diff --git a/.gitea/workflows/docker.yaml b/.gitea/workflows/docker.yaml
index 5cca9e2..02f99e1 100644
--- a/.gitea/workflows/docker.yaml
+++ b/.gitea/workflows/docker.yaml
@@ -4,7 +4,7 @@ on:
   push:
     branches:
       - main
-      - federation-try
+      - develop-calendar
   release:
     types: [published]
 
diff --git a/outlook-addin/README.md b/outlook-addin/README.md
new file mode 100644
index 0000000..82b0085
--- /dev/null
+++ b/outlook-addin/README.md
@@ -0,0 +1,57 @@
+# Redlight Outlook Add-in
+
+An Outlook Add-in (compatible with **Outlook on the Web** and **Outlook 365 / New Outlook**) that lets you create a Redlight meeting room directly from your Outlook calendar.
+
+## Setup
+
+### 1. Configure Environment
+
+Edit `taskpane.html` and replace the `REDLIGHT_BASE_URL` at the top of the script section with your Redlight instance URL:
+
+```js
+const REDLIGHT_BASE_URL = 'https://your-redlight-instance.com';
+```
+
+### 2. Update Manifest
+
+Edit `manifest.xml` and update:
+- All `<bt:Url id="..." DefaultValue="..." />` entries to point to where you host these files.
+- The `<Id>` GUID if you want a unique add-in identifier.
+- `<SupportUrl>` / `<ProviderName>` as needed.
+
+### 3. Host the Add-in Files
+
+The add-in files (`taskpane.html`, `manifest.xml`) must be served over **HTTPS**. Options:
+
+1. **Host on your Redlight server** — place the files in `public/outlook-addin/` and they'll be served at `https://your-domain/outlook-addin/taskpane.html`.
+2. **Host anywhere** — any static HTTPS server works.
+
+### 4. Sideload or Deploy
+
+#### Sideload for Testing (Outlook Web)
+1. Go to **Outlook on the Web** → [https://outlook.office.com](https://outlook.office.com)
+2. Click the **gear icon** → **View all Outlook settings** → **Mail** → **Customize actions** → **Get add-ins**
+3. Click **My add-ins** → **Add a custom add-in** → **Add from file...**
+4. Upload `manifest.xml`
+
+#### Sideload for Testing (Outlook 365 Desktop)
+1. Open Outlook → **File** → **Manage Add-ins** (or **Get Add-ins**)
+2. Click **My Add-ins** → **Add a custom add-in** → **Add from file...**
+3. Select `manifest.xml`
+
+#### Deploy via Microsoft 365 Admin Center
+1. Go to admin.microsoft.com → **Settings** → **Integrated apps**
+2. Upload the manifest to deploy for your organization
+
+## Usage
+
+1. Open your **Outlook Calendar** and create a **new event**
+2. In the compose toolbar, click the **Redlight** icon
+3. Log in with your Redlight credentials (token is cached for future use)
+4. Select an existing room or create a new one
+5. Click **Insert Meeting Link** — the room join URL will be inserted into the event body and location
+
+## Files
+
+- `manifest.xml` — Office Add-in manifest (defines capabilities, icons, URLs)
+- `taskpane.html` — The add-in UI and logic (single-file HTML+CSS+JS)
diff --git a/outlook-addin/assets/icon-16.svg b/outlook-addin/assets/icon-16.svg
new file mode 100644
index 0000000..6727bc2
--- /dev/null
+++ b/outlook-addin/assets/icon-16.svg
@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16">
+  <circle cx="8" cy="8" r="7" fill="#6366f1"/>
+  <circle cx="8" cy="8" r="3" fill="#fff"/>
+</svg>
diff --git a/outlook-addin/assets/icon-32.svg b/outlook-addin/assets/icon-32.svg
new file mode 100644
index 0000000..3f63c70
--- /dev/null
+++ b/outlook-addin/assets/icon-32.svg
@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" viewBox="0 0 32 32">
+  <circle cx="16" cy="16" r="14" fill="#6366f1"/>
+  <circle cx="16" cy="16" r="6" fill="#fff"/>
+</svg>
diff --git a/outlook-addin/assets/icon-80.svg b/outlook-addin/assets/icon-80.svg
new file mode 100644
index 0000000..f098bf1
--- /dev/null
+++ b/outlook-addin/assets/icon-80.svg
@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="80" height="80" viewBox="0 0 80 80">
+  <circle cx="40" cy="40" r="36" fill="#6366f1"/>
+  <circle cx="40" cy="40" r="15" fill="#fff"/>
+</svg>
diff --git a/outlook-addin/manifest.xml b/outlook-addin/manifest.xml
new file mode 100644
index 0000000..f6bb0be
--- /dev/null
+++ b/outlook-addin/manifest.xml
@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<OfficeApp xmlns="http://schemas.microsoft.com/office/appforoffice/1.1"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xmlns:bt="http://schemas.microsoft.com/office/officeappbasictypes/1.0"
+           xmlns:mailappor="http://schemas.microsoft.com/office/mailappversionoverrides/1.0"
+           xsi:type="MailApp">
+
+  <Id>a1b2c3d4-e5f6-7890-abcd-ef1234567890</Id>
+  <Version>1.0.0</Version>
+  <ProviderName>Redlight</ProviderName>
+  <DefaultLocale>en-US</DefaultLocale>
+  <DisplayName DefaultValue="Redlight Meeting" />
+  <Description DefaultValue="Create a Redlight / BigBlueButton meeting room directly from Outlook." />
+  <SupportUrl DefaultValue="https://github.com/your-org/redlight" />
+
+  <Hosts>
+    <Host Name="Mailbox" />
+  </Hosts>
+
+  <Requirements>
+    <Sets>
+      <Set Name="Mailbox" MinVersion="1.5" />
+    </Sets>
+  </Requirements>
+
+  <FormSettings>
+    <Form xsi:type="ItemEdit">
+      <DesktopSettings>
+        <SourceLocation DefaultValue="https://your-redlight-instance.com/outlook-addin/taskpane.html" />
+        <RequestedHeight>600</RequestedHeight>
+      </DesktopSettings>
+    </Form>
+  </FormSettings>
+
+  <Permissions>ReadWriteItem</Permissions>
+  <Rule xsi:type="RuleCollection" Mode="Or">
+    <Rule xsi:type="ItemIs" ItemType="Appointment" FormType="Edit" />
+  </Rule>
+
+  <DisableEntityHighlighting>true</DisableEntityHighlighting>
+
+  <VersionOverrides xmlns="http://schemas.microsoft.com/office/mailappversionoverrides"
+                    xsi:type="VersionOverridesV1_0">
+    <Requirements>
+      <bt:Sets DefaultMinVersion="1.5">
+        <bt:Set Name="Mailbox" />
+      </bt:Sets>
+    </Requirements>
+
+    <Hosts>
+      <Host xsi:type="MailHost">
+        <DesktopFormFactor>
+          <ExtensionPoint xsi:type="AppointmentOrganizerCommandSurface">
+            <OfficeTab id="TabDefault">
+              <Group id="redlightGroup">
+                <Label resid="groupLabel" />
+
+                <Control xsi:type="Button" id="redlightButton">
+                  <Label resid="buttonLabel" />
+                  <Supertip>
+                    <Title resid="buttonLabel" />
+                    <Description resid="buttonDesc" />
+                  </Supertip>
+                  <Icon>
+                    <bt:Image size="16" resid="icon16" />
+                    <bt:Image size="32" resid="icon32" />
+                    <bt:Image size="80" resid="icon80" />
+                  </Icon>
+                  <Action xsi:type="ShowTaskpane">
+                    <SourceLocation resid="taskpaneUrl" />
+                  </Action>
+                </Control>
+
+              </Group>
+            </OfficeTab>
+          </ExtensionPoint>
+        </DesktopFormFactor>
+
+        <!-- Mobile support -->
+        <MobileFormFactor>
+          <ExtensionPoint xsi:type="MobileOnlineMeetingCommandSurface">
+            <Control xsi:type="MobileButton" id="redlightMobileButton">
+              <Label resid="buttonLabel" />
+              <Icon>
+                <bt:Image size="25" resid="icon32" />
+                <bt:Image size="32" resid="icon32" />
+                <bt:Image size="48" resid="icon80" />
+              </Icon>
+              <Action xsi:type="ShowTaskpane">
+                <SourceLocation resid="taskpaneUrl" />
+              </Action>
+            </Control>
+          </ExtensionPoint>
+        </MobileFormFactor>
+      </Host>
+    </Hosts>
+
+    <Resources>
+      <bt:Images>
+        <bt:Image id="icon16" DefaultValue="https://your-redlight-instance.com/outlook-addin/assets/icon-16.png" />
+        <bt:Image id="icon32" DefaultValue="https://your-redlight-instance.com/outlook-addin/assets/icon-32.png" />
+        <bt:Image id="icon80" DefaultValue="https://your-redlight-instance.com/outlook-addin/assets/icon-80.png" />
+      </bt:Images>
+      <bt:Urls>
+        <bt:Url id="taskpaneUrl" DefaultValue="https://your-redlight-instance.com/outlook-addin/taskpane.html" />
+      </bt:Urls>
+      <bt:ShortStrings>
+        <bt:String id="groupLabel" DefaultValue="Redlight" />
+        <bt:String id="buttonLabel" DefaultValue="Redlight Meeting" />
+      </bt:ShortStrings>
+      <bt:LongStrings>
+        <bt:String id="buttonDesc" DefaultValue="Create or select a Redlight meeting room and insert the join link into this event." />
+      </bt:LongStrings>
+    </Resources>
+
+  </VersionOverrides>
+</OfficeApp>
diff --git a/outlook-addin/taskpane.html b/outlook-addin/taskpane.html
new file mode 100644
index 0000000..3944ad4
--- /dev/null
+++ b/outlook-addin/taskpane.html
@@ -0,0 +1,565 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <title>Redlight Meeting</title>
+
+  <!-- Office.js -->
+  <script src="https://appsforoffice.microsoft.com/lib/1/hosted/office.js"></script>
+
+  <style>
+    :root {
+      --accent: #6366f1;
+      --accent-hover: #4f46e5;
+      --bg: #0f1117;
+      --bg-s: #1a1d2e;
+      --card: #161927;
+      --border: #2a2d3e;
+      --text: #e2e8f0;
+      --text-s: #8892a4;
+      --success: #22c55e;
+      --error: #ef4444;
+      --radius: 10px;
+    }
+
+    * { margin: 0; padding: 0; box-sizing: border-box; }
+
+    body {
+      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+      background: var(--bg);
+      color: var(--text);
+      font-size: 13px;
+      line-height: 1.5;
+      padding: 16px;
+      min-height: 100vh;
+    }
+
+    h1 { font-size: 18px; font-weight: 700; margin-bottom: 4px; }
+    h2 { font-size: 14px; font-weight: 600; margin-bottom: 8px; color: var(--text); }
+    .subtitle { font-size: 12px; color: var(--text-s); margin-bottom: 16px; }
+
+    .card {
+      background: var(--card);
+      border: 1px solid var(--border);
+      border-radius: var(--radius);
+      padding: 14px;
+      margin-bottom: 12px;
+    }
+
+    input, select {
+      width: 100%;
+      padding: 8px 12px;
+      background: var(--bg-s);
+      border: 1px solid var(--border);
+      border-radius: 8px;
+      color: var(--text);
+      font-size: 13px;
+      outline: none;
+      transition: border-color 0.2s;
+    }
+    input:focus, select:focus {
+      border-color: var(--accent);
+    }
+    input::placeholder { color: var(--text-s); }
+
+    label {
+      display: block;
+      font-size: 12px;
+      font-weight: 500;
+      color: var(--text);
+      margin-bottom: 4px;
+    }
+
+    .form-group { margin-bottom: 12px; }
+
+    .btn {
+      display: inline-flex;
+      align-items: center;
+      justify-content: center;
+      gap: 6px;
+      padding: 8px 16px;
+      border: none;
+      border-radius: 8px;
+      font-size: 13px;
+      font-weight: 600;
+      cursor: pointer;
+      transition: all 0.2s;
+      width: 100%;
+    }
+    .btn-primary {
+      background: var(--accent);
+      color: white;
+    }
+    .btn-primary:hover { background: var(--accent-hover); }
+    .btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
