[Due for payment 2026-05-26] [Split #88320] PR 7 - Drop FlashList hidden-render workaround

[rlinoz]

Goal: Replace StaticReportActionsPreview hidden render and reveal timer with maintainVisibleContentPosition.startRenderingFromBottom.

Scope:

• Update ReportActionsList.tsx
• Update useReportActionsScroll.ts
• Update useTransactionThread.ts type surface if needed
• Delete StaticReportActionsPreview files
• Extend ReportActions UI tests for startRenderingFromBottom

Risk: Medium-high. First paint and deep-link behavior need QA.

Depends on: #89767

Parent issue: #88320
Source plan: #88320 (comment)

Issue Owner

Current Issue Owner: @mallenexpensify

[VickyStash]

Hi, I'm Vicky from Callstack - expert contributor group - and I would like to work on this issue, as I've been working on FlashList migration and already experimented with replacing the hidden-render workaround with startRenderingFromBottom.

[VickyStash]

Updates:

• I've started with cleaning up the workaround logic [WIP] Drop FlashList hidden-render workaround #89892
• Then I've tried to go with maintainVisibleContentPosition.startRenderingFromBottom solution. I've noticed several issues:
  • WEB: If the top item is longer than the viewport, the top element is aligned to the bottom, not to the top (top of the element looks cropped to the user). I've experimented and I have a patch fix for that, which is not great as we already have a lot of patches. I want to try to upgrade to v2.3.1 and see maybe this fix fix(scroll): maintain scroll position when prepending large items Shopify/flash-list#2138 improves the behviour. Not a blocker though.
  • WEB: Position isn't maintained when new report actions arrive after OpenReport finishes. It's caused due to inconsistency of optimistic CREATED report action id and the real one. Before the data is loaded we don't know the actual report action id. Easy fix is to track CREATED type in keyExtractor.

So overall I made it work on web, but on native platforms, there are visual jumps, even with maintainVisibleContentPosition.startRenderingFromBottom. They are caused by some internal FlashList items pre-measurements.

As an alternative I'm experimenting with initialScrollIndex + initialScrollIndexParams.viewOffset.windowHeight approach when we should mount on top. It works well too on web, but also has small jumps on native.

The goal for tomorrow is to try to make it work smoothly on native platforms.

[VickyStash]

Updates:

After moving back and forth I seems to find a way to make it work with maintainVisibleContentPosition.startRenderingFromBottom + patch + additional usage of initialScrollKey on native 8267390.

But a couple of hours ago this PR was merged #51366 which overlapps with my changes, so I need resolve some conflicts and retest it all.

TODOs:

• Merge latest main and resolve conflicts, verify all works
• Resolve minor TODOs and improve comments
• Check mweb platforms and add fixes if needed
• Do more testing over different scenarios (different screen resolution/chat size)
• Add jest tests
• Prepare PR fpr review

[Julesssss]

Plan sounds good, thanks for the update.

[rlinoz]

That PR was reverted btw, but we are still trying to merge it again soon