feat: complete session preferences and PAM fixture gates

legacy/go/session/x11.go

@@ -1,6 +1,3 @@
-// session — X11 server setup.
-//
-// Mirrors vendor/src/post_login/x.rs:setup_x.
 package session
 
 import (
@@ -47,7 +44,7 @@ func setupX(uid, gid uint32, groups []uint32, cfg *config.Config) (*exec.Cmd, er
 		dd = "0" + dd
 	}
 
-	// Ignore SIGUSR1 so Xorg sends it when ready.
+	// Xorg sends SIGUSR1 only if the parent ignores it during startup.
 	signal.Ignore(syscall.SIGUSR1)
 
 	cmd := exec.Command(cfg.SystemShell, "-c",