Unity live editor loop

Surfaces

Need	Surface
Hierarchy, components, scene edits, console, run C# in the editor	Unity MCP server (Unity_ManageScene, Unity_ManageGameObject, Unity_ReadConsole, Unity_RunCommand, Unity_ManageScript)
Compile status, run tests from the live editor, editor screenshots, execute menu items, Play Mode inspection	Meta XR MCP bridge (when the Meta XR SDK is in the project)
Headless tests and builds, editor state, one-shot editor commands	Unity CLI (unity test, unity build, unity status, unity pipeline list, unity command)
XR head and controller input	Meta XR Operator (OpenXR API layer)

Rules of thumb: a live surface that stops answering means the editor is compiling or importing, so wait and retry; nothing answering usually means Safe Mode or a closed editor; unity test and unity build spawn their own editor and need the project closed.

The loop

1. Read the design or architecture notes for the subsystem before editing.
2. Edit C#; let the editor recompile; check error CS through the console tool.
3. Run EditMode tests (unity test <project> --mode EditMode --report-format junit --output TestResults/editmode.junit.xml or the bridge Test Runner); add tests for pure logic.
4. Enter Play Mode through a tool, drive the scenario, inspect state, capture the Game view, read the console.
5. Exit Play Mode before any further edit; Play Mode edits are lost.
6. Scene, prefab and asset edits go through editor tools; never hand-edit .unity/.prefab/.asset/.mat YAML while an editor has the project open (Temp/UnityLockfile exists). Editing YAML with the editor closed is fine, say so.
7. Package changes go through the package manager tooling, never by hand-editing Packages/manifest.json.
8. Commit small logical steps with evidence (test report, captures) kept for the review.

Safe Mode recovery

1. unity pipeline list --json --no-banner reports instancesInSafeMode.
2. Read only the error lines from the editor log (%LOCALAPPDATA%\Unity\Editor\Editor.log on Windows, ~/Library/Logs/Unity/Editor.log on macOS): filter for error CS; never dump the whole log.
3. Fix the C#; the editor recompiles and leaves Safe Mode; restart it if the MCP bridges do not reconnect.
4. A domain reload that never finishes: look for exceptions in [InitializeOnLoad] code; closing the editor from the OS is the last resort and must be reported.

Hooks worth adding to the project

• A pre-edit hook that asks before writing serialized Unity assets while Temp/UnityLockfile exists.
• A session-start hook printing branch, editor state (running, pipeline package, Safe Mode) and MCP registration.
• Permission denies for secret files (Firebase configs, keystores, API keys) and force pushes.