# Context
We currently have a tracked value of `topic` in the header service that we utilize across the app for determining the presence of a topic.
A simple example is: If you are in a topic, and scroll down the page, we need to communicate to the header that a topic is present and we change the styling of the header.
The issue with this logic is that when entering a topic (and you are at the top of the page), we **haven't** set the topic on the header service yet. We only set the topic when you have scrolled down on the page (set by `app/components/discourse-topic.js`)
This is unhelpful behavior when you are utilizing a plugin outlet that is receiving the `topic` from the header:
17add599e3/app/assets/javascripts/discourse/app/components/header/topic/info.gjs (L85)
As the `topic` won't be present until you scroll down the page.
# Changes
This PR adds a tracked `inTopic` value to the header service that is a boolean value. This is to let the app know
> Yes, we are scrolled within a topic
And instead sets the tracked `topic` value immediately, if you are loading a topic, to allow the necessary data to be populated to the plugin outlets on page load.
caa29ec973