2 Lines of Code Saved 6.4x Memory on My Snake AI

Greetings all! In my previous post I covered Binary Plane Encoding, a 3-channel grid representation for Snake that doubled the best published score. Three binary channels: head, body, apple. For details check my previous post. But there was a fourth channel I left out. Direction. The snake's current heading, encoded as a uint8 (0 = up, 1 = right, 2 = down, 3 = left), is painted uniformly across a 20×20 plane due to matrix shape requirements. That's 400 elements carrying exactly 2 bits of information. A 1,600× overhead at the channel level. Worse, that one integer channel with its 2 bits was blocking the entire state from being bit-packed. The other three grid channels are binary, meaning they could be packed at 1 bit per element. But the direction channel with its scoffs 2 bits, can't. So the replay buffer sees the state as uint8 instead of binary. One channel, 2 bits, holding back one more step of memory optimisation, forcing 1,600 bytes per state instead of 250 (20 × 20 grid,