perf(webf): land layout optimization stack and follow-up fixes

[andycall]

Summary

This branch lands the current layout optimization stack on top of main, plus the follow-up correctness fixes that came out of the rendering regression work.

Highlights:

• land the flex layout profiling and optimization stack for WebF layout hotspots
• fix widget layout reuse so stable proxy reuse does not depend on debug-only layout state
• narrow detached-subtree width fallback so portal-mounted WidgetElement roots use popup/portal constraints without regressing CupertinoContextMenu preview sizing
• avoid phantom trailing scroll range for transformed flex children with negative start-side offsets

Included Commits

• ae3b84cf0 feat: add agent skills
• 896c27c7f profiler: add profiler test specs.
• ec95a67c4 perf(webf): reduce relayouts in flex fast path
• 013f63310 fix(webf): restore stable flex layout behavior
• 5542753e2 perf(webf): reduce redundant flex fast-path relayouts
• 08af71710 perf(webf): narrow mixed flex measurement reuse
• cbcd4013a perf(webf): skip futile early flex run-metrics passes
• 951e67344 perf(webf): reduce layout constraint overhead
• b5efce08d perf(webf): optimize layout hotspots
• ad9948096 perf(webf): narrow flex cache reuse under wrapped layouts
• cd30747e8 perf(webf): optimize flex hotspot profiling
• c6b0d4051 fix(webf): avoid debug-only layout reuse checks
• 94aa230ca fix(webf): correct widget layout reuse in flex
• 5f8c32c95 fix(webf): narrow portal width fallback
• fe8ab2a38 fix(webf): avoid phantom flex scroll range

Validation

• flutter test /Users/andycall/workspace/webf3/webf/test/src/rendering/render_widget_portal_constraints_test.dart
• flutter test /Users/andycall/workspace/webf3/webf/test/src/rendering/render_widget_percentage_width_test.dart
• flutter test /Users/andycall/workspace/webf3/webf/test/src/rendering/flex_item_width_test.dart
• npm run integration -- specs/rendering/widget_cupertino_context_menu_popup_preview_width.ts specs/rendering/widget_portal_cupertino_modal_popup_width_not_clamped.ts
• flutter analyze --no-pub /Users/andycall/workspace/webf3/webf/lib/src/css/render_style.dart
• flutter analyze --no-pub /Users/andycall/workspace/webf3/webf/lib/src/rendering/flex.dart

Notes

This is a stacked branch rather than a single-fix PR. The two latest fixes are:

• portal/detached-subtree width fallback narrowed to WidgetElement roots only
• flex scrollable range corrected for negative transformed offsets

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Project	Deployment	Actions	Updated (UTC)
use-case	Ready	Preview, Comment	Mar 29, 2026 6:15pm
vue_usecase	Ready	Preview, Comment	Mar 29, 2026 6:15pm