Parity catch-up: v3.1.0 -> v3.3.1 + community PRs #42 + #43

CMakeLists.txt

@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.16)
 if(POLICY CMP0169)
   cmake_policy(SET CMP0169 OLD)
 endif()
-project(fastmcpp VERSION 3.1.1 LANGUAGES CXX)
+project(fastmcpp VERSION 3.3.1 LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -14,6 +14,7 @@ option(FASTMCPP_BUILD_EXAMPLES "Build examples" ON)
 option(FASTMCPP_ENABLE_POST_STREAMING "Enable POST streaming via libcurl (optional)" OFF)
 option(FASTMCPP_FETCH_CURL "Fetch and build libcurl statically for POST streaming" ON)
 option(FASTMCPP_ENABLE_SAMPLING_HTTP_HANDLERS "Enable built-in OpenAI/Anthropic sampling handlers (requires libcurl)" OFF)
+option(FASTMCPP_ENABLE_OPENSSL "Enable HTTPS/SSL support via OpenSSL (for cpp-httplib)" OFF)
 
 add_library(fastmcpp_core STATIC
     src/types.cpp
@@ -97,6 +98,16 @@ if(NOT cpp_httplib_POPULATED)
 endif()
 target_include_directories(fastmcpp_core PUBLIC ${cpp_httplib_SOURCE_DIR})
 
+# Optional: OpenSSL for HTTPS/SSL support
+if(FASTMCPP_ENABLE_OPENSSL)
+  find_package(OpenSSL REQUIRED)
+  target_compile_definitions(fastmcpp_core PUBLIC CPPHTTPLIB_OPENSSL_SUPPORT)
+  target_link_libraries(fastmcpp_core PUBLIC OpenSSL::SSL OpenSSL::Crypto)
+  message(STATUS "FASTMCPP_ENABLE_OPENSSL=ON: HTTPS/SSL support enabled")
+else()
+  message(STATUS "FASTMCPP_ENABLE_OPENSSL=OFF: HTTPS/SSL support disabled")
+endif()
+
 # Optional: libcurl for POST streaming and sampling handlers (modular)
 if(FASTMCPP_ENABLE_POST_STREAMING OR FASTMCPP_ENABLE_SAMPLING_HTTP_HANDLERS)
   if(FASTMCPP_FETCH_CURL)

README.md

@@ -15,7 +15,7 @@ fastmcpp is a C++ port of the Python [fastmcp](https://github.com/jlowin/fastmcp
 
 **Status:** Beta – core MCP features track the Python `fastmcp` reference.
 
-**Current version:** 2.15.0
+**Current version:** 3.3.1
 
 ## Features
 

include/fastmcpp/app.hpp

@@ -197,6 +197,19 @@ class FastMCP
         return dereference_schemas_;
     }
 
+    /// Experimental capabilities advertised on `initialize`. Mirrors Python
+    /// `FastMCP(experimental_capabilities=...)` (#4042 / commit `a010927e`):
+    /// the dict is propagated verbatim under `capabilities.experimental` so
+    /// servers can announce protocol extensions without a structural change.
+    const std::optional<Json>& experimental_capabilities() const
+    {
+        return experimental_capabilities_;
+    }
+    void set_experimental_capabilities(std::optional<Json> caps)
+    {
+        experimental_capabilities_ = std::move(caps);
+    }
+
     // Manager accessors
     tools::ToolManager& tools()
     {
@@ -384,6 +397,7 @@ class FastMCP
     mutable std::vector<prompts::Prompt> provider_prompts_cache_;
     int list_page_size_{0};
     bool dereference_schemas_{true};
+    std::optional<Json> experimental_capabilities_;
 
     // Prefix utilities
     static std::string add_prefix(const std::string& name, const std::string& prefix);

include/fastmcpp/client/client.hpp

@@ -1042,12 +1042,19 @@ class Client
         CallToolResult result;
         result.isError = body.value("isError", false);
 
