diff --git a/src/wuttafarm/web/util.py b/src/wuttafarm/web/util.py
index ec88525..938c84b 100644
--- a/src/wuttafarm/web/util.py
+++ b/src/wuttafarm/web/util.py
@@ -27,7 +27,26 @@ from pyramid import httpexceptions
 from webhelpers2.html import HTML
 
 
-def get_farmos_client_for_user(request):
+def get_farmos_client_for_user(request, main_thread=True):
+    """
+    Make and return a new farmOS API client instance.
+
+    This is a wrapper around
+    :meth:`~wuttafarm.farmos.handler.FarmOSHandler.get_farmos_client()`
+    with conveniences to automatically handle token refresh for the
+    current user session.
+
+    :param request: Current web request; this determines the user.
+
+    :param main_thread: Boolean indicating whether this client is for
+       use within the main thread, or a separate one.  In the latter
+       case it must perform certain extra steps to help with token
+       refresh.  This defaults to ``True`` in which case the client is
+       part of the main thread, i.e. the normal request/response
+       cycle.
+
+    :returns: farmOS API client instance
+    """
     token = request.session.get("farmos.oauth2.token")
     if not token:
         raise httpexceptions.HTTPForbidden()
@@ -39,14 +58,14 @@ def get_farmos_client_for_user(request):
     token = dict(token)
 
     def token_updater(token):
-        save_farmos_oauth2_token(request, token)
+        save_farmos_oauth2_token(request, token, main_thread=main_thread)
 
     config = request.wutta_config
     app = config.get_app()
     return app.get_farmos_client(token=token, token_updater=token_updater)
 
 
-def save_farmos_oauth2_token(request, token):
+def save_farmos_oauth2_token(request, token, main_thread=True):
     """
     Common logic for saving the given OAuth2 token within the user
     session.  This function is called from 2 places:
@@ -61,6 +80,12 @@ def save_farmos_oauth2_token(request, token):
     # save token to user session
     request.session["farmos.oauth2.token"] = token
 
+    if not main_thread:
+        # nb. must call persist() explicitly in separate thread, since
+        # pyramid_beaker may not be in effect (iiuc?)
+        request.session.save()
+        request.session.persist()
+
 
 def use_farmos_style_grid_links(config):
     return config.get_bool(f"{config.appname}.farmos_style_grid_links", default=True)
diff --git a/src/wuttafarm/web/views/master.py b/src/wuttafarm/web/views/master.py
index c828b96..e010f56 100644
--- a/src/wuttafarm/web/views/master.py
+++ b/src/wuttafarm/web/views/master.py
@@ -120,7 +120,7 @@ class WuttaFarmMasterView(MasterView):
         if self.app.is_farmos_mirror():
             if self.creating:
                 session.flush()  # need the new uuid
-            client = get_farmos_client_for_user(self.request)
+            client = get_farmos_client_for_user(self.request, main_thread=False)
             thread = threading.Thread(
                 target=self.auto_sync_to_farmos, args=(client, obj.uuid)
             )
@@ -168,7 +168,7 @@ class WuttaFarmMasterView(MasterView):
 
         # maybe delete from farmOS also
         if farmos_uuid:
-            client = get_farmos_client_for_user(self.request)
+            client = get_farmos_client_for_user(self.request, main_thread=False)
             # nb. must use separate thread to avoid some kind of race
             # condition (?) - seems as though maybe a "boomerang"
             # effect is happening; this seems to help anyway