2 files changed, 62 insertions, 0 deletions
diff --git a/internal/version/version.go b/internal/version/version.go
new file mode 100644
index 0000000..030bd4e
--- /dev/null
+++ b/internal/version/version.go
@@ -0,0 +1,30 @@
+// Package version holds build-time version information for both
+// binaries, set via -ldflags "-X mitmux/internal/version.Version=..."
+// (see the Makefile's release target). Defaults to "dev" for a plain
+// `go build` with no ldflags, so `-version` is never blank or
+// misleading about whether a given binary is a tagged release or a
+// local build.
+package version
+
+var (
+	Version = "dev"
+	Commit  = ""
+	Date    = ""
+)
+
+// String returns a one-line version summary for component ("mitmux" or
+// "mitmuxd"): "mitmux dev" for an untagged build, or
+// "mitmux 1.2.3 (abc1234, 2026-01-02)" once Commit/Date are set.
+func String(component string) string {
+	s := component + " " + Version
+	if Commit != "" || Date != "" {
+		s += " ("
+		s += Commit
+		if Commit != "" && Date != "" {
+			s += ", "
+		}
+		s += Date
+		s += ")"
+	}
+	return s
+}
diff --git a/internal/version/version_test.go b/internal/version/version_test.go
new file mode 100644
index 0000000..d2d501b
--- /dev/null
+++ b/internal/version/version_test.go
@@ -0,0 +1,32 @@
+package version
+
+import "testing"
+
+func TestStringDefault(t *testing.T) {
+	orig := Version
+	Version, Commit, Date = "dev", "", ""
+	defer func() { Version = orig }()
+	if got := String("mitmux"); got != "mitmux dev" {
+		t.Errorf("String(%q) = %q, want %q", "mitmux", got, "mitmux dev")
+	}
+}
+
+func TestStringWithCommitAndDate(t *testing.T) {
+	origV, origC, origD := Version, Commit, Date
+	Version, Commit, Date = "1.2.3", "abc1234", "2026-01-02"
+	defer func() { Version, Commit, Date = origV, origC, origD }()
+	want := "mitmuxd 1.2.3 (abc1234, 2026-01-02)"
+	if got := String("mitmuxd"); got != want {
+		t.Errorf("String(%q) = %q, want %q", "mitmuxd", got, want)
+	}
+}
+
+func TestStringCommitOnly(t *testing.T) {
+	origV, origC, origD := Version, Commit, Date
+	Version, Commit, Date = "1.2.3", "abc1234", ""
+	defer func() { Version, Commit, Date = origV, origC, origD }()
+	want := "mitmux 1.2.3 (abc1234)"
+	if got := String("mitmux"); got != want {
+		t.Errorf("String(%q) = %q, want %q", "mitmux", got, want)
+	}
+}