Fix/61550b - Viewport does not return to highlighted message after returning from thread

[dmkt9]

Explanation of Change

Fixed Issues

$ #61550
$ #70367
PROPOSAL: #61550 (comment)

Tests

Same as QA Steps

• Verify that no errors appear in the JS console

Offline tests

Same as QA Steps

QA Steps

Test 1:
1. Go to staging.new.expensify.com
2. Go to workspace chat.
3. Submit at least two expenses.
4. Go to expense report.
5. Send many messages until the chat is scrollable
6. Right click on the newest message > Reply in thread.
7. Click on the link under header subtitle.
8. The viewport will return to the highlighted message (the same way it behaves when returning from thread).

Test 2:
1. Go to staging.new.expensify.com
2. Go to workspace chat.
3. Create two non-reimbursable expenses.
4. Open the expense report.
5. Click on the header subtitle to return to workspace chat.
6. Click Submit.
7. Click Approve.
8. Verify that app will not crash.

Test 3:
1. Launch Expensify app on iOS.
2. Go to workspace chat.
3. Submit two expenses to the workspace chat.
4. After submitting two expenses, quickly open the expense report and open any transaction row.
5. Tap on the header subtitle.
6. Verify that expense report will not turn blank.

Test 4:
1. Go to staging.new.expensify.com
2. Go to workspace chat.
3. Submit two expenses to the workspace chat.
4. Open one of the transaction threads and send a message.
5. Open the transaction thread message on LHN/
6. Click on the header subtitle.
7. Verify that expense report will not turn blank.

Test 5:
1. Go to staging.new.expensify.com
2. Go to workspace chat.
3. Create two expenses in the workspace chat.
4. Open the expense report.
5. Send 20 messages (so that the report is scrollable).
6. Mark the 20th message as unread.
7. Scroll to the top.
8. Click + > Create expense > Manual.
9. Create another expense.
10. Verify that after creating expense, the report view should not scroll down.

• 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
  • MacOS: Desktop
• 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)
• I verified there are no new alerts related to the canBeMissing param for useOnyx
• I followed proper code patterns (see Reviewing the code)
  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick)
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
    • If any non-english text was added/modified, I used JaimeGPT to get English > Spanish translation. I then posted it in #expensify-open-source and it was approved by an internal Expensify engineer. Link to Slack message:
  • I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
  • I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
  • I verified the JSDocs style guidelines (in STYLE.md) were followed
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.ts or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• If any new file was added I verified that:
  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG))
• If new assets were added or existing ones were modified, I verified that:
  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
  • The assets load correctly across all supported platforms.
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• 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:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

Android: Native

android.native.mp4

Android: mWeb Chrome

android.mweb.chrome.mp4

iOS: Native

ios.native.mp4

iOS: mWeb Safari

ios.safari.mp4

MacOS: Chrome / Safari

mac.safari.mp4

MacOS: Desktop

mac.desktop.mp4

Test 2:

2025-09-15.10-41-48.mp4

Test 3

test3.mp4

Test 4

2025-09-15.10-43-39.mp4

Test 5

2025-09-15.10-44-31.mp4

[melvin-bot]

@dominictb 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]

[dominictb]

BUG: When list has only 1 item, the empty expense section is hidden when returning from thread

Screen.Recording.2025-09-18.at.00.17.16-compressed.mov

[dmkt9]

BUG: When list has only 1 item, the empty expense section is hidden when returning from thread

@dominictb Thank you. This bug has been resolved.

I've found that implementing the highlight item feature is significantly more complex than I initially anticipated, so I've been conducting parallel testing throughout. Hopefully, we’ll be able to arrive at the most stable version soon.

[dominictb]

BUG: Scroll to highlight item is broken in single-expense report (all platforms):

Screen.Recording.2025-09-23.at.01.51.12.mov

[dominictb]

BUG: The scroll animation is flaky on native:

Screen.Recording.2025-09-23.at.01.55.00-compressed.mov

This does not happen for inverted list so I expect that for non-inverted either.

[dominictb]

BUG: Top space above the highlighted item on native:

Can we get rid of it?

[dmkt9]

BUG: Scroll to highlight item is broken in single-expense report (all platforms):

I actually noticed this issue before fixing the previous bug, but I assumed it would be reverted soon. And indeed, it was reverted in this pull request: #71010

[dmkt9]

BUG: The scroll animation is flaky on native:

I don't think this is a flaky issue, but rather that the scroll behavior is intended to address the problem where the list doesn't automatically scroll to fill the empty space at the bottom on iOS. I believe we've discussed this issue before — or did I miss something?

This does not happen for inverted list so I expect that for non-inverted either.

In practice, we don't use the list component within the ListHeaderComponent on an inverted list, so its behavior differs from that of a non-inverted list. In other words, on a non-inverted list, we treat the ListHeaderComponent as a regular item — which, by design, should be rendered after the highlighted item.

[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
...ts/InvertedFlatList/BaseInvertedFlatList/index.tsx	41.66% <100.00%> (-43.82%)	⬇️
src/pages/home/report/ReportActionsList.tsx	78.33% <ø> (ø)
...omponents/FlatList/FlatListWithScrollKey/index.tsx	0.00% <0.00%> (ø)
src/hooks/useFlatListScrollKey.ts	92.10% <92.10%> (ø)
...nents/FlatList/FlatListWithScrollKey/index.ios.tsx	11.11% <11.11%> (ø)
...equestReportView/MoneyRequestReportActionsList.tsx	1.08% <0.00%> (-0.41%)	⬇️
...latListWithScrollKey/BaseFlatListWithScrollKey.tsx	6.66% <6.66%> (ø)
... and 39 files with indirect coverage changes

[dmkt9]

BUG: Top space above the highlighted item on native:

Thank you for pointing this out — the issue has now been resolved.

