Attachment - The video thumbnail is blank in conversation history

[applause-bot]

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Version Number: v9.4.20-0
Reproducible in staging?: Yes
Reproducible in production?: Yes
If this was caught during regression testing, add the test name, ID and link from BrowserStack: https://test-management.browserstack.com/projects/2219752/folder/13176710/test-cases/41236938?sort=%2Bidentifier
Email or phone of affected tester (no customers): n/a
Issue reported by: Applause Internal Team
Bug source: Regression TC Execution
Device used: Mac 15.4.1 safari/Chrome, iPhone 13 iOS 26.5
App Component: Chat Report View

Action Performed:

1. Go to https://staging.new.expensify.com
2. Go to any conversation
3. Click the + button in the conversation
4. Click on add attachment
5. Upload a video

Expected Result:

The video thumbnail should be displayed correctly in the conversation history.

Actual Result:

The video thumbnail is blank in conversation history

Workaround:

Unknown

Platforms:

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

Screenshots/Videos

Bug7191525_1782434321092.Recording__2464.mp4

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Applause Internal Information
Exported by: Mita Rachim
Bug ID: 7191525

[applause-bot]

While Applause doesn't embed attachments for this bug, here are the links for quick view:
https://platform.applause.com/services/links/v1/external/d548de5deb8dfc6334e4e04793ed86805766b77468e4dc718458b5eebf31333d

[MelvinBot]

Issue Analysis

Root Cause (Medium confidence): The inline video thumbnail in chat is not generated by the App client — it's rendered purely from a backend-supplied poster URL carried in the data-expensify-thumbnail-url attribute of the <video> tag. When that attribute is missing (or points to an image that fails to load), the App shows only the Play button over a blank background, which is exactly the reported "blank thumbnail." This means the fix is outside the App repo and needs an internal/backend investigation into why the thumbnail isn't being delivered for these uploads.

This appears to be a backend/internal issue. A separate internal investigation is needed (the video poster is server-provided; the App client does not generate video thumbnails). Please escalate to an internal engineer with backend access.

Why this is not an App-side fix: there is no client-side poster generation anywhere in App/src (no createThumbnail / react-native-create-thumbnail). The client only displays whatever poster URL the backend sends, so a blank inline preview points at thumbnail generation/delivery on the server, not the App.

Investigation details & code references

Client render path (all public App code):

1. The video report-action HTML is parsed by VideoRenderer.tsx:23, which reads the poster URL from the data-expensify-thumbnail-url attribute and passes it down as thumbnailUrl.
2. VideoPlayerThumbnail.tsx:38-46 renders the poster <Image> only when thumbnailUrl is truthy. If it's empty, you get just the Play-button overlay on empty space — the blank thumbnail. The video still plays because playback uses a separate source attribute.
3. The optimistic (just-uploaded) HTML built client-side at ReportUtils.ts:6227-6228 does not include any thumbnail attribute, so the inline preview is blank until/unless the backend response supplies one.

What internal investigation should confirm: For a video uploaded in v9.4.20-0, does the server's report-action HTML <video> tag include a non-empty data-expensify-thumbnail-url? If absent → backend thumbnail generation is failing/empty. If present but still blank → the resolved poster URL is failing to load (check for 403/404 and the auth-token vs. Cloudfront branch at VideoPlayerThumbnail.tsx:45).

On the affected platforms: the report only checked iOS App and macOS Chrome/Safari (the two devices the tester used), so the unchecked platforms are untested rather than confirmed-working. The client render path above is platform-agnostic, consistent with the thumbnail being missing/failing regardless of platform.

Related issues scanned (none are duplicates): #94341 (video orientation), #91147 / #91146 (fullscreen video controls) — different symptoms.

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Next Steps: Reply with @MelvinBot <your feedback> to refine this analysis. Because the fix lives in backend/internal code, this should be picked up by an internal engineer rather than implemented in the App repo.

[pvaghasiya087-has]

Proposal

Possible Root Cause

Based on my investigation so far, I think the App does not generate video thumbnails itself. Instead, ImageRenderer resolves the thumbnail URL from htmlAttribs.src and passes it directly to ThumbnailImage.

Code Reference:

https://github.com/Expensify/App/blob/ee1091df42ea144dfa39e465381d9919744fd5ca/src/components/HTMLEngineProvider/HTMLRenderers/ImageRenderer.tsx#L606-L624

const previewSource = tryResolveUrlFromApiRoot(htmlAttribs.src);

const processedPreviewSource =
    typeof previewSource === 'string'
        ? previewSource.replaceAll(/\.png\.(1024|320)\.jpg$/g, '.png')
        : previewSource;

The processed URL is then passed directly to ThumbnailImage.

Code Reference:

https://github.com/Expensify/App/blob/ee1091df42ea144dfa39e465381d9919744fd5ca/src/components/HTMLEngineProvider/HTMLRenderers/ImageRenderer.tsx#L648-L671

<ThumbnailImage
    previewSourceURL={processedPreviewSource}
    ...
/>

From this investigation, I think one of the following is happening:

1. htmlAttribs.src does not contain a valid thumbnail URL for uploaded videos.
2. The thumbnail URL becomes invalid before reaching ImageRenderer.

Proposed Solution

I will continue tracing where htmlAttribs.src is populated. Once the exact source of the missing or invalid thumbnail URL is confirmed, I'll implement the appropriate fix to ensure uploaded videos display their thumbnails correctly in the conversation history.