Add Connect libp2p endpoint transport

[robinbraemer]

Summary

• add the connector-side libp2p endpoint transport for Paper, Velocity, and Bungee platforms
• persist endpoint peer identity in libp2p-identity.key and expose CONNECT_LIBP2P_* configuration
• sign server-challenged relay circuit addresses so Connect edges can publish Machine-specific relay dial addresses while endpoints reserve through public bootstrap addresses
• keep the existing WatchService/WebSocket tunnel path as server-side fallback for older connectors
• remove misleading native naming from the new endpoint code path
• refresh against origin/connect and preserve the WatchService WebSocket liveness fix from PR fix(connect): avoid watch websocket read timeouts #33

Current branch state

• connect-java head: 291803869939
• Paired Moxy PR Stop using regex to replace username GeyserMC/Floodgate#265 merged into main as 9b1e0f58862901e6caf7d908db93f59401c0819f
• Refreshed against current origin/connect on 2026-06-22; conflict in CommonModuleTest resolved by keeping both libp2p token coverage and WatchService WebSocket liveness coverage.

Local verification on 2026-06-22

• ./gradlew :core:test --tests com.minekube.connect.module.CommonModuleTest
• ./gradlew :core:test :spigot:build --quiet

CI status

• GitHub PR build passed for head 291803869939.

Staging evidence

• Moxy PR Stop using regex to replace username GeyserMC/Floodgate#265 was validated and merged with Gate v0.66.36.
• Local Paper runs this PR plugin in tmux session connect-libp2p-paper-staging with endpoint codexstage22a.
• Paper logged Connect libp2p endpoint registered: d8si51qcinjc21qhkqvg, endpoint name codexstage22a, and public address codexstage22a.play.minekube.net.
• Moxy logged libp2p endpoint registration committed and renewed for codexstage22a, endpoint peer 12D3KooWHWp6xF9M6wCjx7Mm3hMN5pvNCnCHi5S5ew67YyZ13AxW.
• Clean-release Java hold validation passed on staging: session d8so4dbi940s206cfb70, selectedTransport=direct, selected address /ip4/172.16.61.34/tcp/64300, warmPath=warm, connectionStatus=success, no keepalive out-of-order/timeout/internal-server-error through 2026-06-22T18:45:52Z.
• Java chat validation passed after setting the local Paper staging backend to enforce-secure-profile=false: session d8t366bi940s21vr1hu0, selectedTransport=direct, selected address /ip4/172.16.61.34/tcp/64414, warmPath=warm; Paper accepted [Not Secure] <RoboFlax2> hi and [Not Secure] <RoboFlax2> test with no new missing-profile-public-key warning.
• Bedrock hold validation passed for the observed 2026-06-23 window through the same endpoint: Paper logged a tunneled RoboFlax2 login from 127.0.0.1:0 with floodgate:* and erosion:msg plugin channels, then ongoing gameplay at 09:25:56 and 09:26:21 Europe/Berlin, with no monitored timeout/disconnect/keepalive kick.

Notes

• For this offline/proxied Paper staging backend, server.properties must keep enforce-secure-profile=false; otherwise Paper rejects chat state with Chat disabled due to missing profile public key.

Update: backend-close diagnostics on 2026-06-23

• Added local diagnostic logs to LocalChannelInboundHandler and TunnelHandler in the staging worktree to distinguish local backend close from tunnel-stream close; preserved the byte-copy fixes already under validation.
• Built with ./gradlew :spigot:shadowJar -x test and installed connect-spigot.jar on the local Paper staging server; SHA-256 8affd0471ee9b7318fc31c41737174483dad1725158a31178cc2cd6a89ed32e6.
• Paper staging now runs under tmux socket connectdebug, session connect-libp2p-paper-staging2, with Java 25 and explicit CONNECT_LIBP2P_EDGE_ADDR / CONNECT_LIBP2P_RELAY_ADDRS pointing at edge peer 12D3KooWCqs14yyxXW5rosC5CJ9tmNsRvQ97KKUx5HzGKK1pyVsN.
• Diagnostic finding: a Java session d8t86sji940s21r2entg closed because the tunnel stream closed first, then the local backend channel closed.
• Bedrock retest then passed the observed >5 minute window: session d8t8713i940s21r2enu0, selectedTransport=direct, selected address /ip4/172.16.61.34/tcp/64766, warmPath=warm, connectionStatus=success, duration 594.886026ms; Paper logged the main local backend channel active for RoboFlax2 and no matching close through 2026-06-23T13:06:22Z.
• Remaining risk is not connect-java packet copying in this successful run; it is Fly anycast reaching different edge peers for peer-specific libp2p addresses.

