fix(shell): make RestoreFromSnapshot idempotent via OpenBoot-Restore sentinel block

Replaces scatter-point ZSH_THEME/plugins= regex replacements with a single guarded block (# >>> OpenBoot-Restore ... # <<< OpenBoot-Restore). On first run, loose theme/plugin lines are stripped before the block is appended. On subsequent runs, only the block is replaced in-place, preventing file growth on repeated restores. Also ensures a trailing newline before the block to avoid comment corruption.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

Author: fullstackjam

internal/shell/shell.go

@@ -48,14 +48,9 @@ func InstallOhMyZsh(dryRun bool) error {
 	return nil
 }
 
-func ConfigureZshrc(dryRun bool) error {
-	home, err := system.HomeDir()
-	if err != nil {
-		return err
-	}
-	zshrcPath := filepath.Join(home, ".zshrc")
+const openbootZshrcSentinel = "# OpenBoot additions"
 
-	additions := `
+const openbootZshrcBlock = `
 # OpenBoot additions
 # Homebrew (must come before /usr/bin)
 if [ -f /opt/homebrew/bin/brew ]; then
@@ -85,9 +80,21 @@ eval "$(zoxide init zsh)"
 [ -f ~/.fzf.zsh ] && source ~/.fzf.zsh
 `
 
+func ConfigureZshrc(dryRun bool) error {
+	home, err := system.HomeDir()
+	if err != nil {
+		return err
+	}
+	zshrcPath := filepath.Join(home, ".zshrc")
+
 	if dryRun {
 		fmt.Println("[DRY-RUN] Would add to .zshrc:")
-		fmt.Println(additions)
+		fmt.Print(openbootZshrcBlock)
+		return nil
+	}
+
+	existing, _ := os.ReadFile(zshrcPath)
+	if strings.Contains(string(existing), openbootZshrcSentinel) {
 		return nil
 	}
 
@@ -97,7 +104,7 @@ eval "$(zoxide init zsh)"
 	}
 	defer f.Close()
 
-	if _, err := f.WriteString(additions); err != nil {
+	if _, err := f.WriteString(openbootZshrcBlock); err != nil {
 		return fmt.Errorf("failed to write to .zshrc: %w", err)
 	}
 
@@ -122,6 +129,59 @@ func SetDefaultShell(dryRun bool) error {
 	return cmd.Run()
 }
 
+const restoreBlockStart = "# >>> OpenBoot-Restore"
+const restoreBlockEnd = "# <<< OpenBoot-Restore"
+
+var restoreBlockRe = regexp.MustCompile(`(?s)# >>> OpenBoot-Restore\n.*?# <<< OpenBoot-Restore\n?`)
+
+func buildRestoreBlock(theme string, plugins []string) string {
+	var sb strings.Builder
+	sb.WriteString(restoreBlockStart + "\n")
+	if theme != "" {
+		sb.WriteString(fmt.Sprintf("ZSH_THEME=\"%s\"\n", theme))
+	}
+	if len(plugins) > 0 {
+		sb.WriteString(fmt.Sprintf("plugins=(%s)\n", strings.Join(plugins, " ")))
+	}
+	sb.WriteString(restoreBlockEnd + "\n")
+	return sb.String()
+}
+
+var (
+	looseThemeRe   = regexp.MustCompile(`(?m)^ZSH_THEME="[^"]*"\n?`)
+	loosePluginsRe = regexp.MustCompile(`(?m)^plugins=\([^)]*\)\n?`)
+)
+
+func patchZshrcBlock(zshrcPath, theme string, plugins []string) error {
+	raw, err := os.ReadFile(zshrcPath)
+	if err != nil {
+		return fmt.Errorf("failed to read .zshrc: %w", err)
+	}
+
+	block := buildRestoreBlock(theme, plugins)
+	content := string(raw)
+
+	if restoreBlockRe.MatchString(content) {
+		content = restoreBlockRe.ReplaceAllString(content, block)
+	} else {
+		if theme != "" {
+			content = looseThemeRe.ReplaceAllString(content, "")
+		}
+		if len(plugins) > 0 {
+			content = loosePluginsRe.ReplaceAllString(content, "")
+		}
+		if len(content) > 0 && content[len(content)-1] != '\n' {
+			content = content + "\n"
+		}
+		content = content + block
+	}
+
+	if err := os.WriteFile(zshrcPath, []byte(content), 0644); err != nil {
+		return fmt.Errorf("failed to write .zshrc: %w", err)
+	}
+	return nil
+}
+
 func RestoreFromSnapshot(ohMyZsh bool, theme string, plugins []string, dryRun bool) error {
 	if !ohMyZsh {
 		return nil
@@ -169,36 +229,9 @@ source $ZSH/oh-my-zsh.sh
 		return nil
 	}
 
