Desync in JobDriver_ConstructFinishFrame (Rand.Value RNG divergence with Mech_Constructoid)

[VanDarkh0lm3]

Summary

A client desyncs with Wrong random state on map when a Mech_Constructoid (Biotech DLC) executes JobDriver_ConstructFinishFrame. The client desynced 3 times in a row on the same map within ~3000 ticks. Reproduced with 3 players, 2 maps, async time off.

Reproduce

• 3 players, 2 maps, no async time, no multifaction
• Have a Mech_Constructoid actively finishing construction frames
• Client (not the Constructoid's owner) desyncs when the Constructoid's JobDriver_ConstructFinishFrame ticks

Cause

The first and only divergence point is a single Rand.Value call in JobDriver_ConstructFinishFrame.<MakeNewToils>b__1. All 40 context traces before it have identical hashes between local and host.

Call stack (trace 777, tick 3266138):

Rand.get_Value_Patch1
  -> JobDriver_ConstructFinishFrame.<>c__DisplayClass8_0.<MakeNewToils>b__1
    -> JobDriver.DriverTickInterval
      -> Pawn_JobTracker.JobTrackerTickInterval
        -> Pawn.TickInterval_Patch1
          -> Thing.DoTick
            -> TickList.Tick
              -> AsyncTimeComp.Tick

Measured

	Local	Host
Hash	1150931754	1150931751
Entity	Mech_Constructoid502450	Mech_Constructoid502450
Faction	16 (Player5616)	16 (Player5616)
Tick	3266138	3266138

Hash differs by only 3, but the sync field diverges significantly (155900486523175166 vs 155900482228207870), indicating different RNG state at call time.

Present on 0.11.5+4a3be27-dirty. Game has third-party mods installed, but the offending call path (Rand.Value -> JobDriver_ConstructFinishFrame) uses only vanilla RimWorld + Multiplayer code.

Desync report: Desync-137.zip (attached to this issue in comments or available on request)

[VanDarkh0lm3]

Desync report: Desync-137.tar.gz

The full desync report is available at:
https://temp.sh/xkqdf/Desync-137.tar.gz

Contains:

• desync_info - tick/version/environment data
• local_traces.txt & host_traces.txt - 81 RNG traces each (3592 total entries per file)
• local_logs.txt - full game log showing 3 consecutive desyncs on map 11
• local_metadata.txt - mod list and Harmony patch list
• local_jitted_methods.txt & host_jitted_methods.txt - JIT method listings

Key findings recap

All context traces (737-776) have identical hashes. Divergence begins at trace 777:

• Local: Hash 1150931754, sync 155900486523175166
• Host: Hash 1150931751, sync 155900482228207870
• Same entity: Mech_Constructoid502450 (faction 16 / Player5616)
• Same call stack through JobDriver_ConstructFinishFrame.<MakeNewToils>b__1 -> Rand.get_Value_Patch1

Player3690 was desynced 3 times consecutively on the same map within ~3000 ticks (ticks 3263281, 3264360, 3266160).

[notfood]

Reproduce without extra mods.