diff --git a/src/ServerState.cc b/src/ServerState.cc
index 4d78ca57..48924f56 100644
--- a/src/ServerState.cc
+++ b/src/ServerState.cc
@@ -888,6 +888,7 @@ void ServerState::load_config_early() {
   AccountSync::configure_from_json(this->config_json->get("AccountSync", phosg::JSON::dict()));
   AccountSync::start_login_lock_heartbeat_task(*this->io_context);
   TeamSync::configure_from_json(this->config_json->get("TeamSync", phosg::JSON::dict()));
+  TeamSync::start_exchange_task(*this->io_context);
   this->psopeeps_dcv2_exp_multiplier = this->config_json->get_int("PsoPeepsDCV2EXPMultiplier", 5);
   if ((this->psopeeps_dcv2_exp_multiplier != 5) && (this->psopeeps_dcv2_exp_multiplier != 10)) {
     throw std::runtime_error("PsoPeepsDCV2EXPMultiplier must be 5 or 10");
diff --git a/src/TeamSync.cc b/src/TeamSync.cc
index 522c9967..ca307a1e 100644
--- a/src/TeamSync.cc
+++ b/src/TeamSync.cc
@@ -1,15 +1,36 @@
 #include "TeamSync.hh"
 
+#include "AsyncUtils.hh"
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <cctype>
 #include <cstddef>
 #include <cstdint>
 #include <cstdio>
+#include <format>
+#include <memory>
 #include <mutex>
+#include <random>
 #include <stdexcept>
+#include <string>
 
 namespace TeamSync {
 
 static std::mutex config_mutex;
 static Config current_config;
+static std::atomic<bool> exchange_task_started(false);
+
+struct ExchangeState {
+  bool bootstrapped = false;
+  uint64_t cursor = 0;
+  uint64_t next_seq = 1;
+  uint64_t consecutive_failures = 0;
+};
+
+static std::mutex exchange_state_mutex;
+static ExchangeState exchange_state;
 
 static std::string source_label(const Config& cfg) {
   if (!cfg.source.empty()) {
@@ -29,19 +50,311 @@ static Config get_config() {
   return current_config;
 }
 
