diff --git a/app/main.py b/app/main.py
index 5570900..d995417 100644
--- a/app/main.py
+++ b/app/main.py
@@ -560,19 +560,21 @@ PAGE_HTML = """<!DOCTYPE html>
 
   <div class="card">
     <h2>Matrix chat</h2>
-    <p class="hint">You're invited to the co-op's Matrix space. Your registered Matrix ID:</p>
+    <p class="hint">We use the Matrix chat protocol to collaborate. You can access our space with an inference.coop account or an account hosted elsewhere.</p>
+    <p class="hint" style="margin-bottom:6px;"><strong>Current Matrix ID:</strong></p>
     <div class="key-reveal" id="mxid-registered">
-      <div class="key-reveal-title">Registered Matrix ID</div>
       <code class="key-reveal-value" id="mxid-registered-value">checking…</code>
-      <div class="key-reveal-name" id="mxid-registered-note"></div>
-      <button class="ghost" id="mxid-clear" onclick="clearMxid()" style="display:none">Use my co-op account instead</button>
+      <div class="new-key" id="mxid-actions" style="margin-top:12px;">
+        <button class="ghost" id="mxid-use-local" onclick="useLocalMxid()" style="display:none"></button>
+        <button class="ghost" id="mxid-use-external" onclick="showExternalField()">Use external account</button>
+      </div>
+      <div class="new-key" id="mxid-field-row" style="display:none; margin-top:12px;">
+        <input id="mxid-input" type="text" placeholder="@username:server.org" maxlength="255" />
+        <button class="primary" id="mxid-btn" onclick="saveMxid()">Save</button>
+        <button class="ghost" onclick="hideExternalField()">Cancel</button>
+      </div>
+      <div class="hint" id="mxid-status"></div>
     </div>
-    <p class="hint" id="mxid-custom-hint" style="display:none">Prefer a different account? Update it below (one account — it replaces the one above).</p>
-    <div class="new-key">
-      <input id="mxid-input" type="text" placeholder="e.g. @you:matrix.org" maxlength="255" />
-      <button class="primary" id="mxid-btn" onclick="saveMxid()">Save</button>
-    </div>
-    <div class="hint" id="mxid-status"></div>
   </div>
 </div>
 
@@ -645,6 +647,11 @@ async function load() {
   }
 }
 
+let mxidLocal = '';   // @username:inference.coop, resolved by the portal
+let mxidCurrent = ''; // what is registered right now (external or local)
+
+function mxidValid(v) { return /^@[^\\s:]+:[^\\s]+\\.[^\\s]+$/.test(v); }
+
 async function loadMxid() {
   try {
     const r = await fetch('/api/matrix-mxid');
@@ -652,38 +659,62 @@ async function loadMxid() {
     const d = await r.json();
     if (d.error) {
       $('mxid-registered-value').textContent = 'unavailable';
-      $('mxid-status').textContent = 'Could not load your Matrix registration: ' + d.error;
+      $('mxid-status').textContent = 'Could not load: ' + d.error;
       return;
     }
-    const custom = (d.matrix_mxid || '').trim();
-    const local = d.local_mxid || '';
-    if (custom) {
-      $('mxid-registered-value').textContent = custom;
-      $('mxid-registered-note').textContent = 'External account — Matrix invites go here; your co-op account will not receive them.';
-      $('mxid-input').value = custom;
-      $('mxid-clear').style.display = '';
-      $('mxid-custom-hint').style.display = '';
-    } else if (local) {
-      $('mxid-registered-value').textContent = local;
-      $('mxid-registered-note').textContent = 'Your co-op account — invites go here.';
+    mxidLocal = (d.local_mxid || '').trim();
+    mxidCurrent = (d.matrix_mxid || '').trim() || mxidLocal;
+    $('mxid-registered-value').textContent = mxidCurrent || 'pending — will use the inference.coop account once it exists';
+    const useLocalBtn = $('mxid-use-local');
+    if (mxidCurrent && mxidLocal && mxidCurrent !== mxidLocal) {
+      useLocalBtn.textContent = 'Use ' + mxidLocal;
+      useLocalBtn.style.display = '';
     } else {
-      $('mxid-registered-value').textContent = 'not set yet — invites go to your co-op account once it exists';
+      useLocalBtn.style.display = 'none';
     }
   } catch (e) {
     $('mxid-registered-value').textContent = 'unavailable';
-    $('mxid-status').textContent = 'Could not load your Matrix registration: ' + e.message;
+    $('mxid-status').textContent = 'Could not load: ' + e.message;
   }
 }
 
-async function clearMxid() {
-  await saveMxid('');
+function showExternalField() {
+  $('mxid-actions').style.display = 'none';
+  $('mxid-field-row').style.display = '';
+  $('mxid-input').value = (mxidCurrent && mxidCurrent !== mxidLocal) ? mxidCurrent : '';
+  $('mxid-status').textContent = '';
+  $('mxid-input').focus();
 }
 
-async function saveMxid(explicit) {
-  const mxid = (explicit !== undefined ? explicit : $('mxid-input').value).trim();
+function hideExternalField() {
+  $('mxid-field-row').style.display = 'none';
+  $('mxid-actions').style.display = '';
+  $('mxid-status').textContent = '';
+}
+
+async function useLocalMxid() {
+  const btn = $('mxid-use-local');
+  btn.disabled = true;
+  try {
+    const r = await fetch('/api/matrix-mxid', {
+      method: 'POST', headers: {'Content-Type': 'application/json'},
+      body: JSON.stringify({ matrix_mxid: '' })
+    });
+    const d = await r.json();
+    if (d.error) { $('mxid-status').textContent = d.error; }
+    else { $('mxid-status').textContent = ''; await loadMxid(); }
+  } catch (e) { $('mxid-status').textContent = 'Could not switch: ' + e.message; }
+  btn.disabled = false;
+}
+
+async function saveMxid() {
+  const mxid = $('mxid-input').value.trim();
+  if (!mxidValid(mxid)) {
+    $('mxid-status').textContent = 'Enter a Matrix ID like @username:server.org';
+    return;
+  }
   const btn = $('mxid-btn');
   btn.disabled = true;
-  $('mxid-status').textContent = '';
   try {
     const r = await fetch('/api/matrix-mxid', {
       method: 'POST', headers: {'Content-Type': 'application/json'},
@@ -691,20 +722,13 @@ async function saveMxid(explicit) {
     });
     const d = await r.json();
     if (d.error) { $('mxid-status').textContent = d.error; }
-    else if (mxid) {
-      const joined = d.invite_sent === false;
-      $('mxid-status').innerHTML = 'Saved. An invite to the co-op Matrix space is on its way to <strong>' + escapeHtml(mxid) + '</strong>' +
-        (joined ? ' — that account could not be reached right now; the nightly sync will retry automatically.' :
-        ' — accept it from that account to join. Your co-op account will no longer receive invites.');
-      $('mxid-status').className = 'hint ok';
-    } else {
-      $('mxid-status').textContent = 'Cleared — your co-op account will be used for Matrix.';
-      $('mxid-status').className = 'hint ok';
-      $('mxid-input').value = '';
-      $('mxid-clear').style.display = 'none';
+    else {
+      hideExternalField();
+      await loadMxid();
+      $('mxid-status').textContent = d.invite_sent === false
+        ? 'Saved — that account could not be reached right now; the nightly sync will retry automatically.'
+        : 'Saved — accept the invite from that account to join the space.';
     }
-    btn.disabled = false;
-    await loadMxid();
   } catch (e) { $('mxid-status').textContent = 'Could not save: ' + e.message; }
   btn.disabled = false;
 }