This functionality is called by the Planner Policy and is used to retrieve possible categories, which might match the user search query.
Queries are formatted as CategoryQuery, which consists of the following fields:
message CategoryQuery{
string text = 1;
int32 top_k = 2;
}The results are stored as CategoryDocument which can be understood by the system and encodes a category.
Each category contains sub_categories, and each sub_category also has taskmap candidates.
Currently, the retrieval is done with a Pyserini index which is built as part of the offline pipeline in TaxonomyBuildRunner.
