feat: add configDir and sendAndWait for v0.1.18 parity

- Add config_dir option to SessionConfig and ResumeSessionConfig
- Implement send_and_wait() method for blocking message send with timeout
- Updates JSON serialization to include configDir in requests

Matches upstream copilot-sdk v0.1.18 features:
- configDir from #15
- sendAndWait from #28

Author: 0xeb

include/copilot/session.hpp

@@ -151,6 +151,15 @@ class Session : public std::enable_shared_from_this<Session>
     /// @return Future that resolves to list of session events
     std::future<std::vector<SessionEvent>> get_messages();
 
+    /// Send a message and wait until the session becomes idle.
+    /// @param options Message options including prompt and attachments
+    /// @param timeout Maximum time to wait (default: 60 seconds)
+    /// @return Future that resolves to the final assistant message, or nullopt if none
+    /// @throws std::runtime_error if timeout is reached or session error occurs
+    std::future<std::optional<SessionEvent>> send_and_wait(
+        MessageOptions options,
+        std::chrono::seconds timeout = std::chrono::seconds(60));
+
     // =========================================================================
     // Event Handling
     // =========================================================================

include/copilot/types.hpp

@@ -605,6 +605,10 @@ struct SessionConfig
     /// When enabled (default), sessions automatically manage context limits and persist state.
     std::optional<InfiniteSessionConfig> infinite_sessions;
 
+    /// Custom configuration directory for the CLI.
+    /// When set, overrides the default config location.
+    std::optional<std::string> config_dir;
+
     /// If true and provider/model not explicitly set, load from COPILOT_SDK_BYOK_* env vars.
     /// Default: false (explicit configuration preferred over environment variables)
     bool auto_byok_from_env = false;
@@ -626,6 +630,10 @@ struct ResumeSessionConfig
     /// List of skill names to disable.
     std::optional<std::vector<std::string>> disabled_skills;
 
+    /// Custom configuration directory for the CLI.
+    /// When set, overrides the default config location.
+    std::optional<std::string> config_dir;
+
     /// If true and provider not explicitly set, load from COPILOT_SDK_BYOK_* env vars.
     /// Default: false (explicit configuration preferred over environment variables)
     bool auto_byok_from_env = false;

src/client.cpp

@@ -93,6 +93,8 @@ json build_session_create_request(const SessionConfig& config)
         request["disabledSkills"] = *config.disabled_skills;
     if (config.infinite_sessions.has_value())
         request["infiniteSessions"] = *config.infinite_sessions;
+    if (config.config_dir.has_value())
+        request["configDir"] = *config.config_dir;
 
     return request;
 }
@@ -146,6 +148,8 @@ json build_session_resume_request(const std::string& session_id, const ResumeSes
         request["skillDirectories"] = *config.skill_directories;
     if (config.disabled_skills.has_value())
         request["disabledSkills"] = *config.disabled_skills;
+    if (config.config_dir.has_value())
+        request["configDir"] = *config.config_dir;
 
     return request;
 }

src/session.cpp

@@ -3,6 +3,7 @@
 
 #include <copilot/client.hpp>
 #include <copilot/session.hpp>
+#include <condition_variable>
 
 namespace copilot
 {
@@ -83,6 +84,68 @@ std::future<std::vector<SessionEvent>> Session::get_messages()
     );
 }
 
+std::future<std::optional<SessionEvent>> Session::send_and_wait(
+    MessageOptions options,
+    std::chrono::seconds timeout)
+{
+    return std::async(
+        std::launch::async,
+        [this, options = std::move(options), timeout]() -> std::optional<SessionEvent>
+        {
+            std::mutex mtx;
+            std::condition_variable cv;
+            bool done = false;
+            std::optional<SessionEvent> last_assistant_message;
+            std::optional<std::string> error_message;
+
+            // Subscribe to events
+            auto subscription = on(
+                [&](const SessionEvent& evt)
+                {
+                    std::lock_guard<std::mutex> lock(mtx);
+                    if (evt.type == SessionEventType::AssistantMessage)
+                    {
+                        last_assistant_message = evt;
+                    }
+                    else if (evt.type == SessionEventType::SessionIdle)
+                    {
+                        done = true;
+                        cv.notify_one();
+                    }
+                    else if (evt.type == SessionEventType::SessionError)
+                    {
+                        if (auto* data = evt.try_as<SessionErrorData>())
+                            error_message = data->message;
+                        else
+                            error_message = "Session error";
+                        done = true;
+                        cv.notify_one();
+                    }
+                }
+            );
+
+            // Send the message
+            send(options).get();
+
+            // Wait for completion or timeout
+            {
+                std::unique_lock<std::mutex> lock(mtx);
+                if (!cv.wait_for(lock, timeout, [&] { return done; }))
+                {
+                    throw std::runtime_error("Timeout waiting for session to become idle");
+                }
+            }
+
+            if (error_message.has_value())
+            {
+                throw std::runtime_error("Session error: " + *error_message);
+            }
+
+            return last_assistant_message;
+        }
+    );
+}
+
 // =============================================================================
 // Event Handling
 // =============================================================================