feat(deps): add minimum beads version check (gt-im3fl)

Add version check that enforces beads >= 0.44.0 at CLI startup,
required for custom type support (bd-i54l). Commands like version,
help, and completion bypass the check.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/beads_version.go

@@ -0,0 +1,134 @@
+// Package cmd provides CLI commands for the gt tool.
+package cmd
+
+import (
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// MinBeadsVersion is the minimum required beads version for Gas Town.
+// This version must include custom type support (bd-i54l).
+const MinBeadsVersion = "0.44.0"
+
+// beadsVersion represents a parsed semantic version.
+type beadsVersion struct {
+	major int
+	minor int
+	patch int
+}
+
+// parseBeadsVersion parses a version string like "0.44.0" into components.
+func parseBeadsVersion(v string) (beadsVersion, error) {
+	// Strip leading 'v' if present
+	v = strings.TrimPrefix(v, "v")
+
+	// Split on dots
+	parts := strings.Split(v, ".")
+	if len(parts) < 2 {
+		return beadsVersion{}, fmt.Errorf("invalid version format: %s", v)
+	}
+
+	major, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return beadsVersion{}, fmt.Errorf("invalid major version: %s", parts[0])
+	}
+
+	minor, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return beadsVersion{}, fmt.Errorf("invalid minor version: %s", parts[1])
+	}
+
+	patch := 0
+	if len(parts) >= 3 {
+		// Handle versions like "0.44.0-dev" - take only numeric prefix
+		patchStr := parts[2]
+		if idx := strings.IndexFunc(patchStr, func(r rune) bool {
+			return r < '0' || r > '9'
+		}); idx != -1 {
+			patchStr = patchStr[:idx]
+		}
+		if patchStr != "" {
+			patch, err = strconv.Atoi(patchStr)
+			if err != nil {
+				return beadsVersion{}, fmt.Errorf("invalid patch version: %s", parts[2])
+			}
+		}
+	}
+
+	return beadsVersion{major: major, minor: minor, patch: patch}, nil
+}
+
+// compare returns -1 if v < other, 0 if equal, 1 if v > other.
+func (v beadsVersion) compare(other beadsVersion) int {
+	if v.major != other.major {
+		if v.major < other.major {
+			return -1
+		}
+		return 1
+	}
+	if v.minor != other.minor {
+		if v.minor < other.minor {
+			return -1
+		}
+		return 1
+	}
+	if v.patch != other.patch {
+		if v.patch < other.patch {
+			return -1
+		}
+		return 1
+	}
+	return 0
+}
+
+// getBeadsVersion executes `bd --version` and parses the output.
+// Returns the version string (e.g., "0.44.0") or error.
+func getBeadsVersion() (string, error) {
+	cmd := exec.Command("bd", "--version")
+	output, err := cmd.Output()
+	if err != nil {
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			return "", fmt.Errorf("bd --version failed: %s", string(exitErr.Stderr))
+		}
+		return "", fmt.Errorf("failed to run bd: %w (is beads installed?)", err)
+	}
+
+	// Parse output like "bd version 0.44.0 (dev)"
+	// or "bd version 0.44.0"
+	re := regexp.MustCompile(`bd version (\d+\.\d+(?:\.\d+)?(?:-\w+)?)`)
+	matches := re.FindStringSubmatch(string(output))
+	if len(matches) < 2 {
+		return "", fmt.Errorf("could not parse beads version from: %s", strings.TrimSpace(string(output)))
+	}
+
+	return matches[1], nil
+}
+
+// CheckBeadsVersion verifies that the installed beads version meets the minimum requirement.
+// Returns nil if the version is sufficient, or an error with details if not.
+func CheckBeadsVersion() error {
+	installedStr, err := getBeadsVersion()
+	if err != nil {
+		return fmt.Errorf("cannot verify beads version: %w", err)
+	}
+
+	installed, err := parseBeadsVersion(installedStr)
+	if err != nil {
+		return fmt.Errorf("cannot parse installed beads version %q: %w", installedStr, err)
+	}
+
+	required, err := parseBeadsVersion(MinBeadsVersion)
+	if err != nil {
+		// This would be a bug in our code
+		return fmt.Errorf("cannot parse required beads version %q: %w", MinBeadsVersion, err)
+	}
+
+	if installed.compare(required) < 0 {
+		return fmt.Errorf("beads version %s is required, but %s is installed\n\nPlease upgrade beads: go install github.com/steveyegge/beads/cmd/bd@latest", MinBeadsVersion, installedStr)
+	}
+
+	return nil
+}