+static ExchangeState get_exchange_state() {
+  std::lock_guard<std::mutex> g(exchange_state_mutex);
+  return exchange_state;
+}
+
+static void reset_exchange_state() {
+  std::lock_guard<std::mutex> g(exchange_state_mutex);
+  exchange_state = ExchangeState();
+}
+
+static bool exchange_enabled(const Config& cfg) {
+  return cfg.enabled && (cfg.relay_team_chat || cfg.relay_team_points || cfg.relay_team_actions);
+}
+
+static uint64_t exchange_sleep_usecs(const Config& cfg, uint64_t consecutive_failures) {
+  uint64_t base = cfg.exchange_interval_usecs;
+  if (consecutive_failures) {
+    uint64_t multiplier = 1ULL << std::min<uint64_t>(consecutive_failures, 5);
+    base = std::min<uint64_t>(30000000, base * multiplier);
+  }
+
+  static std::mutex jitter_mutex;
+  static std::mt19937_64 rng(std::random_device{}());
+  std::lock_guard<std::mutex> g(jitter_mutex);
+  std::uniform_int_distribution<uint64_t> dist(0, std::max<uint64_t>(1, base / 5));
+  return base + dist(rng);
+}
+
+struct ParsedHTTPURL {
+  std::string host;
+  uint16_t port = 80;
+  std::string path = "/";
+};
+
+static ParsedHTTPURL parse_http_url(const std::string& url) {
+  static const std::string prefix = "http://";
+  if (!url.starts_with(prefix)) {
+    throw std::runtime_error("only http:// coordinator URLs are supported");
+  }
+
+  size_t host_start = prefix.size();
+  size_t path_start = url.find('/', host_start);
+  std::string host_port = (path_start == std::string::npos)
+      ? url.substr(host_start)
+      : url.substr(host_start, path_start - host_start);
+
+  ParsedHTTPURL ret;
+  ret.path = (path_start == std::string::npos) ? "/" : url.substr(path_start);
+  if (host_port.empty()) {
+    throw std::runtime_error("coordinator URL has empty host");
+  }
+
+  size_t colon_offset = host_port.rfind(':');
+  if (colon_offset == std::string::npos) {
+    ret.host = host_port;
+  } else {
+    ret.host = host_port.substr(0, colon_offset);
+    std::string port_s = host_port.substr(colon_offset + 1);
+    if (ret.host.empty() || port_s.empty()) {
+      throw std::runtime_error("coordinator URL has invalid host/port");
+    }
+    size_t end_offset = 0;
+    uint64_t port = std::stoull(port_s, &end_offset, 10);
+    if ((end_offset != port_s.size()) || (port == 0) || (port > 0xFFFF)) {
+      throw std::runtime_error("coordinator URL has invalid port");
+    }
+    ret.port = port;
+  }
+
+  return ret;
+}
+
+static std::string join_url_path(std::string base_path, const std::string& suffix) {
+  while ((base_path.size() > 1) && (base_path.back() == '/')) {
+    base_path.pop_back();
+  }
+  if (base_path.empty() || (base_path == "/")) {
+    return suffix;
+  }
+  return base_path + suffix;
+}
+
+static std::string lowercase(std::string s) {
+  std::transform(s.begin(), s.end(), s.begin(), [](unsigned char ch) -> char {
+    return static_cast<char>(std::tolower(ch));
+  });
+  return s;
+}
+
+static void trim_ascii_inplace(std::string& s) {
+  while (!s.empty() && ((s.back() == ' ') || (s.back() == '\t') || (s.back() == '\r') || (s.back() == '\n'))) {
+    s.pop_back();
+  }
+  size_t start = 0;
+  while ((start < s.size()) && ((s[start] == ' ') || (s[start] == '\t') || (s[start] == '\r') || (s[start] == '\n'))) {
+    start++;
+  }
+  if (start) {
+    s = s.substr(start);
+  }
+}
+
+static std::string json_escape(const std::string& s) {
+  std::string ret;
+  ret.reserve(s.size() + 2);
+  for (char ch : s) {
+    if (ch == '\\') {
+      ret += "\\\\";
+    } else if (ch == '"') {
+      ret += "\\\"";
+    } else if (ch == '\n') {
+      ret += "\\n";
+    } else if (ch == '\r') {
+      ret += "\\r";
+    } else if (ch == '\t') {
+      ret += "\\t";
+    } else {
+      ret += ch;
+    }
+  }
+  return ret;
+}
+
+static asio::awaitable<std::string> read_http_line(
+    asio::ip::tcp::socket& sock,
+    std::string& pending_data,
+    size_t max_length) {
+  static const char* delimiter = "\r\n";
+  static const size_t delimiter_size = 2;
+
+  size_t delimiter_pos = pending_data.find(delimiter);
+  while ((delimiter_pos == std::string::npos) && (pending_data.size() < max_length)) {
+    size_t pre_size = pending_data.size();
+    pending_data.resize(std::min(max_length, pending_data.size() + 0x400));
+    size_t bytes_read = co_await sock.async_read_some(
+        asio::buffer(pending_data.data() + pre_size, pending_data.size() - pre_size),
+        asio::use_awaitable);
+    pending_data.resize(pre_size + bytes_read);
+    delimiter_pos = pending_data.find(delimiter, (pre_size >= 1) ? (pre_size - 1) : 0);
+  }
+
+  if (delimiter_pos == std::string::npos) {
+    throw std::runtime_error("HTTP response line exceeds maximum length");
+  }
+
+  std::string ret = pending_data.substr(0, delimiter_pos);
+  pending_data = pending_data.substr(delimiter_pos + delimiter_size);
+  co_return ret;
+}
+
+static asio::awaitable<std::string> read_http_data(
+    asio::ip::tcp::socket& sock,
+    std::string& pending_data,
+    size_t size) {
+  std::string ret;
+  if (pending_data.size() == size) {
+    pending_data.swap(ret);
+  } else if (pending_data.size() > size) {
+    ret = pending_data.substr(0, size);
+    pending_data = pending_data.substr(size);
+  } else {
+    size_t bytes_to_read = size - pending_data.size();
+    pending_data.swap(ret);
+    ret.resize(size);
+    co_await asio::async_read(
+        sock,
+        asio::buffer(ret.data() + size - bytes_to_read, bytes_to_read),
+        asio::use_awaitable);
+  }
+  co_return ret;
+}
+
+static asio::awaitable<phosg::JSON> post_json_with_timeout(
+    const Config& cfg,
+    const std::string& path_suffix,
+    const std::string& body) {
+  ParsedHTTPURL url = parse_http_url(cfg.coordinator_url);
+  std::string path = join_url_path(url.path, path_suffix);
+
+  auto executor = co_await asio::this_coro::executor;
+  auto resolver = std::make_shared<asio::ip::tcp::resolver>(executor);
+  auto sock = std::make_shared<asio::ip::tcp::socket>(executor);
+  auto timer = std::make_shared<asio::steady_timer>(executor);
+  auto timed_out = std::make_shared<bool>(false);
+
+  timer->expires_after(std::chrono::microseconds(cfg.request_timeout_usecs));
+  timer->async_wait([resolver, sock, timed_out](std::error_code ec) -> void {
+    if (!ec) {
+      *timed_out = true;
+      resolver->cancel();
+      if (sock->is_open()) {
+        sock->close();
+      }
+    }
+  });
+
+  try {
+    auto endpoints = co_await resolver->async_resolve(url.host, std::format("{}", url.port), asio::use_awaitable);
+    co_await asio::async_connect(*sock, endpoints, asio::use_awaitable);
+
+    std::string host_header = url.host;
+    if (url.port != 80) {
+      host_header += std::format(":{}", url.port);
+    }
+
+    std::string request = std::format(
+        "POST {} HTTP/1.1\r\n"
+        "Host: {}\r\n"
+        "User-Agent: psopeeps-newserv\r\n"
+        "Content-Type: application/json\r\n"
+        "Accept: application/json\r\n"
+        "Connection: close\r\n"
+        "X-Psopeeps-Team-Sync-Secret: {}\r\n"
+        "Content-Length: {}\r\n"
+        "\r\n"
+        "{}",
+        path,
+        host_header,
+        cfg.shared_secret,
+        body.size(),
+        body);
+
+    co_await asio::async_write(*sock, asio::buffer(request), asio::use_awaitable);
+
+    std::string pending_data;
+    std::string status_line = co_await read_http_line(*sock, pending_data, 0x1000);
+    if (!status_line.starts_with("HTTP/1.")) {
+      throw std::runtime_error("invalid HTTP response from coordinator");
+    }
+
+    size_t first_space = status_line.find(' ');
+    if (first_space == std::string::npos) {
+      throw std::runtime_error("invalid HTTP status line from coordinator");
+    }
+    size_t second_space = status_line.find(' ', first_space + 1);
+    std::string code_s = status_line.substr(
+        first_space + 1,
+        (second_space == std::string::npos) ? std::string::npos : (second_space - first_space - 1));
+    int response_code = std::stoi(code_s);
+
+    size_t content_length = 0;
+    for (;;) {
+      std::string line = co_await read_http_line(*sock, pending_data, 0x10000);
+      if (line.empty()) {
+        break;
+      }
+      size_t colon_offset = line.find(':');
+      if (colon_offset == std::string::npos) {
+        continue;
+      }
+      std::string name = lowercase(line.substr(0, colon_offset));
+      std::string value = line.substr(colon_offset + 1);
+      trim_ascii_inplace(value);
+      if (name == "content-length") {
+        size_t end_offset = 0;
+        content_length = std::stoull(value, &end_offset, 10);
+        if (end_offset != value.size()) {
+          throw std::runtime_error("invalid Content-Length from coordinator");
+        }
+      }
+    }
+
+    if (response_code != 200) {
+      throw std::runtime_error(std::format("coordinator returned HTTP {}", response_code));
+    }
+    if (content_length > 0x100000) {
+      throw std::runtime_error("coordinator response is too large");
+    }
+
+    std::string response_body = co_await read_http_data(*sock, pending_data, content_length);
+    timer->cancel();
+    co_return phosg::JSON::parse(response_body);
+
+  } catch (...) {
+    timer->cancel();
+    if (*timed_out) {
+      throw std::runtime_error("coordinator request timed out");
+    }
+    throw;
+  }
+}
+
 void configure(const Config& cfg) {
+  Config old_cfg;
   {
     std::lock_guard<std::mutex> g(config_mutex);
+    old_cfg = current_config;
     current_config = cfg;
   }
 
