I'm attempting to modify/override functionalities of the CQ client library manager and I was wondering if anyone is familiar with where the code lives?
I've found some js that controls channel detection in DefaultChannelDetector.js and CQClientLibraryManager.js which seemingly only deals with channels, not dependencies or embedding. These are served as a clientlib, etc/clientlibs/foundation/librarymanager.js which I assume can be overriden by pointing htmllibmanager.clientmanager in apps/system/config/com.day.cq.widget.impl.HtmlLibraryManagerImpl.config
So for modifying, I would need to know where the code lives. For overriding, I assume I point the htmllibmanager.clientmanager toward something else but I would still need to know how to access dependencies/categories/embed properties of clientlibs.
Additionally, any low-level insight into how the cq:includeClientLib tag works would be appreciated. (low-level as in point to the code that implements it)
The vast majority of the Client Library functionality is in the HtmlLibraryManager component implemented OOB by the HtmlLibraryManagerImpl class in the com.day.cq.cq-widgets bundle. You can look up this component in Felix to see what bundle it is in and then decompile that bundle if you need to look at the guts of what the implementation does.
At a high level this component handles both the generation of the results of the cq:includeClientLib tag and the concatenation and compilation of libraries when a library URL is requested. Speaking specifically to the cq:includeClientLib tag, the HtmlLibraryManager's writeIncludes method will determine, based on parameters of the request and parameters provided in the cq:includeClientLib tag, how to write includes to the page for the existing libraries.
In the case of dynamic libraries (libraries which are channel based) it will write calls to the library manager JavaScript mechanisms which will dynamically include libraries based on the user's channel. Otherwise appropriate script and link tags for JavaScript and CSS respectively will be written for the requested libraries and their dependencies.