feat(platforms): add CLI support for Linux through Proton by S1M0N38 · Pull Request #134 · coder/balatrobot

S1M0N38 · 2026-01-01T13:53:26Z

Summary

Implements Linux platform support for BalatroBot using Steam's Proton compatibility layer.

Closes #128

Changes

Configuration

Add steam_path field to Config dataclass
Add --steam-path CLI argument
Add BALATROBOT_STEAM_PATH environment variable

Linux Launcher (`src/balatrobot/platforms/linux.py`)

New LinuxLauncher class for running Balatro through Proton
Auto-detect Steam installation from known paths:
- ~/.local/share/Steam (standard)
- ~/.steam/steam (symlink)
- ~/snap/steam/common/.local/share/Steam (Snap)
- ~/.var/app/com.valvesoftware.Steam/.local/share/Steam (Flatpak)
Auto-detect Proton runtime (prefers Experimental, falls back to latest versioned)
Configure required Proton environment variables:
- STEAM_COMPAT_CLIENT_INSTALL_PATH
- STEAM_COMPAT_DATA_PATH
- WINEDLLOVERRIDES="version=n,b" for lovely injection

Tests

Add TestLinuxLauncher with Linux-only tests (@pytest.mark.skipif)
Test path validation, environment building, and command construction

Usage

# Auto-detect Steam installation
balatrobot --platform linux

# Explicit Steam path
balatrobot --platform linux --steam-path ~/.local/share/Steam

# Via environment variable
BALATROBOT_STEAM_PATH=~/.local/share/Steam balatrobot --platform linux

Requirements

Linux with Steam and Proton installed
Balatro installed via Steam
Lovely injector (version.dll) in Balatro directory
Run Balatro once through Steam to create Proton prefix

Add steam_path field to Config dataclass and --steam-path CLI argument for specifying Steam installation path on Linux systems. - Add BALATROBOT_STEAM_PATH environment variable mapping - Add --steam-path CLI flag with help text

Add LinuxLauncher class for running Balatro through Steam's Proton compatibility layer on Linux systems. Features: - Auto-detect Steam installation from known paths: - ~/.local/share/Steam (standard) - ~/.steam/steam (symlink) - ~/snap/steam/common/.local/share/Steam (Snap) - ~/.var/app/com.valvesoftware.Steam/.local/share/Steam (Flatpak) - Auto-detect Proton runtime (Experimental or latest versioned) - Set required Proton environment variables: - STEAM_COMPAT_CLIENT_INSTALL_PATH - STEAM_COMPAT_DATA_PATH - WINEDLLOVERRIDES for lovely injection - Launch via: proton run Balatro.exe Closes #128

Update get_launcher() to return LinuxLauncher for 'linux' platform instead of raising NotImplementedError.

- Add TestLinuxLauncher class with Linux-only tests - Test validate_paths error cases (missing/invalid Steam dir) - Test build_env includes Proton environment variables - Test build_cmd returns correct proton run command - Update test_linux_not_implemented to test_linux_returns_linux_launcher

S1M0N38 · 2026-01-01T13:55:38Z

Hey @stirby 👋

Since you have Balatro installed with Proton on Linux, would you mind testing this PR?

Quick Test Instructions

# Checkout the PR
gh pr checkout 134

# Install dependencies and run all checks
make all

# Run platform tests specifically (Linux-only tests will run on your machine)
pytest tests/cli/test_platforms.py -v

# Run just the new Linux launcher tests
pytest tests/cli/test_platforms.py::TestLinuxLauncher -v

Manual Testing

# Test auto-detection (should find your Steam installation)
balatrobot --platform linux --debug

# Or specify Steam path explicitly
balatrobot --platform linux --steam-path ~/.local/share/Steam --debug

What to verify

Steam path auto-detection works for your setup
Proton runtime is detected correctly
Balatro launches and the API becomes healthy
The mod injects properly (lovely's version.dll)

Let me know if you hit any issues! 🎴

Copilot

Pull request overview

This PR implements Linux platform support for BalatroBot by adding a new launcher that uses Steam's Proton compatibility layer to run the Windows version of Balatro on Linux. The implementation includes automatic detection of Steam installation paths, Proton runtimes, and game files, with comprehensive configuration options via CLI arguments and environment variables.

