How can I automatically hyperlink tag names that are in my post body to the tag page

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If I am guessing it right, it would be a 2 step process.

  1. Store the post title and post id in an assosiative array while publishing the posts (save_post_POST_TYPE hook). For ex: array('Post Title' => 101) where 101 being the id of the post. I’d use WordPress Options table to store them and quickly retrieve when needed.

  2. Now, you can hyperlink (str_replace) them on the fly using the_content filter or even better save them as hyperlinked when saving the posts.