Cake build watcher task. It includes a Windows 10 toast notification when the build completes.

build.cake

#addin "nuget:?package=Cake.Watch" // Put this at the top to pull in the Cake.Watch package for use.

// Add this task in your build file somewhere.  You can update which target to run, the file pattern to watch, and even the toast notification.
Task("Watch")
    .Does(() => {
        var settings = new WatchSettings {
            Recursive = true,
            Path = "./",
            Pattern = "*.*"
        };
        Watch(settings, (changed) => {
            RunTarget("Default");
            StartPowershellFile(@"./build-notification.ps1", args => {
                args.Append("Message", @"""👍 Success!""");
            });
        });
    })
    .ReportError(ex => {
        StartPowershellFile(@"./build-notification.ps1", args => {
            args.Append("Message", @"""FOH Build Error: " + ex + @"""");
        });
    });

build-notification.ps1

#This powershell script can be modified to change how the native Windows toast notification looks.

[CmdletBinding()]
Param(
    [string]$Message = "No message set!"
)

$ErrorActionPreference = "Stop"

$notificationTitle = "Build Status: " + $Message + "`r`n" + "Completed: " + [DateTime]::Now.ToShortTimeString()

[Windows.UI.Notifications.ToastNotificationManager, Windows.UI.Notifications, ContentType = WindowsRuntime] > $null
$template = [Windows.UI.Notifications.ToastNotificationManager]::GetTemplateContent([Windows.UI.Notifications.ToastTemplateType]::ToastText01)

#Convert to .NET type for XML manipuration
$toastXml = [xml] $template.GetXml()
$toastXml.GetElementsByTagName("text").AppendChild($toastXml.CreateTextNode($notificationTitle)) > $null

#Convert back to WinRT type
$xml = New-Object Windows.Data.Xml.Dom.XmlDocument
$xml.LoadXml($toastXml.OuterXml)

$toast = [Windows.UI.Notifications.ToastNotification]::new($xml)
$toast.Tag = "PowerShell"
$toast.Group = "PowerShell"
$toast.ExpirationTime = [DateTimeOffset]::Now.AddMinutes(5)
#$toast.SuppressPopup = $true

$notifier = [Windows.UI.Notifications.ToastNotificationManager]::CreateToastNotifier("PowerShell")
$notifier.Show($toast);