🐛 fix multi-add

[felinae98]

This change is 

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.04%. Comparing base (26d060f) to head (ba71ccc).
⚠️ Report is 52 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #697   +/-   ##
=======================================
  Coverage   85.04%   85.04%           
=======================================
  Files          98       98           
  Lines        5542     5542           
=======================================
  Hits         4713     4713           
  Misses        829      829           

Flag	Coverage Δ
smoke-test	∅ <100.00%> (∅)

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[Copilot]

Pull Request Overview

This pull request addresses the multi-add bug by introducing row-level locking via .with_for_update() on both the user and target queries.

• Update the user query to lock the selected row.
• Update the target query with a similar lock to prevent concurrent modifications.