-        if (!body.contains("content"))
-            throw fastmcpp::ValidationError("tools/call response missing content");
-
-        if (body.contains("content"))
+        // Python fastmcp commit 556fd8fa (#3778): harden client-side parsing of malformed
+        // tools/call results.
+        // - Missing "content" with isError=true is permitted (server may have raised before
+        //   producing content); raise_on_error is handled at a higher layer using result.text().
+        // - Missing "content" with isError=false is treated as an empty result rather than a
+        //   ValidationError so older servers / partial responses do not crash the client.
+        // - "content" present but not an array is treated as empty (do not crash).
+        if (body.contains("content") && body["content"].is_array())
+        {
             for (const auto& c : body["content"])
                 result.content.push_back(parse_content_block(c));
+        }
+        // else: leave result.content empty
 
         if (body.contains("structuredContent"))
         {

include/fastmcpp/client/types.hpp

@@ -375,7 +375,13 @@ inline void from_json(const fastmcpp::Json& j, ToolInfo& t)
 {
     t.name = j.at("name").get<std::string>();
     if (j.contains("version"))
-        t.version = j["version"].get<std::string>();
+    {
+        // Python fastmcp encodes Tool.version as a string, but historic clients may send an int.
+        if (j["version"].is_string())
+            t.version = j["version"].get<std::string>();
+        else if (j["version"].is_number_integer())
+            t.version = std::to_string(j["version"].get<long long>());
+    }
     if (j.contains("title"))
         t.title = j["title"].get<std::string>();
     if (j.contains("description"))
@@ -392,6 +398,19 @@ inline void from_json(const fastmcpp::Json& j, ToolInfo& t)
         t._meta = j["_meta"];
         if (j["_meta"].is_object() && j["_meta"].contains("ui") && j["_meta"]["ui"].is_object())
             t.app = j["_meta"]["ui"].get<fastmcpp::AppConfig>();
+        // Python fastmcp >= 2.x exposes per-tool version via _meta.fastmcp.version (see
+        // fastmcp_slim/fastmcp/utilities/components.py:get_meta). Surface it as ToolInfo.version
+        // if no top-level "version" was provided so the proxy passthrough preserves the field.
+        if (!t.version && j["_meta"].is_object() && j["_meta"].contains("fastmcp")
+            && j["_meta"]["fastmcp"].is_object()
+            && j["_meta"]["fastmcp"].contains("version"))
+        {
+            const auto& v = j["_meta"]["fastmcp"]["version"];
+            if (v.is_string())
+                t.version = v.get<std::string>();
+            else if (v.is_number_integer())
+                t.version = std::to_string(v.get<long long>());
+        }
     }
 }
 

include/fastmcpp/exceptions.hpp

@@ -5,9 +5,42 @@
 namespace fastmcpp
 {
 
+/// Python `logging` module integer level constants. Mirrors Python fastmcp
+/// commit 73b7f2e4 (#4036) which added `FastMCPError.log_level` so
+/// downstream logging adapters can dispatch per-error severity. Values match
+/// Python `logging.{DEBUG,INFO,WARNING,ERROR,CRITICAL}`.
+namespace log_level
+{
+constexpr int Debug = 10;
+constexpr int Info = 20;
+constexpr int Warning = 30;
+constexpr int Error = 40;
+constexpr int Critical = 50;
+} // namespace log_level
+
 struct Error : public std::runtime_error
 {
-    using std::runtime_error::runtime_error;
+    Error(const std::string& msg, int level = log_level::Error)
+        : std::runtime_error(msg), log_level_(level)
+    {
+    }
+    Error(const char* msg, int level = log_level::Error)
+        : std::runtime_error(msg), log_level_(level)
+    {
+    }
+
+    /// Python `logging` integer level (10 Debug … 50 Critical). See `log_level::*` constants.
+    int log_level() const noexcept
+    {
+        return log_level_;
+    }
+    void set_log_level(int level) noexcept
+    {
+        log_level_ = level;
+    }
+
+  private:
+    int log_level_{log_level::Error};
 };
 
 struct NotFoundError : public Error

include/fastmcpp/providers/openapi_provider.hpp

@@ -41,6 +41,7 @@ class OpenAPIProvider : public Provider
         std::vector<std::string> path_params;
         std::vector<std::string> query_params;
         bool has_json_body{false};
+        std::string request_content_type{"application/json"};
         std::optional<std::string> description;
     };
 

