commit db93b6be6c1ff2bec2fb95949fc6d7ba1767a051
Author: Yonah <contrib@gensokyo.uk>
Date:   Sun Jul 13 23:55:04 2025 +0900

    format: format nixos installable

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..47c5249
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,25 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+*.pkg
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+.idea
+.vscode
\ No newline at end of file
diff --git a/format.go b/format.go
new file mode 100644
index 0000000..860b09d
--- /dev/null
+++ b/format.go
@@ -0,0 +1,9 @@
+package nixbuild
+
+const (
+	nixosSuffix0 = "#nixosConfigurations."
+	nixosSuffix1 = ".config.system.build.toplevel"
+)
+
+// NixOSInstallable returns the nixos installable for a given flake and host.
+func NixOSInstallable(flake, host string) string { return flake + nixosSuffix0 + host + nixosSuffix1 }
diff --git a/format_test.go b/format_test.go
new file mode 100644
index 0000000..f8bf8ca
--- /dev/null
+++ b/format_test.go
@@ -0,0 +1,24 @@
+package nixbuild_test
+
+import (
+	"testing"
+
+	"git.gensokyo.uk/yonah/nixbuild"
+)
+
+func TestInstallable(t *testing.T) {
+	testCases := []struct {
+		name, flake, host, want string
+	}{
+		{"satori", "/var/lib/persist/nixos", "satori", "/var/lib/persist/nixos#nixosConfigurations.satori.config.system.build.toplevel"},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := nixbuild.NixOSInstallable(tc.flake, tc.host)
+			if got != tc.want {
+				t.Errorf("Installable(%q, %q): %q, want %q",
+					tc.flake, tc.host, got, tc.want)
+			}
+		})
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..8871f9a
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.gensokyo.uk/yonah/nixbuild
+
+go 1.24.4