The region_names dictionary was a redundant index that needed manual
sync when HistoryManager modified region names. This caused bugs where
resolve_query couldn't find regions by their new (history-modified) names.
Instead of maintaining two data structures (regions[id] and region_names[name]),
we now only use regions[id] as the single source of truth. The _resolve_region
function iterates over regions.values() to find matches by name.
This approach:
- Eliminates the sync bug entirely
- Simplifies the codebase
- Has negligible performance impact (region count is small)
Co-authored-by: Zihao Xu <xzhseh@gmail.com>