+  if ((old_cfg.source_region != cfg.source_region) ||
+      (old_cfg.source_ship != cfg.source_ship) ||
+      (old_cfg.team_namespace != cfg.team_namespace)) {
+    reset_exchange_state();
+  }
+
   if (cfg.enabled) {
     std::fprintf(stderr,
-        "[TeamSync] config enabled source=%s source_region=%s source_ship=%s coordinator_url=%s relay_team_chat=%s relay_team_points=%s relay_team_actions=%s\n",
+        "[TeamSync] config enabled source=%s source_region=%s source_ship=%s team_namespace=%s coordinator_url=%s exchange_interval_usecs=%llu relay_team_chat=%s relay_team_points=%s relay_team_actions=%s\n",
         source_label(cfg).c_str(),
         cfg.source_region.c_str(),
         cfg.source_ship.c_str(),
+        cfg.team_namespace.c_str(),
         cfg.coordinator_url.c_str(),
+        static_cast<unsigned long long>(cfg.exchange_interval_usecs),
         cfg.relay_team_chat ? "true" : "false",
         cfg.relay_team_points ? "true" : "false",
         cfg.relay_team_actions ? "true" : "false");
@@ -70,6 +383,7 @@ void configure_from_json(const phosg::JSON& json) {
     }
   }
 
