- Protocol: RLE packing, TLV chooser, body_2bit_chunk helper, state_full_body builder
- Server: on join, build snapshot body and partition across PART packets if over MTU; include apples only in first part; chunk single oversized snake with 2-bit chunking
- Protocol: SnakeDelta structure; build_state_delta(_body); build_part
- Server: compute per-snake changes (move/grow/blocked-shrink), apples diffs
- Partition large deltas by snake changes with apples in first part; use update_id
- Send STATE_DELTA when under MTU; else PART packets referencing STATE_DELTA
- Input buffer rules: enqueue+consume with 180° guard (len>1)
- Movement: wrap per config; allow moving into own tail when it vacates
- Blocking: head holds, tail shrinks to min 1
- Apples: eat= grow; ensure target apples after tick
- Broadcast: send current snakes/apples as delta (placeholder for real deltas)