2026-06-23 staging update

• Local Paper staging is running this PR head 291803869939 plus diagnostic logging jar SHA-256 8affd0471ee9b7318fc31c41737174483dad1725158a31178cc2cd6a89.
• Endpoint codexstage22a re-registered after the Moxy staging redeploy as endpoint ID d8si51qcinjc21qhkqvg, endpoint peer 12D3KooWHWp6xF9M6wCjx7Mm3hMN5pvNCnCHi5S5ew67YyZ13AxW, endpoint instance 99b7ab62-b29e-4fca-94a1-aced408c54a6.
• Bedrock session d8t9baji940s201ckf9g was accepted at 2026-06-23T14:18:19Z with selectedTransport=direct, warmPath=warm, and Moxy reported connectionStatus=success at 2026-06-23T14:18:21Z.
• Evidence doc updated in Moxy PR Stop using regex to replace username GeyserMC/Floodgate#265 worktree: docs/superpowers/plans/2026-06-18-connect-libp2p-pr265-readiness.md.

Correction to 2026-06-23 staging update: the later disconnect at 16:24:26 Europe/Berlin was caused by locally killing/restarting the deterministic fly proxy processes, which closed Bedrock session d8t9baji940s201ckf9g; it was not the prior fast disconnect.timeout path. Paper re-registered after proxies were restored.

Update: multi-relay endpoint records on 2026-06-23

• Local staging fix makes connect-java include all successfully reserved relay circuit addrs in the signed endpoint record, not only the relay from the edge registration challenge.
• Focused verification passed: ./gradlew :core:test --tests com.minekube.connect.tunnel.p2p.PeerRegistrationHandshakeTest, ./gradlew :core:test --tests 'com.minekube.connect.tunnel.p2p.*' --tests 'com.minekube.connect.network.netty.TunnelHandlerTest', and ./gradlew :spigot:shadowJar.
• Installed local Paper plugin jar SHA-256 cd048c795ff640e7c433e96aa9b250da1a75db949b2d42c83ef9616d30c31031.
• With Moxy staging validation patch deployed, endpoint instance 53010fda-d378-44d1-bb96-839a1d163776 renewed with relayAddrs=3; Bedrock session d8t9vn2fskps2294e7ug was accepted with selectedTransport=direct, warmPath=warm, and delivered successfully.

2026-06-23 Bedrock multi-relay staging retry

• After staging redeploy, e827 regenerated its libp2p identity; local Paper was restarted with relay 14225 updated to 12D3KooWB1riwr5QRN4Uw6sm63jwid2R7tUfFDuJNckWaz5A7bFw.
• Endpoint re-registered cleanly at 2026-06-23T15:18:42Z; Moxy committed codexstage22a endpoint instance b7b2da24-e2dd-424a-8f80-1bb4cbaabe82 with relayAddrs=3, exercising the connect-java change that signs all reserved relay circuit addrs.
• Verified Robin Bedrock retry at 2026-06-23T15:19:24Z: session d8ta7v2fskps23njfh1g, selectedTransport=direct, warmPath=warm, connectionStatus=success, bedrock join attempt result=success, and Paper logged RoboFlax2 joined the game at 17:19:26 Europe/Berlin.
• Remaining staging gap is operational, not endpoint-code: the no-volume bedrock Fly machine changes peer ID on redeploy, so staging needs persistent identity or dynamic relay discovery before production-like multi-machine Bedrock soak.