-	content, err := os.ReadFile(zshrcPath)
-	if err != nil {
-		return fmt.Errorf("failed to read .zshrc: %w", err)
-	}
-
-	updated := string(content)
-
-	if theme != "" {
-		themeRe := regexp.MustCompile(`ZSH_THEME="[^"]*"`)
-		newTheme := fmt.Sprintf(`ZSH_THEME="%s"`, theme)
-		if themeRe.MatchString(updated) {
-			updated = themeRe.ReplaceAllString(updated, newTheme)
-		} else {
-			updated = newTheme + "\n" + updated
-		}
-	}
-
-	if len(plugins) > 0 {
-		pluginsRe := regexp.MustCompile(`plugins=\([^)]*\)`)
-		newPlugins := fmt.Sprintf("plugins=(%s)", strings.Join(plugins, " "))
-		if pluginsRe.MatchString(updated) {
-			updated = pluginsRe.ReplaceAllString(updated, newPlugins)
-		} else {
-			updated = newPlugins + "\n" + updated
-		}
-	}
-
-	if err := os.WriteFile(zshrcPath, []byte(updated), 0644); err != nil {
-		return fmt.Errorf("failed to write .zshrc: %w", err)
+	if theme == "" && len(plugins) == 0 {
+		return nil
 	}
 
-	return nil
+	return patchZshrcBlock(zshrcPath, theme, plugins)
 }

internal/shell/shell_test.go

@@ -3,6 +3,7 @@ package shell
 import (
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -267,3 +268,87 @@ source $ZSH/oh-my-zsh.sh
 	assert.Contains(t, string(result), `ZSH_THEME="robbyrussell"`)
 	assert.Contains(t, string(result), `plugins=(git)`)
 }
+
+func TestConfigureZshrc_Idempotent(t *testing.T) {
+	tmpHome := t.TempDir()
+	t.Setenv("HOME", tmpHome)
+
+	require.NoError(t, ConfigureZshrc(false))
+	require.NoError(t, ConfigureZshrc(false))
+	require.NoError(t, ConfigureZshrc(false))
+
+	zshrcPath := filepath.Join(tmpHome, ".zshrc")
+	content, err := os.ReadFile(zshrcPath)
+	require.NoError(t, err)
+
+	count := strings.Count(string(content), openbootZshrcSentinel)
+	assert.Equal(t, 1, count, "OpenBoot block should appear exactly once after multiple calls")
+}
+
+func TestRestoreFromSnapshot_NoTrailingNewline(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	zshrcPath := filepath.Join(home, ".zshrc")
+	require.NoError(t, os.WriteFile(zshrcPath, []byte(`source $ZSH/oh-my-zsh.sh`), 0644))
+	require.NoError(t, os.MkdirAll(filepath.Join(home, ".oh-my-zsh"), 0755))
+
+	require.NoError(t, RestoreFromSnapshot(true, "agnoster", []string{"git"}, false))
+
+	content, err := os.ReadFile(zshrcPath)
+	require.NoError(t, err)
+
+	assert.Contains(t, string(content), restoreBlockStart)
+	lines := strings.Split(string(content), "\n")
+	for i, line := range lines {
+		if strings.HasSuffix(line, "oh-my-zsh.sh") {
+			assert.NotContains(t, line, restoreBlockStart,
+				"block sentinel must not be joined to previous line (line %d)", i)
+			break
+		}
+	}
+}
+
+func TestRestoreFromSnapshot_Idempotent(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	zshrcPath := filepath.Join(home, ".zshrc")
+	initial := `export ZSH="$HOME/.oh-my-zsh"
+ZSH_THEME="robbyrussell"
+plugins=(git)
+source $ZSH/oh-my-zsh.sh
+`
+	require.NoError(t, os.WriteFile(zshrcPath, []byte(initial), 0644))
+	require.NoError(t, os.MkdirAll(filepath.Join(home, ".oh-my-zsh"), 0755))
+
+	require.NoError(t, RestoreFromSnapshot(true, "agnoster", []string{"git", "docker"}, false))
+	require.NoError(t, RestoreFromSnapshot(true, "agnoster", []string{"git", "docker"}, false))
+	require.NoError(t, RestoreFromSnapshot(true, "agnoster", []string{"git", "docker"}, false))
+
+	content, err := os.ReadFile(zshrcPath)
+	require.NoError(t, err)
+
+	assert.Equal(t, 1, strings.Count(string(content), restoreBlockStart),
+		"restore block should appear exactly once after repeated calls")
+	assert.Contains(t, string(content), `ZSH_THEME="agnoster"`)
+	assert.NotContains(t, string(content), `ZSH_THEME="robbyrussell"`)
+}
+
+func TestConfigureZshrc_IdempotentPreservesExisting(t *testing.T) {
+	tmpHome := t.TempDir()
+	t.Setenv("HOME", tmpHome)
+
+	zshrcPath := filepath.Join(tmpHome, ".zshrc")
+	existing := "# My existing config\nexport EDITOR=vim\n"
+	require.NoError(t, os.WriteFile(zshrcPath, []byte(existing), 0644))
+
+	require.NoError(t, ConfigureZshrc(false))
+	require.NoError(t, ConfigureZshrc(false))
+
+	content, err := os.ReadFile(zshrcPath)
+	require.NoError(t, err)
+
+	assert.Contains(t, string(content), "My existing config")
+	assert.Equal(t, 1, strings.Count(string(content), openbootZshrcSentinel))
+}