Fix merge expense transaction thread navigation

[marufsharifi]

Explanation of Change

Merge expense now follows the same destination behavior across individual and bulk merge flows.

Before this update, merging expenses from search/spend could open the wrong place or leave the RHP loading, especially when the target workspace expense did not already have a transaction thread and the destination was an unreported/self-DM expense.

Now, the app creates the missing optimistic transaction thread when needed, carries that thread through confirmation, and attaches offline optimistic merge data to the correct destination report. This makes post-merge navigation consistent and predictable for workspace, self-DM, split, and offline merge cases.

Fixed Issues

$ #83257
PROPOSAL:

Tests

Flow 1: Workspace expense with self-DM expense

1. Create an expense in self DM.
2. Create an expense in workspace chat.
3. Go to Spend > Expenses.
4. Select the workspace expense via the checkbox.
5. Click the dropdown button > Merge.
6. Select self DM expense > Continue.
7. Select the second option in each section > Next > Merge expenses.
8. Verify the transaction thread opens after merging expenses via the bulk option.
9. Verify the app does not open the self-DM “Your space” page.

Flow 2: Workspace manual expense with split expense

1. Go to a workspace chat.
2. Create an expense split.
3. Create a manual expense.
4. Navigate to Spend > Expenses.
5. Select the manual expense created in Step 3 using the checkbox, then click Merge.
6. In the merge flow, choose the Split Expense option and complete the merge.
7. Verify that the transaction thread opens automatically after the expenses are merged using the bulk merge option.

Flow 3: Offline workspace expense with self-DM expense

1. Create an expense in self DM.
2. Create an expense in workspace chat.
3. Go to Spend > Expenses.
4. Turn off internet connection.
5. Select the workspace expense via the checkbox.
6. Click the dropdown button > Merge.
7. Select self DM expense > Continue.
8. Select the second option in each section > Next > Merge expenses.
9. Verify the transaction thread opens after merging expenses via the bulk option.
10. Verify the RHP does not load infinitely.

• Verify that no errors appear in the JS console

Offline tests

QA Steps

// TODO: These must be filled out, or the issue title must include "[No QA]."

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
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• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
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Screenshots/Videos

Android: Native

Flow:1

flow01.mov

Flow:2

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Flow:3

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Android: mWeb Chrome

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flow1.mp4

Flow:2

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Flow:3

flow3.mp4

iOS: Native

Flow:1

flow001.mov

Flow:2

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Flow:3

flow003.mov

iOS: mWeb Safari

Flow:1

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Flow:2

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Flow:3

Screen.Recording.2026-07-21.at.8.17.39.PM.mov

MacOS: Chrome / Safari

Flow:1

flow1.mov

Flow:2

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Flow:3

flow3.mov

[codecov]

Codecov Report

❌ Looks like you've decreased code coverage for some files. Please write tests to increase, or at least maintain, the existing level of code coverage. See our documentation here for how to interpret this table.

Files with missing lines	Coverage Δ
src/libs/actions/MergeTransaction.ts	70.76% <100.00%> (+1.49%)	⬆️
src/libs/actions/Report/index.ts	71.49% <100.00%> (-0.07%)	⬇️
src/hooks/useSearchBulkActions.ts	53.90% <0.00%> (ø)
src/pages/TransactionMerge/ConfirmationPage.tsx	0.00% <0.00%> (ø)
... and 27 files with indirect coverage changes

[melvin-bot]

@rojiphil Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

[marufsharifi]

@rojiphil, could you please take a look at this. thanks.

[marufsharifi]

@rojiphil, Gentle bump. thanks.