AgentBridge CLAUDE.md

AgentBridge

Unity package (com.dffrnt.llm-dev-tools) that exposes a file-based command bridge so LLM agents can control a running Unity Editor via MCP.

Structure

AgentBridge/
  Editor/         C# EditorWindow + AgentBridge (Unity-side bridge)
  Harness~/       Go agent CLI + tools (excluded from Unity import)
  Example~/       Example Unity project (excluded from Unity import)
  Tests~/         Test package (excluded from Unity import)

Running integration tests

cd AgentBridge/Harness~/dffrnt-agent
go test -timeout 300s

Use -timeout 300s minimum. The full suite takes ~120s; the default 30s timeout will kill it mid-run.

Building the Go agent

cd AgentBridge/Harness~/dffrnt-agent
go build -o dffrnt-agent .        # Linux/macOS
go build -o dffrnt-agent.exe .    # Windows

Run go get ./... first if dependencies are missing.

After editing C# files

Open Unity and let it compile. Check the Console for errors. There is no automated compile trigger — Unity auto-compiles on focus or file change.

Key files

File	Purpose
AgentBridge/Editor/AgentBridge.cs	Main bridge loop — reads Temp/agent_input, writes Temp/agent_output
AgentBridge/Editor/AgentLogWindow.cs	Window > General > LLM Agent Log
AgentBridge/Harness~/dffrnt-agent/main.go	CLI entry point (dffrnt-agent send / dffrnt-agent serve)
AgentBridge/Harness~/dffrnt-agent/serve.go	MCP server (stdio transport)
AgentBridge/Harness~/dffrnt-agent/bridge.go	File I/O helpers, session check, UID generation

Protocol

• Temp/agent_input — newline-delimited JSON written by the agent CLI
• Temp/agent_output — newline-delimited JSON written by Unity
• Temp/agent_session — JSON heartbeat written by Unity every 5 s: pid, state, active_scene, play_mode, compile_errors, written_at
• Output rotates at 2 MB; input is truncated on Unity startup

Notifications

AgentBridge sends notifications/message events when Unity state changes. In serve mode, dffrnt-agent forwards these automatically to connected MCP clients.