diff --git a/map4.js b/map4.js
index 3dd96c7..14f9ca9 100644
--- a/map4.js
+++ b/map4.js
@@ -1,15 +1,14 @@
 // ===================================
 // Supabase 設定
 // ===================================
-const SUPABASE_URL =
-  "https://ogtlmtnjkpsxsqzqlacj.supabase.co";
+const SUPABASE_URL = "https://ogtlmtnjkpsxsqzqlacj.supabase.co";
 const SUPABASE_KEY =
   "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZSIsInJlZiI6Im9ndGxtdG5qa3BzeHNxenFsYWNqIiwicm9sZSI6ImFub24iLCJpYXQiOjE3NjMyOTU3NjUsImV4cCI6MjA3ODg3MTc2NX0.JnCE7oUQwrSgGqiu-QRbwnaLBZrO8JX1_RUb37VIMFI";
 
 const supa = window.supabase.createClient(SUPABASE_URL, SUPABASE_KEY);
 
 // ===================================
-// デバイスID
+// グローバル変数
 // ===================================
 let deviceId = localStorage.getItem("deviceId");
 if (!deviceId) {
@@ -17,19 +16,19 @@
   localStorage.setItem("deviceId", deviceId);
 }
 
-// ===================================
-let allMembers = [];
 let currentGroup = "";
 let currentUser = "";
+let isHost = false;
+
 let map;
 let selfMarker = null;
 let otherMarkers = [];
 let latestByDevice = {};
+let allMembers = [];
+
 let lastLat = null;
 let lastLng = null;
 
-let isHost = false;
-
 // 駅関連
 let stationMarkers = [];
 
@@ -37,59 +36,124 @@
 let targetMarker = null;
 let targetLat = null;
 let targetLng = null;
-let arrived = false;
-let lastShownDistance = null;
-
-// 皇居
-const DEFAULT_LAT = 35.681236;
-const DEFAULT_LNG = 139.767125;
 
 // ===================================
-// アイコン
-// ===================================
-const stationIcon = L.icon({
-  iconUrl:
-    "https://raw.githubusercontent.com/pointhi/leaflet-color-markers/master/img/marker-icon-blue.png",
-  shadowUrl:
-    "https://cdnjs.cloudflare.com/ajax/libs/leaflet/1.7.1/images/marker-shadow.png",
-  iconSize: [25, 41],
-  iconAnchor: [12, 41],
-});
-
-const targetIcon = L.icon({
-  iconUrl:
-    "https://raw.githubusercontent.com/pointhi/leaflet-color-markers/master/img/marker-icon-red.png",
-  shadowUrl:
-    "https://cdnjs.cloudflare.com/ajax/libs/leaflet/1.7.1/images/marker-shadow.png",
-  iconSize: [25, 41],
-  iconAnchor: [12, 41],
-});
-
+// URL パラメータ読み込み
 // ===================================
 function loadParams() {
   const p = new URLSearchParams(location.search);
-  currentGroup = p.get("group");
-  currentUser = p.get("user");
-  document.getElementById("groupName").textContent = currentGroup;
-  document.getElementById("userName").textContent = currentUser;
+  currentGroup = p.get("group") || "";
+  currentUser = p.get("user") || "";
+
+  // host=1 or true ならホスト
+  const hostParam = p.get("host");
+  isHost = hostParam === "1" || hostParam === "true";
+
+  // 画面表示
+  const gSpan = document.getElementById("groupName");
+  const uSpan = document.getElementById("userName");
+  const hostLabel = document.getElementById("hostStatus");
+
+  if (gSpan) gSpan.textContent = currentGroup;
+  if (uSpan) uSpan.textContent = currentUser;
+  if (hostLabel) {
+    hostLabel.textContent = isHost ? "あなたはホストです" : "一般メンバーです";
+  }
+
+  // チャット用に保存（任意）
+  localStorage.setItem("group", currentGroup);
+  localStorage.setItem("userName", currentUser);
 }
 
 // ===================================
-async function decideHost() {
-  const { data } = await supa
-    .from("groups")
-    .select("host_name")
-    .eq("group_name", currentGroup)
-    .maybeSingle();
-
-  isHost = data?.host_name === currentUser;
-
-  const hostLabel = document.getElementById("hostStatus");
-  hostLabel.textContent =
-    isHost ? "あなたはホストです" : "一般メンバーです";
+// 位置情報取得（Promise 化）
+// ===================================
+function getPosition() {
+  return new Promise((resolve, reject) => {
+    if (!navigator.geolocation) {
+      reject(new Error("Geolocation not supported"));
+      return;
+    }
+    navigator.geolocation.getCurrentPosition(
+      (pos) => resolve(pos.coords),
+      (err) => reject(err),
+      { enableHighAccuracy: true }
+    );
+  });
 }
 
