Expo iOS Development MCP Server

Instructions

Implementation Reference

• src/mcp/server.ts:297-316 (registration)

  Registers the 'expo.stop' MCP tool with an empty input schema. The handler calls stopExpo() from expo.ts and returns a standardized MCP response or error.

  server.tool(
    "expo.stop",
    "Stop the Expo/Metro development server",
    {},
    async () => {
      try {
        await stopExpo();
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify({ success: true, message: "Expo stopped" }),
            },
          ],
        };
      } catch (error) {
        return handleToolError(error);
      }
    }
  );

• src/expo/expo.ts:178-213 (handler)

  Core implementation of stopping Expo: checks if process exists, sends SIGTERM, waits 2s, then SIGKILL if needed, clears state variables, updates global state manager, and logs.

  export async function stopExpo(): Promise<void> {
    logger.info("expo", "Stopping Expo/Metro...");
  
    if (!expoProcess) {
      logger.info("expo", "No Expo process running");
      stateManager.updateExpo({ state: "stopped" });
      return;
    }
  
    try {
      // Send SIGTERM first for graceful shutdown
      expoProcess.kill("SIGTERM");
  
      // Wait a bit for graceful shutdown
      await new Promise((resolve) => setTimeout(resolve, 2000));
  
      // If still running, force kill
      if (expoProcess) {
        expoProcess.kill("SIGKILL");
      }
    } catch {
      // Ignore errors during cleanup
    }
  
    expoProcess = null;
    outputBuffer = "";
    startedAt = null;
  
    stateManager.updateExpo({
      state: "stopped",
      metroUrl: undefined,
      processId: undefined,
    });
  
    logger.info("expo", "Expo stopped");
  }