From 941b1d86c36f460e93989ec7f12d4841a3ce213d Mon Sep 17 00:00:00 2001
From: Lukasz Raczylo <lukasz@raczylo.com>
Date: Sat, 23 May 2026 12:42:44 +0100
Subject: [PATCH] feat(cli): add update subcommand for in-place self-update

---
 cmd/harness-sync/main.go    |  1 +
 internal/cli/update.go      | 54 +++++++++++++++++++++++++++++++++++++
 internal/cli/update_test.go | 39 +++++++++++++++++++++++++++
 3 files changed, 94 insertions(+)
 create mode 100644 internal/cli/update.go
 create mode 100644 internal/cli/update_test.go

diff --git a/cmd/harness-sync/main.go b/cmd/harness-sync/main.go
index 11f6e37..0c5a49c 100644
--- a/cmd/harness-sync/main.go
+++ b/cmd/harness-sync/main.go
@@ -36,6 +36,7 @@ func main() {
 	root.AddCommand(cli.NewProfile(reg))
 	root.AddCommand(cli.NewRollback())
 	root.AddCommand(cli.NewAdapter(reg))
+	root.AddCommand(cli.NewUpdate())
 
 	if err := root.Execute(); err != nil {
 		fmt.Fprintln(os.Stderr, err)
diff --git a/internal/cli/update.go b/internal/cli/update.go
new file mode 100644
index 0000000..94c2763
--- /dev/null
+++ b/internal/cli/update.go
@@ -0,0 +1,54 @@
+package cli
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/spf13/cobra"
+)
+
+const installURL = "https://raw.githubusercontent.com/lukaszraczylo/harness-sync/main/install.sh"
+
+// NewUpdate returns the `update` subcommand. It downloads and installs the
+// latest harness-sync release into the same directory the running binary
+// lives in.
+func NewUpdate() *cobra.Command {
+	var (
+		dryRun bool
+		dir    string
+	)
+	cmd := &cobra.Command{
+		Use:   "update",
+		Short: "Download and install the latest harness-sync release in place",
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			if dir == "" {
+				exe, err := os.Executable()
+				if err != nil {
+					return fmt.Errorf("resolve current binary path: %w", err)
+				}
+				resolved, err := filepath.EvalSymlinks(exe)
+				if err == nil {
+					exe = resolved
+				}
+				dir = filepath.Dir(exe)
+			}
+			pipeline := fmt.Sprintf("curl -fsSL %q | INSTALL_DIR=%q bash", installURL, dir)
+			if _, err := fmt.Fprintf(cmd.OutOrStdout(), "Installing latest harness-sync into %s\n", dir); err != nil {
+				return err
+			}
+			if dryRun {
+				_, err := fmt.Fprintln(cmd.OutOrStdout(), pipeline)
+				return err
+			}
+			sh := exec.Command("/bin/bash", "-c", pipeline)
+			sh.Stdout = cmd.OutOrStdout()
+			sh.Stderr = cmd.ErrOrStderr()
+			return sh.Run()
+		},
+	}
+	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "print the install command without executing it")
+	cmd.Flags().StringVar(&dir, "install-dir", "", "override install directory (default: dir of running binary)")
+	return cmd
+}
diff --git a/internal/cli/update_test.go b/internal/cli/update_test.go
new file mode 100644
index 0000000..113b5a9
--- /dev/null
+++ b/internal/cli/update_test.go
@@ -0,0 +1,39 @@
+package cli
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestUpdateDryRunPrintsCommand(t *testing.T) {
+	cmd := NewUpdate()
+	var buf bytes.Buffer
+	cmd.SetOut(&buf)
+	cmd.SetErr(&buf)
+	cmd.SetArgs([]string{"--dry-run", "--install-dir", "/tmp/test-dir"})
+	require.NoError(t, cmd.Execute())
+
+	out := buf.String()
+	assert.Contains(t, out, "Installing latest harness-sync into /tmp/test-dir")
+	assert.Contains(t, out, "curl -fsSL")
+	assert.Contains(t, out, "install.sh")
+	assert.Contains(t, out, "INSTALL_DIR=")
+	// Should NOT have run anything
+	assert.False(t, strings.Contains(out, "[INFO]"), "dry run must not invoke install.sh")
+}
+
+func TestUpdateResolvesCurrentBinaryDirByDefault(t *testing.T) {
+	cmd := NewUpdate()
+	var buf bytes.Buffer
+	cmd.SetOut(&buf)
+	cmd.SetArgs([]string{"--dry-run"})
+	require.NoError(t, cmd.Execute())
+
+	// Should mention SOME absolute path (the test binary's directory)
+	out := buf.String()
+	assert.Contains(t, out, "Installing latest harness-sync into /")
+}