Function should_index 

pub fn should_index(project_dir: &Path) -> bool

True when path is the user’s HOME directory or the filesystem root. Either one hosts a massive tree the indexer should never walk in full. Policy: should the indexer walk this directory?

Used both internally (index_all top guard) and externally by agent/services.rs to decide whether to even spawn the indexer task after a /cd. Returns false for:

• $HOME or / — walking pulls in Library / Downloads / Documents trees with hundreds of thousands of paths.
• “Umbrella” dirs — the target itself has no project marker but three or more of its immediate child dirs are projects (e.g. ~/project with 30+ repos inside). Indexing walks every child.

The escape hatch is [looks_like_project]: drop a .atomcode (or any other marker) at the root and indexing kicks in.