Discord Rich Presence daemon for Visual Novels on Linux. Detects games launched via Lutris or Steam, looks them up on VNDB, and shows the title, cover art, and total playtime in your Discord status.

Voice channel

User activity

Features

• Detects games from Lutris (exact name from wrapper) and Steam (AppID → ACF → store name)
• Fuzzy title matching against VNDB using trigram similarity + full-width character normalisation
• Fallback: searches the release endpoint and follows the relation back to the parent VN
• Suppresses explicit cover images (sexual ≥ 1.80 or violence ≥ 1.80) — title still shows
• Playtime from Lutris DB (pga.db) or Steam VDF (localconfig.vdf) — no API key needed
• Discord elapsed timer reflects total hours played, not just this session
• Editable cache.csv for aliases, hard-links, and SKIP entries — reloaded live while running
• ignore.txt with exact-match for short entries (< 4 chars) to prevent false positives like sh

How it works

Main loop

Every 5 seconds the daemon runs detection, debounces the result, checks the cache, queries VNDB if needed, and updates Discord.

flowchart LR
    A[Detection\nLutris or Steam] --> B[Debounce\nstable 2 polls]
    B --> C{Cache\nlookup}
    C -- hit + fresh --> E[Discord RPC]
    C -- hit + expired --> D[VNDB search]
    C -- miss --> D
    D --> E

Detection

flowchart TD
    P[Scan /proc every 5s]
    P --> L{lutris-wrapper\nin cmdline?}
    L -- yes --> LN[Game name from\nwrapper args]
    L -- no --> S{SteamAppId\nin environ?}
    S -- yes --> SA[Read appmanifest_ID.acf\nfrom all library paths]
    SA --> SN[Steam store name]
    S -- no --> NONE[Nothing detected]
    LN --> ST[Read starttime\nfrom /proc/pid/stat field 22]
    SN --> ST
    ST --> SORT[Sort candidates\nby starttime ascending]

Lutris passes the game name explicitly as command-line arguments after lutris-wrapper, so the name is always exact. Steam injects SteamAppId as an environment variable into every game process — the daemon reads it from /proc/<pid>/environ, then finds the matching .acf file across all Steam library paths (including custom drives read from libraryfolders.vdf).

After all candidates are collected, the daemon reads field 22 (starttime) from each process’s /proc/<pid>/stat. Candidates are then sorted ascending by starttime, so the process that launched first is always tried first during VNDB resolution. This makes multi-candidate priority deterministic and reproducible across polls.

📝 Note

See the proc/[PID]/stat field reference for a full breakdown of all stat fields.

💡 Tip

Run with --verbose to see candidates list in the debug output:

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[DEBUG] src/main.cpp:73 4 game candidate(s) found: [DEBUG] src/main.cpp:75 [lutris] pid=2037324 name="終ノ空 remake" starttime(clock ticks)=4906595 [DEBUG] src/main.cpp:75 [lutris] pid=2086738 name="X-Plane 12" starttime(clock ticks)=4906701 [DEBUG] src/main.cpp:75 [steam-appid] pid=2037822 name="心象天儀本線 ~Per aspera ad astra~ Demo" starttime(clock ticks)=4906857 [DEBUG] src/main.cpp:75 [lutris] pid=2038526 name="サクラノ詩－櫻の森の上を舞う－" starttime(clock ticks)=4907260

VNDB resolution

flowchart TD
    Q[Search query] --> VN[POST /kana/vn]
    VN --> SIM{Trigram similarity\n≥ 0.35 OR substring match?}
    SIM -- yes --> MATCH[VnInfo returned]
    SIM -- no --> REL[POST /kana/release]
    REL --> FOUND{Release found?}
    FOUND -- yes --> ID[Fetch parent VN\nby exact ID]
    ID --> MATCH
    FOUND -- no --> NOMATCH[No match\nclear presence]

Before the similarity check, full-width ASCII (！２→!2, （→() is normalised to half-width so Japanese game names from Lutris match VNDB’s stored titles. There is also a substring boost — if the query appears inside the returned title, the score is raised to at least 0.6, handling cases where the detected name is a short prefix of a long VNDB title.

