[EmandM]

Purpose of this PR

Backport of #4214

Currently, when a client starts the session as a DA session owner their NetworkSceneManger initializes all the existing loaded scenes so they can correctly synchronize incoming clients.

This PR ensures that clients promoted to session owner mid-session also initialize their existing loading scenes.

This fixes an error where an active scene that was loaded before the game started would break synchronization on late-joining clients after a new session owner was promoted.

Jira ticket

UUM-154485

Changelog

• Fixed: Issue where a client promoted to session owner could throw an exception when synchronizing a newly joining client.

Documentation

• No documentation changes or additions were necessary.

Testing & QA (How your changes can be verified during release Playtest)

Functional Testing

Manual testing :

• Manual testing done

Automated tests:

• Covered by existing automated tests
• Covered by new automated tests

Does the change require QA team to:

• Review automated tests?
• Execute manual tests?
• Provide feedback about the PR?

If any boxes above are checked the QA team will be automatically added as a PR reviewer.

Up-port

This is a backport of #4214

Backports

n/a

[u-pr]

💡 Harness Review

The change is focused on session-owner promotion and active-scene synchronization, but the migration handling needs another pass.

_{Reviewed commit 4cb6c5a}

_{🤖 Helpful? 👍/👎}

[NoelStephensUnity]

LGTM!

[codecov-github-com]

Codecov Report

Attention: Patch coverage is 88.46154% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...cts/Runtime/SceneManagement/NetworkSceneManager.cs	86.36%	3 Missing ⚠️

@@                Coverage Diff                @@
##           develop-2.0.0    #4217      +/-   ##
=================================================
+ Coverage          74.25%   74.27%   +0.02%     
=================================================
  Files                172      172              
  Lines              28274    28271       -3     
=================================================
+ Hits               20994    20998       +4     
+ Misses              7280     7273       -7     

Flag	Coverage Δ
NGOv2_project_testproject_ubuntu	73.94% <88.46%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...cts/Runtime/Connection/NetworkConnectionManager.cs	82.21% <ø> (-0.02%)	⬇️
...netcode.gameobjects/Runtime/Core/NetworkManager.cs	79.62% <100.00%> (+0.09%)	⬆️
...me/Messaging/Messages/ConnectionApprovedMessage.cs	67.35% <ø> (+1.09%)	⬆️
...cts/Runtime/SceneManagement/NetworkSceneManager.cs	80.00% <86.36%> (+0.16%)	⬆️

Components	Coverage Δ
com.unity.netcode.gameobjects	74.27% <88.88%> (+0.02%)	⬆️

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