include/fastmcpp/tools/tool_transform.hpp

@@ -145,8 +145,30 @@ build_transformed_schema(const Json& parent_schema,
                 new_prop["description"] = *transform.description;
 
             if (transform.type_schema.has_value())
+            {
+                // Python fastmcp commit b8597f94 (#4101): hoist `$defs` introduced by an
+                // ArgTransform.type_schema to the schema root so MCP clients can resolve any
+                // $ref the new property type references. Without this, properties using complex
+                // annotated types reference `$defs/X` that does not exist anywhere in the
+                // emitted schema.
+                Json hoisted_defs = Json::object();
                 for (auto& [k, v] : transform.type_schema->items())
+                {
+                    if (k == "$defs" && v.is_object())
+                    {
+                        hoisted_defs = v;
+                        continue;  // do not also write it under the property
+                    }
                     new_prop[k] = v;
+                }
+                if (!hoisted_defs.empty())
+                {
+                    if (!result.schema.contains("$defs") || !result.schema["$defs"].is_object())
+                        result.schema["$defs"] = Json::object();
+                    for (auto& [dk, dv] : hoisted_defs.items())
+                        result.schema["$defs"][dk] = dv;
+                }
+            }
 
             if (transform.default_value.has_value())
                 new_prop["default"] = *transform.default_value;
@@ -179,7 +201,20 @@ build_transformed_schema(const Json& parent_schema,
     }
 
     // Build result schema
-    result.schema = parent_schema;
+    {
+        // Preserve any $defs we hoisted above before overwriting properties/required.
+        Json hoisted = Json::object();
+        if (result.schema.contains("$defs") && result.schema["$defs"].is_object())
+            hoisted = result.schema["$defs"];
+        result.schema = parent_schema;
+        if (!hoisted.empty())
+        {
+            if (!result.schema.contains("$defs") || !result.schema["$defs"].is_object())
+                result.schema["$defs"] = Json::object();
+            for (auto& [dk, dv] : hoisted.items())
+                result.schema["$defs"][dk] = dv;
+        }
+    }
     result.schema["properties"] = new_properties;
     result.schema["required"] = Json::array();
     for (const auto& r : new_required)

src/client/sampling_handlers.cpp

@@ -243,6 +243,28 @@ static fastmcpp::Json build_openai_messages(const fastmcpp::Json& params)
                 fastmcpp::Json{{"role", "tool"}, {"tool_call_id", tool_use_id}, {"content", text}});
         }
 
+        // Python fastmcp commit d6b55c0b (#3857): raise on unhandled content types instead of
+        // silently dropping. The OpenAI compatible handler currently supports text + tool_use +
+        // tool_result; image/audio request-body conversion (F16 / commit 734b93b9) is not yet
+        // implemented in C++, so raise a clear error rather than producing an empty assistant
+        // message that misleads upstream code.
+        for (const auto& block : normalize_content_to_array(content))
+        {
+            if (!block.is_object())
+                continue;
+            const std::string t = block.value("type", "");
+            if (t == "text" || t == "tool_use" || t == "tool_result" || t.empty())
+                continue;
+            if (t == "image" || t == "audio")
+                throw std::runtime_error(
+                    "OpenAI sampling handler: '" + t +
+                    "' content not yet supported (F16 / fastmcp #3550); cannot dispatch sampling "
+                    "request");
+            // Unknown type — surface clearly so callers don't get silent data loss.
+            throw std::runtime_error(
+                "OpenAI sampling handler: unhandled content type '" + t + "'");
+        }
+
         std::string text = join_text_blocks(content);
         auto tool_uses = extract_blocks_by_type(content, "tool_use");
 
@@ -388,6 +410,18 @@ static fastmcpp::Json build_anthropic_messages(const fastmcpp::Json& params)
                 blocks.push_back(std::move(out));
                 continue;
             }
+            // Python fastmcp commit d6b55c0b (#3857): raise on unhandled content types.
+            // Anthropic handler does not support audio inputs at all (Anthropic API doesn't
+            // accept audio); image is acknowledged but request-body conversion is part of F16
+            // (commit 734b93b9) and not yet implemented in C++.
+            if (type == "image")
+                throw std::runtime_error(
+                    "Anthropic sampling handler: 'image' content not yet supported "
+                    "(F16 / fastmcp #3550); cannot dispatch sampling request");
+            if (type == "audio")
+                throw std::runtime_error(
+                    "Anthropic sampling handler: 'audio' content is not supported by the "
+                    "Anthropic Messages API");
             if (type == "tool_result")
             {
                 // Anthropic expects tool_use_id and string content.

