Extensions Hub & MCP
The puzzle-piece icon in the sidebar opens the Extensions Hub. It has three tabs: Installed, Install and MCP.
Extensions
A Catenary extension can add its own panel, running in an isolated view of its own. Extensions are managed globally: one installed is available in every workspace.
- Installed lists what you have. Each row turns on and off, and offers Reinstall and Remove.
- Install browses the catalog, by category or by search. Add local folder loads an extension from a folder on disk that has a manifest.
- Catalog sources are the URLs the catalog comes from. Only add sources you trust: an extension can run its own code on your machine.
Open a row to see what the extension may do, such as Read workspace info, Open & edit files, Control the browser or Run the agent on your behalf. Before an extension runs the agent or drives the browser, Catenary asks you.
The MCP tab
The MCP tab shows which MCP servers your agents can reach, and it is honest about what it cannot see.
Configured in this workspace. The servers the project declares in .mcp.json (read by Claude Code) and .pi/mcp.json (read by the Catenary Agent). For each one it shows:
- the name;
- the transport:
stdio,httporsse; - the executable name, or the host of the URL.
Never the arguments, the environment, the headers or the path of the URL: they routinely carry tokens. Catenary also cannot see whether these servers are connected, because the agent that reads the file is the one that connects.
Catenary MCP. The built-in server, with the list of the tools it advertises. See LSP and tools for agents.
Observed MCP connections. Every live connection to the Catenary server: the terminal, the workspace, connected or not, when it was last seen, and the tools exposed to that execution. It refreshes every 5 seconds.
Observed agents and listening ports. What the process monitor sees in each terminal: the agent running there and the ports it listens on. A listening port does not prove that an MCP server is healthy.