feat: restore portable layout on shutdown and before suspend

Add WriteConfig/Prepare backend methods (real for Hyprland, no-op for
Sway), -apply/-prepare/-no-reload CLI flags, ExecStartPre cleanup and
suspend systemd hooks so a stale docked config can never leave the
built-in display disabled after resume.

internal/backend/hyprland.go

@@ -133,6 +133,88 @@ func (h *hyprlandBackend) ApplyLayout(ctx context.Context, monitors []MonitorCon
 	return nil
 }
 
+// WriteConfig writes the monitor configuration to disk without calling
+// hyprctl reload. This is used during shutdown when the compositor may
+// not be available. Resolves monitor names with a short timeout; falls
+// back to plain-name-only entries if resolution fails.
+func (h *hyprlandBackend) WriteConfig(ctx context.Context, monitors []MonitorConfig) error {
+	resolveCtx, cancel := context.WithTimeout(ctx, 3*time.Second)
+	defer cancel()
+
+	resolved, err := resolveMonitorNames(resolveCtx, monitors, h.GetMonitors, h.logger)
+	if err != nil {
+		h.logger.Warn("cannot resolve monitor names for WriteConfig — using plain names only",
+			"error", err)
+		var plain []MonitorConfig
+		for _, m := range monitors {
+			if !strings.HasPrefix(m.Name, "desc:") && !strings.HasPrefix(m.Name, "size:") {
+				plain = append(plain, m)
+			}
+		}
+		if len(plain) == 0 {
+			plain = []MonitorConfig{
+				{Name: "eDP-1", Enabled: true, Mode: "preferred", Position: "auto", Scale: 1.0},
+			}
+		}
+		resolved = plain
+	}
+
+	content := h.generateConf(resolved)
+	destPath, err := h.resolveOutputPath()
+	if err != nil {
+		return fmt.Errorf("resolve output path: %w", err)
+	}
+	if err := atomicWrite(destPath, []byte(content)); err != nil {
+		return fmt.Errorf("write monitor config: %w", err)
+	}
+	h.logger.Info("config written to disk", "path", destPath, "monitors", len(resolved))
+	return nil
+}
+
+// Prepare removes all monitor=...,disabled lines from the monitors.conf
+// file. This prevents the "no active displays" issue when Hyprland starts
+// with a stale config. If the resulting file would be empty (or doesn't
+// exist), a generic built-in entry is written as a fallback.
+func (h *hyprlandBackend) Prepare(ctx context.Context) error {
+	destPath, err := h.resolveOutputPath()
+	if err != nil {
+		return fmt.Errorf("resolve output path: %w", err)
+	}
+
+	data, err := os.ReadFile(destPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			h.logger.Debug("prepare: no config file to clean")
+			return nil
+		}
+		return fmt.Errorf("read %s: %w", destPath, err)
+	}
+
+	lines := strings.Split(string(data), "\n")
+	var cleaned []string
+	for _, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		if trimmed == "" {
+			continue
+		}
+		if strings.HasPrefix(trimmed, "monitor=") && strings.HasSuffix(trimmed, ",disabled") {
+			continue
+		}
+		cleaned = append(cleaned, line)
+	}
+
+	content := strings.Join(cleaned, "\n")
+	if strings.TrimSpace(content) == "" {
+		content = "monitor=eDP-1,preferred,auto,1\n"
+	}
+
+	if err := atomicWrite(destPath, []byte(content)); err != nil {
+		return fmt.Errorf("write cleaned config: %w", err)
+	}
+	h.logger.Info("prepare: cleaned disabled entries from config", "path", destPath)
+	return nil
+}
+
 // Events connects to the socket2 unix socket and emits parsed hotplug events.
 // On connection loss it attempts reconnection with exponential backoff.
 func (h *hyprlandBackend) Events(ctx context.Context) (<-chan Event, <-chan error) {

internal/backend/interface.go

@@ -96,6 +96,18 @@ type Backend interface {
 	// are enabled is ever visible.
 	ApplyLayout(ctx context.Context, monitors []MonitorConfig) error
 
+	// WriteConfig persists the monitor configuration to disk without
+	// reloading the compositor. Used during shutdown (SIGTERM) when
+	// the compositor may not be available. For backends that don't
+	// use a config file (e.g. Sway), this is a no-op.
+	WriteConfig(ctx context.Context, monitors []MonitorConfig) error
+
+	// Prepare ensures the monitor config file has no disabled entries.
+	// This prevents the "no active displays" issue when the compositor
+	// starts with a stale config. For backends that don't use a config
+	// file (e.g. Sway), this is a no-op.
+	Prepare(ctx context.Context) error
+
 	// Events returns a channel of hotplug events and a channel of errors.
 	// The caller must read from both channels. When ctx is cancelled,
 	// the backend closes both channels and stops listening.