 // ===================================
+// 地図初期化
+// ===================================
+function initMap(lat, lng) {
+  map = L.map("map").setView([lat, lng], 16);
+
+  L.tileLayer("https://tile.openstreetmap.org/{z}/{x}/{y}.png", {
+    maxZoom: 19,
+  }).addTo(map);
+
+  // ホストだけ目的地設定
+  map.on("click", async (e) => {
+    if (!isHost) return;
+
+    const newLat = e.latlng.lat;
+    const newLng = e.latlng.lng;
+
+    targetLat = newLat;
+    targetLng = newLng;
+
+    if (targetMarker) {
+      map.removeLayer(targetMarker);
+    }
+
+    targetMarker = L.marker([targetLat, targetLng]).addTo(map);
+
+    // Supabase に共有
+    try {
+      await supa.from("shared_target").upsert({
+        group_name: currentGroup,
+        lat: targetLat,
+        lng: targetLng,
+      });
+
+      const box = document.getElementById("targetInfo");
+      if (box) {
+        box.textContent = "目的地を設定しました！";
+      }
+    } catch (e) {
+      console.error("shared_target への保存失敗", e);
+    }
+  });
+}
+
+// ===================================
+// 自分の位置を保存
+// ===================================
+async function saveMyLocation(lat, lng) {
+  try {
+    // 自分の古いレコード削除
+    await supa
+      .from("locations")
+      .delete()
+      .eq("group_name", currentGroup)
+      .eq("device_id", deviceId);
+
+    // 挿入
+    await supa.from("locations").insert({
+      group_name: currentGroup,
+      user_name: currentUser,
+      device_id: deviceId,
+      lat,
+      lng,
+    });
+  } catch (e) {
+    console.error("位置情報保存エラー", e);
+  }
+}
+
+// ===================================
+// 自分のピン表示
+// ===================================
 function createLabeledMarker(lat, lng, name, isSelf) {
   const pinUrl = isSelf
     ? "https://raw.githubusercontent.com/pointhi/leaflet-color-markers/master/img/marker-icon-green.png"
@@ -112,79 +176,22 @@
   });
 }
 
-// ===================================
-function getPosition() {
-  return new Promise((res, rej) => {
-    navigator.geolocation.getCurrentPosition(
-      (pos) => res(pos.coords),
-      rej,
-      { enableHighAccuracy: true }
-    );
-  });
-}
-
-// ===================================
-function initMap(lat, lng) {
-  map = L.map("map").setView([lat, lng], 16);
-
-  L.tileLayer(
-    "https://tile.openstreetmap.org/{z}/{x}/{y}.png",
-    { maxZoom: 19 }
-  ).addTo(map);
-
-  // ホストだけ目的地設定
-  map.on("click", async (e) => {
-    if (!isHost) return;
-
-    targetLat = e.latlng.lat;
-    targetLng = e.latlng.lng;
-
-    if (targetMarker) map.removeLayer(targetMarker);
-
-    targetMarker = L.marker([targetLat, targetLng], {
-      icon: targetIcon,
-    }).addTo(map);
-
-    await supa.from("shared_target").upsert({
-      group_name: currentGroup,
-      lat: targetLat,
-      lng: targetLng,
-    });
-
-    document.getElementById("targetInfo").textContent =
-      "目的地を設定しました！";
-  });
-}
-
-// ===================================
-async function saveMyLocation(lat, lng) {
-  await supa
-    .from("locations")
-    .delete()
-    .eq("group_name", currentGroup)
-    .eq("device_id", deviceId);
-
-  await supa.from("locations").insert({
-    group_name: currentGroup,
-    user_name: currentUser,
-    device_id: deviceId,
-    lat,
-    lng,
-  });
-}
-
-// ===================================
 function renderSelfMarker() {
+  if (!map || lastLat === null || lastLng === null) return;
   if (selfMarker) map.removeLayer(selfMarker);
   selfMarker = createLabeledMarker(lastLat, lastLng, currentUser, true);
   selfMarker.addTo(map);
 }
 
 // ===================================
-function showMemberList(latest) {
+// 他メンバー表示
+// ===================================
+function showMemberList(latestByDevice) {
   const list = document.getElementById("memberList");
+  if (!list) return;
 
