[sven-n]

Summary

The player's state now shows in their Discord profile, for example:

Lv 380 / ML 120 Blade Knight
In Blood Castle 5 · Party 3/5

Outside the world it shows "Logging in" or "Selecting a character". The client talks to the local Discord app over its IPC pipe or socket (discord-ipc-N), using the bundled json.hpp. No proprietary SDK is shipped.

How it works

• Worker thread (PresenceClient): connects, does the handshake, sends SET_ACTIVITY, answers pings, and reconnects every 15 s while Discord is down. It sends at most one update per 4 s, because Discord throttles faster updates. Changes that arrive in between are merged and only the newest is sent. Every wait has a time limit and can be cancelled, so shutdown and the Off setting take effect at once.
• Frame loop (RichPresence::Update): reads the game state once a second (scene, level and master level, class, map, party, events), builds the activity and passes it to the worker only when it changed. It never waits on Discord. Map changes, level-ups, party changes and entering or leaving events are all picked up by this once-a-second read. The control socket reads map changes the same way, instead of hooking packet handlers.
• Events with a level: Blood Castle 1–8, Chaos Castle 1–7, Illusion Temple 1–6. Also Devil Square, Doppelganger, Empire Guardian, and Castle Siege (Valley of Loren while the siege is running).
• Config: config.ini [Discord] holds Presence (On / HideDetails / Off), ApplicationId, LargeImageKey and SmallImageKey. No application id is built in. Without one the presence stays off, because each server owns its own Discord application.
• Options window: new Discord row (On / Hide details / Off) below Windowed mode. It applies at once. Hide details drops class and level and keeps location and party.
• Compile switch ENABLE_DISCORD, following the ENABLE_CONTROL_SOCKET pattern. It defaults to ON and is forced OFF on Android and iOS. When it is OFF, Integration/Discord/*.cpp is not compiled, RichPresence.h compiles to a no-op, and the options window keeps its old layout.
• Platforms: Windows uses a named pipe. Linux and macOS use a Unix socket under XDG_RUNTIME_DIR, TMPDIR, TMP, TEMP or /tmp; on Linux the Flatpak and Snap locations are searched too.
• Strings: new strings in Game.en.resx and Game.de.resx. Other locales fall back to English.
• Docs: user doc in docs/discord.md, covering what is shown, the setting, and the server-operator setup. Build-option table and options-window doc updated.

Code lives in src/source/Integration/Discord/ (namespace Integration::Discord), one class per file, so C2–C6 have a home.

Tests: tests/network/test_discord_presence.cpp, 16 cases:

• IPC framing and its limits
• handshake and SET_ACTIVITY payloads, including clearing the presence and invalid UTF-8
• READY and ERROR detection, including Discord's "evt": null replies (this caught a crash on the worker thread)
• the presence text in each mode
• on POSIX, a full handshake and publish against a fake Discord socket, and a prompt stop when Discord isn't running

Verification

• Linux linux-x64 Debug build: full ctest run, 437/437 passed.
• With MU_ENABLE_DISCORD undefined, the options window and Winmain compile cleanly. The ENABLE_DISCORD=OFF source filter was checked to drop all 7 .cpp files.
• On the changed lines: clang-format 21.1.8 range check and cppcheck (CI flags) are clean.
• Not tested yet: a run against a real Discord client, and a Windows build. The Windows named-pipe code (IpcConnection.cpp, _WIN32 branch) has never been compiled or run. Please try it on Windows with an application id set.

Related issues

Closes #697 (part of #696)

Checklist

• I have read and followed docs/CODING_RULES.md.
• I have built the project locally (see docs/build/README.md).
• Changes are focused on one concern; the diff is as small as it reasonably can be.

🤖 Generated with Claude Code

https://claude.ai/code/session_012feEciycvL8PGjsezyRFqj

[sven-n]

Part of a review pass over the whole Discord integration — this PR plus #707, #708 and #709 here, and the seven server PRs in MUnique/OpenMU.

This is the strongest code of the eleven PRs. The IPC layer in particular is written like someone who assumed the thing on the other end of the pipe might be hostile, which is the right assumption for a local socket that any process can bind:

• DecodeHeader rejects unknown opcodes and caps the payload at 64 KiB, and the comment in IpcFrame.h names exactly the attack it's preventing ("trusting it would let it make the client allocate whatever it claims"). That's the one bug I went looking for first — a length-prefixed read from an untrusted peer with no cap — and it isn't there.
• ReadExact handles partial reads, cancellation and deadlines separately, and a torn header closes the connection rather than being retried into a desynchronised stream.
• OpenEndpoint checks the path against sizeof(sun_path) before the memcpy, sets FD_CLOEXEC, and uses SO_NOSIGPIPE/MSG_NOSIGNAL so a dead Discord can't kill the client with a signal.
• The recv returning 0 case is treated as the peer's shutdown rather than as a short read, with a comment saying so.

The threading is also clean: m_desired/m_desiredVersion are written under the lock from the caller, m_sentVersion is touched only by the worker, and the destructor sets m_stopping under the lock before joining. I couldn't find a race.

Two comments inline, both minor — one on fixed buffers, one on the default presence mode, which is a product decision rather than a defect.

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