Exclude fluid particles from sensor scanning and reconnector targeting

[Copilot]

Fluid particles (structure objects with numConnections == 0) should be invisible to sensors and reconnectors: sensors should penetrate them (no ray blocking), SensorMode_DetectStructure should not detect them, and ReconnectorMode_Structure should not connect to them.

Core changes

• DensityMap (ObjectProcessor::fillDensityMap): Filter out fluid particles from the structure density map. This fixes both sensor ray blocking and structure detection in one place.

} else if (object->type == ObjectType_Structure && !object->isFluid()) {
    data.preprocessedSimulationData.densityMap.addStructureObject(object);
}

• ReconnectorProcessor (tryCreateConnection): Skip fluid particles in structure reconnect mode.

if (otherObject->type != ObjectType_Structure || otherObject->isFluid()) {
    return;
}

• CellProcessor (performEnergyFlow): Fix pre-existing bug where object->type was checked instead of connectedObject->type, causing cudaErrorIllegalAddress when Cell-to-Structure connections existed (e.g. via reconnector). The comment said "Skip if connected object is not a Cell" but the code checked the wrong variable.

// Before (bug): checked object instead of connectedObject
if (object->type != ObjectType_Cell) { continue; }

// After (fix): correctly checks the connected object
if (connectedObject->type != ObjectType_Cell) { continue; }

Test changes

• Existing structure-mode tests for both ReconnectorTests and SensorTests updated to use connected structure pairs so they aren't classified as fluid
• Three new tests added: structureMode_ignoreFluidParticle, detectStructure_ignoreFluidParticles, rayNotBlockedByFluidParticles
• Set maxForce high in ReconnectorTests to prevent physics-related connection breaking during tests

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[chrxh]

@copilot fix failing tests

[Copilot]

@copilot fix failing tests

Fixed in c598df7. The root cause was a pre-existing bug in CellProcessor::performEnergyFlow at line 314 — it checked object->type != ObjectType_Cell instead of connectedObject->type != ObjectType_Cell. Since object was already verified as Cell at line 302, this check was always false and never skipped non-Cell connected objects. When a reconnector connected a Cell to a Structure, the kernel accessed connectedObject->typeData.cell on the Structure, reading garbage union data (invalid creature pointers), causing cudaErrorIllegalAddress. All 30 ReconnectorTests now pass with -d flag when run together.