---
name: beatsaber-plugin-builder
description: Build, test-compile, or package Beat Saber PC BSIPA plugin source on Linux from local checkouts, GitHub branches, or pull requests. Use when asked to build a Beat Saber plugin, compile a plugin PR, produce a DLL/zip artifact, configure BeatSaberDir/local refs for dotnet builds, or diagnose Linux build failures for .NET Framework BSIPA projects.
---

# Beat Saber Plugin Builder

Use this skill to compile PC BSIPA plugin projects on this Linux host, especially from the `plugin-helper` repo. The workflow is adapted from the Setlist repo's Linux/Cursor build notes.

For detailed Linux/BSMT behavior, read [linux-bsipa-build.md](references/linux-bsipa-build.md) when you need to configure a project, fix missing references, package artifacts, or explain a failure.

## Core Workflow

1. Confirm context.

   ```bash
   pwd
   git status --short
   sed -n '1,220p' plugin-helper.local.toml
   ```

   In `plugin-helper`, run commands from repo root. Treat
   `plugin-helper.local.toml` as the source of truth for profile
   `instances_root` and `state_dir` values, and keep temporary source checkouts
   under the chosen profile's `state_dir` such as
   `<state_dir>/build/<name>`. Do not disturb unrelated dirty files.

2. Resolve source.

   For a GitHub PR, clone or reuse a checkout under the selected profile's
   `<state_dir>/build`, add/fetch the upstream remote if needed, and check out
   the PR head:

   ```bash
   git clone https://github.com/<owner>/<repo>.git <state_dir>/build/<name>
   git -C <state_dir>/build/<name> fetch origin pull/<pr>/head:pr-<pr>
   git -C <state_dir>/build/<name> checkout pr-<pr>
   ```

   If the PR is from a fork and the repo already has a fork remote, preserve it. Never overwrite local source changes without explicit approval.

3. Inspect build shape.

   ```bash
   find <checkout> -maxdepth 3 -name '*.sln' -o -name '*.csproj' -o -name 'manifest.json' -o -name 'Directory.Build.props'
   sed -n '1,240p' <project>.csproj
   ```

   Note target framework, `BeatSaberDir`, `LocalRefsDir`, package references, and whether `DisableCopyToPlugins` is already set.

4. Choose Beat Saber references.

   Prefer a BSManager instance matching the plugin or manifest `gameVersion`.
   Read `plugin-helper.local.toml` and select the intended profile, then use
   that profile's `instances_root` and matching `state_dir` instead of
   searching default BSManager paths manually:

   ```bash
   PYTHONPATH=src .venv/bin/python -m plugin_helper --profile <profile-id> instances
   ```

   Use a local `.csproj.user` or MSBuild properties rather than committing
   machine paths. For test builds, pass `-p:DisableCopyToPlugins=True` and, for
   BSMT projects that expose it, `-p:DisableCopyToGame=True` so compilation
   does not mutate the game install.

5. Restore and build.

   Prefer the solution when present; otherwise build the plugin `.csproj`:

   ```bash
   dotnet restore <solution-or-project>
   dotnet build <solution-or-project> -c Release -p:DisableCopyToPlugins=True -p:DisableCopyToGame=True
   ```

   If the project lacks .NET Framework reference assemblies on Linux, add or
   pass the package matching the project's target framework, usually
   `Microsoft.NETFramework.ReferenceAssemblies.net48` for current BSIPA
   projects, as described in the reference file.

6. Verify Beat Saber API changes before patching gameplay code.

   When a Beat Saber upgrade breaks a type/member reference, first determine
   whether the API moved assemblies before substituting another type. Inspect
   the target game DLLs and nearby mod sources:

   ```bash
   strings "<BeatSaberDir>/Beat Saber_Data/Managed/Main.dll" | rg 'TypeOrMemberName'
   strings "<BeatSaberDir>/Beat Saber_Data/Managed/HMLib.dll" | rg 'TypeOrMemberName'
   ilspycmd -t TypeName "<BeatSaberDir>/Beat Saber_Data/Managed/Main.dll" | sed -n '1,220p'
   rg -n 'TypeOrMemberName|NearbyConcept' ~/src/<owner>/<repo> ~/src/Auros/SiraUtil ~/src/nike4613/BeatSaber-IPA-Reloaded
   ```

7. Collect artifacts.

   Find produced DLLs and release zips:

   ```bash
   find <checkout> -path '*/bin/*' \( -name '*.dll' -o -name '*.zip' \) -print
   ```

   Verify the DLL name, version, and manifest. If the result is meant for
   `plugin-helper`, place a copy under
   `<state_dir>/instances/<instance>/downloads/<plugin-id>/` for the selected
   profile and use the helper plan/apply workflow rather than hand-copying into
   a BSManager instance.

8. Validate.

   For skill edits inside this repo, run:

   ```bash
   python /home/pleb/.codex/skills/.system/skill-creator/scripts/quick_validate.py .agents/skills/beatsaber-plugin-builder
   PYTHONPATH=src .venv/bin/python -m compileall -q src tests
   PYTHONPATH=src .venv/bin/python -m unittest discover -s tests
   ```

   For a plugin build, at minimum report the exact `dotnet build` result and artifact paths. For live game validation, use `docs/SMOKETEST.md` and tear down Beat Saber processes afterward.

## Failure Triage

- Missing `Microsoft.NETFramework.ReferenceAssemblies`: add the package matching the target framework, usually `Microsoft.NETFramework.ReferenceAssemblies.net48` for current projects, or pass an equivalent MSBuild/package restore fix.
- Missing `Main.dll`, `HMUI.dll`, `IPA.Loader.dll`, `BSML.dll`, `SongCore.dll`, or similar: `BeatSaberDir` points at the wrong/unmodded instance, or dependencies are absent from `Plugins/`/`Libs/`.
- BSMT copies to `IPA/Pending` or `Plugins` during build: rebuild with `-p:DisableCopyToPlugins=True -p:DisableCopyToGame=True` unless the user explicitly wants deployment.
- NuGet package restore fails because a source is missing: inspect `NuGet.config` and installed package sources; use repo-local configuration where possible.
- API compile errors from a PR: inspect the target game/dependency versions before changing code. Prefer one target version rather than compatibility branches unless the user asks for multi-version support.