Function acquire_reader_with_attached 

pub async fn acquire_reader_with_attached(
    main_db: &SqliteDatabase,
    specs: Vec<AttachedSpec>,
) -> Result<AttachedReadConnection>

Acquire a read connection with attached database(s)

This function:

1. Acquires a read connection from the main database’s read pool
2. For each attached spec:
   • Validates the attached mode (read-only connections cannot attach read-write)
   • Executes ATTACH DATABASE statement
3. Returns an AttachedReadConnection guard that auto-detaches on drop

Arguments

• main_db - The main database to acquire a connection from
• specs - Specifications for databases to attach

Errors

Returns an error if:

• The main database is closed
• Cannot acquire a read connection
• Attempting to attach read-write to a read connection
• ATTACH DATABASE fails