hmm

modules/nixos/services/matrix/default.nix

@@ -149,6 +149,17 @@ let
       systemd.services.matrix-synapse = {
         after = [ "postgresql.service" ];
         requires = [ "postgresql.service" ];
+        # Prevent unbounded restart loops (e.g. when authentik/OIDC is unreachable at startup).
+        # Without this, synapse will respawn hundreds of times per hour, flooding the kernel
+        # message buffer and risking filesystem corruption on unclean shutdown.
+        startLimitIntervalSec = 300; # 5 minute window
+        startLimitBurst = 5; # max 5 attempts per window, then give up until manual intervention
+        serviceConfig = {
+          # Exponential backoff: starts at 10s, doubles each attempt up to 5 minutes
+          RestartSec = "10s";
+          RestartSteps = 5;
+          RestartMaxDelaySec = "5min";
+        };
       };
     };
   };