Add new HeaderComponent

[vegaro]

• Add HeaderComponent data model mirroring the existing StickyFooterComponent pattern, a wrapper around a StackComponent pinned above the scrollable body content.
• Add HeaderComponentStyle and HeaderComponentView on the UI side, with full style factory and rendering support
• Wire header through the validation pipeline (OfferingToStateMapper → PaywallValidationResult → PaywallState → LoadedPaywallComponents)
• Header is an optional field in components_config.base, rendered above the scrollable stack when present, below it the sticky footer (layout: header | scrollable body | footer)

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Note

Medium Risk
Adds a new paywall component type and threads it through JSON deserialization, validation/state mapping, and Compose rendering, which can affect paywall layout and inset handling. Risk is moderate due to new UI composition/scroll padding logic and expanded component traversal, but changes are additive and covered by new/updated tests.

Overview
Adds a new HeaderComponent (a StackComponent wrapper) to the paywalls data model, including JSON deserialization support (type: "header") and config wiring via an optional header field in PaywallComponentsConfig.

On the UI side, introduces HeaderComponentStyle/HeaderComponentView, updates StyleFactory to build header styles (including window-insets handling and hero-image tracking), and threads the header through OfferingToStateMapper → PaywallValidationResult → PaywallState.

Updates LoadedPaywallComponents to render the header pinned above the scrollable main content (adding top padding equal to the measured header height when appropriate) while keeping the sticky footer behavior, and extends component traversal/unsupported-condition detection plus test coverage to include headers.

^{Reviewed by Cursor Bugbot for commit e57d603. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.19%. Comparing base (0fa5aca) to head (e57d603).

Files with missing lines	Patch %	Lines
...t/purchases/paywalls/components/HeaderComponent.kt	33.33%	1 Missing and 1 partial ⚠️
...purchases/utils/PaywallComponentFilterExtension.kt	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3290      +/-   ##
==========================================
- Coverage   79.20%   79.19%   -0.02%     
==========================================
  Files         352      353       +1     
  Lines       14099    14105       +6     
  Branches     1939     1941       +2     
==========================================
+ Hits        11167    11170       +3     
- Misses       2136     2137       +1     
- Partials      796      798       +2     

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[tonidero]

I think mostly cursor's comments + one of my own but depends on what we want the header to be able to do for this feature.

[tonidero]

So we won't support transparent background header that allows the main content to scroll behind the header with this correct? Not sure if that's something we would want to do... If we do, I think we basically would need to draw the main content below the header, to the top, and then add a top padding to the content the size of the header.

FWIW, I know we don't do this for footers... But feels to me that this pattern might be more requested for headers?

[vegaro]

It took me a bit but I managed to get it working. The main content is drawn from the top inside a Box, with the header overlaid on top via Alignment.TopCenter. We measure the header height with onSizeChanged and conditionally add padding(top = headerHeightDp) to the scroll modifier, but only when there’s no hero image because I learnt that we handle that differently 😄 .

When there IS a hero image (we have a mainStackHasHeroImage), we skip the padding so the image renders behind the header. This way transparent headers with content scrolling behind are supported with and without hero images.

[emerge-tools]

📸 Snapshot Test

582 unchanged

Name	Added	Removed	Modified	Renamed	Unchanged	Errored	Approval
TestPurchasesUIAndroidCompatibility Paparazzi com.revenuecat.testpurchasesuiandroidcompatibility.paparazzi	0	0	0	0	257	0	N/A
TestPurchasesUIAndroidCompatibility com.revenuecat.testpurchasesuiandroidcompatibility	0	0	0	0	325	0	N/A

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit b15fceb. Configure here.}