fix(config): write through a symlinked ~/.ssh/config

internal/adapters/data/ssh_config_file/config_io.go

@@ -49,7 +49,12 @@ func (r *Repository) loadConfig() (*ssh_config.Config, error) {
 
 // saveConfig writes the SSH config back to the file with atomic operations and backup management.
 func (r *Repository) saveConfig(cfg *ssh_config.Config) error {
-	configDir := filepath.Dir(r.configPath)
+	// Write through a symlinked config (e.g. managed by a dotfiles repo) instead of replacing the link.
+	targetPath, err := r.resolveConfigPath()
+	if err != nil {
+		return fmt.Errorf("failed to resolve config path: %w", err)
+	}
+	configDir := filepath.Dir(targetPath)
 
 	tempFile, err := r.createTempFile(configDir)
 	if err != nil {
@@ -75,14 +80,27 @@ func (r *Repository) saveConfig(cfg *ssh_config.Config) error {
 		return fmt.Errorf("failed to create backup: %w", err)
 	}
 
-	if err := r.fileSystem.Rename(tempFile, r.configPath); err != nil {
+	if err := r.fileSystem.Rename(tempFile, targetPath); err != nil {
 		return fmt.Errorf("failed to atomically replace config file: %w", err)
 	}
 
 	r.logger.Infof("SSH config successfully updated: %s", r.configPath)
 	return nil
 }
 
+// resolveConfigPath returns the file the config path points to, following symlinks.
+// A config that does not exist yet resolves to the configured path.
+func (r *Repository) resolveConfigPath() (string, error) {
+	resolved, err := r.fileSystem.EvalSymlinks(r.configPath)
+	if err != nil {
+		if r.fileSystem.IsNotExist(err) {
+			return r.configPath, nil
+		}
+		return "", err
+	}
+	return resolved, nil
+}
+
 // writeConfigToFile writes the SSH config content to the specified file
 func (r *Repository) writeConfigToFile(filePath string, cfg *ssh_config.Config) error {
 	file, err := r.fileSystem.OpenFile(filePath, os.O_WRONLY|os.O_TRUNC, SSHConfigPerms)

internal/adapters/data/ssh_config_file/config_symlink_test.go

@@ -0,0 +1,61 @@
+// Copyright 2025.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ssh_config_file
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/Adembc/lazyssh/internal/core/domain"
+)
+
+func TestAddServerKeepsSymlinkedConfig(t *testing.T) {
+	sshDir := t.TempDir()
+	dotfiles := t.TempDir()
+	target := filepath.Join(dotfiles, "ssh_config")
+	link := filepath.Join(sshDir, "config")
+	writeFile(t, target, "Host a\n    HostName 10.0.0.1\n")
+	if err := os.Symlink(target, link); err != nil {
+		t.Fatal(err)
+	}
+
+	repo := newTestRepo(t, link)
+	if err := repo.AddServer(domain.Server{Alias: "b", Host: "10.0.0.2"}); err != nil {
+		t.Fatal(err)
+	}
+
+	fi, err := os.Lstat(link)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fi.Mode()&os.ModeSymlink == 0 {
+		t.Fatal("config symlink was replaced by a regular file")
+	}
+	if got := readFile(t, target); !strings.Contains(got, "Host b") {
+		t.Errorf("symlink target was not updated:\n%s", got)
+	}
+	if _, err := os.Stat(filepath.Join(sshDir, OriginalBackupName)); err != nil {
+		t.Errorf("expected original backup next to the symlink: %v", err)
+	}
+	entries, err := os.ReadDir(dotfiles)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(entries) != 1 {
+		t.Errorf("expected only the config in the symlink target dir, got %d entries", len(entries))
+	}
+}

internal/adapters/data/ssh_config_file/file_system.go

@@ -17,6 +17,7 @@ package ssh_config_file
 import (
 	"io"
 	"os"
+	"path/filepath"
 )
 
 // FileSystem interface for file operations to enable testing.
@@ -30,6 +31,7 @@ type FileSystem interface {
 	Chmod(path string, perms os.FileMode) error
 	OpenFile(path string, i int, perms os.FileMode) (*os.File, error)
 	ReadDir(dir string) ([]os.DirEntry, error)
+	EvalSymlinks(path string) (string, error)
 }
 
 // DefaultFileSystem implements FileSystem using standard os package.
@@ -73,3 +75,7 @@ func (fs DefaultFileSystem) OpenFile(path string, i int, perms os.FileMode) (*os
 func (fs DefaultFileSystem) ReadDir(dir string) ([]os.DirEntry, error) {
 	return os.ReadDir(dir)
 }
+
+func (fs DefaultFileSystem) EvalSymlinks(path string) (string, error) {
+	return filepath.EvalSymlinks(path)
+}

internal/adapters/data/ssh_config_file/helpers_test.go

@@ -0,0 +1,45 @@
+// Copyright 2025.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ssh_config_file
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"go.uber.org/zap"
+)
+
+func newTestRepo(t *testing.T, configPath string) *Repository {
+	t.Helper()
+	meta := filepath.Join(t.TempDir(), "metadata.json")
+	return NewRepository(zap.NewNop().Sugar(), configPath, meta).(*Repository)
+}
+
+func writeFile(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func readFile(t *testing.T, path string) string {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(data)
+}