diff --git a/luprex/core/cpp/driver-mingw.cpp b/luprex/core/cpp/driver-mingw.cpp
index c2ea0423..64ab144b 100644
--- a/luprex/core/cpp/driver-mingw.cpp
+++ b/luprex/core/cpp/driver-mingw.cpp
@@ -149,7 +149,7 @@ public:
         driven_->drv_get_new_closed(chans);
         for (int chid : chans) {
             if (socket_[chid] != INVALID_SOCKET) {
-                assert(closesocket(socket_[chid] == 0));
+                assert(closesocket(socket_[chid]) == 0);
                 socket_[chid] = INVALID_SOCKET;
                 connected_[chid] = false;
             }
diff --git a/luprex/core/cpp/invocation.cpp b/luprex/core/cpp/invocation.cpp
index efba1c7e..75388681 100644
--- a/luprex/core/cpp/invocation.cpp
+++ b/luprex/core/cpp/invocation.cpp
@@ -1,5 +1,6 @@
 
 #include "invocation.hpp"
+#include <sstream>
 
 const std::string &InvocationData::get(const std::string &key) const {
     static std::string blank_;
@@ -51,3 +52,22 @@ void Invocation::deserialize(StreamBuffer *sb) {
     data_.deserialize(sb);
 }
 
+std::string Invocation::debug_string() {
+    std::ostringstream oss;
+    oss << "inv[";
+    switch (kind_) {
+    case KIND_INVALID: oss << "invalid"; break;
+    case KIND_PLAN: oss << "plan"; break;
+    case KIND_LUA: oss << "lua"; break;
+    case KIND_FLUSH_PRINTS: oss << "flush_prints"; break;
+    default: oss << "UNKNOWN"; break;
+    }
+    oss << " a=" << actor_;
+    oss << " p=" << place_;
+    oss << " " << action_;
+    for (const auto &pair : data_) {
+        oss << " " << pair.first << "=" << pair.second;
+    }
+    oss << "]";
+    return oss.str();
+}
diff --git a/luprex/core/cpp/invocation.hpp b/luprex/core/cpp/invocation.hpp
index a006a3ef..0f6cc3f5 100644
--- a/luprex/core/cpp/invocation.hpp
+++ b/luprex/core/cpp/invocation.hpp
@@ -42,6 +42,8 @@ public:
 
     void serialize(StreamBuffer *sb) const;
     void deserialize(StreamBuffer *sb);
+
+    std::string debug_string();
 };
 
 class InvocationQueue : public std::deque<Invocation> {
diff --git a/luprex/core/cpp/lpxclient.cpp b/luprex/core/cpp/lpxclient.cpp
index 06427d6a..f420345a 100644
--- a/luprex/core/cpp/lpxclient.cpp
+++ b/luprex/core/cpp/lpxclient.cpp
@@ -62,6 +62,8 @@ public:
     }
 
     void abandon_server() {
+        stdostream() << "Abandoning server." << std::endl;
+
         // Put the world model back into a known-good state.
         set_initial_state();
 
@@ -189,10 +191,11 @@ public:
     }
 
     void change_actor_id(int64_t actor_id) {
+        stdostream() << "Actor ID changing: " << actor_id << std::endl;
         print_channeler_.reset();
         actor_id_ = actor_id;
     }
-    
+
     void receive_ack_from_server(StreamBuffer *sb) {
         // An ack is just a single byte, so there's nothing left to read.
         if (unack_.empty()) {
@@ -208,7 +211,7 @@ public:
     void receive_diff_from_server(StreamBuffer *sb) {
         world_to_synchronous();
         try {
-            int nactor = world_->patch_everything(sb);
+            int64_t nactor = world_->patch_everything(sb);
             if (nactor != actor_id_) change_actor_id(nactor);
         } catch (const StreamEof &seof) {
             abandon_server();
@@ -260,10 +263,18 @@ public:
                 stdostream() << "Server closed connection " << channel_->error() << std::endl;
                 abandon_server();
             } else {
-                while (receive_message_from_server(channel_->in()));
+                while (true) {
+                    if (!receive_message_from_server(channel_->in())) break;
+                    if (channel_ == nullptr) break;
+                }
                 world_to_asynchronous();
             }
         }
+
+        // Channel print statements.
+        if (print_channeler_.channel(world_->get_printbuffer(actor_id_), stdostream())) {
+            send_invocation(print_channeler_.invocation(actor_id_));
+        }
     }
 };
 