+
+    .btn-secondary {
+      background: var(--bg-s);
+      color: var(--text);
+      border: 1px solid var(--border);
+    }
+    .btn-secondary:hover { background: var(--border); }
+
+    .btn-success {
+      background: var(--success);
+      color: white;
+    }
+    .btn-success:hover { opacity: 0.9; }
+
+    .btn-sm {
+      padding: 6px 12px;
+      font-size: 12px;
+    }
+
+    .room-item {
+      display: flex;
+      align-items: center;
+      justify-content: space-between;
+      padding: 10px 12px;
+      border: 1px solid var(--border);
+      border-radius: 8px;
+      margin-bottom: 6px;
+      cursor: pointer;
+      transition: all 0.2s;
+    }
+    .room-item:hover { border-color: var(--accent); background: var(--bg-s); }
+    .room-item.selected { border-color: var(--accent); background: var(--accent)20; }
+    .room-item .room-name { font-weight: 600; font-size: 13px; }
+    .room-item .room-uid { font-size: 11px; color: var(--text-s); }
+
+    .divider {
+      border: none;
+      border-top: 1px solid var(--border);
+      margin: 16px 0;
+    }
+
+    .error { color: var(--error); font-size: 12px; margin-top: 6px; }
+    .success-msg { color: var(--success); font-size: 12px; margin-top: 6px; }
+
+    .status {
+      display: inline-flex;
+      align-items: center;
+      gap: 4px;
+      font-size: 11px;
+      padding: 2px 8px;
+      border-radius: 99px;
+      font-weight: 500;
+    }
+    .status-online { background: rgba(34,197,94,0.15); color: var(--success); }
+    .status-offline { background: rgba(255,255,255,0.06); color: var(--text-s); }
+
+    .logo {
+      display: flex;
+      align-items: center;
+      gap: 8px;
+      margin-bottom: 16px;
+    }
+    .logo-dot {
+      width: 24px;
+      height: 24px;
+      border-radius: 50%;
+      background: var(--accent);
+    }
+    .logo-text { font-size: 16px; font-weight: 700; }
+
+    .tabs {
+      display: flex;
+      gap: 4px;
+      background: var(--bg-s);
+      border-radius: 8px;
+      padding: 3px;
+      margin-bottom: 12px;
+    }
+    .tab {
+      flex: 1;
+      padding: 6px;
+      text-align: center;
+      border-radius: 6px;
+      font-size: 12px;
+      font-weight: 500;
+      cursor: pointer;
+      color: var(--text-s);
+      border: none;
+      background: transparent;
+      transition: all 0.2s;
+    }
+    .tab.active {
+      background: var(--accent);
+      color: white;
+    }
+
+    .hidden { display: none !important; }
+    .loading { text-align: center; padding: 20px; color: var(--text-s); }
+
+    .link-preview {
+      background: var(--bg-s);
+      border: 1px solid var(--border);
+      border-radius: 8px;
+      padding: 10px 12px;
+      font-size: 12px;
+      word-break: break-all;
+      color: var(--accent);
+      margin-top: 8px;
+    }
+  </style>
+</head>
+<body>
+
+  <!-- ─── Login View ─── -->
+  <div id="loginView">
+    <div class="logo">
+      <div class="logo-dot"></div>
+      <span class="logo-text">Redlight</span>
+    </div>
+    <h1>Sign in</h1>
+    <p class="subtitle">Connect to your Redlight instance to create meetings.</p>
+
+    <div class="card">
+      <div class="form-group">
+        <label>Redlight URL</label>
+        <input type="url" id="serverUrl" placeholder="https://your-instance.com" />
+      </div>
+      <div class="form-group">
+        <label>Email</label>
+        <input type="email" id="loginEmail" placeholder="name@example.com" />
+      </div>
+      <div class="form-group">
+        <label>Password</label>
+        <input type="password" id="loginPassword" placeholder="••••••••" />
+      </div>
+      <div id="loginError" class="error hidden"></div>
+      <button class="btn btn-primary" id="loginBtn" onclick="handleLogin()">Sign in</button>
+    </div>
+  </div>
+
+  <!-- ─── Main View ─── -->
+  <div id="mainView" class="hidden">
+    <div class="logo">
+      <div class="logo-dot"></div>
+      <span class="logo-text">Redlight</span>
+    </div>
+
+    <div class="tabs">
+      <button class="tab active" id="tabExisting" onclick="switchTab('existing')">Select Room</button>
+      <button class="tab" id="tabCreate" onclick="switchTab('create')">New Room</button>
+    </div>
+
+    <!-- ─── Existing Rooms ─── -->
+    <div id="existingPanel">
+      <div id="roomsList">
+        <div class="loading">Loading rooms...</div>
+      </div>
+    </div>
+
+    <!-- ─── Create Room ─── -->
+    <div id="createPanel" class="hidden">
+      <div class="card">
+        <div class="form-group">
+          <label>Room Name *</label>
+          <input type="text" id="newRoomName" placeholder="e.g. Team Meeting" />
+        </div>
+        <div class="form-group">
+          <label>Access Code</label>
+          <input type="text" id="newAccessCode" placeholder="Optional" />
+        </div>
+        <div id="createError" class="error hidden"></div>
+        <button class="btn btn-primary" id="createRoomBtn" onclick="handleCreateRoom()">Create Room</button>
+      </div>
+    </div>
+
+    <hr class="divider" />
+
+    <!-- ─── Selected Room / Insert ─── -->
+    <div id="selectedRoomPanel" class="hidden">
+      <h2>Selected Room</h2>
+      <div class="card">
+        <div id="selectedRoomName" style="font-weight:600;margin-bottom:4px;"></div>
+        <div id="selectedRoomUid" style="font-size:11px;color:var(--text-s);"></div>
+        <div id="meetingLinkPreview" class="link-preview hidden"></div>
+      </div>
+      <button class="btn btn-success" id="insertBtn" onclick="insertMeetingLink()">
+        &#x2714; Insert Meeting Link
+      </button>
+      <div id="insertSuccess" class="success-msg hidden">Meeting link inserted!</div>
+    </div>
+
+    <div style="margin-top:16px;">
+      <button class="btn btn-secondary btn-sm" onclick="handleLogout()">Sign out</button>
+    </div>
+  </div>
+
+  <script>
+    // ─── Configuration ──────────────────────────────────────────────────────
+    // Will be populated from user input or localStorage
+    let REDLIGHT_BASE_URL = '';
+    let authToken = '';
+    let selectedRoom = null;
+
+    // ─── Office.js initialization ───────────────────────────────────────────
+    Office.onReady(function (info) {
+      // Check for cached credentials
+      const cached = localStorage.getItem('redlight_outlook');
+      if (cached) {
+        try {
+          const data = JSON.parse(cached);
+          REDLIGHT_BASE_URL = data.url;
+          authToken = data.token;
+          document.getElementById('serverUrl').value = data.url;
+
+          // Verify token is still valid
+          verifyToken().then(valid => {
+            if (valid) {
+              showMainView();
+              loadRooms();
+            } else {
+              showLoginView();
+            }
+          });
+        } catch {
+          showLoginView();
+        }
+      }
+    });
+
+    // ─── API Helper ─────────────────────────────────────────────────────────
+    async function apiRequest(method, path, body) {
+      const url = `${REDLIGHT_BASE_URL}/api${path}`;
+      const headers = { 'Content-Type': 'application/json' };
+      if (authToken) headers['Authorization'] = `Bearer ${authToken}`;
+
+      const options = { method, headers };
+      if (body) options.body = JSON.stringify(body);
+
+      const res = await fetch(url, options);
+      if (!res.ok) {
+        const data = await res.json().catch(() => ({}));
+        throw new Error(data.error || `HTTP ${res.status}`);
+      }
+      return res.json();
+    }
+
+    async function verifyToken() {
+      try {
+        await apiRequest('GET', '/auth/me');
+        return true;
+      } catch {
+        return false;
+      }
+    }
+
+    // ─── Login ──────────────────────────────────────────────────────────────
+    async function handleLogin() {
+      const url = document.getElementById('serverUrl').value.trim().replace(/\/+$/, '');
+      const email = document.getElementById('loginEmail').value.trim();
+      const password = document.getElementById('loginPassword').value;
+      const errorEl = document.getElementById('loginError');
+      errorEl.classList.add('hidden');
+
+      if (!url || !email || !password) {
+        errorEl.textContent = 'All fields are required.';
+        errorEl.classList.remove('hidden');
+        return;
+      }
+
+      REDLIGHT_BASE_URL = url;
+      document.getElementById('loginBtn').disabled = true;
+
+      try {
+        const data = await apiRequest('POST', '/auth/login', { email, password });
+        authToken = data.token;
+
+        // Cache credentials
+        localStorage.setItem('redlight_outlook', JSON.stringify({ url, token: authToken }));
+
+        showMainView();
+        loadRooms();
+      } catch (err) {
+        errorEl.textContent = err.message || 'Login failed';
+        errorEl.classList.remove('hidden');
+      } finally {
+        document.getElementById('loginBtn').disabled = false;
+      }
+    }
+
+    function handleLogout() {
+      authToken = '';
+      localStorage.removeItem('redlight_outlook');
+      showLoginView();
+    }
+
+    // ─── Views ──────────────────────────────────────────────────────────────
+    function showLoginView() {
+      document.getElementById('loginView').classList.remove('hidden');
+      document.getElementById('mainView').classList.add('hidden');
+    }
+
+    function showMainView() {
+      document.getElementById('loginView').classList.add('hidden');
+      document.getElementById('mainView').classList.remove('hidden');
+    }
+
+    function switchTab(tab) {
+      document.getElementById('tabExisting').classList.toggle('active', tab === 'existing');
+      document.getElementById('tabCreate').classList.toggle('active', tab === 'create');
+      document.getElementById('existingPanel').classList.toggle('hidden', tab !== 'existing');
+      document.getElementById('createPanel').classList.toggle('hidden', tab !== 'create');
+    }
+
+    // ─── Load Rooms ─────────────────────────────────────────────────────────
+    async function loadRooms() {
+      const container = document.getElementById('roomsList');
+      container.innerHTML = '<div class="loading">Loading rooms...</div>';
+
+      try {
+        const data = await apiRequest('GET', '/rooms');
+        const rooms = data.rooms || [];
+
+        if (rooms.length === 0) {
+          container.innerHTML = '<div class="loading">No rooms found. Create one first.</div>';
+          return;
+        }
+
+        container.innerHTML = rooms.map(r => `
+          <div class="room-item" onclick="selectRoom('${r.uid}', '${escapeHtml(r.name)}')" id="room-${r.uid}">
+            <div>
+              <div class="room-name">${escapeHtml(r.name)}</div>
+              <div class="room-uid">${r.uid}</div>
+            </div>
+          </div>
+        `).join('');
+      } catch (err) {
+        container.innerHTML = `<div class="error">${err.message}</div>`;
+      }
+    }
+
+    function selectRoom(uid, name) {
+      selectedRoom = { uid, name };
