Fix Switch browser back stack error

[p3dr0rv]

Problem

The current DUNA implementation launches BrokerAuthorizationActivity with
FLAG_ACTIVITY_NEW_TASK and FLAG_ACTIVITY_CLEAR_TASK.

This causes:

• Device registration failures
• Other authentication flows failing

The issue arises because the activity stack is cleared, preventing proper continuation of dependent flows.

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Solution

Introduce SwitchBrowserActivity to handle the browser switch during the DUNA authentication flow.

This approach:

• Isolates the browser-based authentication
• Preserves the existing activity stack for device registration and other auth processes
• Leaves non-DUNA flows unchanged

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Activity Stack Behavior

1. Task 1: BrokerAuthorizationActivity launches SwitchBrowserActivity in Task 2
2. Task 1: BrokerAuthorizationActivity | Task 2: SwitchBrowserActivity → Chrome Custom Tabs
3. Task 1: BrokerAuthorizationActivity | Task 2: SwitchBrowserActivity → Chrome Custom Tabs | Task 3: BrokerBrowserRedirectActivity
4. Task 1: BrokerAuthorizationActivity | Task 2: SwitchBrowserActivity → Chrome Custom Tabs | Task 3: BrokerBrowserRedirectActivity (finishes)

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Flow Overview of SwitchBrowserActivity

1. WebViewAuthorizationFragment receives a SwitchBrowser challenge
2. SwitchBrowserActivity is launched with browser configuration parameters
3. Launches external browser (Custom Tabs or standard browser)
4. User completes authentication in the external browser
5. Browser redirects to BrokerBrowserRedirectActivity in a new task
6. BrokerBrowserRedirectActivity forwards redirect result back to SwitchBrowserActivity via onNewIntent()
7. SwitchBrowserActivity passes the result to WebViewAuthorizationFragment
8. SwitchBrowserActivity finishes and removes itself from the task stack

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Security Note

• SwitchBrowserActivity is not exported
• Can only be launched from inside the app
• Prevents external apps from triggering unwanted browser switches

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[Copilot]

Pull Request Overview

This PR implements a redesigned switch browser flow to fix back stack management issues. The changes replace direct browser launching from the challenge handler with a dedicated SwitchBrowserActivity that manages the browser lifecycle more cleanly.

Key Changes:

• Introduced SwitchBrowserActivity to handle browser launch and redirect management
• Updated SwitchBrowserRequestHandler to delegate to the new activity instead of launching browsers directly
• Modified protocol coordinator to support the new activity-based flow

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
SwitchBrowserActivity.kt	New activity that manages browser launch and authentication redirects
SwitchBrowserRequestHandler.kt	Simplified to launch SwitchBrowserActivity instead of managing browsers directly
SwitchBrowserProtocolCoordinator.kt	Updated to work with new activity and renamed property
WebViewAuthorizationFragment.java	Added static bundle management for switch browser resume data
BrokerAuthorizationActivity.java	Removed switch browser specific onNewIntent handling
AuthorizationActivityFactory.kt	Removed switch browser specific intent flags
Test files	Updated to reflect API changes and removed unused dependencies

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