internal/backend/sway.go

@@ -554,4 +554,16 @@ func (s *swayBackend) Close() error {
 	return nil
 }
 
+// ---------------------------------------------------------------------------
+// WriteConfig / Prepare (no-ops for Sway — no persistent config file)
+// ---------------------------------------------------------------------------
+
+func (s *swayBackend) WriteConfig(ctx context.Context, monitors []MonitorConfig) error {
+	return nil
+}
+
+func (s *swayBackend) Prepare(ctx context.Context) error {
+	return nil
+}
+
 

internal/daemon/daemon.go

@@ -45,11 +45,15 @@ func New(b backend.Backend, cfg *config.Config, hr *hook.Runner, logger *slog.Lo
 }
 
 // Run starts the daemon's event loop. It blocks until ctx is cancelled.
-func (d *Daemon) Run(ctx context.Context) error {
+// onReady is called after the initial state is applied (may be nil).
+func (d *Daemon) Run(ctx context.Context, onReady func()) error {
 	d.logger.Info("daemon starting", "backend", d.backend.Name())
 
 	// Phase 1: determine and apply the initial state.
 	d.applyInitialState(ctx)
+	if onReady != nil {
+		onReady()
+	}
 
 	// Phase 2: subscribe to compositor events.
 	events, _ := d.backend.Events(ctx)
@@ -105,10 +109,21 @@ func (d *Daemon) Run(ctx context.Context) error {
 // applyInitialState determines the current hardware state and applies the
 // matching layout. This is the failsafe: if the daemon crashed while docked,
 // a restart will detect that externals are gone and re-enable the built-in.
+//
+// Before determining state, it runs Prepare() to remove disabled entries
+// from the monitor config file, preventing a black screen when loading a
+// stale docked config (e.g. after undocking while suspended).
 func (d *Daemon) applyInitialState(ctx context.Context) {
 	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
 
+	// Step 1: safe fallback — remove disabled entries so at least one
+	// monitor is active even if state detection or layout application fail.
+	if err := d.backend.Prepare(ctx); err != nil {
+		d.logger.Error("safe fallback (prepare) failed", "error", err)
+	}
+
+	// Step 2: determine state and apply the correct layout.
 	monitors, err := d.getMonitorsWithRetry(ctx)
 	if err != nil {
 		d.logger.Error("cannot get monitors on startup", "error", err)
@@ -281,7 +296,10 @@ func (d *Daemon) getMonitorsWithRetry(ctx context.Context) ([]backend.MonitorInf
 	return nil, fmt.Errorf("after %d retries: %w", maxRetries, lastErr)
 }
 
-// onShutdown applies the portable layout before exit if configured.
+// onShutdown writes the portable monitor config before exit if configured.
+// It writes directly to disk without calling hyprctl reload because the
+// compositor may already be unavailable during shutdown. The config file
+// will be read next time the compositor starts.
 func (d *Daemon) onShutdown(ctx context.Context) {
 	if d.config.RestoreOnExit == nil || !*d.config.RestoreOnExit {
 		return
@@ -290,12 +308,30 @@ func (d *Daemon) onShutdown(ctx context.Context) {
 		return // already portable
 	}
 
-	d.logger.Info("shutdown: restoring portable layout")
-	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	d.logger.Info("shutdown: writing portable config")
+
+	mode, ok := d.config.Modes["portable"]
+	if !ok {
+		d.logger.Error("shutdown restore: no portable mode in config")
+		return
+	}
+
+	monitors := make([]backend.MonitorConfig, len(mode.Monitors))
+	for i, e := range mode.Monitors {
+		monitors[i] = backend.MonitorConfig{
+			Name:     e.Name,
+			Enabled:  e.Enabled,
+			Mode:     e.Mode,
+			Position: e.Position,
+			Scale:    e.Scale,
+		}
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
 	defer cancel()
 
-	if err := d.applyState(ctx, backend.StatePortable); err != nil {
-		d.logger.Error("shutdown restore failed", "error", err)
+	if err := d.backend.WriteConfig(ctx, monitors); err != nil {
+		d.logger.Error("shutdown write config failed", "error", err)
 	}
 }