Mod «ISyncYouSyncWeAllSyncForDeSync» for Project Zomboid

ISyncYouSyncWeAllSyncForDeSync

This mod addresses multiplayer desynchronization issues in Project Zomboid Build 42 for both singleplayer and multiplayer modes. It actively combats desync through active position sync, dead reckoning, combat guards, ghost zombie remediation, vehicle animation sync, and threat learning.

Active Position Sync (Dead Reckoning)

• The server broadcasts authoritative positions for players, zombies, and vehicles.
• Clients predict movement between updates using velocity extrapolation with exponential decay.
• Position corrections are blended smoothly instead of teleporting (snap threshold is configurable).
• Zombies within melee range (3 tiles) of any player receive immediate priority sync every 2 ticks.
• The closest zombies to players are prioritized, with a hard cap at a configurable maximum (default 150).
• Combat exclusion zone: zombies within 4 tiles are NOT repositioned during active combat to prevent hit registration failures.
• Vehicle angle interpolation uses shortest-arc math for smooth rotation sync.
• Vehicle light state sync includes headlights, stoplights, and lightbar mode.
• State delta detection ensures only entities whose position, health, or direction actually changed are broadcast.
• UDP chunking is set at 50 entities per packet to prevent buffer overflow.

Combat Guard

• Detects ghost swings—melee attacks that fail to connect due to zombie position desync.
• After 3 or more ghost swings within 8 seconds, the mod requests the server to scan and kill ghost zombies.
• Refunds stamina lost from swinging at desynced air.
• Automatically recovers functionality when hits start connecting again.

Zombie Remediation (Server-Side)

• The server scans nearby zombies when combat failure is reported.
• Kills ghost zombies (health <= 0 but not marked as dead, yet still attacking).
• Preemptive cull removes ghost zombies in areas flagged by the threat memory system.
• Rate-limited to prevent abuse (10s global cooldown, 15s per-player cooldown).

Vehicle Remediation

• Captures vehicle part condition snapshots before entering desync corridors.
• The server can roll back vehicle damage that occurred during confirmed desync windows.
• Snapshots auto-expire after 60 seconds to prevent stale rollbacks.

Vehicle Animation Sync

• Syncs door and window animations between all clients.
• Doors play instantly via playPartAnim.
• Windows use predicted interpolation over time via setOpenDelta for smooth performance without per-tick streaming.
• Compatible with modded vehicles (e.g., Vanilla Vehicles Animated, Filibuster Rhymes).

Threat Memory & Preemption Engine

• Learns where and when desync occurs; patterns persist across server restarts via ModData.
• Records trigger conditions such as zombie density, chunk transitions, player count, and ping spikes.
• Confidence scores increase with repeated incidents and decay when an area remains stable.
• The Preemption Engine checks every 3 seconds and acts before desync recurs in known problem areas.
• Zombie threats trigger preemptive server culls or early warnings.
• Vehicle threats warn the driver and capture defensive snapshots.
• Includes an admin command to dump or clear threat memory.

Detection & Monitoring

• Features zombie combat watchdog and vehicle travel watchdog systems.
• Chunk-based hotspot tracker with decay and severity scoring.
• Server health monitor with configurable sampling.
• Position validator detects rubberbanding (3+ jumps > 3 tiles in 30 seconds).
• Chunk pre-warming pre-loads chunks ahead of vehicle travel direction.

Sync Shield & Mitigation

• Defers risky vehicle interactions while chunk streaming or sync health is unstable.
• Vehicle queue guard clears queued timed actions during dangerous mitigation windows.
• Provides rate-limited player and admin warnings when sync risk increases.

Admin Tools

• Optional lightweight status HUD displays current area risk and recent incidents.
• Context menu allows dumping risk state, events, hotspots, and review summaries.
• Incidents can be tagged for fairness review, and manual hotspots can be marked.
• Options to generate test events and toggle debug logging.
• Ability to dump or clear threat memory patterns.

Sandbox Settings

All features are configurable from the sandbox options menu without requiring a server restart:

• Toggle each feature independently (Position Sync, Combat Guard, Vehicle Anim Sync, etc.).
• Tune sync intervals for player, zombie, and vehicle broadcast ticks.
• Set max synced zombies, sync distance, and snap distance.
• Configure mitigation cooldowns and warning thresholds.

Compatibility

• Designed for Project Zomboid Build 42.
• Supports Singleplayer and Multiplayer (dedicated servers, hosted co-op).
• Every Java API call is wrapped in pcall to prevent server or client crashes.
• If errors occur, the mod silently falls back to vanilla sync behavior.

Installation

• Subscribe on Steam Workshop.
• Add ISyncYouSyncWeAllSyncForDeSync to the Mods= line in your server .ini file.
• Add the Workshop ID to the WorkshopItems= line.
• Clients only need to subscribe; no extra setup is required.

Technical Information:

Workshop ID: 3705645576
Mod ID: ISyncYouSyncWeAllSyncForDeSync