src/client/transports.cpp

@@ -471,6 +471,21 @@ fastmcpp::Json StdioTransport::request(const std::string& route, const fastmcpp:
 
     if (keep_alive_)
     {
+        // Python fastmcp commit f5804f47 (#3630): if the subprocess died between calls,
+        // reset state and respawn on the next request rather than failing forever.
+        if (state_)
+        {
+            auto exit_code = state_->process.try_wait();
+            if (exit_code.has_value())
+            {
+                // Process already exited — tear down so we respawn cleanly below.
+                state_->stderr_running.store(false, std::memory_order_release);
+                if (state_->stderr_thread.joinable())
+                    state_->stderr_thread.join();
+                state_.reset();
+            }
+        }
+
         // --- Keep-alive mode: spawn once, reuse across calls ---
         if (!state_)
         {

src/mcp/handler.cpp

@@ -62,6 +62,16 @@ static void attach_meta_ui(fastmcpp::Json& entry, const std::optional<fastmcpp::
         entry["_meta"] = std::move(merged);
 }
 
+// Inject FastMCP::experimental_capabilities() into the `capabilities` block on `initialize`.
+// Mirrors Python `FastMCP(experimental_capabilities=...)` (#4042 / commit a010927e):
+// the dict is propagated verbatim so servers can advertise protocol extensions.
+static void advertise_experimental(fastmcpp::Json& capabilities, const FastMCP& app)
+{
+    const auto& exp = app.experimental_capabilities();
+    if (exp && exp->is_object() && !exp->empty())
+        capabilities["experimental"] = *exp;
+}
+
 static std::string normalize_resource_uri(std::string uri)
 {
     while (uri.size() > 1 && !uri.empty() && uri.back() == '/')
@@ -1871,6 +1881,7 @@ make_mcp_handler(const FastMCP& app, SessionAccessor session_accessor)
                 if (!app.list_all_prompts().empty())
                     capabilities["prompts"] = fastmcpp::Json::object();
                 advertise_ui_extension(capabilities);
+                advertise_experimental(capabilities, app);
 
                 fastmcpp::Json result_obj = {{"protocolVersion", "2024-11-05"},
                                              {"capabilities", capabilities},
@@ -2577,6 +2588,8 @@ std::function<fastmcpp::Json(const fastmcpp::Json&)> make_mcp_handler(const Prox
                 if (!app.list_all_prompts().empty())
                     capabilities["prompts"] = fastmcpp::Json::object();
                 advertise_ui_extension(capabilities);
+                // Note: ProxyApp does not propagate experimental_capabilities (that field is
+                // FastMCP-only); skip advertise_experimental here intentionally.
 
                 fastmcpp::Json result_obj = {{"protocolVersion", "2024-11-05"},
                                              {"capabilities", capabilities},
@@ -2600,6 +2613,8 @@ std::function<fastmcpp::Json(const fastmcpp::Json&)> make_mcp_handler(const Prox
                 {
                     fastmcpp::Json tool_json = {{"name", tool.name},
                                                 {"inputSchema", tool.inputSchema}};
+                    if (tool.version)
+                        tool_json["version"] = *tool.version;
                     if (tool.description)
                         tool_json["description"] = *tool.description;
                     if (tool.title)
@@ -3046,6 +3061,7 @@ make_mcp_handler_with_sampling(const FastMCP& app, SessionAccessor session_acces
                 if (!app.list_all_prompts().empty())
                     capabilities["prompts"] = fastmcpp::Json::object();
                 advertise_ui_extension(capabilities);
+                advertise_experimental(capabilities, app);
 
                 fastmcpp::Json result_obj = {{"protocolVersion", "2024-11-05"},
                                              {"capabilities", capabilities},