diff --git a/luprex/core/cpp/lpxserver.cpp b/luprex/core/cpp/lpxserver.cpp
index d9d04878..7bc9314a 100644
--- a/luprex/core/cpp/lpxserver.cpp
+++ b/luprex/core/cpp/lpxserver.cpp
@@ -7,20 +7,20 @@
 #include "printbuffer.hpp"
 #include <memory>
 
-class ServerClient {
+class Client {
 public:
     int64_t actor_id_;
     UniqueChannel channel_;
     UniqueWorld sync_;
 };
-using UniqueServerClient = std::unique_ptr<ServerClient>;
-using ServerClientVector = std::vector<UniqueServerClient>;
+using UniqueClient = std::unique_ptr<Client>;
+using ClientVector = std::vector<UniqueClient>;
 
 class LpxServer : public DrivenEngine {
 public:
     UniqueWorld master_;
     LuaConsole console_;
-    ServerClientVector clients_;
+    ClientVector clients_;
     PrintChanneler print_channeler_;
     int64_t admin_id_;
 
@@ -79,10 +79,53 @@ public:
         }
     }
 
-    bool handle_invocation(ServerClient *sclient) {
-        return false;
+    void delete_client(UniqueClient &client) {
+        stdostream() << "Client closed: actor id=" << client->actor_id_ << std::endl;
+        client.reset();
     }
 
+    void send_diffs(UniqueClient &client) {
+        StreamBuffer *sb = client->channel_->out();
+        sb->write_uint8(util::MSG_DIFF);
+        sb->write_uint32(0);
+        int64_t tw_1 = sb->total_writes();
+        stdostream() << "Sending diffs to client " << client->actor_id_ << std::endl;
+        client->sync_->diff_everything(client->actor_id_, master_.get(), sb);
+        int64_t tw_2 = sb->total_writes();
+        sb->overwrite_int32(tw_1, tw_2 - tw_1);
+    }
+
+    bool handle_invocation(UniqueClient &client) {
+        StreamBuffer *sb = client->channel_->in();
+        int64_t tr_before = sb->total_reads();
+        Invocation inv;
+        try {
+            uint8_t msg_type = sb->read_uint8();
+            if (msg_type != util::MSG_INVOKE) {
+                delete_client(client);
+                return false;
+            }
+            inv.deserialize(sb);
+        } catch (const StreamEof &seof) {
+            sb->unread_to(tr_before);
+            return false;
+        } catch (const StreamCorruption &scorr) {
+            delete_client(client);
+            return false;
+        }
+        if (inv.actor() != client->actor_id_) {
+            stdostream() << "Ignoring invoke with wrong actor ID " << inv.actor() << std::endl;
+            return true;
+        }
+        stdostream() << "Invoking: " << inv.debug_string() << std::endl;
+        master_->invoke(inv);
+        client->channel_->out()->write_uint8(util::MSG_ACK);
+        client->channel_->out()->write_uint32(0);
+        client->sync_->invoke(inv);
+        send_diffs(client);
+        return true;
+    }
+    
     virtual void event_update() {
         // Check for keyboard input on stdin.
         while (true) {
@@ -102,28 +145,27 @@ public:
         while (true) {
             UniqueChannel chan = new_incoming_channel();
             if (chan == nullptr) break;
-            ServerClient *client = new ServerClient;
+            Client *client = new Client;
             client->actor_id_ = master_->create_login_actor();
             client->channel_ = std::move(chan);
             client->sync_.reset(new World(util::WORLD_TYPE_S_SYNC));
             client->sync_->create_login_actor();
             clients_.emplace_back(client);
             stdostream() << "New client: actor id=" << client->actor_id_ << std::endl;
+            send_diffs(clients_.back());
         }
 
