Restart InputPlumber and return to source session when switching back to Steam

Fixes broken input after returning from an exclusive OpenGamepadUI session:
the OGPU session leaves InputPlumber intercepting the gamepad in Block mode,
so Steam cannot read it. Restart InputPlumber before switching, and return to
the session recorded by os-session-select instead of hardcoding 'steam' so
the autologin config is preserved.

plugin.gd

@@ -12,6 +12,20 @@ const POWER_MENU_GROUP := "power_menu"
 const BUTTON_NAME := "SwitchToSteamButton"
 const MAX_ATTEMPTS := 600
 
+# ChimeraOS records the session that was active before OpenGamepadUI took over
+# in this file when the OpenGamepadUI session is entered. We return to that
+# session instead of hardcoding a name so the autologin config is not mangled.
+const RETURN_SESSION_FILE := "/.config/chimeraos-session-return"
+const DEFAULT_RETURN_SESSION := "gamescope-session-steam-plus"
+
+# Sessions os-session-select can be told to return to (matching the values it
+# writes to the return-session file).
+const RETURN_SESSIONS := [
+	"gamescope-session-steam-plus",
+	"gamescope-session-steam",
+	"gamescope-session-opengamepadui",
+]
+
 
 func _ready() -> void:
 	logger = Log.get_logger("SessionSwitch", Log.LEVEL.INFO)
@@ -52,7 +66,7 @@ func _try_add_button() -> bool:
 	button.name = BUTTON_NAME
 	button.set("click_focuses", false)
 	button.set("text", "Switch to Steam")
-	button.pressed.connect(_switch_session.bind("steam"))
+	button.pressed.connect(_switch_session)
 
 	container.add_child(button)
 	container.move_child(button, exit_button.get_index())
@@ -70,9 +84,41 @@ func _has_session_switcher() -> bool:
 	return FileAccess.file_exists(SESSION_SELECT_PATH)
 
 
-## Switches to the given session using the OS session switcher.
+## Switches back to the session that was active before OpenGamepadUI took
-func _switch_session(name: String) -> void:
+## over, using the OS session switcher.
+func _switch_session() -> void:
+	_restart_inputplumber()
+	var target := _get_return_session()
 	var out: Array = []
-	var code := OS.execute(SESSION_SELECT_PATH, [name], out)
+	var code := OS.execute(SESSION_SELECT_PATH, [target], out)
 	if code != OK:
-		logger.error("Unable to switch sessions: " + out[0])
+		logger.error("Unable to switch sessions: " + _result_text(out))
+
+
+## Restarts InputPlumber before switching back so the exclusive OpenGamepadUI
+## session does not leave the gamepad intercepted (blocked) for Steam.
+## ChimeraOS ships passwordless sudo for exactly this command in its default
+## sudoers, so the switch itself remains non-interactive.
+func _restart_inputplumber() -> void:
+	var out: Array = []
+	var code := OS.execute("sudo", ["-n", "systemctl", "restart", "inputplumber"], out)
+	if code != OK:
+		logger.warning("Unable to restart InputPlumber: " + _result_text(out))
+
+
+## Returns the session recorded by os-session-select before OpenGamepadUI was
+## entered, falling back to the ChimeraOS default Steam session.
+func _get_return_session() -> String:
+	var home := OS.get_environment("HOME")
+	if home.is_empty():
+		return DEFAULT_RETURN_SESSION
+	var file := FileAccess.open(home + RETURN_SESSION_FILE, FileAccess.READ)
+	if file:
+		var session := file.get_as_text().strip_edges()
+		if session in RETURN_SESSIONS:
+			return session
+	return DEFAULT_RETURN_SESSION
+
+
+func _result_text(out: Array) -> String:
+	return out[0] if not out.is_empty() else ""

plugin.json

@@ -1,7 +1,7 @@
 {
   "plugin.id": "session-switch",
   "plugin.name": "Session Switch",
-  "plugin.version": "0.1.0",
+  "plugin.version": "0.1.1",
   "plugin.min-api-version": "1.1.0",
   "plugin.link": "https://forge.thergic.ar/jose/steam-button-opengamepadui-plugin",
   "plugin.source": "https://forge.thergic.ar/jose/steam-button-opengamepadui-plugin",