[demolaf]

• Related to Customizable SwiftUI auth UI: content slots, per-screen state, and theming #1400

Adds environment-driven theming for the SwiftUI auth flow's text fields, CTA buttons and typography. Unset values keep today's exact appearance. First of the PRs splitting up #1400.

Changes

• Add AuthTextFieldStyle, AuthCTAButtonStyle and AuthTypography, each set with a View modifier and carried through the environment so they reach pushed screens inside the auth sheet.
• Replace bare .buttonStyle(.borderedProminent) and .font(_:) calls across the auth screens with .authCTAButtonStyle() and .authFont(_:weight:). Brand-styled provider buttons and the Delete Account button are unchanged.
• Apply AuthTypography to typed text and AuthTextFieldStyle to the verification code boxes, not just AuthTextField.
• Move MFAResolutionView onto VerificationCodeInputField and the shared button styles, so theming reaches it like the other MFA screens. This is an intentional default appearance change: its buttons now match the other MFA screens instead of hand-rolled blue and grey rectangles.
• Unset styles leave inherited values alone: an app-level .font, .buttonBorderShape or .tint still reaches CTA buttons and text that had no explicit font before.
• Re-export FirebaseAuthUIComponents from FirebaseAuthSwiftUI. It is not a library product, so AuthTextFieldStyle and AuthTypography were otherwise unreachable from import FirebaseAuthSwiftUI.

API Usage

AuthPickerView { authenticatedApp }
  .authTypography(AuthTypography(fontName: "AvenirNext-Regular"))
  .authTextFieldStyle(AuthTextFieldStyle(tint: .purple, cornerRadius: 16))
  .authCTAButtonStyle(AuthCTAButtonStyle(backgroundColor: .purple, shape: .capsule))

Preview

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Maintainer note: Fixes internal CPRN-515

[gemini-code-assist]

Code Review

This pull request introduces a customizable styling and typography system for the authentication flow, including AuthCTAButtonStyle for primary buttons, AuthTextFieldStyle for text fields, and AuthTypography for custom font families. The feedback highlights three key issues: a double-scaling bug in AuthTypography when resolving custom fonts with Dynamic Type, a regression in AuthCTAButtonModifier where passing a nil background color clears the inherited environment tint, and a visual regression in EmailAuthView where the blue color of the switch-auth-flow action label was accidentally removed.

[russellwheatley]

LGTM. Could you add the EmailAuthView weight changes (semibold to medium on the sign up label, medium on the password recovery label) to the intentional default appearance change line in the description? Thanks 🙏