refactor: move backend options into backend_config section

- Add BackendConfig map[string]any to Config struct
- Deprecate top-level output_path (backward compatible via EffectiveBackendConfig())
- NewHyprland now accepts opts map[string]any instead of raw outputPath
- Factory signature unified to func(*slog.Logger, map[string]any) for all backends
- Update README with backend_config docs and fix Sway skeleton signature
- Update example.yaml to show backend_config instead of output_path

README.md

@@ -166,6 +166,25 @@ Two match modes in the `external` list:
 
 Run `hyprctl monitors all` to see your monitor names and descriptions.
 
+### Backend-specific configuration
+
+Use the `backend_config` section for compositor-specific options:
+
+```yaml
+backend_config:
+  output_path: ~/.config/hypr/custom-monitors.conf   # override generated config path
+```
+
+**Hyprland keys:**
+
+| Key | Type | Default | Description |
+|-----|------|---------|-------------|
+| `output_path` | string | `~/.config/hypr/monitors.conf` | Path to the generated monitor config file. Supports `~` expansion. |
+
+The deprecated top-level `output_path` key still works — `backend_config` takes priority if both are set.
+
+When adding new compositor backends, their options go into the same `backend_config` section without changing the core config structure.
+
 ### Hook commands
 
 Hooks are shell commands executed via `sh -c`. Each command gets a **30-second timeout**. Commands run in parallel — one slow hook won't block others.
@@ -273,8 +292,9 @@ package backend
 
 type swayBackend struct { logger *slog.Logger }
 
-func NewSway(logger *slog.Logger) (Backend, error) {
+func NewSway(logger *slog.Logger, opts map[string]any) (Backend, error) {
     // Check if SWAYSOCK is set and swaymsg is available
+    // opts carries backend_config from the config file
     return &swayBackend{logger: logger}, nil
 }
 

cmd/monitor-lets-go/main.go

@@ -60,7 +60,9 @@ func run(logger *slog.Logger) error {
 	logger.Info("config loaded", "path", configPath, "backend", cfg.Backend)
 
 	// Resolve the backend (auto-detect or explicit).
-	b, err := resolveBackend(cfg.Backend, cfg.OutputPath, logger)
+	// EffectiveBackendConfig merges deprecated top-level keys
+	// into the backend_config map with proper priority.
+	b, err := resolveBackend(cfg.Backend, cfg.EffectiveBackendConfig(), logger)
 	if err != nil {
 		return fmt.Errorf("resolve backend: %w", err)
 	}
@@ -86,11 +88,11 @@ func run(logger *slog.Logger) error {
 // resolveBackend returns the first available backend. When backendName is
 // "auto", backends are probed in priority order. To add a new backend,
 // register it in the backends slice below.
-func resolveBackend(backendName, outputPath string, logger *slog.Logger) (backend.Backend, error) {
+func resolveBackend(backendName string, backendConfig map[string]any, logger *slog.Logger) (backend.Backend, error) {
 	// Ordered by priority: preferred backends first.
 	backends := []struct {
 		name    string
-		factory func(*slog.Logger, string) (backend.Backend, error)
+		factory func(*slog.Logger, map[string]any) (backend.Backend, error)
 	}{
 		{"hyprland", backend.NewHyprland},
 		// Future: {"sway", backend.NewSway},
@@ -99,7 +101,7 @@ func resolveBackend(backendName, outputPath string, logger *slog.Logger) (backen
 
 	if backendName == "auto" {
 		for _, entry := range backends {
-			b, err := entry.factory(logger, outputPath)
+			b, err := entry.factory(logger, backendConfig)
 			if err == nil {
 				logger.Info("auto-detected backend", "name", b.Name())
 				return b, nil
@@ -112,7 +114,7 @@ func resolveBackend(backendName, outputPath string, logger *slog.Logger) (backen
 	// Explicit backend selection.
 	for _, entry := range backends {
 		if entry.name == backendName {
-			b, err := entry.factory(logger, outputPath)
+			b, err := entry.factory(logger, backendConfig)
 			if err != nil {
 				return nil, fmt.Errorf("backend %s: %w", backendName, err)
 			}

internal/backend/hyprland.go

@@ -30,6 +30,7 @@ type hyprlandBackend struct {
 
 	// outputPath overrides the generated monitor config file path.
 	// Empty means the default: ~/.config/hypr/monitors.conf.
+	// Read from backend_config.output_path at construction time.
 	outputPath string
 