+  cfg.team_namespace = json.get_string("TeamNamespace", "bb");
   cfg.coordinator_url = json.get_string("CoordinatorURL", "");
   cfg.shared_secret = json.get_string("SharedSecret", "");
 
@@ -81,6 +395,14 @@ void configure_from_json(const phosg::JSON& json) {
   }
   cfg.request_timeout_usecs = static_cast<uint64_t>(request_timeout_usecs);
 
+  int64_t exchange_interval_usecs = json.get_int("ExchangeIntervalUsecs", 1500000);
+  if (exchange_interval_usecs < 250000) {
+    exchange_interval_usecs = 250000;
+  } else if (exchange_interval_usecs > 30000000) {
+    exchange_interval_usecs = 30000000;
+  }
+  cfg.exchange_interval_usecs = static_cast<uint64_t>(exchange_interval_usecs);
+
   cfg.relay_team_chat = json.get_bool("RelayTeamChat", false);
   cfg.relay_team_points = json.get_bool("RelayTeamPoints", false);
   cfg.relay_team_actions = json.get_bool("RelayTeamActions", false);
@@ -88,6 +410,9 @@ void configure_from_json(const phosg::JSON& json) {
   if (cfg.enabled && (cfg.source_region.empty() || cfg.source_ship.empty())) {
     throw std::runtime_error("TeamSync requires SourceRegion and SourceShip, or Source/Region in region-ship form");
   }
+  if (cfg.enabled && cfg.team_namespace.empty()) {
+    throw std::runtime_error("TeamSync requires non-empty TeamNamespace");
+  }
 
   configure(cfg);
 }
@@ -101,4 +426,137 @@ bool relay_team_chat_enabled() {
   return cfg.enabled && cfg.relay_team_chat;
 }
 
