Add masking debug overlay

[markushi]

📜 Description

Masks, revealed
For debugging purposes

Screen_recording_20250516_111258.mp4

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	414.02 ms	435.39 ms	21.37 ms
Size	1.58 MiB	2.08 MiB	510.83 KiB

Previous results on branch: markushi/feat/session-replay-masking-debug-mode

Startup times

Revision	Plain	With Sentry	Diff
a1ad9eb	410.17 ms	447.29 ms	37.12 ms
3334b5a	415.90 ms	436.16 ms	20.26 ms
a08f05e	436.23 ms	466.02 ms	29.79 ms
6e73020	425.81 ms	493.12 ms	67.31 ms

App size

Revision	Plain	With Sentry	Diff
a1ad9eb	1.58 MiB	2.08 MiB	510.65 KiB
3334b5a	1.58 MiB	2.08 MiB	510.82 KiB
a08f05e	1.58 MiB	2.08 MiB	510.82 KiB
6e73020	1.58 MiB	2.08 MiB	507.64 KiB

[romtsn]

Do we want to expose this via options?
How can we ensure the flag to turn it on isn't accidentally committed

Yeah so I talked to @krystofwoldrich yesterday, and turns out iOS also has a similar option - we were thinking of introducing a top-level api like Sentry.toggleMaskingDebugOverlay() so it can be used with some kind of a debug/floating button and easily controlled at runtime instead of an init option. Wdyt?

[krystofwoldrich]

Cocoa has SentrySDK.replay.showMaskPreview(0.5), the number is opacity of the overlay.

Related cocoa PRs:

• feat: Session replay masking preview for SwiftUI sentry-cocoa#4737
• feat: Add showMaskPreview to SentrySDK.replay api to debug replay masking sentry-cocoa#4761

[romtsn]

Cocoa has SentrySDK.replay.showMaskPreview(0.5), the number is opacity of the overlay.

Related cocoa PRs:

• feat: Session replay masking preview for SwiftUI sentry-cocoa#4737
• feat: Add showMaskPreview to SentrySDK.replay api to debug replay masking sentry-cocoa#4761

alright, couldn't we draw stroke rectangles instead of solid? then we wouldn't need the opacity parameter. Just trying to align I guess

[romtsn]

great job!