From cdb489aea2c6983a94fcd215cd455c56713d351d Mon Sep 17 00:00:00 2001
From: Elias Bachaalany <elias.bachaalany@gmail.com>
Date: Fri, 5 Dec 2025 19:47:19 -0800
Subject: [PATCH 1/2] Fix StreamableHttpTransport to build JSON-RPC envelope
 and extract result

The StreamableHttpTransport::request method was passing the params
directly to the server instead of wrapping them in a JSON-RPC envelope.
It was also returning the full JSON-RPC response instead of extracting
the result.

Fixes:
- Build proper JSON-RPC request with jsonrpc, method, params, and id
- Extract result from JSON-RPC response envelope
- Handle JSON-RPC errors by throwing TransportError
---
 src/client/transports.cpp | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/client/transports.cpp b/src/client/transports.cpp
index 3e6aba0..87c618d 100644
--- a/src/client/transports.cpp
+++ b/src/client/transports.cpp
@@ -924,7 +924,7 @@ fastmcpp::Json StreamableHttpTransport::parse_response(const std::string& body,
     }
 }
 
-fastmcpp::Json StreamableHttpTransport::request(const std::string& /*route*/,
+fastmcpp::Json StreamableHttpTransport::request(const std::string& route,
                                                 const fastmcpp::Json& payload)
 {
     auto url = parse_url(base_url_);
@@ -951,11 +951,13 @@ fastmcpp::Json StreamableHttpTransport::request(const std::string& /*route*/,
             request_headers.emplace("Mcp-Session-Id", session_id_);
     }
 
-    // Payload is the full JSON-RPC request
-    // (StreamableHttp transport accepts complete JSON-RPC requests, unlike other transports)
+    // Build JSON-RPC request (route is method, payload is params)
+    int64_t id = next_id_.fetch_add(1, std::memory_order_relaxed);
+    fastmcpp::Json rpc_request = {
+        {"jsonrpc", "2.0"}, {"method", route}, {"params", payload}, {"id", id}};
 
     // Send request
-    auto res = cli.Post(mcp_path_.c_str(), request_headers, payload.dump(), "application/json");
+    auto res = cli.Post(mcp_path_.c_str(), request_headers, rpc_request.dump(), "application/json");
 
     if (!res)
         throw fastmcpp::TransportError("StreamableHttp request failed: no response");
@@ -982,8 +984,20 @@ fastmcpp::Json StreamableHttpTransport::request(const std::string& /*route*/,
     // Parse response
     auto rpc_response = parse_response(res->body, content_type);
 
-    // Return full JSON-RPC response (caller handles error/result extraction)
-    return rpc_response;
+    // Check for JSON-RPC error
+    if (rpc_response.contains("error"))
+    {
+        auto error = rpc_response["error"];
+        std::string message = error.value("message", "Unknown error");
+        throw fastmcpp::TransportError("JSON-RPC error: " + message);
+    }
+
+    // Extract result from JSON-RPC envelope
+    if (rpc_response.contains("result"))
+        return rpc_response["result"];
+
+    // If no result or error, return empty object
+    return fastmcpp::Json::object();
 }
 
 } // namespace fastmcpp::client

From c53b71590b961ddcd6d03ac53ecca82d844911eb Mon Sep 17 00:00:00 2001
From: Elias Bachaalany <elias.bachaalany@gmail.com>
Date: Fri, 5 Dec 2025 20:09:47 -0800
Subject: [PATCH 2/2] Fix clang-format for streaming_demo.cpp and sse.cpp

---
 examples/streaming_demo.cpp | 3 ++-
 tests/server/sse.cpp        | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/examples/streaming_demo.cpp b/examples/streaming_demo.cpp
index f9ee26b..559abf8 100644
--- a/examples/streaming_demo.cpp
+++ b/examples/streaming_demo.cpp
@@ -48,7 +48,8 @@ int main()
     std::thread sse_thread(
         [&, port]()
         {
-            // Create client inside thread - httplib::Client is not thread-safe across threads on Linux
+            // Create client inside thread - httplib::Client is not thread-safe across threads on
+            // Linux
             httplib::Client cli("127.0.0.1", port);
             cli.set_connection_timeout(std::chrono::seconds(10));
             cli.set_read_timeout(std::chrono::seconds(20));
diff --git a/tests/server/sse.cpp b/tests/server/sse.cpp
index ea2148f..661fed7 100644
--- a/tests/server/sse.cpp
+++ b/tests/server/sse.cpp
@@ -66,7 +66,8 @@ int main()
     std::thread sse_thread(
         [&, port]()
         {
-            // Create client inside thread - httplib::Client is not thread-safe across threads on Linux
+            // Create client inside thread - httplib::Client is not thread-safe across threads on
+            // Linux
             httplib::Client sse_client("127.0.0.1", port);
             sse_client.set_read_timeout(std::chrono::seconds(20));
             sse_client.set_connection_timeout(std::chrono::seconds(10));