Ticket #64126: A Game-Changing Update for Output Buffers and HTTP Headers

The WordPress community is abuzz with excitement as a new ticket, #64126, has been created, addressing a long-standing issue that affects the way plugins interact with output buffers. In this update, we'll delve into what's happening behind the scenes and explore how it will impact your plugin development experience.

At first glance, the problem seems relatively minor: sending HTTP headers after rendering an HTML template. However, for those who have struggled with this challenge in the past, you know that it can be a frustrating and time-consuming process. Until now, there was no straightforward way to achieve this using WordPress's built-in functionality.

The current workaround involves modifying the wp_template_enhancement_output_buffer filter to run at an extremely high priority level (PHP_INT_MAX) while preserving the original buffer contents. This hack allows plugins to inject their custom headers, like Server-Timing, into the output stream. However, this approach comes with its own set of risks and limitations.

The good news is that #64126 brings a much-needed solution to the table. With this update, core will introduce an opt-in way for developers to output buffer a rendered template, enabling plugins to send HTTP headers like Server-Timing in a seamless and controlled manner.

This new feature has significant implications for plugin development, particularly those that rely on customizing the response body or sending late headers. By providing a dedicated action to fire right before the output buffer callback returns, WordPress is giving developers the tools they need to craft more sophisticated responses without resorting to workarounds like modifying the filter.

This development not only improves the overall plugin ecosystem but also provides a more consistent and predictable experience for users. As the WordPress community continues to push the boundaries of what's possible with this platform, it will be exciting to see how plugins take advantage of these new features to deliver enhanced functionality and user experiences.