+
+      // Update UI
+      document.querySelectorAll('.room-item').forEach(el => el.classList.remove('selected'));
+      const el = document.getElementById(`room-${uid}`);
+      if (el) el.classList.add('selected');
+
+      // Show selected panel
+      const panel = document.getElementById('selectedRoomPanel');
+      panel.classList.remove('hidden');
+      document.getElementById('selectedRoomName').textContent = name;
+      document.getElementById('selectedRoomUid').textContent = uid;
+      document.getElementById('insertSuccess').classList.add('hidden');
+
+      // Build and show meeting link preview
+      const link = `${REDLIGHT_BASE_URL}/join/${uid}`;
+      const preview = document.getElementById('meetingLinkPreview');
+      preview.textContent = link;
+      preview.classList.remove('hidden');
+    }
+
+    // ─── Create Room ────────────────────────────────────────────────────────
+    async function handleCreateRoom() {
+      const name = document.getElementById('newRoomName').value.trim();
+      const accessCode = document.getElementById('newAccessCode').value.trim();
+      const errorEl = document.getElementById('createError');
+      errorEl.classList.add('hidden');
+
+      if (!name) {
+        errorEl.textContent = 'Room name is required.';
+        errorEl.classList.remove('hidden');
+        return;
+      }
+
+      document.getElementById('createRoomBtn').disabled = true;
+
+      try {
+        const data = await apiRequest('POST', '/rooms', {
+          name,
+          access_code: accessCode || null,
+          mute_on_join: true,
+          record_meeting: true,
+        });
+        const room = data.room;
+        selectRoom(room.uid, room.name);
+        switchTab('existing');
+        loadRooms(); // Refresh list
+
+        // Clear form
+        document.getElementById('newRoomName').value = '';
+        document.getElementById('newAccessCode').value = '';
+      } catch (err) {
+        errorEl.textContent = err.message || 'Could not create room';
+        errorEl.classList.remove('hidden');
+      } finally {
+        document.getElementById('createRoomBtn').disabled = false;
+      }
+    }
+
+    // ─── Insert Meeting Link into Outlook Event ─────────────────────────────
+    function insertMeetingLink() {
+      if (!selectedRoom) return;
+
+      const joinUrl = `${REDLIGHT_BASE_URL}/join/${selectedRoom.uid}`;
+      const meetingHtml = `
+        <br/>
+        <div style="border-left: 3px solid #6366f1; padding: 8px 14px; margin: 12px 0; background: #f8f9fa; border-radius: 4px;">
+          <strong style="color:#6366f1;">Redlight Meeting</strong><br/>
+          <strong>${escapeHtml(selectedRoom.name)}</strong><br/>
+          <a href="${joinUrl}" style="color:#6366f1;">${joinUrl}</a>
+        </div>
+      `;
+
+      try {
+        const item = Office.context.mailbox.item;
+
+        // Set location
+        if (item.location && item.location.setAsync) {
+          item.location.setAsync(joinUrl);
+        }
+
+        // Append meeting link to body
+        item.body.getTypeAsync(function (result) {
+          if (result.status === Office.AsyncResultStatus.Succeeded) {
+            const bodyType = result.value;
+            if (bodyType === Office.CoercionType.Html) {
+              item.body.setSelectedDataAsync(meetingHtml, { coercionType: Office.CoercionType.Html }, function (r) {
+                if (r.status === Office.AsyncResultStatus.Succeeded) {
+                  showInsertSuccess();
+                } else {
+                  // Fallback: append at end
+                  item.body.prependAsync(meetingHtml, { coercionType: Office.CoercionType.Html }, function () {
+                    showInsertSuccess();
+                  });
+                }
+              });
+            } else {
+              // Plain text fallback
+              const textContent = `\n\nRedlight Meeting: ${selectedRoom.name}\n${joinUrl}\n`;
+              item.body.setSelectedDataAsync(textContent, { coercionType: Office.CoercionType.Text }, function () {
+                showInsertSuccess();
+              });
+            }
+          }
+        });
+      } catch (err) {
+        // If Office.js is not available (testing outside Outlook)
+        console.log('Meeting link:', joinUrl);
+        showInsertSuccess();
+      }
+    }
+
+    function showInsertSuccess() {
+      document.getElementById('insertSuccess').classList.remove('hidden');
+      document.getElementById('insertBtn').textContent = '✓ Inserted!';
+      setTimeout(() => {
+        document.getElementById('insertBtn').innerHTML = '&#x2714; Insert Meeting Link';
+      }, 3000);
+    }
+
+    // ─── Utilities ──────────────────────────────────────────────────────────
+    function escapeHtml(str) {
+      const div = document.createElement('div');
+      div.textContent = str;
+      return div.innerHTML;
+    }
+  </script>
+</body>
+</html>
diff --git a/server/config/database.js b/server/config/database.js
index c3b2adc..0f2a220 100644
--- a/server/config/database.js
+++ b/server/config/database.js
@@ -438,6 +438,82 @@ export async function initDatabase() {
     `);
   }
 
+  // ── Calendar tables ──────────────────────────────────────────────────────
+  if (isPostgres) {
+    await db.exec(`
+      CREATE TABLE IF NOT EXISTS calendar_events (
+        id SERIAL PRIMARY KEY,
+        uid TEXT UNIQUE NOT NULL,
+        title TEXT NOT NULL,
+        description TEXT,
+        start_time TIMESTAMP NOT NULL,
+        end_time TIMESTAMP NOT NULL,
+        room_uid TEXT,
+        user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+        color TEXT DEFAULT '#6366f1',
+        federated_from TEXT DEFAULT NULL,
+        federated_join_url TEXT DEFAULT NULL,
+        created_at TIMESTAMP DEFAULT NOW(),
+        updated_at TIMESTAMP DEFAULT NOW()
+      );
+      CREATE INDEX IF NOT EXISTS idx_cal_events_user_id ON calendar_events(user_id);
+      CREATE INDEX IF NOT EXISTS idx_cal_events_uid ON calendar_events(uid);
+      CREATE INDEX IF NOT EXISTS idx_cal_events_start ON calendar_events(start_time);
+
+      CREATE TABLE IF NOT EXISTS calendar_event_shares (
+        id SERIAL PRIMARY KEY,
+        event_id INTEGER NOT NULL REFERENCES calendar_events(id) ON DELETE CASCADE,
+        user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+        created_at TIMESTAMP DEFAULT NOW(),
+        UNIQUE(event_id, user_id)
+      );
+      CREATE INDEX IF NOT EXISTS idx_cal_shares_event ON calendar_event_shares(event_id);
+      CREATE INDEX IF NOT EXISTS idx_cal_shares_user ON calendar_event_shares(user_id);
+    `);
+  } else {
+    await db.exec(`
+      CREATE TABLE IF NOT EXISTS calendar_events (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        uid TEXT UNIQUE NOT NULL,
+        title TEXT NOT NULL,
+        description TEXT,
+        start_time DATETIME NOT NULL,
+        end_time DATETIME NOT NULL,
+        room_uid TEXT,
+        user_id INTEGER NOT NULL,
+        color TEXT DEFAULT '#6366f1',
+        federated_from TEXT DEFAULT NULL,
+        federated_join_url TEXT DEFAULT NULL,
+        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+      );
+      CREATE INDEX IF NOT EXISTS idx_cal_events_user_id ON calendar_events(user_id);
+      CREATE INDEX IF NOT EXISTS idx_cal_events_uid ON calendar_events(uid);
+      CREATE INDEX IF NOT EXISTS idx_cal_events_start ON calendar_events(start_time);
+
+      CREATE TABLE IF NOT EXISTS calendar_event_shares (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        event_id INTEGER NOT NULL,
+        user_id INTEGER NOT NULL,
+        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+        UNIQUE(event_id, user_id),
+        FOREIGN KEY (event_id) REFERENCES calendar_events(id) ON DELETE CASCADE,
+        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+      );
+      CREATE INDEX IF NOT EXISTS idx_cal_shares_event ON calendar_event_shares(event_id);
+      CREATE INDEX IF NOT EXISTS idx_cal_shares_user ON calendar_event_shares(user_id);
+    `);
+  }
+
+  // Calendar migrations: add federated columns if missing
+  if (!(await db.columnExists('calendar_events', 'federated_from'))) {
+    await db.exec('ALTER TABLE calendar_events ADD COLUMN federated_from TEXT DEFAULT NULL');
+  }
+  if (!(await db.columnExists('calendar_events', 'federated_join_url'))) {
+    await db.exec('ALTER TABLE calendar_events ADD COLUMN federated_join_url TEXT DEFAULT NULL');
+  }
+
   // ── Default admin (only on very first start) ────────────────────────────
   const adminAlreadySeeded = await db.get("SELECT value FROM settings WHERE key = 'admin_seeded'");
   if (!adminAlreadySeeded) {
diff --git a/server/index.js b/server/index.js
index 76f7030..f539724 100644
--- a/server/index.js
+++ b/server/index.js
@@ -13,6 +13,7 @@ import recordingRoutes from './routes/recordings.js';
 import adminRoutes from './routes/admin.js';
 import brandingRoutes from './routes/branding.js';
 import federationRoutes, { wellKnownHandler } from './routes/federation.js';
+import calendarRoutes from './routes/calendar.js';
 import { startFederationSync } from './jobs/federationSync.js';
 
 const __filename = fileURLToPath(import.meta.url);
@@ -53,6 +54,9 @@ async function start() {
   app.use('/api/admin', adminRoutes);
   app.use('/api/branding', brandingRoutes);
   app.use('/api/federation', federationRoutes);
+  app.use('/api/calendar', calendarRoutes);
+  // Mount calendar federation receive also under /api/federation for remote instances
+  app.use('/api/federation', calendarRoutes);
   app.get('/.well-known/redlight', wellKnownHandler);
 
   // Serve static files in production
diff --git a/server/routes/calendar.js b/server/routes/calendar.js
new file mode 100644
index 0000000..6a04858
--- /dev/null
+++ b/server/routes/calendar.js
@@ -0,0 +1,489 @@
+import { Router } from 'express';
+import crypto from 'crypto';
+import { getDb } from '../config/database.js';
+import { authenticateToken } from '../middleware/auth.js';
+import { log } from '../config/logger.js';
+import {
+  isFederationEnabled,
+  getFederationDomain,
+  signPayload,
+  verifyPayload,
+  discoverInstance,
+  parseAddress,
+} from '../config/federation.js';
+import { rateLimit } from 'express-rate-limit';
+
+const router = Router();
+
+// Rate limit for federation calendar receive
+const calendarFederationLimiter = rateLimit({
+  windowMs: 15 * 60 * 1000,
+  max: 100,
+  standardHeaders: true,
+  legacyHeaders: false,
+  message: { error: 'Too many requests. Please try again later.' },
+});
+
+// ── GET /api/calendar/events — List events for the current user ─────────────
+router.get('/events', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const { from, to } = req.query;
+
+    let sql = `
+      SELECT ce.*, COALESCE(NULLIF(u.display_name,''), u.name) as organizer_name
+      FROM calendar_events ce
+      JOIN users u ON ce.user_id = u.id
+      WHERE (ce.user_id = ? OR ce.id IN (
+        SELECT event_id FROM calendar_event_shares WHERE user_id = ?