Update: persistent Bedrock relay identity on 2026-06-23

• Staging now uses persistent Bedrock relay machine 1853d9df076d08 with Fly volume vol_rnzk2lxojyn193er; its relay peer ID 12D3KooWH8xrjYnNbBVumsTSUVKYd1e4mREcF1A6ZGKMCogHzKZa was unchanged after machine restart.
• The connect-java multi-relay record path was exercised again: Paper re-registered codexstage22a with three deterministic relay peers, and Moxy committed endpoint instance 8f494346-5971-438f-b55f-4688505fd5b6 with relayAddrs=3.
• Verified Robin Bedrock rejoin at 2026-06-23T15:46:14Z: session d8takhnsc8js21pncpbg, selectedTransport=direct, warmPath=warm, connectionStatus=success, and Paper logged RoboFlax2 joined the game at 17:46:15 Europe/Berlin.
• Fresh Paper list at 17:57:55 Europe/Berlin showed RoboFlax2 still online, so the final observed Bedrock session stayed up at least 11m40s.
• Remaining caveat is in Geyserlite/Bedrock runtime diagnostics, not this endpoint relay-record code: an earlier session closed after ~145s with a Geyserlite channelInactive raw-datagram dump.
• Extended soak update: Paper list checks at 18:00:12, 18:03:02, 18:03:25, 18:04:25, 18:05:25, 18:06:25, and 18:07:25 Europe/Berlin all showed RoboFlax2 online; Paper scrollback showed no later RoboFlax2 left after the 17:46:15 join, proving the observed Bedrock session stayed up at least 21m10s. Bedrock machine 1853d9df076d08 stayed on instance 01KVTJ38S40XPDGZD88G75H5ZK with no Fly event after the manual 17:39:03 restart.
• Final soak extension: a fresh Paper list at 18:10:39 Europe/Berlin still showed RoboFlax2 online, and Paper scrollback showed no later RoboFlax2 left after the 17:46:15 join; latest observed Bedrock hold is at least 24m24s.
• Fresh Java public-listener check during the Bedrock hold: status ping to connect-proxy-staging.minekube.net:25565 returned packet id 0, version {protocol: 772, name: "26.1.2"}, players 1/512, description Paper, RTT 216.45ms.

[robinbraemer]

Update: pushed d09e07b to reconnect native libp2p registration after Moxy restarts.\n\nVerification:\n- ./gradlew :core:test --tests '*PeerRegistrationClientTest' --tests '*NativeStatusReporterTest' --no-daemon\n- ./gradlew test shadowJar --no-daemon\n- copied rebuilt Spigot jar into local Paper and verified it re-registered automatically after staging Moxy restart/deploy without restarting Paper\n- staging Java status/login via connect-proxy-staging.fly.dev succeeded over native libp2p after reconnect

[robinbraemer]

Update after relay hardening (c02d1c9):

• Added JVM libp2p circuit relay client support for native endpoint hosts.
• Added CONNECT_LIBP2P_NATIVE_RELAY_ADDRS; endpoint reserves each relay and advertises /p2p-circuit/p2p/<endpoint-peer-id> addresses.
• Added an in-process relay test proving a Moxy-like host can open a stream to the endpoint through a relay circuit address.
• Split stable peer id from per-process endpoint instance id for registration/status records.
• Native session responder now rejects wrong-endpoint and expired offers before opening a local session.
• Status reports now refresh every 5s with 15s TTL.
• README documents the native libp2p env vars.

Fresh local verification:

git diff --check
./gradlew :core:test --no-daemon

Both passed locally on 2026-06-16. GitHub Actions build was still in progress when checked after push.

[robinbraemer]

Staging validation after af618ca:

• Built :spigot:shadowJar and installed the resulting plugin into the local Paper staging endpoint.
• Restarted Paper with native libp2p relay config:
  • CONNECT_LIBP2P_NATIVE_MOXY_ADDR=/dns4/connect-proxy-staging.fly.dev/tcp/4001/p2p/12D3KooWNXa3WQenRYKVJCHxcadnp3JPcxRALCqk97qpMiqAG1tt
  • CONNECT_LIBP2P_NATIVE_RELAY_ADDRS=/dns4/connect-proxy-staging.fly.dev/tcp/4001/p2p/12D3KooWNXa3WQenRYKVJCHxcadnp3JPcxRALCqk97qpMiqAG1tt
• Java status through Fly staging passed: mcstatus connect-proxy-staging.minekube.net status, 0/512, ~80ms.
• Java login probe through Fly staging passed: node /tmp/connect-libp2p-staging-paper/mc-login-probe.cjs connect-proxy-staging.minekube.net 25565.
• Moxy staging log shows native libp2p session accepted with endpoint instance UUID 2fddead1-e3ed-4d27-a800-7ff6a496f923 and player joined endpoint.
• Bedrock status ping through Fly staging passed: connect-proxy-staging.minekube.net:19132 OK rtt=76ms name="Minekube" sub="Bedrock cross-play" protocol=26.30.

