To validate whether a file's symbols are still valid, the CacheService computes the file's current hash with the checksum in the cache file.

The former (current hash) is computed with this.project.fs.hash(root) which uses externals.crypto.getSha1(await externals.fs.readFile(uri)) internally. But the latter is done via this.project.externals.crypto.getSha1(doc.getText()) when the documentUpdate event is emitted.

This means that the hashes are always different when saving the cache and later validating it, putting unnecessary files in the changedFiles list.