Add support for controlling the sound played with notifications

docs/desktop-notifications.rst

@@ -333,6 +333,25 @@ The terminal *must not* send a response unless report is requested with
 
 .. _notifications_query:
 
+Playing a sound with notifications
+-----------------------------------------
+
+.. versionadded:: 0.36.0
+   The ability to control the sound played with notifications
+
+By default, notifications may or may not have a sound associated with them
+depending on the policies of the OS notifications service. Sometimes it
+might be useful to ensure a notification is not accompanied by a sound.
+This can be done by using the ``s`` key which accepts :ref:`base64` encoded
+UTF-8 text as its value. Using a value of ``silent`` means the notification
+will not be accompanied with a sound. A value of ``system`` (the default)
+means that the OS notifications default policies are followed. Any other name
+is implementation dependent. For example, on Linux, one can use the `standard
+sound names
+<https://specifications.freedesktop.org/sound-naming-spec/latest/#names>`__.
+Support for sounds can be queried as described below.
+
+
 Querying for support
 -------------------------
 
@@ -372,6 +391,12 @@ Key      Value
          ``p`` key that the terminal implements). These must contain at least
          ``title``.
 
+``s``    Comma separated list of keywords ``silent`` and ``xdg-names`` indicating
+         support for silent notifications and for passing of `Freedesktop
+         standard sound names
+         <https://specifications.freedesktop.org/sound-naming-spec/latest/#names>`__ to the
+         desktop notification service for custom sounds.
+
 ``u``    Comma separated list of urgency values that the terminal implements.
          If urgency is not supported, the ``u`` key must be absent from the
          query response.
@@ -441,6 +466,10 @@ Key      Value                 Default    Description
          ``?``, ``alive``,
          ``buttons``
 
+``s``    :ref:`base64`         ``system`` The sound name to play with the notification. ``silent`` means no sound.
+         encoded sound                    ``system`` means to play the default sound, if any, of the platform notification service.
+         name                             Other names are implementation dependent.
+
 ``t``    :ref:`base64`         ``unset``  The type of the notification. Used to filter out notifications. Can be specified multiple times.
          encoded UTF-8
          notification type

docs/notifications.py

@@ -34,6 +34,9 @@ def main(nc: NotificationCommand) -> bool:
     if 'unwanted' in nc.title.lower():
         return True
 
+    # force the notification to be silent
+    nc.sound_name = 'silent'
+
     # filter out notifications from the application badapp
     if nc.application_name == 'badapp':
         return True