Local verification run:

• ./gradlew :core:test --no-daemon
• ./gradlew :spigot:shadowJar --no-daemon

[robinbraemer]

Update after peer-auth review:

• Native session responder now authorizes incoming session streams against the configured Moxy peer ids from CONNECT_LIBP2P_NATIVE_MOXY_ADDR.
• Added config/test coverage for extracting the configured Moxy peer id.
• Downgraded transient native reconnect/status-report failures to warning summaries instead of full ERROR stack traces.

Verification:

• ./gradlew :core:test --no-daemon passed locally.
• ./gradlew :spigot:shadowJar --no-daemon passed locally.
• PR CI build passed: https://github.com/minekube/connect-java/actions/runs/27604045064

Staging used the freshly built Spigot plugin jar and re-registered against Moxy. Public Java login and Bedrock status probes passed through connect-proxy-staging.minekube.net; Moxy logged selectedTransport=relay for the Java login probe.

[robinbraemer]

Updated native registration signing in 4771056c:

• PeerRecordSigningPayload now writes deterministic protobuf bytes via CodedOutputStream#useDeterministicSerialization() instead of the temporary JSON payload.
• Added a golden hex test vector generated from Moxy's deterministic Go protobuf marshal path.

Fresh local verification:

./gradlew :core:test --no-daemon
# BUILD SUCCESSFUL

./gradlew :spigot:shadowJar --no-daemon
# BUILD SUCCESSFUL

This is the matching endpoint-side change for Moxy PR GeyserMC#265 commit 4a75ee8; both sides need to land/deploy together because native registration signatures are intentionally changing to the spec format.

[robinbraemer]

Latest staging evidence for 4771056c:

• Rebuilt :spigot:shadowJar and deployed the resulting Connect.jar to the local staging Paper server used for the Moxy staging test.
• The plugin registered native endpoint codexp2p3 successfully with peer 12D3KooWEzZpASrUwA3s8CM3UCDCCYjQzfh91ZyJnxRqaZ9xTi31.
• Moxy staging, running 4a75ee8, accepted a native libp2p session from that plugin: session d8ohhgji940s21q3691g, endpoint instance 0aedb6a9-31ad-41fe-9f3a-624df2416476, selected transport relay.
• Java login probe through connect-proxy-staging.minekube.net:25565 completed with login then clean end done.
• Paper logs show CodexBot joined through Connect and disconnected cleanly.
• Bedrock RakNet status against connect-proxy-staging.minekube.net:19132 returned OK with MOTD Minekube, sub-MOTD Bedrock cross-play, protocol 26.30.

GitHub Actions for this PR is green at 4771056c (build succeeded). The paired Moxy PR currently has red Actions caused by GitHub account billing/spending limits before any job step starts; local Moxy gates and staging validation passed.

[robinbraemer]

Review/staging follow-up after the senior-pass review:

• Pushed 7fc9a4f8 so native status reports half-close the write side with Stream.closeWrite() instead of resetting the full stream after a one-shot report.
• The staging symptom before this was repeated Moxy native libp2p status stream failed logs with stream reset; after installing the new jar and filtering logs from 2026-06-16T10:57:00Z, only the expected native relay session/join lines remain.
• Local verification passed on this head:
  • ./gradlew :core:test --tests 'com.minekube.connect.tunnel.p2p.NativeStatusReporterTest' --no-daemon
  • ./gradlew :core:test :spigot:shadowJar --no-daemon
• Built and installed spigot/build/libs/connect-spigot.jar into the staging Paper server; SHA-256: 588e67efa6038d3f1a977e945641abc25f24217705866a0109c0041bfa647fda.
• Runtime validation against staging passed:
  • Paper registered native libp2p for codexp2p3.
  • Java probe node /tmp/connect-libp2p-staging-paper/mc-login-probe.cjs connect-proxy-staging.fly.dev 25565 logged in successfully.
  • Moxy accepted the session via native libp2p relay with endpoint peer 12D3KooWEzZpASrUwA3s8CM3UCDCCYjQzfh91ZyJnxRqaZ9xTi31 and selectedTransport: "relay".

GitHub PR build is green on the latest commit.