Field report (first internet-join attempt): both join bats 'hard
crash' on the remote machine. Root cause was procedural -- the host
session was not running -- but the failure PRESENTATION was the bug:
Release Fail() is a bare abort(), so a dead relay = silent process
death + instantly-closing console window.
- L4NET: the two player-facing dead-ends (LAN discovery no-answer,
seat request unreachable/full) now show a MessageBox saying what
happened and what to do before exiting (verified live against a
dead relay: 'BattleTech -- can't join the game' appears).
- join bats: echo + pause after exit so the window stays readable;
join_lan.bat header now says it is LAN-only (the remote user ran
both -- join_lan can never work over the internet).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
A pod launched with no BT_SELF asks the relay for a seat before joining:
new control frames SEAT_REQUEST (-6) -> relay reserves the lowest roster
seat not claimed or reserved (60s reservation so simultaneous joiners
can't race onto one seat) -> SEAT_ASSIGN (-7, int32 hostID + NUL tag)
becomes relaySelf; everything downstream (egg self-match, HELLO) runs
exactly as if BT_SELF had been set. Roster full -> SEAT_FULL (-8) ->
clean Fail(). A real HELLO pops the reservation; a pod drop frees the
seat. Explicit BT_SELF still claims a specific seat (the operator's
local launches use it).
Client: L4NetworkManager::RelayRequestSeat (throwaway TCP dial to the
relay game port, 10s reply window). Relay: SEAT_REQUEST branch in
_handle_game_frame. Operator exporter collapsed from per-seat
join_as_playerN.bat to ONE universal join.bat (+ join_lan.bat with
BT_RELAY=auto) -- every player gets the same file, first come first
served, the arcade walk-up-to-a-pod model. players/ regenerated.
Verified: 8/8 seat stub tests (distinct seats in roster order, FULL on
exhaustion, claimed+reserved stays FULL, HELLO claim accepted, duplicate
HELLO refused); 2-node localhost e2e with NO BT_SELF on either pod ->
both seated, full ladder, RunMission pair, UDP flowing post-launch;
regression smoke: explicit-BT_SELF relay session clean with zero seat
requests, classic mesh (no BT_RELAY) un-regressed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
LAN players now find the game with zero configuration -- the 90s arcade
model (cabinets locate the operator station) restored:
- Client (L4NET RelayDiscover): BT_RELAY=auto broadcasts 'BTR1DISC' on
udp/15999 (255.255.255.255 AND 127.0.0.1 -- broadcast doesn't reliably
loop back on Windows; covers same-box sessions), 5 x 1s attempts; the
answering relay's SOURCE IP + its advertised console port become the
relay address. Explicit <host>:<port> path unchanged; mesh untouched.
- Relay (btconsole.py): best-effort discovery responder on udp/15999
answers 'BTR1HERE' + <u16 consolePort>; degrades gracefully (logged) if
the port is taken.
- Operator app: Export player scripts now writes a join_as_playerN_lan.bat
pair (BT_RELAY=auto) next to each internet script -- LAN guests
double-click and are found; internet guests use the public-host script.
Verified 2-node: both pods BT_RELAY=auto -> probe answered through a real
interface (not just loopback) -> discovered 172.19.x.x:1500 -> full session
to RunningMission. KB: multiplayer.md D1 section updated (+ the operator
console entry).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The ~60Hz entity update records now ride UDP in relay mode, so a lost/late
datagram is dropped (dead reckoning absorbs the gap) instead of head-of-line-
blocking the reliable TCP stream -- the fix for internet rubber-banding.
Reliable traffic (make/damage/death/control/egg/launch) stays on TCP.
This RESTORES the authentic 1995 NETNUB split, it doesn't invent one:
Receiver::Message defaults messageFlags=ReliableFlag; the update path clears
it (flags=0, ENTITY.cpp:590); Mode(UnreliableMode) fires at LoadingMission
(APP.cpp:704 -- the 2007 port's Mode() was a no-op, now it STORES the mode).
Routing gate = (mode==UnreliableMode && !(flags & ReliableFlag)) -- flag AND
mode, so the map-stream creation messages (also flags=0 but flowing during the
still-Reliable CreatingMission window) ride TCP for free.
Client (L4NET):
- Mode() stores currentNetworkMode (was ignored).
- ConnectRelayUdp: UDP socket connect()ed to the relay game port; HELLO
(outbound punch-through, relay learns our endpoint); udpUp on HELLO-ACK.
BT_RELAY_TCP_ONLY=1 disables the channel (UDP-blocked nets degrade to the
pure-TCP checkpoint automatically -- no ACK => everything stays on TCP).
- RelayUdpSendFrame: {route, fromHost, seq} envelope + frame, best-effort.
- RelayUdpKeepalive: ~15s NAT-hold + ~1s HELLO retry until acked.
- CheckRelayUdp: HELLO-ACK sets udpUp; per-sender seq gate drops stale/
out-of-order datagrams; frames handed up envelope-stripped like TCP.
