Report the embedded release version

internal/app/commands.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 )
 
-var supportedCommands = []string{"run", "regenerate-artifacts", "run-stage", "analyze", "publish", "clean", "session"}
+var supportedCommands = []string{"version", "run", "regenerate-artifacts", "run-stage", "analyze", "publish", "clean", "session"}
 
 var runCommandFn = Run
 
@@ -24,6 +24,8 @@ func Execute(args []string, stdout, stderr io.Writer) int {
 
 	var err error
 	switch cmd {
+	case "version":
+		err = Version(cmdArgs, stdout)
 	case "run":
 		err = runCommandFn(ctx, cmdArgs, stdout)
 	case "regenerate-artifacts":

internal/app/version.go

@@ -0,0 +1,17 @@
+package app
+
+import (
+	"fmt"
+	"io"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/buildinfo"
+)
+
+// Version prints the version embedded in the current Narratio binary.
+func Version(args []string, out io.Writer) error {
+	if len(args) != 0 {
+		return fmt.Errorf("version: unexpected arguments")
+	}
+	_, err := fmt.Fprintf(out, "narratio %s\n", buildinfo.Version)
+	return err
+}

internal/app/version_test.go

@@ -0,0 +1,38 @@
+package app
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/buildinfo"
+)
+
+func TestExecuteVersionReportsEmbeddedBuildVersion(t *testing.T) {
+	original := buildinfo.Version
+	buildinfo.Version = "v1.5.0-test"
+	t.Cleanup(func() { buildinfo.Version = original })
+
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	if code := Execute([]string{"version"}, &stdout, &stderr); code != 0 {
+		t.Fatalf("Execute() code = %d, stderr = %q", code, stderr.String())
+	}
+	if got, want := stdout.String(), "narratio v1.5.0-test\n"; got != want {
+		t.Fatalf("stdout = %q, want %q", got, want)
+	}
+	if stderr.Len() != 0 {
+		t.Fatalf("stderr = %q, want empty", stderr.String())
+	}
+}
+
+func TestExecuteVersionRejectsArguments(t *testing.T) {
+	var stderr bytes.Buffer
+	if code := Execute([]string{"version", "extra"}, io.Discard, &stderr); code == 0 {
+		t.Fatal("Execute() code = 0, want failure")
+	}
+	if !strings.Contains(stderr.String(), "version: unexpected arguments") {
+		t.Fatalf("stderr = %q, want argument error", stderr.String())
+	}
+}

internal/buildinfo/buildinfo.go

@@ -0,0 +1,6 @@
+// Package buildinfo exposes metadata supplied by the release build.
+package buildinfo
+
+// Version is the Narratio release identifier. Source builds report "dev";
+// release automation replaces it with the exact Git tag through -ldflags -X.
+var Version = "dev"