Fix MCP initialize response to follow specification

- Remove sessionId field from initialize response body (not in MCP spec)
- Set Mcp-Session-Id header in initialize response using visit ID
- Maintain proper header setting for other methods that return sessionId
- Ensure MCP protocol compliance for initialization flow

@@ -107,8 +107,7 @@
                     protocolVersion: "2025-06-18",
                     capabilities: serverCapabilities,
                     serverInfo: serverInfo,
-                    instructions: "This server provides access to Moqui ERP through MCP. For common business queries: Use screen_PopCommerce_screen_PopCommerceAdmin.Catalog for product catalog, screen_PopCommerce_screen_PopCommerceAdmin_Order.FindOrder for order status, screen_PopCommerce_screen_PopCommerceRoot.Customer for customer management, and screen_PopCommerce_screen_PopCommerceAdmin.QuickSearch for general searches. All screens support parameterized queries for filtering results.",
-                    sessionId: visit.visitId
+                    instructions: "This server provides access to Moqui ERP through MCP. For common business queries: Use screen_PopCommerce_screen_PopCommerceAdmin.Catalog for product catalog, screen_PopCommerce_screen_PopCommerceAdmin_Order.FindOrder for order status, screen_PopCommerce_screen_PopCommerceRoot.Customer for customer management, and screen_PopCommerce_screen_PopCommerceAdmin.QuickSearch for general searches. All screens support parameterized queries for filtering results."
                 ]
                 
                 ec.logger.info("MCP Initialize for user ${userId} (session ${sessionId}): capabilities negotiated")

@@ -812,8 +812,11 @@ logger.info("Handling Enhanced SSE connection from ${request.remoteAddr}")
         }
         
         // Set Mcp-Session-Id header BEFORE any response data (per MCP 2025-06-18 spec)
-        if (result?.sessionId) {
-            response.setHeader("Mcp-Session-Id", result.sessionId)
+        // For initialize method, always use sessionId we have (from visit or header)
+        if (rpcRequest.method == "initialize" && sessionId) {
+            response.setHeader("Mcp-Session-Id", sessionId.toString())
+        } else if (result?.sessionId) {
+            response.setHeader("Mcp-Session-Id", result.sessionId.toString())
         }
         
         // Build JSON-RPC response for regular requests
@@ -868,7 +871,8 @@ logger.info("Handling Enhanced SSE connection from ${request.remoteAddr}")
                     }
                     params.actualUserId = ec.user.userId
                     logger.info("Initialize - actualUserId: ${params.actualUserId}, sessionId: ${params.sessionId}")
-                    return callMcpService("mcp#Initialize", params, ec)
+                    def serviceResult = callMcpService("mcp#Initialize", params, ec)
+                    return serviceResult
                 case "ping":
                     // Simple ping for testing - bypass service for now
                     return [pong: System.currentTimeMillis(), sessionId: visit?.visitId, user: ec.user.username]