- Send / ExclusiveBroadcast: route unreliable-window traffic to UDP, else TCP.
- CheckBuffers polls the UDP channel first, then TCP; keepalive tick.
(The relay-side UDP forwarder + endpoint learning + --udp-drop hook landed in
phase 1.)
Verified 2-node localhost relay: during a drive the update stream flows on UDP
(relay udp tx 2->190+, TCP frozen at 53) and the peer's replicant tracks the
master to sub-2u; 15% forced drop (--udp-drop 15) stays coherent (tracked to
0.1u); TCP-only fallback confirmed (udp-known drops the TCP-only pod); no
crashes; mesh mode un-regressed. KB: context/multiplayer.md gains the D1
RELAY MODE section.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The pod can now run entirely over the relay: one outbound TCP connection
carries both the console protocol (egg/launch) and all game traffic
(envelope-multiplexed), so internet play works behind NAT with no port
forwarding. All new code is behind 'if (relayMode)' (BT_RELAY unset => mesh
mode byte-for-byte untouched; verified un-regressed).
Env gates (parsed once in the ctor, after WSAStartup so gethostbyname works):
- BT_RELAY=<host>:<consolePort> (host may be a DNS name; game port = +1)
- BT_SELF=<exact [pilots] entry> (NIC matching can't identify us across NAT)
L4NET changes:
- CreateConsoleHost: relay branch dials OUT to the relay console port
(bounded retry; console-less continue on a re-dial) instead of listening.
- StartConnecting: relay self-match by BT_SELF string; peers become VIRTUAL
hosts (INVALID_SOCKET, NoNetworkConnectionStatus) flipped online by the
relay's PEER_UP; then ConnectRelayGame dials the game port + HELLOs. HostID
assignment / remoteHostCount / the connection gate / app ladder unchanged.
- CheckRelay (new): the receive seam -- drains {route,length} envelopes,
synthesizes HostConnected/Disconnected from PEER_UP/DOWN (same messages the
mesh accept path routes), returns game frames envelope-stripped (they
self-identify via NetworkPacketHeader.fromHost; consumers route by payload).
- Send: game-host traffic -> relay unicast envelope (console host excluded --
its legacy protocol is relay-TERMINATED, not routed).
- ExclusiveBroadcast: build ONCE, send ONCE with the broadcast route -- the
relay fans out, killing the mesh's (N-1)x upload duplication.
- RelaySendAll (new): partial-send-safe transmit (required on the multiplexed
socket -- a partial write would desync framing for all peers).
- CheckBuffers: polls CheckRelay first; skips recv on virtual game hosts.
- RelayGameDown: relay-loss synthesizes all-peers-disconnected (match
continues peer-less; pod never exits mid-match).
- Mode(): now STORES the reliable/unreliable mode (was ignored) for the UDP
phase's authentic mode+flag routing.
Verified 2-node localhost relay (MP_RELAY.EGG, tagged [pilots]):
- both pods reach 'All connections completed!' via PEER_UP, then
RunningMission; both mechs' MakeMessages cross the relay (paint x2 each) and
bidirectional 148-byte update records flow (net-tx/net-rx traces; relay
stats tcp rx==tx, registered [2,3]); cockpit/HUD render; no crashes.
- driving one node transmits pose/damage/death frames through the relay.
- mesh smoke (no BT_RELAY): 2-node session still forms + simulates unchanged.
Plan: ~/.claude/plans/partitioned-snuggling-piglet.md. Next: UDP channel.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Investigated the "console death froze peer replication" open question (2026-07-14)
with a direct 2-node repro (BT_REPL_LOG on a circling peer, affinity-pinned):
- Clean relay kill -> replicant kept circling smoothly through the kill, NO
disconnect logged, node survived. Replication did NOT freeze.
- Deliberately STUCK console (scratchpad/btconsole_stuck.py: connect, start
mission, then stop recv() while holding the socket OPEN = the exact
"receive pad full -> close never seen" mode hypothesized) -> replicant kept
moving the whole run. Replication did NOT freeze.
Conclusion: peer replication is INDEPENDENT of the console (pods replicate
peer-to-peer over the GAME socket; the console is a separate egg/mission/status
channel). The original freeze was a transient -- plausibly the same single-box
packet-jitter/CPU-contention artifact root-caused in 49d73dc -- or was fixed by
later MP work.
