Two keyboard maestro macros to emulate continuous undo of closed tabs / windows in Safari (initial attempt)

Record closing tab.kmmacros

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
	<dict>
		<key>Activate</key>
		<string>Normal</string>
		<key>IsActive</key>
		<true/>
		<key>Macros</key>
		<array>
			<dict>
				<key>Actions</key>
				<array>
					<dict>
						<key>DisplayKind</key>
						<string>Variable</string>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>MacroActionType</key>
						<string>ExecuteJavaScript</string>
						<key>Path</key>
						<string></string>
						<key>Text</key>
						<string>window.location.href;</string>
						<key>TimeOutAbortsMacro</key>
						<true/>
						<key>TrimResults</key>
						<true/>
						<key>TrimResultsNew</key>
						<true/>
						<key>UseText</key>
						<true/>
						<key>Variable</key>
						<string>safari_tmp</string>
						<key>WebBrowser</key>
						<string>Safari</string>
					</dict>
					<dict>
						<key>Conditions</key>
						<dict>
							<key>ConditionList</key>
							<array>
								<dict>
									<key>ConditionType</key>
									<string>Variable</string>
									<key>Variable</key>
									<string>safari_tmp</string>
									<key>VariableConditionType</key>
									<string>IsNot</string>
									<key>VariableValue</key>
									<string>topsites://</string>
								</dict>
								<dict>
									<key>ConditionType</key>
									<string>Variable</string>
									<key>Variable</key>
									<string>safari_tmp</string>
									<key>VariableConditionType</key>
									<string>IsNot</string>
									<key>VariableValue</key>
									<string>about:blank</string>
								</dict>
								<dict>
									<key>ConditionType</key>
									<string>Variable</string>
									<key>Variable</key>
									<string>safari_tmp</string>
									<key>VariableConditionType</key>
									<string>DoesNotContain</string>
									<key>VariableValue</key>
									<string>file://</string>
								</dict>
							</array>
							<key>ConditionListMatch</key>
							<string>All</string>
						</dict>
						<key>ElseActions</key>
						<array/>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>MacroActionType</key>
						<string>IfThenElse</string>
						<key>ThenActions</key>
						<array>
							<dict>
								<key>DisplayKind</key>
								<string>Variable</string>
								<key>IsActive</key>
								<true/>
								<key>IsDisclosed</key>
								<true/>
								<key>MacroActionType</key>
								<string>ExecuteJavaScript</string>
								<key>Path</key>
								<string></string>
								<key>Text</key>
								<string>var tmp = null; 
if(document.kmvar.safari == "") { 
  tmp = window.location.href;
} else {
  tmp = window.location.href + ";" + document.kmvar.safari; 
}
console.log(tmp);
tmp;</string>
								<key>TimeOutAbortsMacro</key>
								<true/>
								<key>TrimResults</key>
								<true/>
								<key>TrimResultsNew</key>
								<true/>
								<key>UseText</key>
								<true/>
								<key>Variable</key>
								<string>safari</string>
								<key>WebBrowser</key>
								<string>Safari</string>
							</dict>
						</array>
						<key>TimeOutAbortsMacro</key>
						<true/>
					</dict>
					<dict>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>KeyCode</key>
						<integer>13</integer>
						<key>MacroActionType</key>
						<string>SimulateKeystroke</string>
						<key>Modifiers</key>
						<integer>256</integer>
						<key>ReleaseAll</key>
						<false/>
					</dict>
				</array>
				<key>IsActive</key>
				<true/>
				<key>ModificationDate</key>
				<real>418676461.776815</real>
				<key>Name</key>
				<string>Record closing tab</string>
				<key>Triggers</key>
				<array>
					<dict>
						<key>FireType</key>
						<string>Pressed</string>
						<key>KeyCode</key>
						<integer>13</integer>
						<key>MacroTriggerType</key>
						<string>HotKey</string>
						<key>Modifiers</key>
						<integer>256</integer>
					</dict>
				</array>
				<key>UID</key>
				<string>85E209FB-B5D6-476E-8CD2-BC8671820078</string>
			</dict>
		</array>
		<key>Name</key>
		<string>Safari Tabs Fix</string>
		<key>Targeting</key>
		<dict>
			<key>Targeting</key>
			<string>Included</string>
			<key>TargetingApps</key>
			<array>
				<dict>
					<key>BundleIdentifier</key>
					<string>com.apple.Safari</string>
					<key>Name</key>
					<string>Safari</string>
					<key>NewFile</key>
					<string>/Applications/Safari.app</string>
				</dict>
			</array>
		</dict>
		<key>UID</key>
		<string>02BEBF32-B1D8-4E41-8086-D2EE7ACB9EC4</string>
	</dict>
</array>
</plist>

