feat: backup the original file before manage it by lazyssh (#49)

README.md

@@ -53,6 +53,14 @@ It is simply a UI/TUI wrapper around your existing `~/.ssh/config` file.
 - File permissions on your SSH config are preserved to ensure security.
 
 
+## 🛡️ Config Safety: Non‑destructive writes and backups
+
+- Non‑destructive edits: lazyssh only writes the minimal required changes to your ~/.ssh/config. It uses a parser that preserves existing comments, spacing, order, and any settings it didn’t touch. Your handcrafted comments and formatting remain intact.
+- Atomic writes: updates are written to a temporary file and then atomically renamed over the original, minimizing the risk of partial writes.
+- Backups:
+  - One‑time original backup: before lazyssh makes its first change, it creates a single snapshot named config.original.backup beside your SSH config. If this file is present, it will never be recreated or overwritten.
+  - Rolling backups: on every subsequent save, lazyssh also creates a timestamped backup named like: ~/.ssh/config-<timestamp>-lazyssh.backup. The app keeps at most 10 of these backups, automatically removing the oldest ones.
+
 ## 📷 Screenshots
 
 <div align="center">

internal/adapters/data/ssh_config_file/backup.go

@@ -125,3 +125,29 @@ func (r *Repository) findBackupFiles(dir string) ([]os.FileInfo, error) {
 
 	return backupFiles, nil
 }
+
+// createOriginalBackupIfNeeded creates a one-time original backup of the current SSH config.
+func (r *Repository) createOriginalBackupIfNeeded() error {
+	// If no SSH config file, nothing to do.
+	if _, err := r.fileSystem.Stat(r.configPath); os.IsNotExist(err) {
+		return nil
+	} else if err != nil {
+		return fmt.Errorf("failed to check if config file exists: %w", err)
+	}
+
+	configDir := filepath.Dir(r.configPath)
+	originalBackupPath := filepath.Join(configDir, OriginalBackupName)
+
+	if _, err := r.fileSystem.Stat(originalBackupPath); err == nil {
+		return nil
+	} else if !r.fileSystem.IsNotExist(err) {
+		return fmt.Errorf("failed to check if original backup exists: %w", err)
+	}
+
+	if err := r.copyFile(r.configPath, originalBackupPath); err != nil {
+		return fmt.Errorf("failed to create original backup: %w", err)
+	}
+
+	r.logger.Infof("Created original backup: %s", originalBackupPath)
+	return nil
+}

internal/adapters/data/ssh_config_file/config_io.go

@@ -66,6 +66,11 @@ func (r *Repository) saveConfig(cfg *ssh_config.Config) error {
 		return fmt.Errorf("failed to write config to temporary file: %w", err)
 	}
 
+	// Ensure a one-time original backup exists before any modifications managed by lazyssh.
+	if err := r.createOriginalBackupIfNeeded(); err != nil {
+		return fmt.Errorf("failed to create original backup: %w", err)
+	}
+
 	if err := r.createBackup(); err != nil {
 		return fmt.Errorf("failed to create backup: %w", err)
 	}

internal/adapters/data/ssh_config_file/crud.go

@@ -23,10 +23,11 @@ import (
 )
 
 const (
-	MaxBackups     = 10
-	TempSuffix     = ".tmp"
-	BackupSuffix   = "lazyssh.backup"
-	SSHConfigPerms = 0o600
+	MaxBackups         = 10
+	TempSuffix         = ".tmp"
+	BackupSuffix       = "lazyssh.backup"
+	SSHConfigPerms     = 0o600
+	OriginalBackupName = "config.original.backup"
 )
 
 // filterServers filters servers based on the query string.