[WIP] Refactor everything server to be more modular and use recommended APIs.

Adding Trigger Elicitation Request and Get Roots List tools

* Updated architecture.md

* Added roots.ts
  - tracks roots by sessionId
  - setRootsListChangedHandler
    - listens for roots changed notification from the client
      - updates the roots map by sessionId
      - sends log notification or error to the client

* In server/index.ts
  - import setRootsListChangedHandler
  - in clientConnected callback
    - call setRootsListChangedHandler passing server and sessionId

* In sse.ts, stdio.ts, and streamableHttp.ts
  - receive clientConnected from server factory
  - call clientConnected when server is connected to transport
* Added get-roots-list.ts
  - registerGetRootsListTool
    - Registers the 'get-roots-list' tool with the given MCP server.

* Added trigger-elicitation-request.ts
  - registerTriggerElicitationRequestTool
    - registered tool sends an elicitation request that exercises all supported field types

* In tools/index.ts
  - imports registerTriggerElicitationRequestTool and registerGetRootsListTool
  - in registerTools
    - call registerTriggerElicitationRequestTool and registerGetRootsListTool, passing server

src/everything/transports/sse.ts

@@ -21,7 +21,7 @@ const transports: Map<string, SSEServerTransport> = new Map<
 
 app.get("/sse", async (req, res) => {
   let transport: SSEServerTransport;
-  const { server, cleanup } = createServer();
+  const { server, clientConnected, cleanup } = createServer();
 
   if (req?.query?.sessionId) {
     const sessionId = req?.query?.sessionId as string;
@@ -38,6 +38,8 @@ app.get("/sse", async (req, res) => {
     // Connect server to transport
     await server.connect(transport);
     const sessionId = transport.sessionId;
+    clientConnected(sessionId);
+
     console.error("Client Connected: ", sessionId);
 
     // Handle close of connection

src/everything/transports/stdio.ts

@@ -7,10 +7,10 @@ console.error("Starting default (STDIO) server...");
 
 async function main() {
   const transport = new StdioServerTransport();
-  const { server, cleanup } = createServer();
+  const { server, clientConnected, cleanup } = createServer();
 
   await server.connect(transport);
-
+  clientConnected();
   // Cleanup on exit
   process.on("SIGINT", async () => {
     await server.close();

src/everything/transports/streamableHttp.ts

@@ -35,7 +35,7 @@ app.post("/mcp", async (req: Request, res: Response) => {
       // Reuse existing transport
       transport = transports.get(sessionId)!;
     } else if (!sessionId) {
-      const { server, cleanup } = createServer();
+      const { server, clientConnected, cleanup } = createServer();
 
       // New initialization request
       const eventStore = new InMemoryEventStore();
@@ -47,6 +47,7 @@ app.post("/mcp", async (req: Request, res: Response) => {
           // This avoids race conditions where requests might come in before the session is stored
           console.log(`Session initialized with ID: ${sessionId}`);
           transports.set(sessionId, transport);
+          clientConnected(sessionId);
         },
       });