feat(replay): Check CRC messages from all players in replays

[Caball009]

The original behavior wrt replays is that only the CRC messages from the player that recorded the replay are checked. This means that players can experience a 'live' mismatch, but the game won't show the mismatch for their replay if they didn't cause it.

That's not a big deal for regular players but still unexpected behavior. For developers it can be very useful to get the exact frame the mismatch happens, regardless of which player recorded the replay or which player caused the mismatch.

This PR changes the default behavior so that the CRC messages from all players are checked. I also added an opt-out command line -replayLocalPlayerCRC because developers with large replay collections may want to rely on the original behavior. As a small bonus the name of the mismatching player is now displayed on screen if it's possible to determine which player is responsible.

See commits for cleaner diff.

Before:

replay_crc_before.mp4

After:

replay_crc_after.mp4

TODO:

• Replicate in Generals.
• Do another large replay test before merging.
• Clean up commits.
• Update this post with the updated command line options.
• Create separate commit for the deprecation of the CRC playback argument.
• Move changes from last commit to other commits.
• Split into smaller commits.
• Add comments

[greptile-apps]

Greptile Summary

This PR changes replay CRC verification to check messages from all recorded players (not just the one who recorded the replay), so a desync shows up regardless of which player caused it or saved the file. The mismatch dialog now includes the responsible player's name where attribution is possible, and a new -replayCRCMode command-line option lets developers revert to the original per-recorder behavior.

• RecorderClass::CRCInfo is overhauled: a single std::list is replaced with a separate playback queue plus per-player std::vector arrays, and handleCRCMessage() is split into handlePlaybackCRCMessage() / handlePlayerCRCMessage() / checkForMismatch().
• GameLogic::m_shouldValidateCRCs (bool) is promoted to m_validationModeCRC (enum), and the mismatch-check block in processCommandList() is extracted into a dedicated checkForMismatch() method.
• The RETAIL_COMPATIBLE_CRC preprocessor guard now gates the boolean "isPlayback" argument on CRC messages, making the argument optional for non-retail builds.

Confidence Score: 5/5

Safe to merge; the new all-players CRC path is logically equivalent to the old single-player path for existing replays, and the mode flag defaults to the new behaviour without breaking backward compatibility.

The refactored CRCInfo correctly uses signed Byte sentinel values (-1, -2) that rely on Byte being typedef'd to char (confirmed in BaseTypeCore.h). Queue synchronisation between m_playbackData and m_playerData is maintained by the same REPLAY_CRC_INTERVAL cadence. The sawCRCMismatch() early-exit guard is preserved via the return-false in onLogicCrc(), and the getFrame()>0 guard from the old code is effectively covered by the existing m_skippedOne logic. The extracted GameLogic::checkForMismatch() is functionally identical to the old inline block.

No files require special attention; Recorder.cpp carries the most new complexity but the generateMismatchData() logic and queue-drain path have been traced through all edge cases.

Important Files Changed

Filename	Overview
GeneralsMD/Code/GameEngine/Source/Common/Recorder.cpp	Core of the change: CRCInfo refactored into separate playback and per-player queues; generateMismatchData() implements multi-player mismatch attribution with correct queue-drain and frame calculation. Logic is sound, including the signed-Byte sentinel values (-1, -2) which work correctly because Byte is typedef'd to char (signed).
Core/GameEngine/Source/GameLogic/System/GameLogicDispatch.cpp	onLogicCrc() now routes messages to handlePlaybackCRCMessage or handlePlayerCRCMessage based on isLocalPlayer(); early-exit guards for sawCRCMismatch() preserve the previous "stop after first mismatch" invariant.
GeneralsMD/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp	processCommandList() now dispatches to GameLogic::checkForMismatch() (network) or TheRecorder->checkForMismatch() (replay) via the new CRCValidationMode enum; extracted checkForMismatch() is equivalent to the old inline block.
GeneralsMD/Code/GameEngine/Include/Common/Recorder.h	CRCInfo API redesigned with MismatchData struct and mode enum; clean separation of playback vs player CRC operations.
GeneralsMD/Code/GameEngine/Source/Common/CommandLine.cpp	Adds -replayCRCMode option with numeric argument (0/1/2 → all-single/all-multi/local); out-of-range values fall through to mode 0 gracefully.
GeneralsMD/Code/GameEngine/Include/Common/Player.h	getPlayerDisplayName() gains const qualifier, required for calls on const Player* in the new mismatch reporting path.
GeneralsMD/Code/GameEngine/Include/Common/GlobalData.h	m_replayCRCCheckMode field added (UnsignedByte); initialized to 0 in GlobalData.cpp constructor.
GeneralsMD/Code/GameEngine/Include/GameLogic/GameLogic.h	m_shouldValidateCRCs (Bool) replaced by m_validationModeCRC (CRCValidationMode enum); checkForMismatch() declared private.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant GL as GameLogic::update()
    participant CL as TheCommandList
    participant GLD as onLogicCrc()
    participant REC as RecorderClass
    participant CI as CRCInfo

