if (i@path_bound == 0)
{
    // Find the nearest path at the *spawn* position (frame-locked input 2)
    int    p;
    vector uv;
    vector spawnP = point(2, "P", @ptnum);

    xyzdist(1, spawnP, p, uv);   // search all paths once
    i@path_prim = p;             // remember which path matches this agent
    i@path_bound = 1;
}

// Now compute closest uv on corresponding prim only, at current position
int p_now;
vector uv_now;
float  d = xyzdist(1, sprintf(“%d”, @path_prim), @P, p_now, uv_now);  // the prim input must be a string according to documentation

float u = clamp(uv_now.x, 0.0, 1.0);
f@pathpos = u;

over "Render"
{
    over "Products"
    {
        over "data"
        {
            append rel orderedVars = [
                </Render/Products/Vars/rv0>,
                </Render/Products/Vars/rv1>,
            ]
        }
    }
}

productprim_spec = Sdf.CreatePrimInLayer(layer, Sdf.Path(product_path))
orderedVars_spec = Sdf.RelationshipSpec(productprim_spec, 'orderedVars')
orderedVars_spec.targetPathList.Append(Sdf.Path(var_path))

over "Render"
{
    over "Products"
    {
        over "data"
        {
            custom rel orderedVars
            append rel orderedVars = [
                </Render/Products/Vars/rv0>,
                </Render/Products/Vars/rv1>,
            ]
        }
    }
}

def random_primvars(self, node_path):
    lop_node = hou.node(node_path)    
  
    stage = lop_node.stage()  
    stage.SetEditTarget(stage.GetSessionLayer())
    
    min_val = self.min_input.value()
    max_val = self.max_input.value()
    
    for prim in stage.Traverse():
        primvars_api = UsdGeom.PrimvarsAPI(prim)
        for pv in primvars_api.GetPrimvars():
            if "to_update_" in pv.GetName():
                new_val = random.uniform(min_val, max_val)
                pv.Set(new_val)