma.

A manual tray toggle temporarily overrides an active schedule. The override expires when the schedule next changes naturally.

Keyboard access

The settings window starts with focus on Strength. Use Tab and Shift+Tab to move through settings and the Save/Cancel buttons. Only the selected schedule option is a tab stop; use the arrow keys to select another schedule. Disabled custom-time fields are skipped.

Shortcut	Action
Alt+G / Alt+B	Focus Strength / Brightness
Alt+N / Alt+U / Alt+H	Select manual / sunset / custom-hour scheduling
Alt+O / Alt+F	Focus the custom turn-on / turn-off time
Alt+T	Focus transition duration
Alt+A	Toggle start at sign-in
Alt+S / Alt+C	Save / Cancel

In time fields, Left/Right selects the hour, minute, or AM/PM segment and Up/Down adjusts it. In the transition field, Up/Down adjusts the duration by 50 milliseconds. Modified arrow keys retain normal text-editing behavior. While typing a time, Left/Right moves the caret so you can correct the text; committing a valid edit restores segment navigation. Inside these fields, Enter commits the edit and Escape restores it; use Alt+S or Alt+C to save or cancel the whole window. Elsewhere, Enter and Escape activate the default Save and Cancel actions when not consumed by a control.

Invalid times and transition durations stay visible when you press Enter or leave the field. A themed error outline and inline message explain what needs correcting; Save keeps the window open and focuses the first invalid input. Correct the text or press Escape in the field to restore its last accepted value. Transition durations must be whole numbers from 0 to 5000 ms. Custom turn-on/off times must differ; unused custom-time fields do not block saving manual or sunset schedules.

For the tray icon, press Win+B, then use the arrow keys to select Night Ember (open the hidden-icons area if needed). Enter opens settings; Shift+F10 or the context-menu key opens its menu. In the menu, use Up/Down and Enter, or press T to toggle the tint, S for settings, and X to exit. Escape dismisses the menu and returns focus to the notification area.

Portable settings

Settings are saved as NightEmber.config.json beside NightEmber.exe:

Setting	Range	Default	Purpose
Temperature	1200-6500	3400	Color temperature while enabled
Brightness	50-100	100	Brightness percentage (100% = no dimming)
Mode	Manual, Sunset, Custom	Sunset	Scheduling mode
CustomOn	HH:mm	21:00	Custom schedule start
CustomOff	HH:mm	07:00	Custom schedule end
FadeMs	0-5000	300	Transition duration

The executable must be in a folder the current user can write to. A folder under the user profile is recommended; protected folders such as Program Files prevent the portable configuration from being saved.

Configuration values are validated when loaded. Invalid values use safe defaults, and malformed or inaccessible files produce a visible warning. Saves use a temporary file and atomic replacement to reduce the chance of corruption.

Sunset schedule

Sunrise and sunset are calculated locally. Night Ember uses a representative latitude for recognized Windows time zones and derives longitude from the UTC offset. Unknown time-zone IDs use a clearly labeled equatorial estimate rather than guessing a hemisphere. This avoids network access and location permissions, but the estimate can differ from local solar time, especially when an equatorial fallback is used.

Start at sign-in

Select Start automatically when I sign in and save. Night Ember creates a shortcut in the current user's Startup folder with the --hidden option. Clearing the setting removes that shortcut. No elevation or registry change is used.

Build

Requirements:

• Windows
• .NET 10 SDK

dotnet build .\NightEmber.slnx

Publish a self-contained portable executable

dotnet publish .\src\NightEmber\NightEmber.csproj --configuration Release /p:PublishProfile=win-x64 /p:RestoreLockedMode=true

Output is written to:

src\NightEmber\bin\publish\win-x64

The published NightEmber.exe contains the .NET runtime and targets 64-bit Windows. No separate runtime installation or application installer is required.

Display behavior and cleanup

Gamma ramps live in the display driver rather than the application process. Night Ember therefore starts a second, minimal instance of its own executable as a watchdog. Normal shutdown signals the watchdog and restores neutral gamma directly. If the main process is terminated unexpectedly, the watchdog detects that exit and restores every display.

Some display drivers reject strong gamma ramps. Night Ember clamps channel values to the minimum accepted by Windows and retries once after rebuilding stale display handles. Hardware and driver behavior can still limit the visible strength on some systems.

Windows applies gamma ramps globally through a legacy, driver-dependent API that can take up to 200 milliseconds on some hardware. The display may briefly flicker or appear gray while a ramp is applied or restored. Windows can also reset the ramp during display changes, and behavior is undefined with HDR or other color-calibration software. See Microsoft's SetDeviceGammaRamp documentation.

Force-stopping an entire process tree, as some IDE Stop commands do, can terminate both Night Ember and its watchdog before either can restore neutral gamma. Exit through the tray before stopping a debug session. If a tint remains, relaunch Night Ember and choose Exit.

Software dimming reduces the display signal, not the physical backlight. Lowering a monitor's actual backlight is generally preferable when available.