In the case of using pumps to achieve high throughput 3000+ there are some abnormalities.
When converting 2 pipes of 3000 p/s to 1 6000 p/s line, the order of placement can't result is only 4800 fluids being moved.


pipes-default.png
Note the throughput of 4800
pipes-placebotfirst.png ...

game.get_surface(1).request_path{
bounding_box = {
left_top = {
x = -8.5625,
y = 11.34765625
},
right_bottom = {
x = -7.1640625,
y = 12.74609375
}
},
collision_mask = {"player-layer"},
start = {-20, 0},
goal = {70, 0},
force = game.players[1].force,
radius = 1,
pathfind_flags ...

playerSurface.request_path{
bounding_box = unit.bounding_box,
collision_mask = {"player-layer"},
start = unit.position,
goal = next_pos,
force = game.players[event.player_index].force,
radius = 1,
pathfind_flags = {prefer_straight_paths = true, cache = false, no_break = false},
can ...

what

Add mouse_surface_position & surface_index as attribute to the CustomInput event

These would be the same params found in the on_script_trigger_effect surface_index & source_position .

note: surface_index is likely not needed, but certain mods allow you to view different surfaces, where ...