bonsai: add a noop delay transition at the root of the state machine, hopefully improves reliability

hosts/common/programs/bonsai.nix

@@ -53,7 +53,21 @@ in
   # plug into the (proposed) nixpkgs bonsaid service.
   # it's a user service, and since i don't use the service manager it doesn't actually activate:
   # i just steal the config file generation from it :)
-  services.bonsaid.settings = lib.mkIf cfg.enabled cfg.config.transitions;
+  services.bonsaid.settings = lib.mkIf cfg.enabled (lib.mkMerge [
+    cfg.config.transitions
+    [{
+      type = "delay";
+      transitions = [];
+      # speculative: i've observed a hang inside bonsai (rather, hare-ev) where it
+      # attempts to read from a timer, assuming it to have expired, and the read *never* returns.
+      # i think this can happen when an `exec` and a `delay` trigger simultaneously?
+      # particularly, hare-ev does the exec action callback, during which bonsaid enters a node w/o delay and *disables* the timer, and then reading the timer hangs.
+      # if true, then adding a delay to the root node alleviates that (so long as all other nodes also have delays).
+      #
+      # long term, it may be best to move away from bonsai. aside from the above, it's really easy to get it to segfault.
+      delay_duration = 30000 * 1000000;
+    }]
+  ]);
   # vvv not actually necessary. TODO: delete this line once the service is upstreamed?
   services.bonsaid.enable = lib.mkIf cfg.enabled true;
 }