
ID	0104
Class	BUG
Severity	2
Status	blocked

Models: Trawl/Vessel (ToVessel), Seine/Vessel (VesselDeploy), Seine/Operation, Seine/Cable (the shared attractors)

Found: 2026-10-06, feature trawlwriter (thread-race review). The data races were fixed (locks and atomics); the order dependence they exposed is left, because removing it moves the SeineOperation and SeineCable baselines.

Decision needed: Owner: may the seine baselines move so that these values become functions of (T, X)? The phase schedule looks meant as a function of time, but the latch is what the baselines record.

Evidence

src/trawl/TrawlVessel.cpp CalcOutput: the Vel and WarpVel ports use the speed command the latest OdeFcn stored (m_desiredSpeed), not the Vel input at the port's (T, X). Before the first OdeFcn it is InitialSpeed. OdeJacobian uses the same stored value.
src/seine/SeineOperation.cpp SetOperationalPhase: the phase is a latch on the largest time any caller has passed, never stepped down. A rejected or overshooting step past a phase start switches the phase for the retried, earlier evaluations too, and every extra caller (the vessel reading VesselSpeed from its port calculation, say) can move it.
WarpConnectedVessel latches BuoyPos from the vessel position of the latest call in Phase_NotSet.
src/seine/VesselDeploy.cpp DoDerivedOutputUpdate: the attractors are moved to the vessel position at the (T, X) of whichever port read ran last; Seine/Cable reads them in OdeFcn.

Effect

With NumCores > 1 a value can come from another stage than the reader's, so runs need not be reproducible. The SeineCable case gives identical output on 1 and 8 cores today (test SeineCable_SameOutputOnOneAndEightCores), because every object reads at the same time within a stage and the speed command does not change before 15 s; a command that changes inside a step is exposed.

Possible fix

TrawlVessel::DesiredSpeed(T, X)/DesiredHeading(T, X) read the inputs wherever they are needed (OdeFcn, CalcOutput, OdeJacobian with the model-global state X - m_IStatePos), and SeineOperation::PhaseAt(T) is a pure function of time used by every port. Tried on 2026-10-06: the trawl Vessel baseline holds; SeineOperation and SeineCable move (vessel position RMS up to 9e-2 m, the vessel turns at the phase start rather than at the first evaluation past it). The buoy latch needs the vessel position at the start of Phase_SetFirstLeg, for example latched in AcceptedStep.

Test that would prove it

A port read at one (T, X), an OdeFcn at another, and the same port read again gives the first value; a VesselSpeed read at an earlier time after a WarpConnectedVessel read at a later one gives the earlier phase's speed.

Risk

Moves the seine baselines; the seine cases are format illustrations, not validated scenarios.