Cache TTL

VNDB results are stored persistently in cache.csv. On each cache hit the daemon compares the entry’s cached_at timestamp against VNDB_CACHE_TTL. If the entry is older than the TTL, it is treated as expired and a fresh VNDB query is issued, updating the stored data and timestamp.

flowchart TD
    HIT[Cache hit] --> AGE{age > VNDB_CACHE_TTL?}
    AGE -- no --> USE[Use cached VnInfo]
    AGE -- yes --> REQUERY[Re-query VNDB\nupdate cache.csv]
    REQUERY --> USE

This means ratings, cover images, and release dates in the cache are automatically refreshed over time without any manual intervention. The log line when a re-query fires looks like:

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[INFO] Cache expired for "..."  age=1442min/1440min — re-querying VNDB

Playtime → Discord elapsed timer

flowchart TD
    SRC{Source?}
    SRC -- lutris --> LDB[Lutris DB\npga.db · hours]
    SRC -- steam-appid --> VDF[Steam VDF\nlocalconfig.vdf · minutes]
    LDB --> PT[playtime in seconds]
    VDF --> PT
    PT --> TS[start_ts = now − playtime]
    TS --> DISC[Discord: elapsed timer\ncounts up from start_ts]

Cache file (cache.csv / cache.db)

Located at ~/.config/vn-discord-rpc/cache.csv (default) or cache.db when CACHE_USE_DB = true. Reloaded automatically whenever the file changes on disk.

Examples:

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# Alias — fix wrong or garbled detection
Nice boat!,School Days,,,,,,,,

# Skip — suppress presence for this title
妹ぱらだいす！２,,SKIP,,,,,,,

# Hard-link — bypass VNDB query, point directly to an entry
My VN Title,,v67,,,,,,,

Ignore list (ignore.txt)

Located at ~/.config/vn-discord-rpc/ignore.txt. One entry per line, # for comments. Reloaded automatically while running.

Matching rules:

• Entry < 4 characters: exact match (case-insensitive) — (ie. prevents sh matching Higurashi)
• Entry ≥ 4 characters: case-insensitive substring match

The default file includes common false-positives: Steam runtimes, Proton, Wine helpers, and launchers.

⚠️ Warning

If a title has no VNDB match and is not in the ignore list, the daemon will not add it to ignore automatically. It will retry the VNDB query on every detection. Add a SKIP entry in cache.csv or an entry in ignore.txt to suppress it permanently.

Configuration (src/config.hpp)

🚨 Caution

Be caution on changing IMAGE_SEXUAL and IMAGE_VIOLENCE thresholds in src/config.hpp. Those thresholds are set to 1.80 (slightly below VNDB’s Explicit level of 2.00) because VNDB image ratings are user-reported and may be underrated by a small margin — the 0.20 buffer ensures borderline explicit covers are still suppressed. Raising the threshold above 2.00 would cause explicit (pornographic) cover art to appear in your Discord status, visible to everyone on your friends list. Displaying explicit content in Discord Rich Presence may violates Discord’s Terms of Service and may result in a permanent account ban.

Architecture

The project is composed of nine focused, single-responsibility modules:

Key Design Decisions

Deterministic multi-candidate priority — when multiple games are running, candidates are sorted by /proc/<pid>/stat field 22 (starttime, clock ticks since boot). The process that launched earliest is always tried first, making priority stable and reproducible across polls without any user configuration.

Discord rate-limit compliance — Discord silently drops SET_ACTIVITY calls faster than ~15 seconds apart. RpcManager tracks the wall-clock time of the last successful push and defers any call that falls within a 16-second window. Deferred updates are flushed on the next runCallbacks() tick, ensuring no update is ever lost.

No presence flicker on stable sessions — the early-out in the main loop checks whether the currently displayed VN is still in the candidate set before doing any cache or VNDB work. If it is still running, the loop sleeps immediately, so Discord is never unnecessarily cleared and re-set.

Cache-first, ignore-list-second — VNDB HTTP queries are only issued on a true cache miss or TTL expiry. Candidates that fail VNDB resolution are added to the ignore list so subsequent polls skip them instantly, letting the next candidate be tried without any network round trip.

Live file reloading without restart — both cache.csv and ignore.txt are checked for mtime changes on every poll using std::filesystem::last_write_time. Edits made while the daemon is running take effect within one poll cycle with no signals or process restart needed.

Explicit content safety — image ratings are only trusted when backed by at least IMAGE_VOTECOUNT votes. Cover URLs are stripped from cache entries for explicit results so they can never accidentally appear after a cache reload even if thresholds are later changed.

Building

📌 Important

Initialise submodules before building — the two header-only dependencies are not downloaded automatically.

1	git submodule update --init --recursive

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cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

Dependencies

Usage

💡 Tip

Run with --verbose if a title is not being detected or matched — the debug output shows exactly which process was found, what VNDB returned, and the similarity score.

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./vn-discord-rpc            # normal
./vn-discord-rpc --verbose  # debug logging
./vn-discord-rpc --help

Launch a game through Lutris or Steam, and the daemon will detect it automatically. Press Ctrl+C to quit cleanly.

File locations