In a realm where code was magic and programming incantations shaped the world, the Wishmaster embarked on a new adventure. This day marked the seventh in a saga filled with trials and triumphs as the Wishmaster sought to enhance the Codex with the ability to filter and order the sacred scrolls known as posts.

The day began with the introduction of a search functionality, bringing forth a whimsical filter bar that danced under the navigation menu. This new addition allowed visitors to sift through the mystical posts by their associated tags. As the Wishmaster crafted the user interface, each tag transformed into a clickable entity, glowing with potential. With the flick of a wand—or perhaps a click of a mouse—the tags would reveal their hidden associations, fetching the posts that bore their mark.

The power of the fetch API was harnessed, allowing for seamless communication between the front end and the enchanted back end. The function fetchPostsByTags was summoned to pull relevant data based on the selected tags. Yet, the path was not without obstacles. Duplicate tags threatened to clutter the Codex, but with wisdom from prior explorations, the Wishmaster learned to banish these duplicates from the realm of data.

In the midst of this journey, the Wishmaster encountered the ancient wisdom of JavaScript and Python, weaving together the strengths of both languages. The intricacies of managing arrays in JavaScript were unveiled, teaching the importance of maintaining clarity and efficiency when adding or removing elements. With each iteration, the code grew cleaner and more robust, showcasing the magic of refactoring.

As the day progressed, the Wishmaster sought to format the date of each post, ensuring it matched the enchanting layout of the Codex. By employing Python’s strftime method, the dates transformed into the elegant YYYY-MM-DD format, enhancing the readability of the sacred scrolls.

Finally, with a wave of a hand, the Wishmaster ordered the posts by date, ensuring that the most recent scrolls would grace the top of the Codex. The enchantment was complete: the Codex now flowed like a well-crafted tale, guiding visitors effortlessly through the realms of information.

As the sun set on this productive day, the Wishmaster reflected on the journey: a harmonious blend of user experience, data management, and aesthetic grace. With each challenge met and every spell cast, the Codex grew stronger, a testament to the power of perseverance and the magic of programming.