-  Object.values(latest).forEach((row) => {
+  // 新しいメンバーを allMembers に追加
+  Object.values(latestByDevice).forEach((row) => {
     if (!allMembers.some((m) => m.device_id === row.device_id)) {
       allMembers.push({
         device_id: row.device_id,
@@ -193,79 +200,102 @@
     }
   });
 
-  allMembers.forEach((m) => {
-    let li = list.querySelector(`li[data-id="${m.device_id}"]`);
+  // 表示更新
+  allMembers.forEach((member) => {
+    let li = list.querySelector(`li[data-id="${member.device_id}"]`);
+
     if (!li) {
       li = document.createElement("li");
-      li.dataset.id = m.device_id;
+      li.dataset.id = member.device_id;
       li.innerHTML = `
         <div class="member-icon"></div>
-        <span class="member-name"></span>
-        <span class="member-status"></span>`;
+        <div class="member-name"></div>
+      `;
       list.appendChild(li);
     }
 
-    li.querySelector(".member-name").textContent = m.user_name;
+    const row = latestByDevice[member.device_id];
 
-    const row = latest[m.device_id];
-    const online =
-      row &&
-      (Date.now() - new Date(row.updated_at)) / 1000 < 6;
+    // 名前
+    const nameElem = li.querySelector(".member-name");
+    if (nameElem) nameElem.textContent = member.user_name;
 
-    li.querySelector(".member-icon").style.background =
-      m.device_id === deviceId ? "#58c16b" : "#FFD700";
+    // オンライン判定
+    let online = false;
+    if (row && row.updated_at) {
+      const diffSec = (Date.now() - new Date(row.updated_at)) / 1000;
+      online = diffSec < 6;
+    }
 
-    li.querySelector(".member-status").textContent =
-      online ? "🟢" : "🔴";
+    if (online) {
+      li.classList.add("online");
+      li.classList.remove("offline");
+    } else {
+      li.classList.add("offline");
+      li.classList.remove("online");
+    }
   });
 }
 
-// ===================================
 async function showOtherUsers() {
-  const { data } = await supa
-    .from("locations")
-    .select("*")
-    .eq("group_name", currentGroup)
-    .order("updated_at", { ascending: false });
+  try {
+    const { data, error } = await supa
+      .from("locations")
+      .select("*")
+      .eq("group_name", currentGroup)
+      .order("updated_at", { ascending: false });
 
-  latestByDevice = {};
-  data?.forEach((r) => {
-    if (!latestByDevice[r.device_id]) latestByDevice[r.device_id] = r;
-  });
+    if (error) {
+      console.error("locations 取得エラー", error);
+      return;
+    }
 
-  showMemberList(latestByDevice);
+    latestByDevice = {};
+    (data || []).forEach((r) => {
+      if (!latestByDevice[r.device_id]) {
+        latestByDevice[r.device_id] = r;
+      }
+    });
 
-  otherMarkers.forEach((m) => map.removeLayer(m));
-  otherMarkers = [];
+    showMemberList(latestByDevice);
 
-  Object.values(latestByDevice).forEach((row) => {
-    if (row.device_id === deviceId) return;
-    const mk = createLabeledMarker(
-      row.lat,
-      row.lng,
-      row.user_name,
-      false
-    );
-    mk.addTo(map);
-    otherMarkers.push(mk);
-  });
+    // マーカー更新
+    otherMarkers.forEach((m) => map.removeLayer(m));
+    otherMarkers = [];
+
+    Object.values(latestByDevice).forEach((row) => {
+      if (row.device_id === deviceId) return;
+      const mk = createLabeledMarker(row.lat, row.lng, row.user_name, false);
+      mk.addTo(map);
+      otherMarkers.push(mk);
+    });
+  } catch (e) {
+    console.error("他ユーザー表示エラー", e);
+  }
 }
 
 // ===================================
-function distanceMeters(a, b, c, d) {
+// 距離計算
+// ===================================
+function distanceMeters(lat1, lng1, lat2, lng2) {
   const R = 6371000;
-  const toRad = (x) => (x * Math.PI) / 180;
-  const dLat = toRad(c - a);
-  const dLng = toRad(d - b);
-  const y =
+  const toRad = (deg) => (deg * Math.PI) / 180;
+
+  const dLat = toRad(lat2 - lat1);
+  const dLng = toRad(lng2 - lng1);
+
+  const a =
     Math.sin(dLat / 2) ** 2 +
-    Math.cos(toRad(a)) *
-      Math.cos(toRad(c)) *
+    Math.cos(toRad(lat1)) *
+      Math.cos(toRad(lat2)) *
       Math.sin(dLng / 2) ** 2;
-  return R * 2 * Math.atan2(Math.sqrt(y), Math.sqrt(1 - y));
+
+  return R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
 }
 
