Remove hardcoded styling and unused colors from DiffRenderer

[paololeonardi]

Summary

Removes opinionated layout defaults baked into DiffRenderer so that consumers have full control over spacing and background appearance.
Fixes dark-corner artifacts that appeared when the view was embedded in a grouped List in dark mode.

Changes

• Remove hardcoded .padding() from DiffRenderer — callers apply it externally
• Remove fixed Color.appBackground from the ScrollView background, letting the view inherit its container's background
• Delete PlatformColors.swift and the now-unused Color.appBackground extension, along with the import references in DiffFileView and DiffLineView

Breaking Changes

Consumers that relied on DiffRenderer's built-in padding will need to add .padding() at the call site.

DiffRenderer(diffText: diffText)
   .padding()

DiffRenderer(diffText: diffText)
   .padding(EdgeInsets(top: 8, leading: 16, bottom: 8, trailing: 16))

Testing

Verified manually by embedding DiffRenderer in a grouped List in both light and dark mode — no background artifacts observed.

Before	After

Summary by CodeRabbit

• Refactor
  • Removed cross-platform background color abstraction
  • Updated preview styling for diff views
  • Simplified layout by removing padding and background styling from the diff renderer

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 870c2d25-cc18-4731-b7f3-fa534fa2bd1b

📥 Commits

Reviewing files that changed from the base of the PR and between d773f17 and 8d17ce0.

📒 Files selected for processing (4)

• Sources/gitdiff/Core/PlatformColors.swift
• Sources/gitdiff/Views/DiffFileView.swift
• Sources/gitdiff/Views/DiffLineView.swift
• Sources/gitdiff/Views/DiffRenderer.swift

💤 Files with no reviewable changes (4)

• Sources/gitdiff/Views/DiffFileView.swift
• Sources/gitdiff/Views/DiffLineView.swift
• Sources/gitdiff/Views/DiffRenderer.swift
• Sources/gitdiff/Core/PlatformColors.swift

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📝 Walkthrough

Walkthrough

The pull request removes the PlatformColors.swift file that abstracted a cross-platform system background color and deletes all references to its Color.appBackground property from preview and view definitions, simplifying background styling across the codebase.

Changes

Cohort / File(s)	Summary
Platform Color Abstraction Removal Sources/gitdiff/Core/PlatformColors.swift	Deleted the platform color abstraction file containing conditional UIKit/AppKit imports and the Color.appBackground computed property.
Preview Background Modifier Cleanup Sources/gitdiff/Views/DiffFileView.swift, Sources/gitdiff/Views/DiffLineView.swift	Removed .background(Color.appBackground) modifier from preview definitions, allowing default system backgrounds to apply instead.
View Layout Adjustments Sources/gitdiff/Views/DiffRenderer.swift	Removed padding and background color modifiers from loading, empty-state, and populated content containers in the scrollable view.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 Colors simplified, abstractions fade away,
Platform secrets no longer on display,
Views stand lighter, backgrounds now so plain,
Cleaner code, with less to maintain! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: removing hardcoded styling and unused colors from DiffRenderer, which is the primary focus across deleted files and modified view files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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