cdrop — 跨 OS 剪贴板与文件传输服务

Commilitia Drop：自托管的跨设备剪贴板同步与点对点文件传输。

- 后端 Go（chi / SQLite WAL / SSE Hub / WebRTC signaling + 状态机 / Relay ring buffer），编译进单个 distroless 镜像（前端 go:embed）。
- 前端 React + TanStack Router + Zustand，自实现 SSE + WebRTC P2P，NAT 受阻时回退服务端中继；聚珍（Juzhen）CJK 综合排版。
- 桌面端 Wails v2（macOS / Windows），瘦客户端复用 web。
- 鉴权 OIDC PKCE（自建 Casdoor 等），refresh_token 信封加密存系统密钥库；iOS Shortcut 用 HS256 scoped token。

架构文档与变更记录见 docs 分支（PROJECT_BRIEF / FRONTEND_DESIGN / CHANGELOG）。

本次为公开发布初始提交：完整开发历史（含部署细节）留存于私有归档，公开仓库自此干净起步。

desktop/platform/appsettings.go

@@ -0,0 +1,104 @@
+package platform
+
+import (
+	"encoding/json"
+	"errors"
+	"os"
+	"path/filepath"
+)
+
+// DesktopConfig is the desktop-only preference set, persisted as JSON under the
+// user config dir. json tags are the contract with the WebView settings page.
+type DesktopConfig struct {
+	ClipboardSyncEnabled bool   `json:"clipboard_sync_enabled"`
+	LaunchAtLogin        bool   `json:"launch_at_login"`
+	DeviceName           string `json:"device_name"`  // empty = use the hostname
+	DownloadDir          string `json:"download_dir"` // empty = system Downloads dir
+}
+
+// ResolveDeviceName returns the persisted device name, or the hostname when the
+// user hasn't renamed it. Persisting it Go-side is required because the WebView's
+// localStorage doesn't survive restart on the wails:// scheme (see session.go).
+func ResolveDeviceName() string {
+	cfg, _ := LoadConfig()
+	if cfg.DeviceName != "" {
+		return cfg.DeviceName
+	}
+	if h, err := os.Hostname(); err == nil && h != "" {
+		return h
+	}
+	return "cdrop-desktop"
+}
+
+// DefaultConfig is what a fresh install gets: clipboard sync on, no autostart.
+func DefaultConfig() DesktopConfig {
+	return DesktopConfig{ClipboardSyncEnabled: true, LaunchAtLogin: false}
+}
+
+// ResolveDownloadDir returns the directory received files land in: the user's
+// configured override, or the system Downloads dir when unset.
+func ResolveDownloadDir() string {
+	cfg, _ := LoadConfig()
+	if cfg.DownloadDir != "" {
+		return cfg.DownloadDir
+	}
+	return DefaultDownloadDir()
+}
+
+// DefaultDownloadDir is ~/Downloads (the OS default download folder; its path is
+// stable across locales on macOS/Windows). Falls back to the cwd if the home
+// dir can't be resolved.
+func DefaultDownloadDir() string {
+	if home, err := os.UserHomeDir(); err == nil && home != "" {
+		return filepath.Join(home, "Downloads")
+	}
+	return "."
+}
+
+// configPath is ~/Library/Application Support/cdrop/config.json on macOS
+// (os.UserConfigDir resolves the per-OS base).
+func configPath() (string, error) {
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "cdrop", "config.json"), nil
+}
+
+// LoadConfig reads the persisted config, falling back to defaults when the file
+// is absent or unreadable so the app always has a usable preference set.
+func LoadConfig() (DesktopConfig, error) {
+	p, err := configPath()
+	if err != nil {
+		return DefaultConfig(), err
+	}
+	data, err := os.ReadFile(p)
+	if errors.Is(err, os.ErrNotExist) {
+		return DefaultConfig(), nil
+	}
+	if err != nil {
+		return DefaultConfig(), err
+	}
+	cfg := DefaultConfig()
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return DefaultConfig(), err
+	}
+	return cfg, nil
+}
+
+// SaveConfig writes the config atomically-ish (mkdir + write) under the user
+// config dir.
+func SaveConfig(cfg DesktopConfig) error {
+	p, err := configPath()
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+		return err
+	}
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(p, data, 0o644)
+}