improve handling attachments

[DenBond7]

This PR improved handling attachments.

1. Added the ability to use any app to preview attachments for users who have a problem with a common approach.

Doesn't affect users with existing RESTRICT_ANDROID_ATTACHMENT_HANDLING policy.

Screen_recording_20250218_125036_smart_mode.mp4

Added a test to cover the following case: Test visibility for Settings -> General when RESTRICT_ANDROID_ATTACHMENT_HANDLING is present and vice versa.

As intents are handled by the system, it's hard to test 'smart mode' via Espresso(outside of the app scope). Tested manually.

2. Fixed the issue with a wrong name for duplicated downloads.

close #2894
close #2944

Tests (delete all except exactly one):

• Tests added or updated

---

To be filled by reviewers

I have reviewed that this PR... (tick whichever items you personally focused on during this review):

• addresses the issue it closes (if any)
• code is readable and understandable
• is accompanied with tests, or tests are not needed
• is free of vulnerabilities

[sosnovsky]

Hi @ioanmo226, will you be able to perform reviews for Android PRs as you did before?
If so, please start by checking this PR, thanks!

[DenBond7]

Works well!. Btw I can only see MainSettingsFragmentEnterpriseFlowTest.kt test added. I don't see tests which cover #2894 and #2944.

Maybe it is difficult to add UI test for this case?

Added a test to cover the following case: Test visibility for Settings -> General when RESTRICT_ANDROID_ATTACHMENT_HANDLING is present and vice versa.

As intents are handled by the system, it's hard to test 'smart mode' via Espresso(outside of the app scope). Tested manually.

I've updated the PR details.

[martgil]

Hi @ioanmo226 Sorry for the late reply. I will have it tested the newer updates and let you know of the result.

[martgil]

I tested the current one and notices that it still shows blank white images when the image attachment was previewed using the apps default photo app - I thought it was just happened on AOSP (with older android version).

I think it needs to be corrected. For instance, if user doesn't have an alternative app such as Google Photos, then I'll be problematic for them and will received just a white blank image.

Please feel free to review the follow screen recording below:

FlowCrypt.-.default.photo.app.shows.blank.white.image.mp4

[DenBond7]

I tested the current one and notices that it still shows blank white images when the image attachment was previewed using the apps default photo app - I thought it was just happened on AOSP (with older android version).
I think it needs to be corrected. For instance, if user doesn't have an alternative app such as Google Photos, then I'll be problematic for them and will received just a white blank image.

1. unfortunately, it can't be improved on our side with the current realization(data in RAM cache). We use a common standard way to share data for other apps. How to handle received data is the responsibility of the app-receiver. If a user can't preview an attachment via existing installed apps we can just advise him to install one more file-viewer in this case(or download a file and preview it via existing apps direcrlty). For example, I've attested a lot of image-viewers(modern apps). And all of them worked well.
2. Or we can change our implementation to store attachments locally before the preview. In that case, we will have a behavior similar to download case. As for me, it's a worst case. The current one is secure and provides a safe way to preview received data. A user can preview an attachment and doesn't care about a file(don't need to delete it).

[DenBond7]

I tested the current one and notices that it still shows blank white images when the image attachment was previewed using the apps default photo app - I thought it was just happened on AOSP (with older android version).

One more addition. We should understand that there are millions of Android devices with different Android versions and from different manufacturers.

default photo app - it can be a different app from version to version(Android), from manufacturer to manufacturer. A manufacturer can delete the default implementation when creating its firmware and add the custom implementation.

[martgil]

Thanks for the detailed explanation, Den. I agree that don't want to store them locally during attachment preview as it was less secure so would be just okay to inform users to install compatible apps such as Google Photos or just download the image attachment anyway.

[martgil]

Please approve this PR if it's fine for you too

Thanks Ioan, its LGTM 👍🏼