    Note over GL: Every REPLAY_CRC_INTERVAL frames
    GL->>CL: appendMessage(MSG_LOGIC_CRC, crc, isPlayback)
    Note over CL: Replay file CRCs also in list

    GL->>GLD: processCommandList() → logicMessageDispatcher()

    alt isLocalPlayer (observer/playback)
        GLD->>REC: handlePlaybackCRCMessage(crc)
        REC->>CI: pushPlaybackCRC(crc)
        Note over CI: Skips first in multiplayer (m_skippedOne)
    else non-local player (recorded)
        GLD->>REC: handlePlayerCRCMessage(playerIndex, crc)
        REC->>CI: pushPlayerCRC(playerIndex, crc)
        GLD->>GL: "m_validationModeCRC = CRCMODE_REPLAY"
    end

    GL->>REC: checkForMismatch() [if CRCMODE_REPLAY]
    REC->>CI: generateMismatchData()

    loop for each accumulated CRC interval j
        CI->>CI: popPlaybackCRC()
        loop for each player i
            CI->>CI: compare m_playerData[i][j] vs playbackCRC
        end
        alt single mismatch and MULTIPLEMISMATCH mode
            CI-->>CI: ignore, continue
        else mismatch confirmed
            CI-->>REC: MismatchData(playerIndex, frame, crcs)
        end
    end

    alt mmData.mismatched
        REC->>REC: "TheInGameUI->message(GUI:CRCMismatch)"
        REC->>REC: "TheInGameUI->message(details with player name)"
        REC->>REC: setGamePaused() + setSawCRCMismatch()
    end

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sequenceDiagram
    participant GL as GameLogic::update()
    participant CL as TheCommandList
    participant GLD as onLogicCrc()
    participant REC as RecorderClass
    participant CI as CRCInfo

    Note over GL: Every REPLAY_CRC_INTERVAL frames
    GL->>CL: appendMessage(MSG_LOGIC_CRC, crc, isPlayback)
    Note over CL: Replay file CRCs also in list

    GL->>GLD: processCommandList() → logicMessageDispatcher()

    alt isLocalPlayer (observer/playback)
        GLD->>REC: handlePlaybackCRCMessage(crc)
        REC->>CI: pushPlaybackCRC(crc)
        Note over CI: Skips first in multiplayer (m_skippedOne)
    else non-local player (recorded)
        GLD->>REC: handlePlayerCRCMessage(playerIndex, crc)
        REC->>CI: pushPlayerCRC(playerIndex, crc)
        GLD->>GL: "m_validationModeCRC = CRCMODE_REPLAY"
    end

    GL->>REC: checkForMismatch() [if CRCMODE_REPLAY]
    REC->>CI: generateMismatchData()

    loop for each accumulated CRC interval j
        CI->>CI: popPlaybackCRC()
        loop for each player i
            CI->>CI: compare m_playerData[i][j] vs playbackCRC
        end
        alt single mismatch and MULTIPLEMISMATCH mode
            CI-->>CI: ignore, continue
        else mismatch confirmed
            CI-->>REC: MismatchData(playerIndex, frame, crcs)
        end
    end

    alt mmData.mismatched
        REC->>REC: "TheInGameUI->message(GUI:CRCMismatch)"
        REC->>REC: "TheInGameUI->message(details with player name)"
        REC->>REC: setGamePaused() + setSawCRCMismatch()
    end

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_{Reviews (10): Last reviewed commit: "Expanded CRC check modes." | Re-trigger Greptile}

[Caball009]

@greptileai re-review this pull request now that the previous review concerns are addressed.

[Caball009]

Perhaps this deserves special attention during reviewing due to potential issues wrt backward compatibility of the replay format.