Expense – Extra expense displayed when deleting a split expense offline

[mitarachim]

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Version Number: v9.3.83-3
Reproducible in staging?: Yes
Reproducible in production?: No
If this was caught during regression testing, add the test name, ID and link from BrowserStack: https://test-management.browserstack.com/projects/2219752/test-runs/TR-34310/folder/13176791/90921087/1444112006
Email or phone of affected tester (no customers): applausetester+abd2r2@applause.expensifail.com
Issue reported by: Applause Internal Team
Bug source: Exploratory - Significant User Experience Deterioration
Device used: Web, Android, IOS
App Component: Money Requests

Action Performed:

1. Go to staging.new.expensify.com.
2. Open a workspace chat and create a manual expense.
3. Split the created expense.
4. Go offline.
5. Select one of the split expenses and delete it.

Expected Result:

Only the selected split expense should be deleted, and no extra expense should appear while offline.

Actual Result:

An extra expense is displayed after deleting one of the split expenses while offline.

Workaround:

Unknown

Platforms:

• Android: App
• Android: mWeb Chrome
• iOS: App
• iOS: mWeb Safari
• iOS: mWeb Chrome
• Windows: Chrome
• MacOS: Chrome / Safari

Screenshots/Videos

Bug7164595_1779910825197.2026-05-27_21-30-00.mp4

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[melvin-bot]

Triggered auto assignment to @yuwenmemon (DeployBlockerCash), see https://stackoverflowteams.com/c/expensify/questions/9980/ for more details.

[melvin-bot]

💬 A slack conversation has been started in #expensify-open-source

[github-actions]

👋 Friendly reminder that deploy blockers are time-sensitive ⏱ issues! Check out the open `StagingDeployCash` deploy checklist to see the list of PRs included in this release, then work quickly to do one of the following:

1. Identify the pull request that introduced this issue and revert it.
2. Find someone who can quickly fix the issue.
3. Fix the issue yourself.

[OSBotify]

Investigation Summary

Classification: Frontend bug
Causing PR: #84382 - "Add splits for unreported expenses" by @ZhenjaHorbach (High confidence)
Related Issues: None

Recommendation: REVERT

PR 84382 introduced a regression in offline split-expense deletion. The fix is contained within a single, identifiable line change in SplitTransactionUpdate.ts that directly maps to the reported symptom.

Assigned: @ZhenjaHorbach (PR author), @dmkt9, @lakchote (approving reviewers) from highest-confidence causing PR only
Labels: DeployBlockerCash kept (Frontend bug — App PR caused the issue). DeployBlocker not present, no change needed.

Detailed Analysis

Evidence

• The issue is staging-only (not reproducible in production), which aligns with the staging deploy containing PR 84382.
• The bug is triggered by: create a manual expense in a workspace chat, split it, go offline, then delete one of the split expenses — an extra expense appears.
• PR 84382 ("Add splits for unreported expenses") was merged on 2026-05-27 and is included in the current staging deploy (v9.3.83-3 / 9.3.84-0).
• PR 84382 directly modifies src/libs/actions/IOU/SplitTransactionUpdate.ts, src/libs/actions/IOU/SplitExpenseItems.ts, src/libs/actions/SplitExpenses.ts, and src/hooks/useDeleteTransactions.ts — all the core split-expense code paths.

Verification

The affected file is /home/runner/_work/App/App/src/libs/actions/IOU/SplitTransactionUpdate.ts.

PR 84382 modifies this file and introduces the following change at line 1251:

Before:

const forceDeleteSplitTransactionID = isReverseSplitOperation
  ? splitExpenses.at(0)?.transactionID
  : undefined;

After:

const forceDeleteSplitTransactionID =
  isReverseSplitOperation && !isOffline
    ? splitExpenses.at(0)?.transactionID
    : undefined;

• The PR modifies src/libs/actions/IOU/SplitTransactionUpdate.ts (confirmed via gh pr view 84382 --json files).
• The change at line 1251 directly controls offline split-deletion behavior.
• The pre-existing comment directly above this line reads: "resulting in 3 transactions (deleted, undeleted, and original) being shown at the same time when offline. Since original transaction will be reverted and both splits will eventually be deleted, we remove the undeleted split entirely instead of marking it for deletion."

Root Cause

The updateSplitTransactions function has a known edge case in offline reverse-split operations: when a split expense is deleted, an "undeleted" split and the original transaction can temporarily both be visible at once, producing an extra phantom expense. The pre-existing code handled this by using forceDeleteSplitTransactionID to immediately remove the undeleted split from Onyx (force-delete) even while offline.

PR 84382 added the && !isOffline guard, disabling this force-delete when the device is offline. When isOffline is true, forceDeleteSplitTransactionID becomes undefined, so the undeleted split is no longer removed from Onyx. This means all three items — the deleted split, the undeleted split, and the original transaction — are visible simultaneously while offline, exactly matching the reported symptom of "an extra expense is displayed after deleting one of the split expenses while offline."