 	// conn is the current socket2 connection; guarded by mu.
@@ -40,9 +41,12 @@ type hyprlandBackend struct {
 // NewHyprland creates a Hyprland backend. The backend auto-detects the
 // Hyprland instance signature from the environment.
 //
-// outputPath overrides the generated monitor config file location.
+// opts carries backend-specific configuration from the config file's
-// When empty, defaults to ~/.config/hypr/monitors.conf.
+// backend_config section. Hyprland supports:
-func NewHyprland(logger *slog.Logger, outputPath string) (Backend, error) {
+//
+//	output_path — path to the generated monitor config file
+//	              (default: ~/.config/hypr/monitors.conf)
+func NewHyprland(logger *slog.Logger, opts map[string]any) (Backend, error) {
 	sig := os.Getenv("HYPRLAND_INSTANCE_SIGNATURE")
 	if sig == "" {
 		return nil, errors.New("HYPRLAND_INSTANCE_SIGNATURE is not set; is Hyprland running?")
@@ -57,6 +61,13 @@ func NewHyprland(logger *slog.Logger, outputPath string) (Backend, error) {
 		return nil, fmt.Errorf("socket2 not found at %s: %w", socketPath, err)
 	}
 
+	var outputPath string
+	if opts != nil {
+		if v, ok := opts["output_path"]; ok {
+			outputPath, _ = v.(string)
+		}
+	}
+
 	return &hyprlandBackend{logger: logger, outputPath: outputPath}, nil
 }
 

internal/config/config.go

@@ -52,9 +52,16 @@ type Config struct {
 
 	// OutputPath overrides the generated monitor config file path.
 	// Supports ~ for home directory expansion.
+	// Deprecated: use backend_config.output_path instead.
 	// Empty means the default: ~/.config/hypr/monitors.conf.
 	OutputPath string `yaml:"output_path"`
 
+	// BackendConfig holds backend-specific configuration options.
+	// Keys and values vary by the selected backend.
+	// Hyprland supports:
+	//   output_path — path to the generated monitor config file
+	BackendConfig map[string]any `yaml:"backend_config"`
+
 	// External lists monitor identifiers that trigger docked mode.
 	// Each entry is a name (DP-1) or a desc: prefix (desc:Dell U2723QE).
 	External []string `yaml:"external"`
@@ -158,6 +165,25 @@ func (c *Config) validate() error {
 	return nil
 }
 
+// EffectiveBackendConfig merges top-level deprecated backend keys
+// (OutputPath) into the BackendConfig map. backend_config values
+// take priority over deprecated top-level keys.
+//
+// The caller receives a non-nil map even when no backend_config is
+// set and no deprecated keys are present.
+func (c *Config) EffectiveBackendConfig() map[string]any {
+	bc := c.BackendConfig
+	if bc == nil {
+		bc = make(map[string]any)
+	}
+	if c.OutputPath != "" {
+		if _, exists := bc["output_path"]; !exists {
+			bc["output_path"] = c.OutputPath
+		}
+	}
+	return bc
+}
+
 // countEnabled returns how many MonitorEntries are enabled.
 func countEnabled(entries []MonitorEntry) int {
 	n := 0

monitor-lets-go.example.yaml

@@ -15,10 +15,12 @@ poll_interval: 5s
 # Whether to restore the portable layout when the daemon shuts down.
 restore_on_exit: true
 
-# Optional: override where the generated Hyprland monitor config is written.
+# Backend-specific options. Keys depend on the selected backend.
-# Supports ~ for home directory expansion.
+# Hyprland supports:
-# Defaults to ~/.config/hypr/monitors.conf.
+#   output_path — path to the generated monitor config file
-# output_path: ~/.config/hypr/custom-monitors.conf
+#                 (default: ~/.config/hypr/monitors.conf)
+# backend_config:
+#   output_path: ~/.config/hypr/custom-monitors.conf
 
 # External monitors that trigger docked mode.
 #   Plain name: matches the connector name (e.g. DP-1, HDMI-A-1).