         // Traverse all existing channels, process any communication.
-        ServerClientVector keep;
-        for (UniqueServerClient &client : clients_) {
+        for (UniqueClient &client : clients_) {
             if (client->channel_->closed()) {
-                stdostream() << "Client closed: actor id=" << client->actor_id_ << std::endl;
+                delete_client(client);
                 continue;
             }
+            
             // Check for received invocations.
-            while (handle_invocation(client.get()));
-            // Transfer the client to the keep vector.
-            keep.emplace_back(std::move(client));
+            while (handle_invocation(client));
         }
-        clients_ = std::move(keep);
+        util::remove_nullptrs(clients_);
     }
 };
 
diff --git a/luprex/core/cpp/printbuffer.cpp b/luprex/core/cpp/printbuffer.cpp
index 52ef15e6..d1c69662 100644
--- a/luprex/core/cpp/printbuffer.cpp
+++ b/luprex/core/cpp/printbuffer.cpp
@@ -103,7 +103,7 @@ bool PrintChanneler::channel(const PrintBuffer *printbuffer, std::ostream &ostre
         line_ = printbuffer->first_line();
     }
     while (line_ < printbuffer->first_unchecked()) {
-        ostream << printbuffer->nth(line_) << std::endl;
+        ostream << "[" << printbuffer->nth(line_) << "]" << std::endl;
         line_ += 1;
     }
     return line_ > printbuffer->first_line();
diff --git a/luprex/core/cpp/streambuffer.cpp b/luprex/core/cpp/streambuffer.cpp
index 2bd1fd21..a467a0bc 100644
--- a/luprex/core/cpp/streambuffer.cpp
+++ b/luprex/core/cpp/streambuffer.cpp
@@ -27,6 +27,7 @@ StreamBuffer::StreamBuffer(int64_t size, bool fixed) {
 StreamBuffer::StreamBuffer(const char *s, int64_t size) {
     assert(size >= 0);
     init(true, false, const_cast<char *>(s), size);
+    write_cursor_ = buf_hi_;
 }
 
 StreamBuffer::~StreamBuffer() {
diff --git a/luprex/core/cpp/util.hpp b/luprex/core/cpp/util.hpp
index 92846b9e..9466b51a 100644
--- a/luprex/core/cpp/util.hpp
+++ b/luprex/core/cpp/util.hpp
@@ -94,6 +94,14 @@ std::string trim(std::string s);
 // Calculate distance between two points
 double distance_squared(double x1, double y1, double x2, double y2);
 
+// Remove nullptrs from a vector of unique pointers.
+template<class T>
+void remove_nullptrs(std::vector<std::unique_ptr<T>> &vec) {
+    std::unique_ptr<T> nullp;
+    auto iter = std::remove(vec.begin(), vec.end(), nullp);
+    vec.erase(iter, vec.end());
+}
+
 // Read the lua source code from the specified directory.
 LuaSourcePtr read_lua_source(const std::string &directory);
 
diff --git a/luprex/core/cpp/world-core.cpp b/luprex/core/cpp/world-core.cpp
index b4c910a7..90f82416 100644
--- a/luprex/core/cpp/world-core.cpp
+++ b/luprex/core/cpp/world-core.cpp
@@ -665,8 +665,6 @@ void World::close_lthread_state() {
         }
         if (pbuffer != nullptr) {
             pbuffer->add_string(output);
-        } else {
-            std::cerr << output;
         }
     }
     // Now clean up everything.