After loading planner.el, make sure that planner-id.el is in your load path and add this to your .emacs (or _emacs):
(require 'planner-id)
This module modifies the behavior of planner.el, adding global task IDs so that tasks can be edited and updated. Planner IDs are of the form ‘{{Identifier:Number}}’.
Non-nil means automatically add global task IDs to newly-created tasks. If nil, use planner-id-add-task-id to add IDs to existing tasks, or planner-id-add-task-id-to-all to add to all tasks on the current page.
Non-nil means automatically update linked tasks whenever a page is saved. If nil, use planner-update-task to update the linked task. By default, linked tasks are automatically updated.
File that contains ID tracking data. This file is automatically overwritten.
The following interactive functions are defined in planner-id.el:
Display the linked task page. If info is specified, follow that task instead.
Add a task ID for the current task if it does not have one yet. Update the linked task page, if any.
Update all tasks on this page. Completed or cancelled tasks are not updated. This can be added to
write-file-functions. If force is non-nil, completed and cancelled tasks are also updated.