first commit

cli/internal/installer/installer.go

@@ -0,0 +1,44 @@
+package installer
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os/exec"
+
+	"github.com/maximhq/bifrost/cli/internal/harness"
+)
+
+// IsInstalled reports whether the harness binary exists in the system PATH.
+func IsInstalled(h harness.Harness) bool {
+	_, err := exec.LookPath(h.Binary)
+	return err == nil
+}
+
+// InstallCommand returns the command and arguments needed to install the harness globally via npm.
+func InstallCommand(h harness.Harness) (string, []string) {
+	return "npm", []string{"install", "-g", h.InstallPkg}
+}
+
+// EnsureNPM checks that npm is available in the system PATH.
+func EnsureNPM() error {
+	_, err := exec.LookPath("npm")
+	if err != nil {
+		return fmt.Errorf("npm not found in path: %w", err)
+	}
+	return nil
+}
+
+// RunInstall executes the npm install command for the given harness,
+// streaming output to the provided writers.
+func RunInstall(ctx context.Context, stdout, stderr io.Writer, h harness.Harness) error {
+	cmdName, args := InstallCommand(h)
+	cmd := exec.CommandContext(ctx, cmdName, args...)
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	cmd.Stdin = nil
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("install %s: %w", h.Label, err)
+	}
+	return nil
+}