+      ))
+    `;
+    const params = [req.user.id, req.user.id];
+
+    if (from) {
+      sql += ' AND ce.end_time >= ?';
+      params.push(from);
+    }
+    if (to) {
+      sql += ' AND ce.start_time <= ?';
+      params.push(to);
+    }
+
+    sql += ' ORDER BY ce.start_time ASC';
+    const events = await db.all(sql, params);
+
+    // Mark shared events
+    for (const ev of events) {
+      ev.is_owner = ev.user_id === req.user.id;
+    }
+
+    res.json({ events });
+  } catch (err) {
+    log.server.error(`Calendar list error: ${err.message}`);
+    res.status(500).json({ error: 'Events could not be loaded' });
+  }
+});
+
+// ── GET /api/calendar/events/:id — Get single event ─────────────────────────
+router.get('/events/:id', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const event = await db.get(`
+      SELECT ce.*, COALESCE(NULLIF(u.display_name,''), u.name) as organizer_name
+      FROM calendar_events ce
+      JOIN users u ON ce.user_id = u.id
+      WHERE ce.id = ?
+    `, [req.params.id]);
+
+    if (!event) return res.status(404).json({ error: 'Event not found' });
+
+    // Check access
+    if (event.user_id !== req.user.id) {
+      const share = await db.get('SELECT id FROM calendar_event_shares WHERE event_id = ? AND user_id = ?', [event.id, req.user.id]);
+      if (!share) return res.status(403).json({ error: 'No permission' });
+    }
+
+    // Get shared users
+    const sharedUsers = await db.all(`
+      SELECT u.id, u.name, u.display_name, u.email, u.avatar_color, u.avatar_image
+      FROM calendar_event_shares ces
+      JOIN users u ON ces.user_id = u.id
+      WHERE ces.event_id = ?
+    `, [event.id]);
+
+    event.is_owner = event.user_id === req.user.id;
+    res.json({ event, sharedUsers });
+  } catch (err) {
+    log.server.error(`Calendar get event error: ${err.message}`);
+    res.status(500).json({ error: 'Event could not be loaded' });
+  }
+});
+
+// ── POST /api/calendar/events — Create event ────────────────────────────────
+router.post('/events', authenticateToken, async (req, res) => {
+  try {
+    const { title, description, start_time, end_time, room_uid, color } = req.body;
+
+    if (!title || !title.trim()) return res.status(400).json({ error: 'Title is required' });
+    if (!start_time || !end_time) return res.status(400).json({ error: 'Start and end time are required' });
+    if (title.length > 200) return res.status(400).json({ error: 'Title must not exceed 200 characters' });
+    if (description && description.length > 5000) return res.status(400).json({ error: 'Description must not exceed 5000 characters' });
+
+    const startDate = new Date(start_time);
+    const endDate = new Date(end_time);
+    if (isNaN(startDate.getTime()) || isNaN(endDate.getTime())) {
+      return res.status(400).json({ error: 'Invalid date format' });
+    }
+    if (endDate <= startDate) {
+      return res.status(400).json({ error: 'End time must be after start time' });
+    }
+
+    // Verify room exists if specified
+    const db = getDb();
+    if (room_uid) {
+      const room = await db.get('SELECT id FROM rooms WHERE uid = ?', [room_uid]);
+      if (!room) return res.status(400).json({ error: 'Linked room not found' });
+    }
+
+    const uid = crypto.randomBytes(12).toString('hex');
+    const result = await db.run(`
+      INSERT INTO calendar_events (uid, title, description, start_time, end_time, room_uid, user_id, color)
+      VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+    `, [
+      uid,
+      title.trim(),
+      description || null,
+      startDate.toISOString(),
+      endDate.toISOString(),
+      room_uid || null,
+      req.user.id,
+      color || '#6366f1',
+    ]);
+
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ?', [result.lastInsertRowid]);
+    res.status(201).json({ event });
+  } catch (err) {
+    log.server.error(`Calendar create error: ${err.message}`);
+    res.status(500).json({ error: 'Event could not be created' });
+  }
+});
+
+// ── PUT /api/calendar/events/:id — Update event ─────────────────────────────
+router.put('/events/:id', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ? AND user_id = ?', [req.params.id, req.user.id]);
+    if (!event) return res.status(404).json({ error: 'Event not found or no permission' });
+
+    const { title, description, start_time, end_time, room_uid, color } = req.body;
+
+    if (title && title.length > 200) return res.status(400).json({ error: 'Title must not exceed 200 characters' });
+    if (description && description.length > 5000) return res.status(400).json({ error: 'Description must not exceed 5000 characters' });
+
+    if (start_time && end_time) {
+      const s = new Date(start_time);
+      const e = new Date(end_time);
+      if (isNaN(s.getTime()) || isNaN(e.getTime())) return res.status(400).json({ error: 'Invalid date format' });
+      if (e <= s) return res.status(400).json({ error: 'End time must be after start time' });
+    }
+
+    if (room_uid) {
+      const room = await db.get('SELECT id FROM rooms WHERE uid = ?', [room_uid]);
+      if (!room) return res.status(400).json({ error: 'Linked room not found' });
+    }
+
+    await db.run(`
+      UPDATE calendar_events SET
+        title = COALESCE(?, title),
+        description = ?,
+        start_time = COALESCE(?, start_time),
+        end_time = COALESCE(?, end_time),
+        room_uid = ?,
+        color = COALESCE(?, color),
+        updated_at = CURRENT_TIMESTAMP
+      WHERE id = ?
+    `, [
+      title || null,
+      description !== undefined ? description : event.description,
+      start_time || null,
+      end_time || null,
+      room_uid !== undefined ? (room_uid || null) : event.room_uid,
+      color || null,
+      req.params.id,
+    ]);
+
+    const updated = await db.get('SELECT * FROM calendar_events WHERE id = ?', [req.params.id]);
+    res.json({ event: updated });
+  } catch (err) {
+    log.server.error(`Calendar update error: ${err.message}`);
+    res.status(500).json({ error: 'Event could not be updated' });
+  }
+});
+
+// ── DELETE /api/calendar/events/:id — Delete event ──────────────────────────
+router.delete('/events/:id', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ? AND user_id = ?', [req.params.id, req.user.id]);
+    if (!event) return res.status(404).json({ error: 'Event not found or no permission' });
+
+    await db.run('DELETE FROM calendar_events WHERE id = ?', [req.params.id]);
+    res.json({ message: 'Event deleted' });
+  } catch (err) {
+    log.server.error(`Calendar delete error: ${err.message}`);
+    res.status(500).json({ error: 'Event could not be deleted' });
+  }
+});
+
+// ── POST /api/calendar/events/:id/share — Share event with local user ───────
+router.post('/events/:id/share', authenticateToken, async (req, res) => {
+  try {
+    const { user_id } = req.body;
+    if (!user_id) return res.status(400).json({ error: 'User ID is required' });
+
+    const db = getDb();
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ? AND user_id = ?', [req.params.id, req.user.id]);
+    if (!event) return res.status(404).json({ error: 'Event not found or no permission' });
+    if (user_id === req.user.id) return res.status(400).json({ error: 'Cannot share with yourself' });
+
+    const existing = await db.get('SELECT id FROM calendar_event_shares WHERE event_id = ? AND user_id = ?', [event.id, user_id]);
+    if (existing) return res.status(400).json({ error: 'Already shared with this user' });
+
+    await db.run('INSERT INTO calendar_event_shares (event_id, user_id) VALUES (?, ?)', [event.id, user_id]);
+
+    const sharedUsers = await db.all(`
+      SELECT u.id, u.name, u.display_name, u.email, u.avatar_color, u.avatar_image
+      FROM calendar_event_shares ces
+      JOIN users u ON ces.user_id = u.id
+      WHERE ces.event_id = ?
+    `, [event.id]);
+
+    res.json({ sharedUsers });
+  } catch (err) {
+    log.server.error(`Calendar share error: ${err.message}`);
+    res.status(500).json({ error: 'Could not share event' });
+  }
+});
+
+// ── DELETE /api/calendar/events/:id/share/:userId — Remove share ────────────
+router.delete('/events/:id/share/:userId', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ? AND user_id = ?', [req.params.id, req.user.id]);
+    if (!event) return res.status(404).json({ error: 'Event not found or no permission' });
+
+    await db.run('DELETE FROM calendar_event_shares WHERE event_id = ? AND user_id = ?', [event.id, parseInt(req.params.userId)]);
+
+    const sharedUsers = await db.all(`
+      SELECT u.id, u.name, u.display_name, u.email, u.avatar_color, u.avatar_image
+      FROM calendar_event_shares ces
+      JOIN users u ON ces.user_id = u.id
+      WHERE ces.event_id = ?
+    `, [event.id]);
+
+    res.json({ sharedUsers });
+  } catch (err) {
+    log.server.error(`Calendar unshare error: ${err.message}`);
+    res.status(500).json({ error: 'Could not remove share' });
+  }
+});
+
+// ── GET /api/calendar/events/:id/ics — Download event as ICS ────────────────
+router.get('/events/:id/ics', authenticateToken, async (req, res) => {
+  try {
+    const db = getDb();
+    const event = await db.get(`
+      SELECT ce.*, COALESCE(NULLIF(u.display_name,''), u.name) as organizer_name, u.email as organizer_email
+      FROM calendar_events ce
+      JOIN users u ON ce.user_id = u.id
+      WHERE ce.id = ?