+// This helper only builds empty event batches from trusted config fields.
+// Do not extend the format-string JSON path for player-controlled data; use a
+// real JSON object/serializer when team chat events are added.
+static std::string exchange_body_for_empty_events(const Config& cfg, const ExchangeState& state) {
+  if (state.bootstrapped) {
+    return std::format(
+        "{{\"source\":\"{}\",\"source_region\":\"{}\",\"source_ship\":\"{}\",\"team_namespace\":\"{}\",\"cursor\":{},\"events\":[]}}",
+        json_escape(source_label(cfg)),
+        json_escape(cfg.source_region),
+        json_escape(cfg.source_ship),
+        json_escape(cfg.team_namespace),
+        state.cursor);
+  }
+
+  return std::format(
+      "{{\"source\":\"{}\",\"source_region\":\"{}\",\"source_ship\":\"{}\",\"team_namespace\":\"{}\",\"cursor\":\"\",\"events\":[]}}",
+      json_escape(source_label(cfg)),
+      json_escape(cfg.source_region),
+      json_escape(cfg.source_ship),
+      json_escape(cfg.team_namespace));
+}
+
+static asio::awaitable<void> run_empty_exchange_once(const Config& cfg) {
+  auto before_state = get_exchange_state();
+  std::string body = exchange_body_for_empty_events(cfg, before_state);
+  phosg::JSON response = co_await post_json_with_timeout(cfg, "/team-sync/exchange", body);
+
+  if (!response.get_bool("ok", false)) {
+    throw std::runtime_error("coordinator returned ok=false");
+  }
+
+  uint64_t ack_max_seq = response.get_int("ack_max_seq", 0);
+  uint64_t next_cursor = response.get_int("next_cursor", 0);
+  bool truncated = response.get_bool("truncated", false);
+  size_t inbound_events = response.get("events", phosg::JSON::list()).as_list().size();
+
+  {
+    std::lock_guard<std::mutex> g(exchange_state_mutex);
+
+    bool cursor_regressed = exchange_state.bootstrapped && (next_cursor < exchange_state.cursor);
+    bool ack_regressed = exchange_state.bootstrapped && (exchange_state.next_seq > 1) && (ack_max_seq < (exchange_state.next_seq - 1));
+    if (cursor_regressed || ack_regressed) {
+      std::fprintf(stderr,
+          "[TeamSync] warning exchange_state_reset_detected source=%s team_namespace=%s old_cursor=%llu new_cursor=%llu old_next_seq=%llu ack_max_seq=%llu\n",
+          source_label(cfg).c_str(),
+          cfg.team_namespace.c_str(),
+          static_cast<unsigned long long>(exchange_state.cursor),
+          static_cast<unsigned long long>(next_cursor),
+          static_cast<unsigned long long>(exchange_state.next_seq),
+          static_cast<unsigned long long>(ack_max_seq));
+      exchange_state = ExchangeState();
+      co_return;
+    }
+
+    if (!exchange_state.bootstrapped) {
+      exchange_state.next_seq = ack_max_seq + 1;
+      exchange_state.bootstrapped = true;
+      std::fprintf(stderr,
+          "[TeamSync] exchange bootstrap source=%s team_namespace=%s ack_max_seq=%llu next_seq=%llu cursor=%llu\n",
+          source_label(cfg).c_str(),
+          cfg.team_namespace.c_str(),
+          static_cast<unsigned long long>(ack_max_seq),
+          static_cast<unsigned long long>(exchange_state.next_seq),
+          static_cast<unsigned long long>(next_cursor));
+    }
+    exchange_state.cursor = next_cursor;
+    exchange_state.consecutive_failures = 0;
+  }
+
+  if (inbound_events || truncated) {
+    std::fprintf(stderr,
+        "[TeamSync] exchange received source=%s team_namespace=%s inbound_events=%zu truncated=%s cursor=%llu\n",
+        source_label(cfg).c_str(),
+        cfg.team_namespace.c_str(),
+        inbound_events,
+        truncated ? "true" : "false",
+        static_cast<unsigned long long>(next_cursor));
+  }
+
+  co_return;
+}
+
+static asio::awaitable<void> exchange_task() {
+  for (;;) {
+    auto cfg = get_config();
+
+    if (!exchange_enabled(cfg)) {
+      co_await async_sleep(std::chrono::seconds(5));
+      continue;
+    }
+
+    if (cfg.coordinator_url.empty()) {
+      std::fprintf(stderr,
+          "[TeamSync] warning exchange_skipped reason=coordinator_url_not_configured source=%s team_namespace=%s\n",
+          source_label(cfg).c_str(),
+          cfg.team_namespace.c_str());
+      co_await async_sleep(std::chrono::microseconds(exchange_sleep_usecs(cfg, 1)));
+      continue;
+    }
+
+    try {
+      co_await run_empty_exchange_once(cfg);
+
+    } catch (const std::exception& e) {
+      uint64_t failures = 0;
+      {
+        std::lock_guard<std::mutex> g(exchange_state_mutex);
+        exchange_state.consecutive_failures++;
+        failures = exchange_state.consecutive_failures;
+      }
+
+      std::fprintf(stderr,
+          "[TeamSync] warning exchange_failed source=%s team_namespace=%s failures=%llu error=%s\n",
+          source_label(cfg).c_str(),
+          cfg.team_namespace.c_str(),
+          static_cast<unsigned long long>(failures),
+          e.what());
+    }
+
+    co_await async_sleep(std::chrono::microseconds(exchange_sleep_usecs(cfg, get_exchange_state().consecutive_failures)));
+  }
+}
+
+void start_exchange_task(asio::io_context& io_context) {
+  bool expected = false;
+  if (!exchange_task_started.compare_exchange_strong(expected, true)) {
+    return;
+  }
+
+  asio::co_spawn(io_context, exchange_task(), asio::detached);
+  std::fprintf(stderr, "[TeamSync] exchange task started\n");
+}
+
 } // namespace TeamSync
diff --git a/src/TeamSync.hh b/src/TeamSync.hh
index 25eaf41b..6dbfca2d 100644
--- a/src/TeamSync.hh
+++ b/src/TeamSync.hh
@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <string>
 
+#include <asio.hpp>
 #include <phosg/JSON.hh>
 
 namespace TeamSync {
@@ -13,10 +14,12 @@ struct Config {
   std::string source;
   std::string source_region;
   std::string source_ship;
+  std::string team_namespace = "bb";
 
   std::string coordinator_url;
   std::string shared_secret;
   uint64_t request_timeout_usecs = 3000000;
+  uint64_t exchange_interval_usecs = 1500000;
 
   bool relay_team_chat = false;
   bool relay_team_points = false;
@@ -29,4 +32,6 @@ void configure_from_json(const phosg::JSON& json);
 bool enabled();
 bool relay_team_chat_enabled();
 
+void start_exchange_task(asio::io_context& io_context);
+
 } // namespace TeamSync