 // ===================================
+// 駅関連
+// ===================================
 async function fetchStationsAround(lat, lng) {
   const query = `
     [out:json];
@@ -275,14 +305,15 @@
   const url =
     "https://overpass-api.de/api/interpreter?data=" +
     encodeURIComponent(query);
+
   const res = await fetch(url);
   const json = await res.json();
   return json.elements || [];
 }
 
-// ===================================
 async function loadStations() {
   const box = document.getElementById("nearestBox");
+  if (!box || lastLat === null || lastLng === null) return;
 
   try {
     const stations = await fetchStationsAround(lastLat, lastLng);
@@ -291,7 +322,7 @@
     stationMarkers = [];
 
     if (stations.length === 0) {
-      box.textContent = "駅なし";
+      box.textContent = "駅が見つかりませんでした。";
       return;
     }
 
@@ -299,148 +330,202 @@
     let nearestDist = Infinity;
 
     stations.forEach((st) => {
-      const d = distanceMeters(lastLat, lastLng, st.lat, st.lon);
+      const sLat = st.lat;
+      const sLng = st.lon;
+      const name = (st.tags && st.tags.name) || "駅名不明";
+
+      const d = distanceMeters(lastLat, lastLng, sLat, sLng);
       if (d < nearestDist) {
         nearestDist = d;
-        nearest = st;
+        nearest = { name, lat: sLat, lng: sLng };
       }
-      const mk = L.marker([st.lat, st.lon], {
-        icon: stationIcon,
-      }).addTo(map);
+
+      const mk = L.marker([sLat, sLng]).addTo(map);
+      mk.bindPopup(name + "駅");
       stationMarkers.push(mk);
     });
 
-    box.textContent = `最寄り駅：${nearest.tags.name}（約 ${(nearestDist /
-      1000).toFixed(2)} km）`;
-  } catch {
-    box.textContent = "駅情報エラー";
+    box.textContent =
+      "最寄り駅：" +
+      nearest.name +
+      "（約 " +
+      (nearestDist / 1000).toFixed(2) +
+      " km）";
+  } catch (e) {
+    console.error("駅情報取得エラー", e);
+    box.textContent = "駅情報を取得できませんでした。";
   }
 }
 
 // ===================================
+// 共有目的地の読込
+// ===================================
 async function loadSharedTarget() {
-  const { data } = await supa
-    .from("shared_target")
-    .select("*")
-    .eq("group_name", currentGroup)
-    .maybeSingle();
+  const box = document.getElementById("targetInfo");
+  if (!box) return;
 
-  if (!data) return;
+  try {
+    const { data, error } = await supa
+      .from("shared_target")
+      .select("*")
+      .eq("group_name", currentGroup)
+      .maybeSingle();
 
-  if (targetLat === data.lat && targetLng === data.lng) return;
+    if (error) {
+      console.error("shared_target 読み込みエラー", error);
+      return;
+    }
+    if (!data) return;
 
-  targetLat = data.lat;
-  targetLng = data.lng;
-  arrived = false;
+    if (targetLat === data.lat && targetLng === data.lng) return;
 
-  if (targetMarker) map.removeLayer(targetMarker);
+    targetLat = data.lat;
+    targetLng = data.lng;
 
-  targetMarker = L.marker([targetLat, targetLng], {
-    icon: targetIcon,
-  }).addTo(map);
+    if (targetMarker) {
+      map.removeLayer(targetMarker);
+    }
+    targetMarker = L.marker([targetLat, targetLng]).addTo(map);
 
-  document.getElementById("targetInfo").textContent =
-    "目的地が共有されました！";
+    box.textContent = "目的地が共有されました！";
+  } catch (e) {
+    console.error("共有目的地読込エラー", e);
+  }
 }
 
 // ===================================
+// チャット機能
+// ===================================
+async function loadMessages() {
+  const chatList = document.getElementById("chatList");
+  if (!chatList) return;
+
+  try {
+    const { data, error } = await supa
+      .from("messages")
+      .select("*")
+      .eq("group_name", currentGroup)
+      .order("created_at", { ascending: true });
+
+    if (error) {
+      console.error("messages 読み込みエラー", error);
+      return;
+    }
+
+    chatList.innerHTML = (data || [])
+      .map(
+        (m) =>
+          `<div><strong>${m.user_name}:</strong> ${m.message}</div>`
+      )
+      .join("");
+
+    chatList.scrollTop = chatList.scrollHeight;
+  } catch (e) {
+    console.error("チャット読込エラー", e);
+  }
+}
+
+async function sendMessage() {
+  const input = document.getElementById("chatInput");
+  if (!input) return;
+
+  const text = input.value.trim();
+  if (!text) return;
+
+  try {
+    await supa.from("messages").insert({
+      group_name: currentGroup,
+      user_name: currentUser,
+      message: text,
+    });
+    input.value = "";
+    loadMessages();
+  } catch (e) {
+    console.error("メッセージ送信エラー", e);
+  }
+}
+
+// ===================================
+// メイン処理
+// ===================================
 async function main() {
   loadParams();
-  await decideHost();
 