Key Changes:

Added LinuxLauncher class with auto-detection for Steam, Proton, and Balatro paths
Extended configuration system with steam_path field and BALATROBOT_STEAM_PATH environment variable
Implemented Proton environment setup with Wine DLL overrides for lovely injector support

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`src/balatrobot/platforms/linux.py`	New launcher implementation with Steam/Proton detection and validation logic
`src/balatrobot/platforms/__init__.py`	Updated platform factory to return `LinuxLauncher` for Linux platform
`src/balatrobot/config.py`	Added `steam_path` field to Config dataclass and environment variable mapping
`src/balatrobot/cli.py`	Added `--steam-path` CLI argument for specifying Steam installation path
`tests/cli/test_platforms.py`	Added basic test coverage for `LinuxLauncher` validation and command building

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Copilot · 2026-01-01T13:56:40Z

+    # Find versioned Proton installations (e.g., "Proton 9.0", "Proton 8.0")
+    proton_dirs = []
+    for entry in common.iterdir():
+        if entry.is_dir() and entry.name.startswith("Proton "):
+            match = re.match(r"Proton (\d+(?:\.\d+)?)", entry.name)
+            if match:
+                version = float(match.group(1))


Converting version strings to float for comparison can lead to incorrect sorting for versions with multiple decimal points. For example, "Proton 8.0.5" would be captured as "8.0" and converted to 8.0, while "Proton 8.1" would be 8.1. However, the regex r"Proton (\d+(?:\.\d+)?)" only captures one optional decimal component, so this limitation is consistent. Consider documenting this limitation or using a more robust version comparison approach if multi-decimal versions are expected in the future.

Suggested change

# Find versioned Proton installations (e.g., "Proton 9.0", "Proton 8.0")

proton_dirs = []

for entry in common.iterdir():

if entry.is_dir() and entry.name.startswith("Proton "):

match = re.match(r"Proton (\d+(?:\.\d+)?)", entry.name)

if match:

version = float(match.group(1))

# Find versioned Proton installations (e.g., "Proton 9.0", "Proton 8.0", "Proton 8.0.5")

proton_dirs = []

for entry in common.iterdir():

if entry.is_dir() and entry.name.startswith("Proton "):

# Capture one or more dot-separated numeric components after "Proton "

match = re.match(r"Proton (\d+(?:\.\d+)*)", entry.name)

if match:

version_str = match.group(1)

# Parse version into a tuple of integers for correct numeric sorting

version = tuple(int(part) for part in version_str.split("."))

Copilot · 2026-01-01T13:56:40Z

+@pytest.mark.skipif(not IS_LINUX, reason="Linux only")
+class TestLinuxLauncher:
+    """Tests for LinuxLauncher (Linux only)."""
+
+    def test_validate_paths_missing_steam(self, tmp_path):
+        """Raises RuntimeError when Steam installation not found."""
+        launcher = LinuxLauncher()
+        config = Config(steam_path=str(tmp_path / "nonexistent"))
+
+        with pytest.raises(RuntimeError, match="Steam directory not found"):
+            launcher.validate_paths(config)
+
+    def test_validate_paths_invalid_steam(self, tmp_path):
+        """Raises RuntimeError when Steam directory has no steamapps."""
+        # Create a fake Steam directory without steamapps
+        steam_path = tmp_path / "Steam"
+        steam_path.mkdir()
+
+        launcher = LinuxLauncher()
+        config = Config(steam_path=str(steam_path))
+
+        with pytest.raises(RuntimeError, match="Invalid Steam directory"):
+            launcher.validate_paths(config)
+
+    def test_build_env_includes_proton_vars(self, tmp_path):
+        """build_env includes Proton compatibility environment variables."""
+        launcher = LinuxLauncher()
+        config = Config(steam_path="/path/to/Steam")
+
+        env = launcher.build_env(config)
+
+        assert env["STEAM_COMPAT_CLIENT_INSTALL_PATH"] == "/path/to/Steam"
+        assert "compatdata/2379780" in env["STEAM_COMPAT_DATA_PATH"]
+        assert env["WINEDLLOVERRIDES"] == "version=n,b"
+
+    def test_build_cmd(self, tmp_path):
+        """build_cmd returns proton run command."""
+        launcher = LinuxLauncher()
+        config = Config(
+            balatro_path="/path/to/proton",
+            love_path="/path/to/Balatro.exe",
+        )
+
+        cmd = launcher.build_cmd(config)
+
+        assert cmd == ["/path/to/proton", "run", "/path/to/Balatro.exe"]


