Добавлена проверка на наличие установленного git в системе

source/app.d

@@ -1,6 +1,7 @@
 import snag;
 import commandr;
 import std.file;
+import std.stdio : writeln;
 
 import core.stdc.stdlib : EXIT_SUCCESS, EXIT_FAILURE;
 
@@ -8,6 +9,11 @@ private string programName = "snag";
 
 int main(string[] args)
 {
+	if (!checkGit()) {
+		"Using snag requires Git to be installed".writeln;
+		return EXIT_FAILURE;
+	}
+
 	auto argumets = new Program(programName, snagVersion)
 		.add(new Command("init", "Initializing the repository for storing snapshots"))
 		.add(new Command("status", "Checking the status of tracked files"))

source/snag/lib/lib.d

@@ -1,6 +1,7 @@
 module snag.lib.lib;
 
 import std.regex;
+import std.process;
 
 bool isValidHash(string hash) {
 	auto hashPattern = ctRegex!r"^[a-fA-F0-9]{7}$";
@@ -11,3 +12,8 @@ bool isValidEmail(string email) {
 	auto emailPattern = ctRegex!r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$";
 	return !matchFirst(email, emailPattern).empty;
 }
+
+bool checkGit() {
+	auto result = execute(["which", "git"]);
+	return !result.status;
+}