Invoice Retainer Applications Table Structure:
id - int(11) - NO - 
invoice_id - int(11) - NO - 
retainer_amount_applied - decimal(10,2) - NO - 
retainer_balance_before - decimal(10,2) - NO - 
retainer_balance_after - decimal(10,2) - NO - 
created_at - timestamp - NO - current_timestamp()

Retainer Balance Snapshots Table Structure:
id - int(11) - NO - 
client_id - int(11) - NO - 
balance - decimal(10,2) - NO - 
as_of_date - date - NO - 
created_at - timestamp - NO - current_timestamp()

Sample Invoice Retainer Applications:
Invoice ID: 565
Client: Erica Ehrenberg
Amount Applied: 8250.00
Balance Before: 10650.00
Balance After: 2400.00
-------------------
Invoice ID: 568
Client: Ran Liu
Amount Applied: 2900.00
Balance Before: 10000.00
Balance After: 7100.00
-------------------
Invoice ID: 567
Client: Ronald Dal Bello
Amount Applied: 2700.00
Balance Before: 5000.00
Balance After: 2300.00
-------------------
Invoice ID: 565
Client: Erica Ehrenberg
Amount Applied: 8250.00
Balance Before: -5850.00
Balance After: -14100.00
-------------------
Invoice ID: 565
Client: Erica Ehrenberg
Amount Applied: 8250.00
Balance Before: 2400.00
Balance After: -5850.00
-------------------

Sample Retainer Balance Snapshots:
Client: a a
Balance: 4.00
As of Date: 2025-06-28
-------------------
Client: a a
Balance: 1.00
As of Date: 2025-06-28
-------------------
Client: a a
Balance: 3.00
As of Date: 2025-06-28
-------------------
Client: Jessen Malathu
Balance: 5000.00
As of Date: 2025-06-09
-------------------
Client: Patricia Ford
Balance: 0.00
As of Date: 2025-07-08
-------------------