The test coverage for LinuxLauncher is incomplete compared to other platform launchers. Consider adding tests for:

Missing Balatro.exe (similar to test_validate_paths_missing_balatro_exe in WindowsLauncher)

Missing version.dll (similar to test_validate_paths_missing_version_dll in WindowsLauncher)

Missing Proton runtime

Missing Proton prefix (compatdata directory)

Platform check validation (testing the RuntimeError when not on Linux)

- Add --steam-path option to CLI options table - Add 'Linux Platform (Proton)' section with: - Auto-detected paths (Steam, Balatro.exe, version.dll, Proton) - Requirements (Steam, Proton, Lovely, Proton prefix) - Launch examples

Use tuple instead of float for semantic version comparison to correctly handle multi-decimal versions like 'Proton 8.0.5'. - Change regex from \d+(?:\.\d+)? to \d+(?:\.\d+)* to capture all parts - Parse version as tuple: '8.10' -> (8, 10) for correct comparison - Fixes: (8, 10) > (8, 9) vs incorrect float 8.10 < 8.9

Add test_validate_paths_missing_proton_prefix to verify LinuxLauncher raises RuntimeError when compatdata directory doesn't exist.

S1M0N38 · 2026-01-13T15:16:34Z

This is PR was merge for error and manually reverted. We still need to add support for Linux through Proton.

charlesmerritt · 2026-03-28T06:53:14Z

Do you happen to recall what wasn't working here? Is this still an open issue?

S1M0N38 · 2026-03-28T12:57:59Z

@charlesmerritt

Nope. This PR was just created with an agent (I'm okay with agent PR). The problem is that I don't have a Linux x86 with Proton where I can test this PR.
Yeah, this is still an open issue (see feat(balatrobot): CLI support for Linux through Proton #128).

If you have a Linux x86 with Proton where you can test the generated code, you can give a shot to this open issue. You can use the implementation for the other platform as an example. I think it's better to start a new PR forking the current main to avoid any merging conflicts.

charlesmerritt · 2026-03-28T16:04:55Z

I see, I’m going to be testing this on Steam Deck.

S1M0N38 added 4 commits January 1, 2026 14:52

feat(config): add steam_path configuration option

d46781e

Add steam_path field to Config dataclass and --steam-path CLI argument for specifying Steam installation path on Linux systems. - Add BALATROBOT_STEAM_PATH environment variable mapping - Add --steam-path CLI flag with help text

feat(platforms): register LinuxLauncher for linux platform

08d132b

Update get_launcher() to return LinuxLauncher for 'linux' platform instead of raising NotImplementedError.

Copilot AI review requested due to automatic review settings January 1, 2026 13:53

Copilot started reviewing on behalf of S1M0N38 January 1, 2026 13:53 View session

Copilot AI reviewed Jan 1, 2026

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S1M0N38 added 3 commits January 1, 2026 15:07

docs(cli): add Linux (Proton) platform documentation

100c71a

- Add --steam-path option to CLI options table - Add 'Linux Platform (Proton)' section with: - Auto-detected paths (Steam, Balatro.exe, version.dll, Proton) - Requirements (Steam, Proton, Lovely, Proton prefix) - Launch examples

test(platforms): add test for missing Proton prefix

ede933b

Add test_validate_paths_missing_proton_prefix to verify LinuxLauncher raises RuntimeError when compatdata directory doesn't exist.

S1M0N38 force-pushed the main branch from 006ed29 to 905609f Compare January 1, 2026 14:43

S1M0N38 assigned stirby Jan 1, 2026

S1M0N38 merged commit 30b38cc into main Jan 13, 2026
4 checks passed

S1M0N38 deleted the platforms-8g5v branch January 26, 2026 21:21

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feat(platforms): add CLI support for Linux through Proton#134

feat(platforms): add CLI support for Linux through Proton#134
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S1M0N38 commented Jan 1, 2026

Summary

Changes

Configuration

Linux Launcher (src/balatrobot/platforms/linux.py)

Tests

Usage

Requirements

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Quick Test Instructions

Manual Testing

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S1M0N38 commented Jan 13, 2026

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Linux Launcher (`src/balatrobot/platforms/linux.py`)

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