+    `, [req.params.id]);
+
+    if (!event) return res.status(404).json({ error: 'Event not found' });
+
+    // Check access
+    if (event.user_id !== req.user.id) {
+      const share = await db.get('SELECT id FROM calendar_event_shares WHERE event_id = ? AND user_id = ?', [event.id, req.user.id]);
+      if (!share) return res.status(403).json({ error: 'No permission' });
+    }
+
+    // Build room join URL if linked
+    const baseUrl = process.env.APP_URL || `${req.protocol}://${req.get('host')}`;
+    let location = '';
+    if (event.room_uid) {
+      location = `${baseUrl}/join/${event.room_uid}`;
+    }
+
+    const ics = generateICS(event, location, baseUrl);
+
+    res.setHeader('Content-Type', 'text/calendar; charset=utf-8');
+    res.setHeader('Content-Disposition', `attachment; filename="${encodeURIComponent(event.title)}.ics"`);
+    res.send(ics);
+  } catch (err) {
+    log.server.error(`ICS download error: ${err.message}`);
+    res.status(500).json({ error: 'Could not generate ICS file' });
+  }
+});
+
+// ── POST /api/calendar/events/:id/federation — Send event to remote user ────
+router.post('/events/:id/federation', authenticateToken, async (req, res) => {
+  try {
+    if (!isFederationEnabled()) {
+      return res.status(400).json({ error: 'Federation is not configured on this instance' });
+    }
+
+    const { to } = req.body;
+    if (!to) return res.status(400).json({ error: 'Remote address is required' });
+
+    const { username, domain } = parseAddress(to);
+    if (!domain) return res.status(400).json({ error: 'Remote address must be in format username@domain' });
+    if (domain === getFederationDomain()) {
+      return res.status(400).json({ error: 'Cannot send to your own instance. Use local sharing instead.' });
+    }
+
+    const db = getDb();
+    const event = await db.get('SELECT * FROM calendar_events WHERE id = ? AND user_id = ?', [req.params.id, req.user.id]);
+    if (!event) return res.status(404).json({ error: 'Event not found or no permission' });
+
+    const baseUrl = process.env.APP_URL || `${req.protocol}://${req.get('host')}`;
+    let joinUrl = null;
+    if (event.room_uid) {
+      joinUrl = `${baseUrl}/join/${event.room_uid}`;
+    }
+
+    const payload = {
+      type: 'calendar_event',
+      event_uid: event.uid,
+      title: event.title,
+      description: event.description || '',
+      start_time: event.start_time,
+      end_time: event.end_time,
+      room_uid: event.room_uid || null,
+      join_url: joinUrl,
+      from_user: `@${req.user.name}@${getFederationDomain()}`,
+      to_user: to,
+      timestamp: new Date().toISOString(),
+    };
+
+    const signature = signPayload(payload);
+    const { baseUrl: remoteApi } = await discoverInstance(domain);
+
+    const response = await fetch(`${remoteApi}/calendar-event`, {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        'X-Federation-Signature': signature,
+        'X-Federation-Origin': getFederationDomain(),
+      },
+      body: JSON.stringify(payload),
+      signal: AbortSignal.timeout(15_000),
+    });
+
+    if (!response.ok) {
+      const data = await response.json().catch(() => ({}));
+      throw new Error(data.error || `Remote server responded with ${response.status}`);
+    }
+
+    res.json({ success: true });
+  } catch (err) {
+    log.server.error(`Calendar federation send error: ${err.message}`);
+    res.status(500).json({ error: err.message || 'Could not send event to remote instance' });
+  }
+});
+
+// ── POST /receive-event or /calendar-event — Receive calendar event from remote ──
+// '/receive-event' when mounted at /api/calendar
+// '/calendar-event' when mounted at /api/federation (for remote instance discovery)
+router.post(['/receive-event', '/calendar-event'], calendarFederationLimiter, async (req, res) => {
+  try {
+    if (!isFederationEnabled()) {
+      return res.status(400).json({ error: 'Federation is not configured on this instance' });
+    }
+
+    const signature = req.headers['x-federation-signature'];
+    const payload = req.body || {};
+
+    if (!signature) return res.status(401).json({ error: 'Missing federation signature' });
+
+    const { event_uid, title, description, start_time, end_time, room_uid, join_url, from_user, to_user } = payload;
+
+    if (!event_uid || !title || !start_time || !end_time || !from_user || !to_user) {
+      return res.status(400).json({ error: 'Incomplete event payload' });
+    }
+
+    // Validate lengths
+    if (event_uid.length > 100 || title.length > 200 || (description && description.length > 5000) ||
+        from_user.length > 200 || to_user.length > 200 || (join_url && join_url.length > 2000)) {
+      return res.status(400).json({ error: 'Payload fields exceed maximum allowed length' });
+    }
+
+    // Verify signature
+    const { domain: senderDomain } = parseAddress(from_user);
+    if (!senderDomain) return res.status(400).json({ error: 'Sender address must include a domain' });
+
+    const { publicKey } = await discoverInstance(senderDomain);
+    if (!publicKey) return res.status(400).json({ error: 'Sender instance did not provide a public key' });
+    if (!verifyPayload(payload, signature, publicKey)) {
+      return res.status(403).json({ error: 'Invalid federation signature' });
+    }
+
+    // Find local user
+    const { username } = parseAddress(to_user);
+    const db = getDb();
+    const targetUser = await db.get('SELECT id, name, email FROM users WHERE LOWER(name) = LOWER(?)', [username]);
+    if (!targetUser) return res.status(404).json({ error: 'User not found on this instance' });
+
+    // Check duplicate
+    const existing = await db.get('SELECT id FROM calendar_events WHERE uid = ? AND user_id = ?', [event_uid, targetUser.id]);
+    if (existing) return res.json({ success: true, message: 'Event already received' });
+
+    // Create event for the target user
+    await db.run(`
+      INSERT INTO calendar_events (uid, title, description, start_time, end_time, room_uid, user_id, color, federated_from, federated_join_url)
+      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+    `, [
+      event_uid,
+      title,
+      description || null,
+      start_time,
+      end_time,
+      room_uid || null,
+      targetUser.id,
+      '#6366f1',
+      from_user,
+      join_url || null,
+    ]);
+
+    res.json({ success: true });
+  } catch (err) {
+    log.server.error(`Calendar federation receive error: ${err.message}`);
+    res.status(500).json({ error: 'Failed to process calendar event' });
+  }
+});
+
+// ── Helper: Generate ICS content ────────────────────────────────────────────
+function generateICS(event, location, prodIdDomain) {
+  const formatDate = (dateStr) => {
+    const d = new Date(dateStr);
+    return d.toISOString().replace(/[-:]/g, '').replace(/\.\d{3}/, '');
+  };
+
+  const escapeICS = (str) => {
+    if (!str) return '';
+    return str.replace(/\\/g, '\\\\').replace(/;/g, '\\;').replace(/,/g, '\\,').replace(/\n/g, '\\n');
+  };
+
+  const now = formatDate(new Date().toISOString());
+  const dtStart = formatDate(event.start_time);
+  const dtEnd = formatDate(event.end_time);
+
+  let ics = [
+    'BEGIN:VCALENDAR',
+    'VERSION:2.0',
+    `PRODID:-//${prodIdDomain}//Redlight Calendar//EN`,
+    'CALSCALE:GREGORIAN',
+    'METHOD:PUBLISH',
+    'BEGIN:VEVENT',
+    `UID:${event.uid}@${prodIdDomain}`,
+    `DTSTAMP:${now}`,
+    `DTSTART:${dtStart}`,
+    `DTEND:${dtEnd}`,
+    `SUMMARY:${escapeICS(event.title)}`,
+  ];
+
+  if (event.description) {
+    ics.push(`DESCRIPTION:${escapeICS(event.description)}`);
+  }
+  if (location) {
+    ics.push(`LOCATION:${escapeICS(location)}`);
+    ics.push(`URL:${location}`);
+  }
+  if (event.organizer_name && event.organizer_email) {
+    ics.push(`ORGANIZER;CN=${escapeICS(event.organizer_name)}:mailto:${event.organizer_email}`);
+  }
+
+  ics.push('END:VEVENT', 'END:VCALENDAR');
+  return ics.join('\r\n');
+}
+
+export default router;
diff --git a/src/App.jsx b/src/App.jsx
index 74a6536..1552f3d 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -16,6 +16,7 @@ import Admin from './pages/Admin';
 import GuestJoin from './pages/GuestJoin';
 import FederationInbox from './pages/FederationInbox';
 import FederatedRoomDetail from './pages/FederatedRoomDetail';
+import Calendar from './pages/Calendar';
 
 export default function App() {
   const { user, loading } = useAuth();
@@ -54,6 +55,7 @@ export default function App() {
       {/* Protected routes */}
       <Route element={<ProtectedRoute><Layout /></ProtectedRoute>}>
         <Route path="/dashboard" element={<Dashboard />} />
+        <Route path="/calendar" element={<Calendar />} />
         <Route path="/rooms/:uid" element={<RoomDetail />} />
         <Route path="/settings" element={<Settings />} />
         <Route path="/admin" element={<Admin />} />
diff --git a/src/components/Sidebar.jsx b/src/components/Sidebar.jsx
index a8b334d..d4cd0c0 100644
--- a/src/components/Sidebar.jsx
+++ b/src/components/Sidebar.jsx
@@ -1,5 +1,5 @@
 import { NavLink } from 'react-router-dom';
-import { LayoutDashboard, Settings, Shield, X, Palette, Globe } from 'lucide-react';
+import { LayoutDashboard, Settings, Shield, X, Palette, Globe, CalendarDays } from 'lucide-react';
 import BrandLogo from './BrandLogo';
 import { useAuth } from '../contexts/AuthContext';
 import { useLanguage } from '../contexts/LanguageContext';
@@ -30,6 +30,7 @@ export default function Sidebar({ open, onClose }) {
 
   const navItems = [
     { to: '/dashboard', icon: LayoutDashboard, label: t('nav.dashboard') },
+    { to: '/calendar', icon: CalendarDays, label: t('nav.calendar') },
     { to: '/federation/inbox', icon: Globe, label: t('nav.federation'), badge: federationCount },
     { to: '/settings', icon: Settings, label: t('nav.settings') },
   ];
diff --git a/src/i18n/de.json b/src/i18n/de.json
index 7d41010..afb6d1b 100644
--- a/src/i18n/de.json
+++ b/src/i18n/de.json
@@ -32,6 +32,7 @@
     "appearance": "Darstellung",
     "changeTheme": "Theme ändern",
     "navigation": "Navigation",
+    "calendar": "Kalender",
     "federation": "Einladungen"
   },
   "auth": {
@@ -408,5 +409,58 @@
     "joinUrl": "Beitritts-URL",
     "roomDeleted": "Gelöscht",
     "roomDeletedNotice": "Dieser Raum wurde vom Besitzer auf der Ursprungsinstanz gelöscht und ist nicht mehr verfügbar."
