scenes/server_player.tscn was a bare CharacterBody3D with NO CollisionShape3D,
so on the server move_and_slide() never hit the ground and is_on_floor() was
always false -> the server player fell forever, and the client (which snaps to
the server's authoritative position past a drift threshold) fell with it.
Give the server player the same CapsuleShape3D (r=0.35, h=1.6) as the client.
The 2-player test now also asserts the server keeps the player on the ground
(on_floor / min_y), which is how this slipped through -- the tests only
checked "position changes" and "sees the other player".
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ
Made the multiplayer core actually work (it had never run a real sim):
- project.godot: physics pinned to 30 Hz -- the shared sim/snapshot/prediction rate.
- server.gd: loads the world's level (real ground + collision), spawns a
server Player per peer at the level's PlayerSpawn, broadcasts a full
snapshot every physics frame with each peer's state AND last_seq (the last
input seq applied for that peer). Accepts `--port/--world/--status-file`
args (status file = player count for a future idle reaper); defaults keep
`godot res://scenes/server.tscn` working standalone.
- player_spawner.gd (server Player): rewrote -- drains its whole input queue
each physics frame in seq order, integrates gravity/walk/jump with the
shared constants, move_and_slide(), tracks last_applied_seq. No more no-op
process_server_input().
- network_client.gd: rewrote reconciliation -- drops inputs the server has
acked (last_seq), re-simulates the still-in-flight ones from the
authoritative state, snaps only on real drift. Exposes get_remote_states()
(peer_id -> latest snapshot state) for the game to render other players.
predict_and_send() now also sends body yaw.
- proxies trimmed to the RPC set the rewrite actually uses.
- scripts/mp_test_client.gd + run_multiplayer_2p_test.sh: two real client
processes vs one real server -- client A sees client B and its own
movement round-trips. PASS.
- run_checkpoint_tests.py: also run the 2p shell test.
smoke_test_network_client 4/4, player 15/15, avatar_in_world 10/10, all green.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ
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