[EmandM]

Purpose of this PR

Override WriteFieldSynchronization in NetworkList so a client synchronized while local changes are still pending receives the list as of the last sent delta, mirroring NetworkVariable. The pending events are then applied exactly once with the next delta.

Fixes #4179

Jira ticket

n/a

Changelog

• Fixed: Issue where a client synchronized while a NetworkList<T> still had unsent changes applied those changes twice, resulting in duplicate entries and index-based events landing on the wrong elements on that 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

n/a

Backports

2.x.x PR: #4215

[u-pr]

💡 Harness Review

The change addresses the tested late-join scenario, but the captured snapshot relies on delta delivery that other synchronization paths do not guarantee.

_{Reviewed commit c112f59}

_{🤖 Helpful? 👍/👎}

[u-pr]

An initially empty list populated with Add before SpawnWithOwnership(clientId) now spawns empty on that owner when write permission is Owner. CannotWrite() permits pre-initialization edits, so CaptureLastSentList records the empty list. InternalOnSpawned leaves those events pending because the spawning server lacks owner write permission. WriteFieldSynchronization therefore sends the empty snapshot. NetworkVariableDeltaMessage.Serialize suppresses owner-write deltas to the owner, so the initial values never arrive. Treat pre-initialization edits as initial state rather than a pending-delta snapshot. Add a regression test for prepopulating a list before spawning with remote ownership.

_{🤖 Helpful? 👍/👎}

[u-pr]

A client shown a list through NetworkShow while updates are throttled can remain permanently on the pre-change contents. NetworkShow calls ForceSendIfDirtyOnNetworkShow before serializing the spawn. CanSend() blocks sending and resetting the pending events, but ForceSendIfDirtyOnNetworkShow still removes the object from both updater sets. WriteFieldSynchronization now sends m_LastSentList, although the assumed next delta is no longer scheduled. Without another mutation, expiration of the update interval does not correct the client. Keep unsent objects queued after ForceSendIfDirtyOnNetworkShow. Add a throttled NetworkShow regression test with no subsequent mutations.

_{🤖 Helpful? 👍/👎}

[u-pr]

💡 Harness Review

The change adds a pending-state snapshot for list synchronization and a late-join regression test. I examined mutation capture, snapshot cleanup, serialization, and delta delivery paths and found no additional actionable issues beyond those already reported.

_{Reviewed commit 2d19f42}

_{⚠️ Earlier blocking findings with unresolved threads: 2. The rating above does not cover them; resolve each thread after addressing it.}

_{🤖 Helpful? 👍/👎}

[u-pr]

💡 Harness Review

The change adds a pre-delta list snapshot for client synchronization and a late-join regression test. I examined mutation coverage, snapshot cleanup, delta forwarding, and ownership transitions; I found no additional issues beyond those already reported.

_{Reviewed commit 2d19f42}

_{⚠️ Earlier blocking findings with unresolved threads: 2. The rating above does not cover them; resolve each thread after addressing it.}

_{🤖 Helpful? 👍/👎}

[codecov-github-com]

Codecov Report

All modified and coverable lines are covered by tests ✅

@@                Coverage Diff                @@
##           develop-3.x.x    #4216      +/-   ##
=================================================
+ Coverage          76.03%   76.10%   +0.07%     
=================================================
  Files                159      159              
  Lines              27344    27375      +31     
=================================================
+ Hits               20791    20835      +44     
+ Misses              6553     6540      -13     

Flag	Coverage Δ
NGOv2_project_testproject_ubuntu	75.14% <100.00%> (+0.05%)	⬆️

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

Files with missing lines	Coverage Δ
...Runtime/NetworkVariable/Collections/NetworkList.cs	81.49% <100.00%> (+1.73%)	⬆️

... and 2 files with indirect coverage changes

Components	Coverage Δ
com.unity.netcode.gameobjects	76.10% <100.00%> (+0.07%)	⬆️

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