Diagram showing the flows of gas at the different scales investigated in this work. The yellow star indicates the position of the protostar. Left: infall of fresh gas (green clouds) from B5 dense core toward the filaments (black dashed contours), with the flow direction indicated by the light green arrows. Black solid contours outline the condensations. Black dashed contours represent the NH₃ filament boundaries. Center: infall of fresh gas from the filament toward the condensations (black solid contours) and the protostar, showing the change in direction from the filament to the condensations. The yellow curve shows the streamer transporting material toward the protostellar disk. Top Right: infall of gas into the protostellar disk (brown disk) through the streamer (yellow flow), which is behind the blue outflow cone (blue cone). The blue arrow indicates the flow direction of the blueshifted streamer. Bottom right: same as in the top right, but rotated by 90° to observe the streamer unobstructed by the outflow cone.