feat(web): ambient banner, snooze/focus actions, settings controls

internal/web/static/app.js

@@ -381,10 +381,27 @@ function renderOffscreen(m) {
   if (retryBtn) retryBtn.onclick = () => post('/mode/offscreen/start');
 }
 
+// updateAmbient shows the always-on drift banner whenever the server reports an
+// ambient coaching line, regardless of the active mode. It clears when empty.
+function updateAmbient(env) {
+  const el = document.getElementById('ambientBanner');
+  const line = (env && env.ambient) || '';
+  if (!line) { el.hidden = true; el.innerHTML = ''; return; }
+  el.hidden = false;
+  el.innerHTML = `<span class="ambient-line">⚠ ${esc(line)}</span>
+    <span class="ambient-actions">
+      <button type="button" class="btn btn-ghost" id="ambientSnooze">Snooze 1h</button>
+      <button type="button" class="btn btn-primary" id="ambientFocus">Start focus</button>
+    </span>`;
+  document.getElementById('ambientSnooze').onclick = () => post('/ambient/snooze');
+  document.getElementById('ambientFocus').onclick = () => post('/mode/focus/start');
+}
+
 // route dispatches the state envelope to the active mode's renderer. On a mode
 // switch it resets the focus in-place trackers so stale DOM never leaks across.
 function route(env) {
   const am = (env && env.active_mode) || '';
+  updateAmbient(env);
   if (am !== renderedMode) {
     renderedMode = am;
     renderedState = null;
@@ -420,6 +437,14 @@ function openSettings() {
           <button type="button" class="btn btn-ghost" id="setBrowse">Browse…</button>
         </div>
         <div id="browsePane" class="browse" hidden></div>
+        <label>Ambient coach</label>
+        <select id="setAmbient">
+          <option value="notify">notify (status + toast)</option>
+          <option value="status">status only</option>
+          <option value="off">off</option>
+        </select>
+        <label>Ambient check every (seconds)</label>
+        <input id="setAmbientCadence" type="number" min="30" placeholder="300">
         <div id="setError" class="set-error"></div>
         <div class="modal-actions">
           <button type="button" class="btn btn-ghost" id="setCancel">Cancel</button>
@@ -429,6 +454,8 @@ function openSettings() {
     document.getElementById('setBackend').value = s.ai_backend || 'claude';
     document.getElementById('setMarvin').value = s.marvin_cmd || '';
     document.getElementById('setKnow').value = s.knowledge_path || '';
+    document.getElementById('setAmbient').value = s.ambient_mode || 'notify';
+    document.getElementById('setAmbientCadence').value = s.ambient_cadence_secs || 300;
     ov.hidden = false;
     document.getElementById('setCancel').onclick = closeSettings;
     document.getElementById('setSave').onclick = saveSettings;
@@ -454,6 +481,8 @@ function saveSettings() {
     ai_backend: document.getElementById('setBackend').value,
     marvin_cmd: document.getElementById('setMarvin').value.trim(),
     knowledge_path: document.getElementById('setKnow').value.trim(),
+    ambient_mode: document.getElementById('setAmbient').value,
+    ambient_cadence_secs: parseInt(document.getElementById('setAmbientCadence').value, 10) || 300,
   };
   post('/settings', body).then(r => {
     if (r.ok) { closeSettings(); return; }