Agent skill

steam-linux

This skill should be used when working with Steam on Linux - managing non-Steam game shortcuts, configuring Proton/Wine compatibility, parsing VDF files, or finding Steam paths and prefixes.

View SKILL.md on GitHub Repository
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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/steam-linux

SKILL.md

Steam Linux Management

Use this skill when modifying Steam shortcuts, configuring Proton, or working with Steam's configuration files on Linux.

Steam Paths

STEAM_ROOT = ~/.local/share/Steam
├── config/
│   ├── config.vdf          # Text VDF - Proton mappings, settings
│   └── libraryfolders.vdf  # Text VDF - Steam library locations
├── steamapps/
│   ├── common/             # Installed games and Proton versions
│   ├── compatdata/         # Proton prefixes (Wine bottles)
│   └── libraryfolders.vdf  # Library paths
└── userdata/{USER_ID}/
    └── config/
        └── shortcuts.vdf   # Binary VDF - Non-Steam game shortcuts

Finding Steam User ID

python
from pathlib import Path
STEAM_ROOT = Path.home() / ".local/share/Steam"
userdata = STEAM_ROOT / "userdata"
user_id = next((d.name for d in userdata.iterdir() if d.is_dir() and d.name.isdigit()), None)

Finding Steam Library Folders

Parse libraryfolders.vdf (text VDF):

python
libs = [STEAM_ROOT]
with open(STEAM_ROOT / "steamapps/libraryfolders.vdf") as f:
    for line in f:
        if '"path"' in line:
            path = line.split('"')[3]
            libs.append(Path(path))

Binary VDF Format (shortcuts.vdf)

Non-Steam shortcuts use binary VDF format.

Type Bytes

  • 0x00 - Nested object start
  • 0x01 - String value
  • 0x02 - Int32 value (little-endian)
  • 0x08 - Object end

Structure

0x00 "shortcuts" 0x00
  0x00 "0" 0x00           # First shortcut (index)
    0x02 "appid" 0x00 [4 bytes LE int]
    0x01 "AppName" 0x00 "Game Name" 0x00
    0x01 "Exe" 0x00 "\"path/to/exe\"" 0x00
    0x01 "StartDir" 0x00 "\"path/to/dir\"" 0x00
    0x01 "LaunchOptions" 0x00 "options" 0x00
    ...
  0x08                     # End of shortcut
0x08 0x08                  # End of shortcuts, end of root

Parsing Example

See references/vdf-parser.py for complete implementation.

Shortcut App ID Generation

Steam generates app IDs for non-Steam games using CRC32:

python
import zlib
def generate_app_id(exe_path, app_name):
    key = f'"{exe_path}"{app_name}'
    crc = zlib.crc32(key.encode('utf-8')) & 0xFFFFFFFF
    return crc | 0x80000000

Shortcut Fields

Required fields for a shortcut entry:

python
{
    'appid': int,           # Generated app ID
    'AppName': str,         # Display name
    'Exe': str,             # Path in quotes: '"path/to/exe"'
    'StartDir': str,        # Working dir in quotes
    'icon': str,            # Icon path (optional)
    'ShortcutPath': str,    # Usually empty
    'LaunchOptions': str,   # Command line args
    'IsHidden': int,        # 0 or 1
    'AllowDesktopConfig': int,
    'AllowOverlay': int,
    'OpenVR': int,
    'Devkit': int,
    'DevkitGameID': str,
    'DevkitOverrideAppID': int,
    'LastPlayTime': int,    # Unix timestamp
    'FlatpakAppID': str,
    'tags': {}              # Nested object for categories
}

Text VDF Format (config.vdf)

Steam's main config uses text VDF format - key-value pairs with tabs.

Proton Compatibility Tool Mapping

Located in config.vdf under CompatToolMapping:

"CompatToolMapping"
{
    "APP_ID"
    {
        "name"      "proton_experimental"
        "config"    ""
        "priority"  "250"
    }
}

Adding Proton Mapping

python
def add_compat_tool_mapping(app_id, tool="proton_experimental"):
    config_path = STEAM_ROOT / "config/config.vdf"
    with open(config_path, 'r') as f:
        content = f.read()

    # Check if already exists in CompatToolMapping section
    compat_start = content.find('"CompatToolMapping"')
    if compat_start != -1:
        compat_section = content[compat_start:compat_start+5000]
        if f'"{app_id}"' in compat_section:
            return  # Already configured

    # Find insertion point after CompatToolMapping {
    pos = content.find('"CompatToolMapping"')
    brace_pos = content.find('{', pos)

    # Build entry (use chr(9) for tabs to avoid template issues)
    TAB = chr(9)
    NL = chr(10)
    entry = NL + TAB*5 + f'"{app_id}"' + NL
    entry += TAB*5 + '{' + NL
    entry += TAB*6 + '"name"' + TAB*2 + f'"{tool}"' + NL
    entry += TAB*6 + '"config"' + TAB*2 + '""' + NL
    entry += TAB*6 + '"priority"' + TAB*2 + '"250"' + NL
    entry += TAB*5 + '}'

    new_content = content[:brace_pos+1] + entry + content[brace_pos+1:]
    with open(config_path, 'w') as f:
        f.write(new_content)

Proton/Compatdata

Each game/shortcut has a Wine prefix in compatdata:

~/.local/share/Steam/steamapps/compatdata/{APP_ID}/
├── pfx/                    # Wine prefix root
│   └── drive_c/           # C: drive
│       ├── Program Files/
│       ├── Program Files (x86)/
│       └── users/steamuser/
├── version                 # Proton version used
└── config_info            # Configuration metadata

Finding a Game's Prefix

python
def find_game_prefix(game_name_pattern):
    """Find compatdata prefix containing a specific game/app."""
    for lib in get_steam_libraries():
        compatdata = lib / "steamapps/compatdata"
        if not compatdata.exists():
            continue
        for prefix in compatdata.iterdir():
            # Check for the game in common Windows install locations
            for check_path in [
                prefix / "pfx/drive_c/Program Files" / game_name_pattern,
                prefix / "pfx/drive_c/Program Files (x86)" / game_name_pattern,
            ]:
                if check_path.exists():
                    return prefix
    return None

Sharing Prefixes Between Shortcuts

To make a shortcut use an existing prefix (e.g., for Battle.net games):

LaunchOptions: STEAM_COMPAT_DATA_PATH="/path/to/compatdata/APP_ID" %command% [args]

Proton Versions

Common Proton tool IDs:

  • proton_experimental - Proton Experimental
  • proton_10 - Proton 10.0
  • proton_9 - Proton 9.0

Proton locations:

{LIBRARY}/steamapps/common/Proton - Experimental/proton
{LIBRARY}/steamapps/common/Proton 10.0/proton

Launching Games

Via Steam Protocol

bash
steam steam://rungameid/{APP_ID}
xdg-open steam://rungameid/{APP_ID}

Via Command Line

bash
steam -applaunch {APP_ID}

Note: These require Steam to be running and may not work reliably for non-Steam shortcuts.

Important Notes

  1. Close Steam before modifying config files - Steam may overwrite changes
  2. Restart Steam after changes - New shortcuts won't appear until restart
  3. App IDs for shortcuts - Must use the CRC32-based generation algorithm
  4. Quote paths in Exe/StartDir - Always wrap paths in double quotes
  5. Template escaping - When using in chezmoi templates, avoid \n, \t, use chr() instead

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