+  },
+  "calendar": {
+    "title": "Kalender",
+    "subtitle": "Meetings planen und verwalten",
+    "newEvent": "Neues Event",
+    "createEvent": "Event erstellen",
+    "editEvent": "Event bearbeiten",
+    "eventTitle": "Titel",
+    "eventTitlePlaceholder": "z.B. Team Meeting",
+    "description": "Beschreibung",
+    "descriptionPlaceholder": "Beschreibung hinzufügen...",
+    "startTime": "Beginn",
+    "endTime": "Ende",
+    "linkedRoom": "Verknüpfter Raum",
+    "noRoom": "Kein Raum (kein Videomeeting)",
+    "linkedRoomHint": "Verknüpfe einen Raum, um die Beitritts-URL automatisch ins Event einzufügen.",
+    "color": "Farbe",
+    "eventCreated": "Event erstellt!",
+    "eventUpdated": "Event aktualisiert!",
+    "eventDeleted": "Event gelöscht",
+    "saveFailed": "Event konnte nicht gespeichert werden",
+    "deleteFailed": "Event konnte nicht gelöscht werden",
+    "deleteConfirm": "Dieses Event wirklich löschen?",
+    "loadFailed": "Events konnten nicht geladen werden",
+    "today": "Heute",
+    "month": "Monat",
+    "week": "Woche",
+    "more": "weitere",
+    "mon": "Mo",
+    "tue": "Di",
+    "wed": "Mi",
+    "thu": "Do",
+    "fri": "Fr",
+    "sat": "Sa",
+    "sun": "So",
+    "downloadICS": "ICS herunterladen",
+    "icsDownloaded": "ICS-Datei heruntergeladen",
+    "icsFailed": "ICS-Datei konnte nicht heruntergeladen werden",
+    "share": "Teilen",
+    "shareEvent": "Event teilen",
+    "shareAdded": "Benutzer zum Event hinzugefügt",
+    "shareRemoved": "Freigabe entfernt",
+    "shareFailed": "Event konnte nicht geteilt werden",
+    "sendFederated": "An Remote senden",
+    "sendFederatedTitle": "Event an Remote-Instanz senden",
+    "sendFederatedDesc": "Sende dieses Kalender-Event an einen Benutzer auf einer anderen Redlight-Instanz.",
+    "send": "Senden",
+    "fedSent": "Event an Remote-Instanz gesendet!",
+    "fedFailed": "Event konnte nicht an Remote-Instanz gesendet werden",
+    "openRoom": "Verknüpften Raum öffnen",
+    "organizer": "Organisator",
+    "federatedFrom": "Von Remote-Instanz",
+    "joinFederatedMeeting": "Remote-Meeting beitreten"
   }
 }
\ No newline at end of file
diff --git a/src/i18n/en.json b/src/i18n/en.json
index 54faaf0..93ac9d6 100644
--- a/src/i18n/en.json
+++ b/src/i18n/en.json
@@ -32,6 +32,7 @@
     "appearance": "Appearance",
     "changeTheme": "Change theme",
     "navigation": "Navigation",
+    "calendar": "Calendar",
     "federation": "Invitations"
   },
   "auth": {
@@ -408,5 +409,58 @@
     "joinUrl": "Join URL",
     "roomDeleted": "Deleted",
     "roomDeletedNotice": "This room has been deleted by the owner on the origin instance and is no longer available."
+  },
+  "calendar": {
+    "title": "Calendar",
+    "subtitle": "Plan and manage your meetings",
+    "newEvent": "New Event",
+    "createEvent": "Create Event",
+    "editEvent": "Edit Event",
+    "eventTitle": "Title",
+    "eventTitlePlaceholder": "e.g. Team Meeting",
+    "description": "Description",
+    "descriptionPlaceholder": "Add a description...",
+    "startTime": "Start",
+    "endTime": "End",
+    "linkedRoom": "Linked Room",
+    "noRoom": "No room (no video meeting)",
+    "linkedRoomHint": "Link a room to automatically include the join-URL in the event.",
+    "color": "Color",
+    "eventCreated": "Event created!",
+    "eventUpdated": "Event updated!",
+    "eventDeleted": "Event deleted",
+    "saveFailed": "Could not save event",
+    "deleteFailed": "Could not delete event",
+    "deleteConfirm": "Really delete this event?",
+    "loadFailed": "Events could not be loaded",
+    "today": "Today",
+    "month": "Month",
+    "week": "Week",
+    "more": "more",
+    "mon": "Mon",
+    "tue": "Tue",
+    "wed": "Wed",
+    "thu": "Thu",
+    "fri": "Fri",
+    "sat": "Sat",
+    "sun": "Sun",
+    "downloadICS": "Download ICS",
+    "icsDownloaded": "ICS file downloaded",
+    "icsFailed": "Could not download ICS file",
+    "share": "Share",
+    "shareEvent": "Share Event",
+    "shareAdded": "User added to event",
+    "shareRemoved": "Share removed",
+    "shareFailed": "Could not share event",
+    "sendFederated": "Send to remote",
+    "sendFederatedTitle": "Send Event to Remote Instance",
+    "sendFederatedDesc": "Send this calendar event to a user on another Redlight instance.",
+    "send": "Send",
+    "fedSent": "Event sent to remote instance!",
+    "fedFailed": "Could not send event to remote instance",
+    "openRoom": "Open linked room",
+    "organizer": "Organizer",
+    "federatedFrom": "From remote instance",
+    "joinFederatedMeeting": "Join remote meeting"
   }
 }
\ No newline at end of file
diff --git a/src/index.css b/src/index.css
index 5d80802..6f57c6b 100644
--- a/src/index.css
+++ b/src/index.css
@@ -440,6 +440,32 @@
     --gradient-end: #d6336a;
   }
 
+    /* ===== RED MODULAR LIGHT ===== */
+  [data-theme="red-modular-light"] {
+    --bg-primary: #ffffff;
+    --bg-secondary: #f5f5f5;
+    --bg-tertiary: #e0e0e0;
+    --text-primary: #000000;
+    --text-secondary: #333333;
+    --accent: #e60000;
+    --accent-hover: #ff3333;
+    --accent-text: #ffffff;
+    --border: rgba(255, 255, 255, 0.1);
+    --card-bg: #ffffff;
+    --input-bg: #ffffff;
+    --input-border: #d3cbb7;
+    --nav-bg: #ffffff;
+    --sidebar-bg: #ffffff;
+    --hover-bg: #e0e0e0;
+    --success: #86b300;
+    --warning: #ecb637;
+    --error: #ec4137;
+    --ring: #b30051;
+    --shadow-color: rgba(0, 0, 0, 0.3);
+    --gradient-start: #b30051;
+    --gradient-end: #d6336a;
+  }
+
 
 @layer components {
   .btn-primary {
diff --git a/src/pages/Calendar.jsx b/src/pages/Calendar.jsx
new file mode 100644
index 0000000..bfeff3f
--- /dev/null
+++ b/src/pages/Calendar.jsx
@@ -0,0 +1,744 @@
+import { useState, useEffect, useMemo } from 'react';
+import {
+  ChevronLeft, ChevronRight, Plus, Calendar as CalendarIcon, Clock, Video,
+  Loader2, Download, Share2, Globe, Trash2, Edit, X, UserPlus, Send,
+} from 'lucide-react';
+import api from '../services/api';
+import { useAuth } from '../contexts/AuthContext';
+import { useLanguage } from '../contexts/LanguageContext';
+import Modal from '../components/Modal';
+import toast from 'react-hot-toast';
+
+const COLORS = ['#6366f1', '#ef4444', '#f59e0b', '#10b981', '#3b82f6', '#8b5cf6', '#ec4899', '#14b8a6'];
+
+export default function Calendar() {
+  const { user } = useAuth();
+  const { t } = useLanguage();
+
+  const [events, setEvents] = useState([]);
+  const [loading, setLoading] = useState(true);
+  const [currentDate, setCurrentDate] = useState(new Date());
+  const [view, setView] = useState('month'); // month | week
+  const [rooms, setRooms] = useState([]);
+
+  // Modal state
+  const [showCreate, setShowCreate] = useState(false);
+  const [showDetail, setShowDetail] = useState(null);
+  const [editingEvent, setEditingEvent] = useState(null);
+  const [showShare, setShowShare] = useState(null);
+  const [showFedShare, setShowFedShare] = useState(null);
+
+  // Create/Edit form
+  const [form, setForm] = useState({
+    title: '', description: '', start_time: '', end_time: '',
+    room_uid: '', color: '#6366f1',
+  });
+  const [saving, setSaving] = useState(false);
+
+  // Share state
+  const [shareSearch, setShareSearch] = useState('');
+  const [shareResults, setShareResults] = useState([]);
+  const [sharedUsers, setSharedUsers] = useState([]);
+  const [fedAddress, setFedAddress] = useState('');
+  const [fedSending, setFedSending] = useState(false);
+
+  // Load events on month change
+  useEffect(() => {
+    fetchEvents();
+  }, [currentDate]);
+
+  useEffect(() => {
+    fetchRooms();
+  }, []);
+
+  const fetchEvents = async () => {
+    try {
+      const year = currentDate.getFullYear();
+      const month = currentDate.getMonth();
+      const from = new Date(year, month - 1, 1).toISOString();
+      const to = new Date(year, month + 2, 0).toISOString();
+      const res = await api.get(`/calendar/events?from=${from}&to=${to}`);
+      setEvents(res.data.events || []);
+    } catch {
+      toast.error(t('calendar.loadFailed'));
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  const fetchRooms = async () => {
+    try {
+      const res = await api.get('/rooms');
+      setRooms(res.data.rooms || []);
+    } catch { /* ignore */ }
+  };
+
+  // Calendar grid computation
+  const calendarDays = useMemo(() => {
+    const year = currentDate.getFullYear();
+    const month = currentDate.getMonth();
+    const firstDay = new Date(year, month, 1);
+    const lastDay = new Date(year, month + 1, 0);
+
+    // Start from Monday (ISO week)
+    let startOffset = firstDay.getDay() - 1;
+    if (startOffset < 0) startOffset = 6;
+    const calStart = new Date(year, month, 1 - startOffset);
+
+    const days = [];
+    const current = new Date(calStart);
+    for (let i = 0; i < 42; i++) {
+      days.push(new Date(current));
+      current.setDate(current.getDate() + 1);
+    }
+    return days;
+  }, [currentDate]);
+
+  const weekDays = useMemo(() => {
+    const year = currentDate.getFullYear();
+    const month = currentDate.getMonth();
+    const date = currentDate.getDate();
+    const dayOfWeek = currentDate.getDay();
+    let mondayOffset = dayOfWeek - 1;
+    if (mondayOffset < 0) mondayOffset = 6;
+    const monday = new Date(year, month, date - mondayOffset);
+    const days = [];
+    for (let i = 0; i < 7; i++) {
+      days.push(new Date(monday.getFullYear(), monday.getMonth(), monday.getDate() + i));
+    }
+    return days;
+  }, [currentDate]);
+
+  const eventsForDay = (day) => {
+    const dayStr = day.toISOString().split('T')[0];
+    return events.filter(ev => {
+      const start = ev.start_time.split('T')[0];
+      const end = ev.end_time.split('T')[0];
+      return dayStr >= start && dayStr <= end;
+    });
+  };
+
+  const isToday = (day) => {
+    const today = new Date();
+    return day.toDateString() === today.toDateString();
+  };
+
+  const isCurrentMonth = (day) => {
+    return day.getMonth() === currentDate.getMonth();
+  };
+
+  const navigatePrev = () => {
+    const d = new Date(currentDate);
+    if (view === 'month') d.setMonth(d.getMonth() - 1);
+    else d.setDate(d.getDate() - 7);
+    setCurrentDate(d);
+  };
+
+  const navigateNext = () => {
+    const d = new Date(currentDate);
+    if (view === 'month') d.setMonth(d.getMonth() + 1);
+    else d.setDate(d.getDate() + 7);
+    setCurrentDate(d);
+  };
+
+  const goToToday = () => setCurrentDate(new Date());
+
+  const monthLabel = currentDate.toLocaleString('default', { month: 'long', year: 'numeric' });
+
+  const openCreateForDay = (day) => {
+    const start = new Date(day);
+    start.setHours(9, 0, 0, 0);
+    const end = new Date(day);
+    end.setHours(10, 0, 0, 0);
+
+    setForm({
+      title: '', description: '',
+      start_time: toLocalDateTimeStr(start),
+      end_time: toLocalDateTimeStr(end),
+      room_uid: '', color: '#6366f1',
+    });
+    setEditingEvent(null);
+    setShowCreate(true);
+  };
+
+  const openEdit = (ev) => {
+    setForm({
+      title: ev.title,
+      description: ev.description || '',
+      start_time: toLocalDateTimeStr(new Date(ev.start_time)),
+      end_time: toLocalDateTimeStr(new Date(ev.end_time)),
+      room_uid: ev.room_uid || '',
+      color: ev.color || '#6366f1',
+    });
+    setEditingEvent(ev);
+    setShowDetail(null);
+    setShowCreate(true);
+  };
+
+  const handleSave = async (e) => {
+    e.preventDefault();
+    setSaving(true);
+    try {
+      const data = {
+        ...form,
+        start_time: new Date(form.start_time).toISOString(),
+        end_time: new Date(form.end_time).toISOString(),
+      };
+
+      if (editingEvent) {
+        await api.put(`/calendar/events/${editingEvent.id}`, data);
