MoonBase Bridge

Local execution engine for MoonBase Studio

MoonBase Bridge is a separate process that the operator downloads and runs next to MoonBase Studio. It has no operator window. Studio edits the project document. Bridge executes it.

• It opens cameras, microphones, screens, and media files.
• It renders one Program Output in scene.elements order.
• FFmpeg publishes that same picture and the program mix over RTMP.
• It reports session state, devices, and runtime numbers (FPS, bitrate, latency, CPU, memory) back to Studio.

Studio works on its own (Standalone): edit, undo, and save. With Bridge running it switches to Connected, and streaming, the program frame, monitoring, and the director become available. Losing Studio does not stop a running program. Losing Bridge does not stop editing. Losing one source does not stop the program.

MoonBase AI scores camera frames that it gets from Bridge. Its shot recommendation reaches Bridge as a command. AI does not write the project and does not open devices.

Status: early skeleton. The Studio ↔ Bridge contract (STU-23) comes next. Work is tracked in Linear, project MoonBase Bridge (target: 18 December 2026).

Supported platforms

OS	Architectures	Notes
Windows 10 / 11	x64, arm64	ffmpeg.exe ships with the package
Linux (Wayland or X11)	x64, arm64	needs ffmpeg, PipeWire, and xdg-desktop-portal with a backend for your compositor

Both systems have the same feature set. Device ids are platform-specific, so a project moved between Windows and Linux needs its cameras assigned again.

Development

Requirements

• rustup. The toolchain version comes from rust-toolchain.toml.

• Tools:

  # Arch Linux
  sudo pacman -S --needed just taplo-cli typos cargo-deny cargo-nextest committed
  
  # Anywhere else (or cargo install --locked ...)
  cargo binstall just taplo-cli typos-cli cargo-deny cargo-nextest committed
  
  # Git hooks
  cargo binstall prek

Running

# debug build with debug logs
just run

# release build
just build
./target/release/moonbase-bridge --help

Logs go to stderr and to a daily file:

• Windows: %LOCALAPPDATA%\MoonBase\Bridge\logs
• Linux: $XDG_STATE_HOME/moonbase/bridge/logs (usually ~/.local/state/...)

Use --log-dir / MOONBASE_BRIDGE_LOG_DIR and --log-filter / MOONBASE_BRIDGE_LOG to change them. On Linux you can run Bridge as a user service, see docs/moonbase-bridge.service.

Checks

just lint      # rustfmt, clippy (-D warnings), taplo, typos
just test      # nextest + doc tests
just deny      # licenses, advisories, bans, sources
just lint-fix  # apply automatic fixes

Git hooks

prek runs the hooks from prek.toml. Install them once per clone:

prek install

Stage	Hooks
pre-commit	whitespace and end-of-file fixes, TOML/YAML syntax, merge markers, typos, cargo fmt, taplo fmt
commit-msg	committed: Conventional Commits, same rules as @commitlint/config-conventional in the TypeScript repositories
pre-push	cargo clippy -D warnings, cargo nextest

CI

.github/workflows/ci.yaml runs on pull requests and on main:

• lint on Linux and Windows
• Conventional Commits check on pull request commits
• cargo deny
• tests on Linux and Windows

On main it also builds release packages on native runners for linux-x64, linux-arm64, windows-x64, and windows-arm64, and uploads them as workflow artifacts.

Project setup

Directory structure

crates
├── bridge-contract  # Studio ↔ Bridge contract, platform-neutral
└── moonbase-bridge  # the executable: CLI, logging, process lifecycle
docs
├── architecture.md  # crates, platform boundaries, data flow
└── decisions.md     # architecture decision records

The project document format is owned by Studio (ProjectFile v2 in moonbase-studio-web). Bridge reads it and never writes it.

Stack

Area	Choice
Async runtime and local transport	Tokio, Axum (HTTP + WebSocket on 127.0.0.1), Serde
Rendering	wgpu (D3D12 on Windows, Vulkan on Linux), glyphon for text
Cameras	Media Foundation (windows crate) / V4L2 (v4l)
Screen capture	Windows.Graphics.Capture (windows-capture) / xdg-desktop-portal ScreenCast + PipeWire (ashpd, pipewire)
Audio	cpal and an in-house DSP chain (EQ, compressor, limiter, gate)
Encoding and RTMP	an ffmpeg child process fed with raw frames and PCM

The reasons are in docs/decisions.md.

VS Code helpers

Recommended extensions are in .vscode/extensions.json. rust-analyzer runs clippy on save.