1MCP Server

import { ServerCapabilities } from '@modelcontextprotocol/sdk/types.js'; import { setupClientToServerNotifications, setupServerToClientNotifications, } from '@src/core/protocol/notificationHandlers.js'; import { registerRequestHandlers } from '@src/core/protocol/requestHandlers.js'; import { InboundConnection, OutboundConnections } from '@src/core/types/index.js'; import logger from '@src/logger/logger.js'; /** * Collects capabilities from all clients and registers them with the server * @param clients Record of client instances * @param server The MCP server instance * @param tags Array of tags to filter clients by * @returns The combined server capabilities */ export async function setupCapabilities(clients: OutboundConnections, serverInfo: InboundConnection) { // Collect capabilities from all clients const capabilities = collectCapabilities(clients); // Set up notification handlers setupClientToServerNotifications(clients, serverInfo); setupServerToClientNotifications(clients, serverInfo); // Register request handlers based on capabilities registerRequestHandlers(clients, serverInfo); return capabilities; } /** * Collects capabilities from all clients * @param clients Record of client instances * @returns The combined server capabilities */ function collectCapabilities(clients: OutboundConnections): ServerCapabilities { const capabilities: ServerCapabilities = {}; for (const [name, clientInfo] of clients.entries()) { try { const serverCapabilities = clientInfo.client.getServerCapabilities() || {}; logger.debug(`Capabilities from ${name}: ${JSON.stringify(serverCapabilities)}`); // Store capabilities per client clientInfo.capabilities = serverCapabilities; // Aggregate capabilities with conflict handling capabilities.resources = mergeCapabilities( capabilities.resources, serverCapabilities.resources, 'resources', name, ); capabilities.tools = mergeCapabilities(capabilities.tools, serverCapabilities.tools, 'tools', name); capabilities.prompts = mergeCapabilities(capabilities.prompts, serverCapabilities.prompts, 'prompts', name); capabilities.experimental = mergeCapabilities( capabilities.experimental, serverCapabilities.experimental, 'experimental', name, ); capabilities.logging = mergeCapabilities(capabilities.logging, serverCapabilities.logging, 'logging', name); } catch (error) { logger.error(`Failed to get capabilities from ${name}: ${error}`); } } return capabilities; } /** * Check if a capability key represents a notification capability * Notification capabilities can be independently supported by multiple servers * @param key The capability key to check * @returns True if the key represents a notification capability */ function isNotificationCapability(key: string): boolean { return key === 'listChanged' || key === 'subscribe'; } /** * Merges capability objects with conflict detection and resolution * @param existing The existing capability object * @param incoming The incoming capability object * @param capabilityType The type of capability being merged * @param clientName The name of the client providing the incoming capability * @returns The merged capability object */ function mergeCapabilities<T extends Record<string, unknown>>( existing: T | undefined, incoming: T | undefined, capabilityType: string, clientName: string, ): T | undefined { if (!incoming) { return existing; } if (!existing) { return incoming; } const merged = { ...existing }; const conflicts: string[] = []; for (const [key, value] of Object.entries(incoming)) { if (key in existing) { // Special handling for notification capabilities if (isNotificationCapability(key)) { // Use OR logic for boolean notification capabilities if (typeof value === 'boolean' && typeof existing[key] === 'boolean') { (merged as any)[key] = existing[key] || value; } else { (merged as any)[key] = value; // Non-boolean, use last value } continue; // Skip conflict logging } // Check if values are different (potential conflict) if (JSON.stringify(existing[key]) !== JSON.stringify(value)) { conflicts.push(key); logger.warn(`Capability conflict in ${capabilityType}.${key}: client ${clientName} overriding existing value`); logger.debug(`Existing: ${JSON.stringify(existing[key])}, New: ${JSON.stringify(value)}`); } } (merged as any)[key] = value; } if (conflicts.length > 0) { logger.info( `Client ${clientName} has ${conflicts.length} ${capabilityType} capability conflicts: ${conflicts.join(', ')}`, ); } return merged; }