The general idea of Toru is to have a to-do app which uses distinct, mutually exclusive vaults of tasks with configuration which is in a human readable and easy to export and import format (to completely separate personal, work, study, etc), however within a vault, to use tags and dependencies as a means of organising notes, rather than mutually exclusive folders.
For example, in a given vault, one may have a big project they are working on. This project, and all of the subtasks are listed together on the top level (and not organised according to projects). In order to conveniently organise and view tasks, use tags and dependencies, and filter searches for tasks to get the desired information. This allows you to categorise tasks even when they do not fall into any one obvious category.
Toru stores tasks and other metadata locally in the folder of the vault in the interest of making that data easily accessible for backups, syncing across devices, and to be easy to export from. However, because Toru uses sequential IDs, sharing a vault across computers asynchronously, such as with Git, can cause different notes to be in conflict with each other. If all vault metadata is synced across devices completely before use, such conflicts can be avoided.