fix(session-replay): Extend masking and focus masking on sensitive information

[philprime]

📜 Description

This PR fixes several session replay masking issues and adds comprehensive test coverage for the redaction builder to prevent regressions.

💡 Motivation and Context

Fixed Masking Issues

SwiftUI.List Background Clipping Issue (#6292)
One screen in the dogfooding app Flinky had significant masking problems where the entire top half of a screen with SwiftUI.List was unmasked. Analysis revealed that _UICollectionViewListLayoutSectionBackgroundColorDecorationView has an extremely large frame (-20 -1135.33; 442 2336) that extends far beyond the visible list bounds, causing incorrect clipping calculations.

Implementation Improvements

String-Based Class Comparison

• Introduced ExtendedClassIdentifier to compare view classes by string description instead of direct class references
• Prevents triggering Objective-C +initialize on private UIKit classes when running off the main thread
• Supports optional layer class filtering for multi-purpose views (e.g., SwiftUI._UIGraphicsView)

Rendering & Layer Improvements

• Fixed sublayer rendering order by sorting layers by zPosition (with insertion order as tie-breaker)
• Switched from view-based to layer-based traversal for accurate presentation state
• Properly handle presentation layers during animations vs model layers

Edge Case Handling

• UISwitch subtree ignoring to prevent internal UIImageView from being incorrectly redacted
• UITextField placeholder handling via UITextFieldLabel detection
• SwiftUI.List background decoration view treated as special case (direct redact, no clip-out)
• Axis-aligned transform detection to optimize opaque view clipping
• Custom anchor point support in transform calculations

Test Coverage

Added 49 new tests to systematically verify:

• ExtendedClassIdentifier matching with layer filtering
• UIImageView boundary conditions (nil, 9x9, 10x10, 11x11 pixels)
• Hidden views and zero opacity handling
• Transform calculations with custom anchor points
• Region ordering and SwiftUI region prioritization
• Nested clipping regions
• Class hierarchy inheritance patterns
• iOS version-specific behavior (iOS 26 UISlider visual element)

Note: SwiftUI-specific integration tests (Text, Image, List, Label, Button) will be added in a follow-up PR.

💚 How did you test it?

Manual Testing

• Verified fix in Flinky app - SwiftUI.List screens now mask correctly
• Tested across iOS 15.5, 16.4, 17.5, 18.6, and 26.0 simulators

Automated Testing

• 49 new test cases added
• All 118+ tests passing (0 failures)
• Tests follow Arrange-Act-Assert pattern
• Standardized snapshot naming (masked/unmasked)

Files Changed

• Sources/Swift/Core/Tools/ViewCapture/SentryUIRedactBuilder.swift - Core fixes
• Tests/SentryTests/ViewCapture/SentryUIRedactBuilderTests+EdgeCases.swift - New (32 tests)
• Tests/SentryTests/ViewCapture/SentryUIRedactBuilderTests+Common.swift - Enhanced (8 new tests)
• Tests/SentryTests/ViewCapture/SentryUIRedactBuilderTests+UIKit.swift - Enhanced (5 new tests, removed 2 duplicates)
• Tests/SentryTests/ViewCapture/SentryUIRedactBuilderTests+SpecialViews.swift - Updated naming

📝 Checklist

You have to check all boxes before merging:

• 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.

[codecov]

Codecov Report

❌ Patch coverage is 94.66667% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.444%. Comparing base (caa7e70) to head (05f3e6a).
⚠️ Report is 20 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...Core/Tools/ViewCapture/SentryUIRedactBuilder.swift	96.551%	7 Missing ⚠️
...ft/Core/Tools/ViewCapture/SentryRedactRegion.swift	72.222%	5 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #6292       +/-   ##
=============================================
+ Coverage   86.865%   87.444%   +0.578%     
=============================================
  Files          445       450        +5     
  Lines        37505     37751      +246     
  Branches     17440     17428       -12     
=============================================
+ Hits         32579     33011      +432     
+ Misses        4880      4697      -183     
+ Partials        46        43        -3     

Files with missing lines	Coverage Δ
...ore/Tools/ViewCapture/SentryViewPhotographer.swift	76.000% <100.000%> (+2.086%)	⬆️
...ft/Core/Tools/ViewCapture/SentryRedactRegion.swift	82.142% <72.222%> (-17.858%)	⬇️
...Core/Tools/ViewCapture/SentryUIRedactBuilder.swift	95.052% <96.551%> (-0.221%)	⬇️

... and 88 files with indirect coverage changes

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1190.59 ms	1244.60 ms	54.01 ms
Size	23.75 KiB	1.00 MiB	1006.18 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
aff3b66	1229.53 ms	1263.08 ms	33.55 ms
570f725	1206.00 ms	1238.96 ms	32.96 ms
2481950	1221.04 ms	1248.98 ms	27.94 ms
d3f650a	1225.45 ms	1241.86 ms	16.41 ms
07f6759	1232.98 ms	1267.59 ms	34.61 ms
1fecbb8	1242.78 ms	1265.40 ms	22.62 ms
6e99155	1223.96 ms	1249.25 ms	25.29 ms
fc05805	1220.63 ms	1252.16 ms	31.54 ms
0e9c5ae	1226.10 ms	1254.14 ms	28.04 ms
397b9c9	1230.23 ms	1249.29 ms	19.06 ms

App size

Revision	Plain	With Sentry	Diff
aff3b66	23.75 KiB	978.53 KiB	954.78 KiB
570f725	23.74 KiB	913.38 KiB	889.63 KiB
2481950	23.74 KiB	872.74 KiB	849.00 KiB
d3f650a	23.75 KiB	902.48 KiB	878.73 KiB
07f6759	23.75 KiB	997.26 KiB	973.52 KiB
1fecbb8	23.75 KiB	969.28 KiB	945.53 KiB
6e99155	23.75 KiB	963.18 KiB	939.43 KiB
fc05805	23.75 KiB	908.02 KiB	884.27 KiB
0e9c5ae	23.75 KiB	969.29 KiB	945.54 KiB
397b9c9	23.75 KiB	959.44 KiB	935.70 KiB

Previous results on branch: philprime/fix-masking

Startup times

Revision	Plain	With Sentry	Diff
bb49b7a	1229.51 ms	1260.31 ms	30.80 ms
d70d220	1238.80 ms	1262.08 ms	23.29 ms
5a4767b	1206.00 ms	1238.21 ms	32.21 ms
8d1f930	1241.27 ms	1263.71 ms	22.44 ms

App size

Revision	Plain	With Sentry	Diff
bb49b7a	23.75 KiB	1014.06 KiB	990.32 KiB
d70d220	23.75 KiB	994.81 KiB	971.06 KiB
5a4767b	23.75 KiB	1.01 MiB	1006.46 KiB
8d1f930	23.75 KiB	981.78 KiB	958.03 KiB