@modelcontextprotocol/server-everything/dist/server/roots.js

MCP server that exercises all the features of the MCP protocol

// The 2025-era roots sync: after `initialize`, a server whose client supports
// Roots asks for the list with `roots/list`, and asks again each time the
// client sends `notifications/roots/list_changed`, reporting each answer to
// the client as a log message.
//
// 2025-era only, and deprecated: the 2026-07-28 revision removes
// server-to-client requests and `notifications/roots/list_changed`, and
// deprecates Roots. There a server asks for roots in-band, by returning an
// `input_required` result from a call, which `get-roots-list` does on both
// eras (#4852). Nothing is cached: the answer is only reported.
/** The servers whose `roots/list_changed` handler is installed. */
const watching = new WeakSet();
/**
 * Ask the client for its roots and report the answer, and re-ask on each
 * `notifications/roots/list_changed`. Does nothing for a client without Roots.
 * Safe to call more than once: the notification handler is installed once.
 *
 * A failed request is logged to stderr, not thrown, since the caller is a
 * timer with nothing to report the failure to.
 *
 * @param {McpServer} server - The 2025-era server whose client is asked.
 */
export const syncRoots = async (server) => {
    const clientCapabilities = server.server.getClientCapabilities() || {};
    if (clientCapabilities.roots === undefined)
        return;
    const requestRoots = async () => {
        try {
            const response = await server.server.listRoots();
            await server.sendLoggingMessage({
                level: "info",
                logger: "everything-server",
                data: `Roots updated: ${response.roots.length} root(s) received from client`,
            }, server.server.transport?.sessionId);
        }
        catch (error) {
            console.error(`Failed to request roots from client: ${
            /* v8 ignore start -- the SDK always rejects listRoots() with an Error (ProtocolError or SdkError) */
            error instanceof Error ? error.message : String(error)
            /* v8 ignore stop */
            }`);
        }
    };
    if (!watching.has(server)) {
        watching.add(server);
        server.server.setNotificationHandler("notifications/roots/list_changed", requestRoots);
    }
    await requestRoots();
};