feat(cli): add version command

README.md

@@ -67,6 +67,7 @@ by `vyb`.
 | `init`         | Create `.vyb/metadata.yaml` in the project root            |
 | `update`       | Re-scan workspace, merge & (re)generate annotations        |
 | `remove`       | Delete `.vyb` completely                                   |
+| `version`      | Print binary version                                       |
 | `code`         | Implement `TODO(vyb)`s or the file passed as argument      |
 | `document`     | Generate / refresh `README.md` files                       |
 | `refine`       | Polish `SPEC.md` content                                   |

cmd/README.md

@@ -9,6 +9,8 @@ subcommands, implemented using the Cobra library.
   metadata (metadata.yaml).
 - remove: Deletes all .vyb metadata from the current project root
   (or forcibly from the entire directory hierarchy using --force-root).
-- root: The root command that prints help if no subcommand is specified.
-- template: Registers specialized commands for AI-based tasks such
-  as 'refine', 'code', 'summarize', etc.
+- update: Updates the vyb project metadata.
+- version: Prints the vyb CLI version.
+- template-based commands: A dynamic set of commands for AI-based tasks
+  such as 'refine', 'code', 'document', etc., are registered from `.vyb`
+  template files.

cmd/root.go

@@ -34,4 +34,5 @@ func init() {
 	rootCmd.AddCommand(initCmd)
 	rootCmd.AddCommand(updateCmd)
 	rootCmd.AddCommand(removeCmd)
+	rootCmd.AddCommand(versionCmd)
 }

cmd/version.go

@@ -0,0 +1,74 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"runtime/debug"
+	"strings"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Prints the vyb CLI version.",
+	Run:   Version,
+}
+
+// Version is the cobra handler for `vyb version`.
+func Version(_ *cobra.Command, _ []string) {
+	if version, err := deriveVersion(); err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "%q", err)
+	} else {
+		fmt.Println(version)
+	}
+
+}
+
+func deriveVersion() (string, error) {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", fmt.Errorf("could not read build info")
+	}
+
+	if info.Main.Version != "" && info.Main.Version != "(devel)" {
+		return info.Main.Version, nil
+	}
+
+	return derivePseudoVersionFromVCS(info)
+}
+
+// derivePseudoVersionFromVCS produces a pseudo version based on VCS tags,
+// as described at https://go.dev/ref/mod#pseudo-versions
+func derivePseudoVersionFromVCS(info *debug.BuildInfo) (string, error) {
+	var revision, at string
+	for _, s := range info.Settings {
+		if s.Key == "vcs.revision" {
+			revision = s.Value
+		}
+		if s.Key == "vcs.time" {
+			at = s.Value
+		}
+	}
+
+	if revision == "" && at == "" {
+		return "", fmt.Errorf("version information is not available")
+	}
+
+	buf := strings.Builder{}
+	buf.WriteString("0.0.0")
+	if revision != "" {
+		buf.WriteString("-")
+		buf.WriteString(revision[:12])
+	}
+	if at != "" {
+		// the commit time is of the form 2023-01-25T19:57:54Z
+		p, err := time.Parse(time.RFC3339, at)
+		if err == nil {
+			buf.WriteString("-")
+			buf.WriteString(p.Format("20060102150405"))
+		}
+	}
+	return buf.String(), nil
+}