-  let lat = DEFAULT_LAT;
-  let lng = DEFAULT_LNG;
+  // 位置初期値（皇居）
+  let lat = 35.681236;
+  let lng = 139.767125;
 
   try {
     const pos = await getPosition();
     lat = pos.latitude;
     lng = pos.longitude;
-  } catch {}
+  } catch (e) {
+    console.warn("位置情報が取得できなかったのでデフォルト位置を使用します", e);
+  }
 
   lastLat = lat;
   lastLng = lng;
 
   initMap(lat, lng);
   renderSelfMarker();
-
   await saveMyLocation(lat, lng);
   await showOtherUsers();
-
   loadStations();
   loadSharedTarget();
+  loadMessages();
 
+  // 位置情報の定期更新
   setInterval(async () => {
     try {
       const pos = await getPosition();
       lastLat = pos.latitude;
       lastLng = pos.longitude;
+
       renderSelfMarker();
       await saveMyLocation(lastLat, lastLng);
-    } catch {}
+    } catch (e) {
+      console.warn("位置情報更新失敗", e);
+    }
   }, 2000);
 
+  // 他ユーザー位置の定期更新
   setInterval(showOtherUsers, 1200);
+
+  // 目的地の定期チェック
   setInterval(loadSharedTarget, 10000);
 
-  document.getElementById("exitBtn").onclick = () => {
-    location.href = "index.html";
-  };
+  // チャットの定期更新
+  setInterval(loadMessages, 2000);
 
-  setTimeout(() => map.invalidateSize(), 300);
+  // 駅情報は1回だけでOK（必要ならボタンで再読込でもいい）
+  // setInterval(loadStations, 60000);
+
+  // 退出ボタン
+  const exitBtn = document.getElementById("exitBtn");
+  if (exitBtn) {
+    exitBtn.onclick = () => {
+      location.href = "index.html";
+    };
+  }
+
+  // チャット送信ボタン
+  const chatSend = document.getElementById("chatSend");
+  if (chatSend) {
+    chatSend.onclick = sendMessage;
+  }
+
+  // Enterキーで送信
+  const chatInput = document.getElementById("chatInput");
+  if (chatInput) {
+    chatInput.addEventListener("keydown", (e) => {
+      if (e.key === "Enter") sendMessage();
+    });
+  }
+
+  // 地図サイズ調整
+  setTimeout(() => {
+    if (map) map.invalidateSize();
+  }, 400);
 }
 
 window.addEventListener("DOMContentLoaded", main);
-
-// ===================================
-// ★ チャット機能（ここから下だけ追加）
-// ===================================
-
-// ユーザー名
-let chatUser = localStorage.getItem("userName");
-if (!chatUser) {
-  chatUser = prompt("名前を入力してください");
-  localStorage.setItem("userName", chatUser);
-}
-
-// グループ
-const chatGroup = localStorage.getItem("group");
-
-// DOM
-const chatList = document.getElementById("chatList");
-const chatInput = document.getElementById("chatInput");
-const chatSend = document.getElementById("chatSend");
-
-// メッセージ送信
-chatSend.addEventListener("click", async () => {
-  const text = chatInput.value.trim();
-  if (text === "") return;
-
-  await supa.from("messages").insert({
-    group_name: chatGroup,
-    user_name: chatUser,
-    message: text,
-  });
-
-  chatInput.value = "";
-});
-
-// メッセージ取得
-async function loadMessages() {
-  const { data } = await supa
-    .from("messages")
-    .select("*")
-    .eq("group_name", chatGroup)
-    .order("created_at", { ascending: true });
-
-  chatList.innerHTML = data
-    .map(
-      (m) =>
-        `<div><strong>${m.user_name}:</strong> ${m.message}</div>`
-    )
-    .join("");
-
-  chatList.scrollTop = chatList.scrollHeight;
-}
-
-setInterval(loadMessages, 2000);
-loadMessages();