[dominictb]

BUG: The list does not scroll to the last message location when coming back from its thread. Same issue if the list has only 1 message.

Screen.Recording.2025-09-29.at.22.18.51.mov

Also only the last 30 items are rendered, the rest would not show until I started scrolling the list.

[dominictb]

I don't think this is a flaky issue, but rather that the scroll behavior is intended to address the problem where the list doesn't automatically scroll to fill the empty space at the bottom on iOS. I believe we've discussed this issue before — or did I miss something?

Yeah but I think it's just too noticeable and cause an unpleasant UX. Could you fix it? Maybe we can defer rendering the list until the list header component height is known?

[dominictb]

BUG: Top space above the highlighted item on native

This is still reproducible for me #70534 (comment)

[dmkt9]

@dominictb Thanks for your patience. This PR is ready for review again.

[dominictb]

#70367 still reproducible on web:

Screen.Recording.2025-10-26.at.23.16.11.mov

[dominictb]

BUG: List does not scroll to highlighted item when the report has only 1 message

Screen.Recording.2025-10-26.at.23.19.23-compressed.mov

[dmkt9]

#70367 still reproducible on web:

What is the section above your transaction list? I tested on the latest main branch and didn’t see those fields.

Also, the scrolling happens because the added item is outside the visible area, so it gets scrolled into view. You can try testing on the latest main. So this is no longer caused by our PR.

[dmkt9]

BUG: List does not scroll to highlighted item when the report has only 1 message

Resolved:

Videos

anroid.chrome.test.mp4

ios.safari.test.mp4

mac.safari.test.mp4

mac.desktop.test.mp4

[dmkt9]

@dominictb When you have a moment, could you please take a look? Thanks!

[dominictb]

BUG

When list has many messages (38 in this case), returning from thread does not render all messages until you scroll to the top:

Screen.Recording.2025-11-13.at.13.12.40.mov

Notice that at 0:10, the list stops at 22 message, it never loaded until I scroll the list to the topmost position.

[dmkt9]

When list has many messages (38 in this case), returning from thread does not render all messages until you scroll to the top:

This bug has been fixed.

Tests on all platforms: PASS

[joekaufmanexpensify]

Good from a product perspective 👍

[dominictb]

Reviewer Checklist

• I have verified the author checklist is complete (all boxes are checked off).
• I verified the correct issue is linked in the ### Fixed Issues section above
• I verified testing steps are clear and they cover the changes made in this PR
  • I verified the steps for local testing are in the Tests section
  • I verified the steps for Staging and/or Production testing are in the QA steps section
  • I verified the steps cover any possible 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 checked that screenshots or videos are included for tests on all platforms
• I included screenshots or videos for tests on all platforms
• I verified that the composer does not automatically focus or open the keyboard on mobile unless explicitly intended. This includes checking that returning the app from the background does not unexpectedly open the keyboard.
• I verified tests pass on all platforms & I tested again on:
  • Android: HybridApp
  • Android: mWeb Chrome
  • iOS: HybridApp
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• If there are any errors in the console that are unrelated to this PR, I either fixed them (preferred) or linked to where I reported them in Slack
• I verified there are no new alerts related to the canBeMissing param for useOnyx
• I verified proper code patterns were followed (see Reviewing the code)
  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick).
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
  • I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
  • I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
  • I verified the JSDocs style guidelines (in STYLE.md) were followed
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I verified that this PR follows the guidelines as stated in the Review Guidelines
• I verified other components that can be impacted by these changes have been tested, and I retested again (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar have been tested & I retested again)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.ts or at the top of the file that uses the constant) are defined as such
• If a new component is created I verified that:
  • A similar component doesn't exist in the codebase
  • All props are defined accurately and each prop has a /** comment above it */
  • The file is named correctly
  • The component has a clear name that is non-ambiguous and the purpose of the component can be inferred from the name alone
  • The only data being stored in the state is data necessary for rendering and nothing else
  • For Class Components, any internal methods passed to components event handlers are bound to this properly so there are no scoping issues (i.e. for onClick={this.submit} the method this.submit should be bound to this in the constructor)
  • Any internal methods bound to this are necessary to be bound (i.e. avoid this.submit = this.submit.bind(this); if this.submit is never passed to a component event handler like onClick)
  • All JSX used for rendering exists in the render method
  • The component has the minimum amount of code necessary for its purpose, and it is broken down into smaller components in order to separate concerns and functions
• If any new file was added I verified that:
  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG)
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• 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:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• For any bug fix or new feature in this PR, I verified that sufficient unit tests are included to prevent regressions in this flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.
• I have checked off every checkbox in the PR reviewer checklist, including those that don't apply to this PR.

Screenshots/Videos

Android: HybridApp

Screen.Recording.2025-11-28.at.16.13.57.mov

Android: mWeb Chrome

Screen.Recording.2025-11-28.at.16.16.55.mov

iOS: HybridApp

Screen.Recording.2025-11-28.at.16.04.31.mov

iOS: mWeb Safari

Screen.Recording.2025-11-28.at.16.07.13-compressed.mov

MacOS: Chrome / Safari

Screen.Recording.2025-11-28.at.16.08.16.mov

[dominictb]

🎀

[OSBotify]

✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

[OSBotify]

🚀 Deployed to staging by https://github.com/carlosmiceli in version: 9.2.66-0 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

[OSBotify]

🚀 Deployed to production by https://github.com/jasperhuangg in version: 9.2.66-3 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