+        toast.success(t('calendar.eventUpdated'));
+      } else {
+        await api.post('/calendar/events', data);
+        toast.success(t('calendar.eventCreated'));
+      }
+      setShowCreate(false);
+      setEditingEvent(null);
+      fetchEvents();
+    } catch (err) {
+      toast.error(err.response?.data?.error || t('calendar.saveFailed'));
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  const handleDelete = async (ev) => {
+    if (!confirm(t('calendar.deleteConfirm'))) return;
+    try {
+      await api.delete(`/calendar/events/${ev.id}`);
+      toast.success(t('calendar.eventDeleted'));
+      setShowDetail(null);
+      fetchEvents();
+    } catch {
+      toast.error(t('calendar.deleteFailed'));
+    }
+  };
+
+  const handleDownloadICS = async (ev) => {
+    try {
+      const res = await api.get(`/calendar/events/${ev.id}/ics`, { responseType: 'blob' });
+      const url = window.URL.createObjectURL(res.data);
+      const a = document.createElement('a');
+      a.href = url;
+      a.download = `${ev.title}.ics`;
+      a.click();
+      window.URL.revokeObjectURL(url);
+      toast.success(t('calendar.icsDownloaded'));
+    } catch {
+      toast.error(t('calendar.icsFailed'));
+    }
+  };
+
+  // Share functions
+  const openShareModal = async (ev) => {
+    setShowShare(ev);
+    setShareSearch('');
+    setShareResults([]);
+    try {
+      const res = await api.get(`/calendar/events/${ev.id}`);
+      setSharedUsers(res.data.sharedUsers || []);
+    } catch { /* ignore */ }
+  };
+
+  const searchUsers = async (query) => {
+    setShareSearch(query);
+    if (query.length < 2) { setShareResults([]); return; }
+    try {
+      const res = await api.get(`/rooms/users/search?q=${encodeURIComponent(query)}`);
+      const sharedIds = new Set(sharedUsers.map(u => u.id));
+      setShareResults(res.data.users.filter(u => !sharedIds.has(u.id)));
+    } catch { setShareResults([]); }
+  };
+
+  const handleShare = async (userId) => {
+    if (!showShare) return;
+    try {
+      const res = await api.post(`/calendar/events/${showShare.id}/share`, { user_id: userId });
+      setSharedUsers(res.data.sharedUsers);
+      setShareSearch('');
+      setShareResults([]);
+      toast.success(t('calendar.shareAdded'));
+    } catch (err) {
+      toast.error(err.response?.data?.error || t('calendar.shareFailed'));
+    }
+  };
+
+  const handleUnshare = async (userId) => {
+    if (!showShare) return;
+    try {
+      const res = await api.delete(`/calendar/events/${showShare.id}/share/${userId}`);
+      setSharedUsers(res.data.sharedUsers);
+      toast.success(t('calendar.shareRemoved'));
+    } catch { toast.error(t('calendar.shareFailed')); }
+  };
+
+  const handleFedSend = async (e) => {
+    e.preventDefault();
+    if (!showFedShare) return;
+    const normalized = fedAddress.startsWith('@') ? fedAddress.slice(1) : fedAddress;
+    if (!normalized.includes('@') || normalized.endsWith('@')) {
+      toast.error(t('federation.addressHint'));
+      return;
+    }
+    setFedSending(true);
+    try {
+      await api.post(`/calendar/events/${showFedShare.id}/federation`, { to: fedAddress });
+      toast.success(t('calendar.fedSent'));
+      setShowFedShare(null);
+      setFedAddress('');
+    } catch (err) {
+      toast.error(err.response?.data?.error || t('calendar.fedFailed'));
+    } finally {
+      setFedSending(false);
+    }
+  };
+
+  const dayNames = [
+    t('calendar.mon'), t('calendar.tue'), t('calendar.wed'),
+    t('calendar.thu'), t('calendar.fri'), t('calendar.sat'), t('calendar.sun'),
+  ];
+
+  if (loading) {
+    return (
+      <div className="flex items-center justify-center py-20">
+        <Loader2 size={32} className="animate-spin text-th-accent" />
+      </div>
+    );
+  }
+
+  return (
+    <div>
+      {/* Header */}
+      <div className="flex items-center justify-between mb-6">
+        <div>
+          <h1 className="text-2xl font-bold text-th-text">{t('calendar.title')}</h1>
+          <p className="text-sm text-th-text-s mt-1">{t('calendar.subtitle')}</p>
+        </div>
+        <button onClick={() => {
+          const now = new Date();
+          now.setHours(now.getHours() + 1, 0, 0, 0);
+          const end = new Date(now);
+          end.setHours(end.getHours() + 1);
+          setForm({
+            title: '', description: '',
+            start_time: toLocalDateTimeStr(now),
+            end_time: toLocalDateTimeStr(end),
+            room_uid: '', color: '#6366f1',
+          });
+          setEditingEvent(null);
+          setShowCreate(true);
+        }} className="btn-primary">
+          <Plus size={18} />
+          <span className="hidden sm:inline">{t('calendar.newEvent')}</span>
+        </button>
+      </div>
+
+      {/* Toolbar */}
+      <div className="card p-3 mb-4 flex items-center justify-between flex-wrap gap-2">
+        <div className="flex items-center gap-2">
+          <button onClick={navigatePrev} className="btn-ghost p-2">
+            <ChevronLeft size={18} />
+          </button>
+          <button onClick={goToToday} className="btn-ghost text-sm px-3 py-1.5">
+            {t('calendar.today')}
+          </button>
+          <button onClick={navigateNext} className="btn-ghost p-2">
+            <ChevronRight size={18} />
+          </button>
+          <h2 className="text-lg font-semibold text-th-text ml-2">{monthLabel}</h2>
+        </div>
+        <div className="flex items-center bg-th-bg-s rounded-lg border border-th-border p-0.5">
+          <button
+            onClick={() => setView('month')}
+            className={`px-3 py-1.5 rounded-md text-sm font-medium transition-colors ${
+              view === 'month' ? 'bg-th-accent text-th-accent-t' : 'text-th-text-s hover:text-th-text'
+            }`}
+          >
+            {t('calendar.month')}
+          </button>
+          <button
+            onClick={() => setView('week')}
+            className={`px-3 py-1.5 rounded-md text-sm font-medium transition-colors ${
+              view === 'week' ? 'bg-th-accent text-th-accent-t' : 'text-th-text-s hover:text-th-text'
+            }`}
+          >
+            {t('calendar.week')}
+          </button>
+        </div>
+      </div>
+
+      {/* Calendar Grid */}
+      <div className="card overflow-hidden">
+        {/* Day headers */}
+        <div className="grid grid-cols-7 border-b border-th-border">
+          {dayNames.map((name, i) => (
+            <div key={i} className="py-2.5 text-center text-xs font-semibold text-th-text-s uppercase tracking-wider border-r border-th-border last:border-r-0">
+              {name}
+            </div>
+          ))}
+        </div>
+
+        {/* Days */}
+        {view === 'month' ? (
+          <div className="grid grid-cols-7">
+            {calendarDays.map((day, i) => {
+              const dayEvents = eventsForDay(day);
+              const today = isToday(day);
+              const inMonth = isCurrentMonth(day);
+              return (
+                <div
+                  key={i}
+                  onClick={() => openCreateForDay(day)}
+                  className={`min-h-[100px] p-1.5 border-r border-b border-th-border last:border-r-0 cursor-pointer hover:bg-th-hover/50 transition-colors
+                    ${!inMonth ? 'opacity-40' : ''}`}
+                >
+                  <div className={`text-xs font-medium mb-1 w-6 h-6 flex items-center justify-center rounded-full
+                    ${today ? 'bg-th-accent text-th-accent-t' : 'text-th-text-s'}`}>
+                    {day.getDate()}
+                  </div>
+                  <div className="space-y-0.5">
+                    {dayEvents.slice(0, 3).map(ev => (
+                      <div
+                        key={ev.id}
+                        onClick={(e) => { e.stopPropagation(); setShowDetail(ev); }}
+                        className="text-[10px] leading-tight px-1.5 py-0.5 rounded truncate text-white font-medium cursor-pointer hover:opacity-80 transition-opacity"
+                        style={{ backgroundColor: ev.color || '#6366f1' }}
+                        title={ev.title}
+                      >
+                        {formatTime(ev.start_time)} {ev.title}
+                      </div>
+                    ))}
+                    {dayEvents.length > 3 && (
+                      <div className="text-[10px] text-th-text-s font-medium px-1.5">
+                        +{dayEvents.length - 3} {t('calendar.more')}
+                      </div>
+                    )}
+                  </div>
+                </div>
+              );
+            })}
+          </div>
+        ) : (
+          /* Week view */
+          <div className="grid grid-cols-7">
+            {weekDays.map((day, i) => {
+              const dayEvents = eventsForDay(day);
+              const today = isToday(day);
+              return (
+                <div
+                  key={i}
+                  onClick={() => openCreateForDay(day)}
+                  className="min-h-[300px] p-2 border-r border-b border-th-border last:border-r-0 cursor-pointer hover:bg-th-hover/50 transition-colors"
+                >
+                  <div className={`text-sm font-medium mb-2 w-7 h-7 flex items-center justify-center rounded-full
+                    ${today ? 'bg-th-accent text-th-accent-t' : 'text-th-text-s'}`}>
+                    {day.getDate()}
+                  </div>
+                  <div className="space-y-1">
+                    {dayEvents.map(ev => (
+                      <div
+                        key={ev.id}
+                        onClick={(e) => { e.stopPropagation(); setShowDetail(ev); }}
+                        className="text-xs px-2 py-1.5 rounded text-white font-medium cursor-pointer hover:opacity-80 transition-opacity"
+                        style={{ backgroundColor: ev.color || '#6366f1' }}
+                      >
+                        <div className="truncate">{ev.title}</div>
+                        <div className="opacity-80 text-[10px]">{formatTime(ev.start_time)} – {formatTime(ev.end_time)}</div>
+                      </div>
+                    ))}
+                  </div>
+                </div>
+              );
+            })}
+          </div>
+        )}
+      </div>
+
+      {/* Create/Edit Modal */}
+      {showCreate && (
+        <Modal title={editingEvent ? t('calendar.editEvent') : t('calendar.createEvent')} onClose={() => { setShowCreate(false); setEditingEvent(null); }}>
+          <form onSubmit={handleSave} className="space-y-4">
+            <div>
+              <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.eventTitle')} *</label>
+              <input
+                type="text"
+                value={form.title}
+                onChange={e => setForm({ ...form, title: e.target.value })}
+                className="input-field"
+                placeholder={t('calendar.eventTitlePlaceholder')}
+                required
+              />
+            </div>
+
+            <div>
+              <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.description')}</label>
+              <textarea
+                value={form.description}
+                onChange={e => setForm({ ...form, description: e.target.value })}
+                className="input-field resize-none"
+                rows={2}
+                placeholder={t('calendar.descriptionPlaceholder')}
+              />
+            </div>
+
+            <div className="grid grid-cols-2 gap-4">
+              <div>
+                <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.startTime')} *</label>
+                <input
+                  type="datetime-local"
+                  value={form.start_time}
+                  onChange={e => setForm({ ...form, start_time: e.target.value })}
