Add runtime version reporting

internal/runtimeinfo/version.go

@@ -0,0 +1,26 @@
+// Package runtimeinfo implements the private runtime version state used by the
+// public buildinfo facade.
+package runtimeinfo
+
+import "runtime/debug"
+
+var injectedVersion string
+
+// Version returns the injected version or the running executable's main module
+// version, falling back to "dev" when neither provides a release identifier.
+func Version() string {
+	return version(injectedVersion, debug.ReadBuildInfo)
+}
+
+func version(injected string, readBuildInfo func() (*debug.BuildInfo, bool)) string {
+	if injected != "" {
+		return injected
+	}
+
+	info, ok := readBuildInfo()
+	if ok && info != nil && info.Main.Version != "" && info.Main.Version != "(devel)" {
+		return info.Main.Version
+	}
+
+	return "dev"
+}