Restore Tab.kmmacros

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
	<dict>
		<key>Activate</key>
		<string>Normal</string>
		<key>IsActive</key>
		<true/>
		<key>Macros</key>
		<array>
			<dict>
				<key>Actions</key>
				<array>
					<dict>
						<key>DisplayKind</key>
						<string>Variable</string>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>MacroActionType</key>
						<string>ExecuteJavaScript</string>
						<key>Path</key>
						<string></string>
						<key>Text</key>
						<string>console.log(document.kmvar.safari);
var parts = document.kmvar.safari.split(";");
var result = null;
if(parts.lenght == 0) { 
  result = undefined;
} else { 
 result  = parts.shift();
}
result;</string>
						<key>TimeOutAbortsMacro</key>
						<true/>
						<key>TrimResults</key>
						<true/>
						<key>TrimResultsNew</key>
						<true/>
						<key>UseText</key>
						<true/>
						<key>Variable</key>
						<string>safari_tmp</string>
						<key>WebBrowser</key>
						<string>Safari</string>
					</dict>
					<dict>
						<key>Conditions</key>
						<dict>
							<key>ConditionList</key>
							<array>
								<dict>
									<key>ConditionType</key>
									<string>Variable</string>
									<key>Variable</key>
									<string>safari_tmp</string>
									<key>VariableConditionType</key>
									<string>Is</string>
									<key>VariableValue</key>
									<string>undefined</string>
								</dict>
								<dict>
									<key>ConditionType</key>
									<string>Variable</string>
									<key>Variable</key>
									<string>safari_tmp</string>
									<key>VariableConditionType</key>
									<string>IsEmpty</string>
									<key>VariableValue</key>
									<string>value</string>
								</dict>
							</array>
							<key>ConditionListMatch</key>
							<string>None</string>
						</dict>
						<key>ElseActions</key>
						<array/>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>MacroActionType</key>
						<string>IfThenElse</string>
						<key>ThenActions</key>
						<array>
							<dict>
								<key>Argument</key>
								<string>%Variable%safari_tmp%</string>
								<key>Command</key>
								<string>NewTab</string>
								<key>IsActive</key>
								<true/>
								<key>IsDisclosed</key>
								<true/>
								<key>MacroActionType</key>
								<string>SafariControl</string>
								<key>WebBrowser</key>
								<string>Safari</string>
							</dict>
						</array>
						<key>TimeOutAbortsMacro</key>
						<true/>
					</dict>
					<dict>
						<key>DisplayKind</key>
						<string>Variable</string>
						<key>IsActive</key>
						<true/>
						<key>IsDisclosed</key>
						<true/>
						<key>MacroActionType</key>
						<string>ExecuteJavaScript</string>
						<key>Path</key>
						<string></string>
						<key>Text</key>
						<string>console.log(document.kmvar.safari);
var parts = document.kmvar.safari.split(";");
parts.shift();
var rest = parts.join(";");
rest;</string>
						<key>TimeOutAbortsMacro</key>
						<true/>
						<key>TrimResults</key>
						<true/>
						<key>TrimResultsNew</key>
						<true/>
						<key>UseText</key>
						<true/>
						<key>Variable</key>
						<string>safari</string>
						<key>WebBrowser</key>
						<string>Safari</string>
					</dict>
				</array>
				<key>IsActive</key>
				<true/>
				<key>ModificationDate</key>
				<real>418676104.31371999</real>
				<key>Name</key>
				<string>Restore Tab</string>
				<key>Triggers</key>
				<array>
					<dict>
						<key>FireType</key>
						<string>Pressed</string>
						<key>KeyCode</key>
						<integer>17</integer>
						<key>MacroTriggerType</key>
						<string>HotKey</string>
						<key>Modifiers</key>
						<integer>768</integer>
					</dict>
				</array>
				<key>UID</key>
				<string>06EA07CA-0436-4E62-B003-A5E8A4B6960A</string>
			</dict>
		</array>
		<key>Name</key>
		<string>Safari Tabs Fix</string>
		<key>Targeting</key>
		<dict>
			<key>Targeting</key>
			<string>Included</string>
			<key>TargetingApps</key>
			<array>
				<dict>
					<key>BundleIdentifier</key>
					<string>com.apple.Safari</string>
					<key>Name</key>
					<string>Safari</string>
					<key>NewFile</key>
					<string>/Applications/Safari.app</string>
				</dict>
			</array>
		</dict>
		<key>UID</key>
		<string>02BEBF32-B1D8-4E41-8086-D2EE7ACB9EC4</string>
	</dict>
</array>
</plist>

• closed tabs / windows are only registered if you're using the ⌘+W shortcut
• history of close tabs is lost, url present at the time of closing will be restored