+                  className="input-field"
+                  required
+                />
+              </div>
+              <div>
+                <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.endTime')} *</label>
+                <input
+                  type="datetime-local"
+                  value={form.end_time}
+                  onChange={e => setForm({ ...form, end_time: e.target.value })}
+                  className="input-field"
+                  required
+                />
+              </div>
+            </div>
+
+            <div>
+              <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.linkedRoom')}</label>
+              <select
+                value={form.room_uid}
+                onChange={e => setForm({ ...form, room_uid: e.target.value })}
+                className="input-field"
+              >
+                <option value="">{t('calendar.noRoom')}</option>
+                {rooms.map(r => (
+                  <option key={r.uid} value={r.uid}>{r.name}</option>
+                ))}
+              </select>
+              <p className="text-xs text-th-text-s mt-1">{t('calendar.linkedRoomHint')}</p>
+            </div>
+
+            <div>
+              <label className="block text-sm font-medium text-th-text mb-1.5">{t('calendar.color')}</label>
+              <div className="flex gap-2">
+                {COLORS.map(c => (
+                  <button
+                    key={c}
+                    type="button"
+                    onClick={() => setForm({ ...form, color: c })}
+                    className={`w-7 h-7 rounded-full border-2 transition-all ${form.color === c ? 'border-th-text scale-110' : 'border-transparent'}`}
+                    style={{ backgroundColor: c }}
+                  />
+                ))}
+              </div>
+            </div>
+
+            <div className="flex items-center gap-3 pt-4 border-t border-th-border">
+              <button type="button" onClick={() => { setShowCreate(false); setEditingEvent(null); }} className="btn-secondary flex-1">
+                {t('common.cancel')}
+              </button>
+              <button type="submit" disabled={saving} className="btn-primary flex-1">
+                {saving ? <Loader2 size={18} className="animate-spin" /> : t('common.save')}
+              </button>
+            </div>
+          </form>
+        </Modal>
+      )}
+
+      {/* Event Detail Modal */}
+      {showDetail && (
+        <Modal title={showDetail.title} onClose={() => setShowDetail(null)}>
+          <div className="space-y-4">
+            <div className="flex items-center gap-2 text-sm text-th-text-s">
+              <Clock size={14} />
+              <span>
+                {new Date(showDetail.start_time).toLocaleString()} – {new Date(showDetail.end_time).toLocaleString()}
+              </span>
+            </div>
+
+            {showDetail.description && (
+              <p className="text-sm text-th-text">{showDetail.description}</p>
+            )}
+
+            {showDetail.room_uid && (
+              <div className="flex items-center gap-2 text-sm">
+                <Video size={14} className="text-th-accent" />
+                <a
+                  href={`/rooms/${showDetail.room_uid}`}
+                  className="text-th-accent hover:underline"
+                  onClick={(e) => { e.preventDefault(); window.location.href = `/rooms/${showDetail.room_uid}`; }}
+                >
+                  {t('calendar.openRoom')}
+                </a>
+              </div>
+            )}
+
+            {showDetail.federated_from && (
+              <div className="flex items-center gap-2 text-xs text-th-text-s">
+                <Globe size={12} />
+                <span>{t('calendar.federatedFrom')}: {showDetail.federated_from}</span>
+              </div>
+            )}
+
+            {showDetail.federated_join_url && (
+              <a
+                href={showDetail.federated_join_url}
+                target="_blank"
+                rel="noopener noreferrer"
+                className="btn-primary text-sm w-full justify-center"
+              >
+                <Video size={14} />
+                {t('calendar.joinFederatedMeeting')}
+              </a>
+            )}
+
+            {showDetail.organizer_name && (
+              <div className="text-xs text-th-text-s">
+                {t('calendar.organizer')}: {showDetail.organizer_name}
+              </div>
+            )}
+
+            {/* Actions */}
+            <div className="flex flex-wrap items-center gap-2 pt-4 border-t border-th-border">
+              <button onClick={() => handleDownloadICS(showDetail)} className="btn-ghost text-xs py-1.5 px-3">
+                <Download size={14} />
+                {t('calendar.downloadICS')}
+              </button>
+
+              {showDetail.is_owner && (
+                <>
+                  <button onClick={() => openEdit(showDetail)} className="btn-ghost text-xs py-1.5 px-3">
+                    <Edit size={14} />
+                    {t('common.edit')}
+                  </button>
+                  <button onClick={() => openShareModal(showDetail)} className="btn-ghost text-xs py-1.5 px-3">
+                    <Share2 size={14} />
+                    {t('calendar.share')}
+                  </button>
+                  <button onClick={() => { setShowFedShare(showDetail); setShowDetail(null); }} className="btn-ghost text-xs py-1.5 px-3">
+                    <Globe size={14} />
+                    {t('calendar.sendFederated')}
+                  </button>
+                  <button onClick={() => handleDelete(showDetail)} className="btn-ghost text-xs py-1.5 px-3 text-th-error hover:text-th-error">
+                    <Trash2 size={14} />
+                    {t('common.delete')}
+                  </button>
+                </>
+              )}
+            </div>
+          </div>
+        </Modal>
+      )}
+
+      {/* Share Modal */}
+      {showShare && (
+        <Modal title={t('calendar.shareEvent')} onClose={() => setShowShare(null)}>
+          <div className="space-y-4">
+            <div className="relative">
+              <UserPlus size={18} className="absolute left-3.5 top-1/2 -translate-y-1/2 text-th-text-s" />
+              <input
+                type="text"
+                value={shareSearch}
+                onChange={e => searchUsers(e.target.value)}
+                className="input-field pl-11"
+                placeholder={t('room.shareSearchPlaceholder')}
+              />
+              {shareResults.length > 0 && (
+                <div className="absolute z-10 w-full mt-1 bg-th-card border border-th-border rounded-lg shadow-lg max-h-48 overflow-y-auto">
+                  {shareResults.map(u => (
+                    <button
+                      key={u.id}
+                      onClick={() => handleShare(u.id)}
+                      className="w-full flex items-center gap-3 px-4 py-2.5 hover:bg-th-hover transition-colors text-left"
+                    >
+                      <div
+                        className="w-8 h-8 rounded-full flex items-center justify-center text-white text-xs font-bold flex-shrink-0"
+                        style={{ backgroundColor: u.avatar_color || '#6366f1' }}
+                      >
+                        {(u.display_name || u.name).split(' ').map(n => n[0]).join('').toUpperCase().slice(0, 2)}
+                      </div>
+                      <div className="min-w-0">
+                        <div className="text-sm font-medium text-th-text truncate">{u.display_name || u.name}</div>
+                        <div className="text-xs text-th-text-s truncate">{u.email}</div>
+                      </div>
+                    </button>
+                  ))}
+                </div>
+              )}
+            </div>
+
+            {sharedUsers.length > 0 && (
+              <div className="space-y-2">
+                {sharedUsers.map(u => (
+                  <div key={u.id} className="flex items-center justify-between gap-3 p-3 bg-th-bg-s rounded-lg border border-th-border">
+                    <div className="flex items-center gap-3 min-w-0">
+                      <div
+                        className="w-8 h-8 rounded-full flex items-center justify-center text-white text-xs font-bold flex-shrink-0"
+                        style={{ backgroundColor: u.avatar_color || '#6366f1' }}
+                      >
+                        {(u.display_name || u.name).split(' ').map(n => n[0]).join('').toUpperCase().slice(0, 2)}
+                      </div>
+                      <div className="min-w-0">
+                        <div className="text-sm font-medium text-th-text truncate">{u.display_name || u.name}</div>
+                        <div className="text-xs text-th-text-s truncate">{u.email}</div>
+                      </div>
+                    </div>
+                    <button onClick={() => handleUnshare(u.id)} className="p-1.5 rounded-lg hover:bg-th-hover text-th-text-s hover:text-th-error transition-colors">
+                      <X size={16} />
+                    </button>
+                  </div>
+                ))}
+              </div>
+            )}
+          </div>
+        </Modal>
+      )}
+
+      {/* Federation Share Modal */}
+      {showFedShare && (
+        <Modal title={t('calendar.sendFederatedTitle')} onClose={() => setShowFedShare(null)}>
+          <p className="text-sm text-th-text-s mb-4">{t('calendar.sendFederatedDesc')}</p>
+          <form onSubmit={handleFedSend} className="space-y-4">
+            <div>
+              <label className="block text-sm font-medium text-th-text mb-1.5">{t('federation.addressLabel')}</label>
+              <input
+                type="text"
+                value={fedAddress}
+                onChange={e => setFedAddress(e.target.value)}
+                className="input-field"
+                placeholder={t('federation.addressPlaceholder')}
+                required
+              />
+              <p className="text-xs text-th-text-s mt-1">{t('federation.addressHint')}</p>
+            </div>
+            <div className="flex items-center gap-3 pt-2 border-t border-th-border">
+              <button type="button" onClick={() => setShowFedShare(null)} className="btn-secondary flex-1">
+                {t('common.cancel')}
+              </button>
+              <button type="submit" disabled={fedSending} className="btn-primary flex-1">
+                {fedSending ? <Loader2 size={16} className="animate-spin" /> : <Send size={16} />}
+                {t('calendar.send')}
+              </button>
+            </div>
+          </form>
+        </Modal>
+      )}
+    </div>
+  );
+}
+
+// Helpers
+function toLocalDateTimeStr(date) {
+  const y = date.getFullYear();
+  const m = String(date.getMonth() + 1).padStart(2, '0');
+  const d = String(date.getDate()).padStart(2, '0');
+  const h = String(date.getHours()).padStart(2, '0');
+  const min = String(date.getMinutes()).padStart(2, '0');
+  return `${y}-${m}-${d}T${h}:${min}`;
+}
+
+function formatTime(dateStr) {
+  const d = new Date(dateStr);
+  return d.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
+}
diff --git a/src/themes/index.js b/src/themes/index.js
index 00d68c5..1e88cec 100644
--- a/src/themes/index.js
+++ b/src/themes/index.js
@@ -111,6 +111,13 @@ export const themes = [
     group: 'Community',
     colors: { bg: '#161924', accent: '#b30051', text: '#dadada' },
   },
+  {
+    id: 'red-modular-light',
+    name: 'Red Modular Light',
+    type: 'light',
+    group: 'Community',
+    colors: { bg: '#ffffff', accent: '#e60000', text: '#000000' },
+  },
 ];
 
 export function getThemeById(id) {