Client half of the layer-stream protocol (codec only; transport wiring next).
- protocol.gd: encode_atlas_layer_request (bare {body_id, up_to} map so the
server demux routes it to the proxy, not the PlayerInput array) and
decode_atlas_layer_response (-> {body_id, status, error, layer1}; returns null
for non-atlas frames, e.g. a snapshot, so receive_bytes can disambiguate).
- gen_fixtures.rs: cross-language fixtures (atlas_response_ready/pending/
not_found) from real rmp_serde output, matching the test_protocol.gd pattern.
- test_protocol.gd: 5 tests decode the fixtures + verify a snapshot is not
mistaken for a response + the request encodes to the right shape. 68/68 pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>