FIX (the one real bug found): L4NetworkManager::HostDisconnectedMessageHandler's
ConsoleHostType branch closed gameListenerSocket (the GAME listener) on a CONSOLE
disconnect -- a naming bug (the comment + commented-out OpenConnection intended a
CONSOLE re-listen, which CreateConsoleHost already does). Removed. Harmless to
established peer sockets (why a live match survives console loss) but it would
have blocked a NEW peer from joining after a console cycle. Verified: 2-node
still connects (All connections completed!) + the peer circles.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Session-in-progress peer-motion work, checkpointed before bisecting the
07-13/07-14 gait regression. Contains: TCP_NODELAY on game sockets (L4NET),
every-frame dense position send while moving + came-to-rest/REST send +
per-frame BT_JIT/BT_ANIM smoothness probes (mech4). bodyTargetSpeed feed
reverted to derived-velocity default. MOVER.cpp spline experiment already
reverted. NOT a fix -- a checkpoint.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The prior commit (c78662a) filed cross-pod damage failure under a
"cross-TU Entity/EntityID layout divergence" (and the P5 base-region
audit). A compile-time offsetof probe injected into BOTH translation
units disproves that: game/reconstructed AND engine/MUNGA compute an
IDENTICAL Entity layout --
sizeof(Entity)=444 offsetof(entityID)=380 (0x17C)
offsetof(ownerID)=388 offsetof(simulationFlags)=32
offsetof(Mech,entityID)=380 (Entity subobject at 0)
So Entity::Dispatch reads this->entityID at the SAME offset mech4's
GetEntityID() does -- there is no per-TU read difference, and the
logged 3:22 (mech4 candidate) vs 3:19 (engine Dispatch) cannot be one
object read two ways. Those lines were different objects/messages,
mis-correlated. The distinct, REAL P5 "base-region layout divergence"
(HARD_PROBLEMS.md) is about raw-offset stomps at this+0x2d4..0x2f0 --
far above entityID -- and is unrelated to #47.
Changes:
- Revert the committed BT_MP_NET engine diagnostics (ENTITY/EVENT/
NTTMGR/RECEIVER/L4NET) to the clean a9c3e96 baseline -- those are
the very instruments that produced the mis-correlated data.
- mech4 BT_MP_FORCE_DMG hook: dispatch via the real m->Dispatch(&td)
path (no false id stamping); comment records the offsetof finding.
- context/multiplayer.md: layout-divergence RULED OUT; 3:22/3:19 marked
unconfirmed; leading hypotheses reframed as H2 (wire host-relative
(de)serialization) vs H3 (replicant id != master's registered key),
to be distinguished by a 2-node run with per-message correlation.
Solo un-regressed (mech walks + targets, 0 faults). Cross-pod delivery
remains open, but the investigation is redirected off the wrong (large,
structural) layout-audit path onto the EntityID wire/id-assignment path.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Traced the dispatched-message delivery end to end with BT_MP_NET /
BT_MP_FORCE_DMG. Everything works except one wire step:
- A's Entity::Dispatch reroutes the replicant's TakeDamage
(application->SendMessage(ownerID=3, EntityManager, msg)); POST-Dispatch
the message carries entityID=3:22 (host:local) -- the replicant's own
ID, matching B's master (GetEntityID()==3:22). VERIFIED sent.
- On B the message ARRIVES, GetEntityPointer finds an entity, Posts it,
the event drains (ProcessEventTask = ProcessOneEvent(0)), Event::Process
runs, Receive finds+calls a handler. VERIFIED the full deliver chain.
- BUG: B receives entityID=3:19, NOT 3:22 -- the localID dropped by
exactly the hostID (3) between A's send and B's receive. So
GetEntityPointer(3:19) returns the WRONG entity (classID 48, not the
mech 0xBB9), whose base handler ignores the unaimed hit -> 0 damage.
Auto-replicated UPDATE records (msgID 18) arrive with the correct 3:22
and find the mech, so the corruption is specific to the dispatched-
message wire path/direction.
Next: the host-relative EntityID (de)serialization on the dispatched-msg
path (RoutePacket / packet EntityID encoding) -- diff vs the update path
which translates correctly. Diagnostics retained (all BT_MP_NET-gated,
off in solo -- verified: solo 22 hits, 0 probe noise).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Clean, self-contained extraction of the BattleTech-specific work from the
reverse-engineering workspace -- engine + game + content + build, with nothing
from Red Planet or the raw archive dumps. Builds green (Win32) and runs the
single-player drive->animate->target->fire->damage->destroy loop out of the box.
Layout:
engine/ MUNGA + MUNGA_L4 shared 2007 engine, carrying our BT render/loader
work (bgfload/L4D3D/L4VIDEO: BSL bit-slice decode, LOD/ground/shadow
models) + image codec; the minimal rp/ headers the audio HAL needs
game/ reconstructed BT logic + surviving-original BT source + fwd shims
+ WinMain launcher
content/ full runtime tree (BTL4.RES, VIDEO/, GAUGE/, AUDIO/, eggs, BTDPL.INI)
docs/ format specs + reconstruction ledgers
reference/ raw Ghidra pseudocode (recon source-of-truth) + decomp exporter
tools/ MP console emulator + map/resource scanners
One top-level CMake builds munga_engine lib + bt410_l4 game lib + btl4.exe.
All paths relativized (186 fwd shims + ~437 CMake abs paths -> repo-relative);
DXSDK is the one external, overridable via -DDXSDK. Verified: builds to a
byte-identical 2.27MB exe and runs combat (TARGET DESTROYED, 0 crashes) against
the bundled content.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
