diff --git a/app.py b/app.py
index 4a8a12df8..90543fba8 100644
--- a/app.py
+++ b/app.py
@@ -595,6 +595,14 @@ webhook_manager = WebhookManager(api_key_manager=api_key_manager)
 auth_router = setup_auth_routes(auth_manager)
 app.include_router(auth_router)
 
+
+@app.post("/api/activity/heartbeat")
+async def activity_heartbeat():
+    from src.interactive_gate import mark_browser_activity
+    await mark_browser_activity()
+    return {"ok": True}
+
+
 # Uploads
 from routes.upload_routes import setup_upload_routes
 upload_router, upload_cleanup_func = setup_upload_routes(upload_handler)
diff --git a/src/interactive_gate.py b/src/interactive_gate.py
index cdb3892cf..7cfd01154 100644
--- a/src/interactive_gate.py
+++ b/src/interactive_gate.py
@@ -15,6 +15,7 @@ import time
 
 _ACTIVE_REQUESTS = 0
 _LAST_ACTIVITY = 0.0
+_LAST_BROWSER_ACTIVITY = 0.0
 _COND: asyncio.Condition | None = None
 
 
@@ -37,6 +38,14 @@ def _max_wait_seconds() -> float:
         return 0.0
 
 
+def _browser_active_seconds() -> float:
+    """How long a visible Odysseus browser heartbeat blocks background tasks."""
+    try:
+        return max(0.0, float(os.getenv("BACKGROUND_TASK_BROWSER_ACTIVE_SECONDS", "45")))
+    except Exception:
+        return 45.0
+
+
 def _condition() -> asyncio.Condition:
     global _COND
     if _COND is None:
@@ -45,6 +54,7 @@ def _condition() -> asyncio.Condition:
 
 
 _PASSIVE_EXACT_PATHS = {
+    "/api/activity/heartbeat",
     "/api/tasks/notifications",
     "/api/research/active",
     "/api/email/urgency-state",
@@ -69,6 +79,24 @@ def should_track_interactive_request(path: str, method: str = "GET") -> bool:
     return True
 
 
+async def mark_browser_activity() -> None:
+    """Record that an authenticated browser tab is visibly using Odysseus."""
+    global _LAST_BROWSER_ACTIVITY
+    if not _enabled():
+        return
+    cond = _condition()
+    async with cond:
+        _LAST_BROWSER_ACTIVITY = time.monotonic()
+        cond.notify_all()
+
+
+def _has_recent_browser_activity(now: float | None = None) -> bool:
+    ttl = _browser_active_seconds()
+    if ttl <= 0 or _LAST_BROWSER_ACTIVITY <= 0:
+        return False
+    return ((now if now is not None else time.monotonic()) - _LAST_BROWSER_ACTIVITY) < ttl
+
+
 def _has_active_chat_stream() -> bool:
     """Best-effort check for foreground model work that outlives HTTP requests.
 
@@ -133,11 +161,12 @@ async def wait_for_interactive_quiet(label: str = "") -> bool:
             now = time.monotonic()
             quiet_remaining = quiet - (now - _LAST_ACTIVITY)
             active_stream = _has_active_chat_stream()
-            if _ACTIVE_REQUESTS <= 0 and quiet_remaining <= 0 and not active_stream:
+            browser_active = _has_recent_browser_activity(now)
+            if _ACTIVE_REQUESTS <= 0 and quiet_remaining <= 0 and not active_stream and not browser_active:
                 return waited
 
             waited = True
-            timeout = 0.25 if (_ACTIVE_REQUESTS > 0 or active_stream) else min(max(quiet_remaining, 0.05), 0.5)
+            timeout = 0.25 if (_ACTIVE_REQUESTS > 0 or active_stream or browser_active) else min(max(quiet_remaining, 0.05), 0.5)
             if deadline is not None:
                 remaining = deadline - now
                 if remaining <= 0:
diff --git a/static/app.js b/static/app.js
index a32fdf77c..6d11106b4 100644
--- a/static/app.js
+++ b/static/app.js
@@ -53,6 +53,40 @@ window.uiModule = uiModule;
 window.adminModule = adminModule;
 window.cookbookModule = cookbookModule;
 
+function initForegroundActivityHeartbeat() {
+  let lastSent = 0;
+  const minGapMs = 12000;
+  const send = (force = false) => {
+    if (document.visibilityState === 'hidden') return;
+    const now = Date.now();
+    if (!force && now - lastSent < minGapMs) return;
+    lastSent = now;
+    try {
+      if (navigator.sendBeacon) {
+        const body = new Blob(['{}'], { type: 'application/json' });
+        if (navigator.sendBeacon('/api/activity/heartbeat', body)) return;
+      }
+    } catch (_) {}
+    fetch('/api/activity/heartbeat', {
+      method: 'POST',
+      credentials: 'same-origin',
+      keepalive: true,
+      headers: { 'Content-Type': 'application/json' },
+      body: '{}',
+    }).catch(() => {});
+  };
+  send(true);
+  window.addEventListener('focus', () => send(true));
+  document.addEventListener('visibilitychange', () => {
+    if (document.visibilityState !== 'hidden') send(true);
+  });
+  ['pointerdown', 'keydown', 'touchstart', 'scroll'].forEach(type => {
+    window.addEventListener(type, () => send(false), { passive: true, capture: true });
+  });
+  setInterval(() => send(false), 15000);
+}
+initForegroundActivityHeartbeat();
+
 // Redirect to login on 401 from any fetch
 const _origFetch = window.fetch;
 window.fetch = async function(...args) {