clangd does not (by default) parse/index source files not explicitly part of the project (source files linked/added to the project) unless they are manually added to the command_compile.json file. Since the command_compile.json file is auto-generated, it is not generally recommended to manually modify this file.

The typical use case where this is an issue is for cases when working with source files in that part of an external library being linked in. The source files are not part of the project.

Since modifying command_compile.json is not desirable, one option to explore is using clangd-indexer to pre-index the library source and then passing in the generated index file to clangd. The idea is to have a GUI interface in CCS to allow users to add source directories and then have CCS run the clangd-indexer under the hood, generate the index file, and automatically restart clangd with that index file. This would need to be explored first for feasibility.