diff --git a/CHANGELOG.md b/CHANGELOG.md
index 251cd248..351dfcc9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Passive background refreshes such as sidebar/project polling, health checks, cron-status watches, and client-event logging no longer surface generic timeout toasts; explicit user actions still show timeout errors. (Related to #3024)
+
 ## [v0.51.151] — 2026-05-28 — Release DW (stage-batch33 — 3-PR mid-risk batch: SSE reattach + title-lang + composer cap)
 
 ### Fixed
diff --git a/static/panels.js b/static/panels.js
index 3261d900..fc8d4757 100644
--- a/static/panels.js
+++ b/static/panels.js
@@ -1145,7 +1145,7 @@ function _startCronWatch(jobId) {
   _cronWatchStart = Date.now();
   _cronWatchInterval = setInterval(async () => {
     try {
-      const data = await api(`/api/crons/status?job_id=${encodeURIComponent(jobId)}`);
+      const data = await api(`/api/crons/status?job_id=${encodeURIComponent(jobId)}`,{timeoutToast:false});
       if (!data.running) {
         _stopCronWatch();
         if (_currentCronDetail && _currentCronDetail.id === jobId) {
@@ -1200,7 +1200,7 @@ function _formatElapsed(seconds) {
 
 function _checkCronWatchOnDetail(jobId) {
   // When opening a detail view, check if job is running
-  api(`/api/crons/status?job_id=${encodeURIComponent(jobId)}`).then(data => {
+  api(`/api/crons/status?job_id=${encodeURIComponent(jobId)}`,{timeoutToast:false}).then(data => {
     if (data.running && _currentCronDetail && _currentCronDetail.id === jobId) {
       _startCronWatch(jobId);
     }
diff --git a/static/sessions.js b/static/sessions.js
index fb51405e..ddfa1d4c 100644
--- a/static/sessions.js
+++ b/static/sessions.js
@@ -2278,8 +2278,8 @@ async function renderSessionList(opts={}){
     if(!($('sessionSearch').value||'').trim()) _contentSearchResults = [];
     const allProfilesQS = _showAllProfiles ? '?all_profiles=1' : '';
     const [sessData, projData] = await Promise.all([
-      api('/api/sessions' + allProfilesQS),
-      api('/api/projects' + allProfilesQS),
+      api('/api/sessions' + allProfilesQS,{timeoutToast:false}),
+      api('/api/projects' + allProfilesQS,{timeoutToast:false}),
     ]);
     // Discard stale response — a newer renderSessionList() call superseded us.
     if (_gen !== _renderSessionListGen) return;
@@ -2352,7 +2352,7 @@ async function refreshActiveSessionIfExternallyUpdated(reason){
   const localLast = Number(S.session.last_message_at || S.session.updated_at || 0);
   _activeSessionExternalRefreshInFlight = true;
   try{
-    const data = await api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=0&resolve_model=0`);
+    const data = await api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=0&resolve_model=0`,{timeoutToast:false});
     if(!data || !data.session) return;
     if(!S.session || S.session.session_id !== sid) return;
     if(S.busy || S.activeStreamId) return;
diff --git a/static/ui.js b/static/ui.js
index a4bab419..d119b7cf 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -475,7 +475,7 @@ async function refreshDashboardStatus(force=false){
     return _dashboardStatusCache;
   }
   try{
-    const status=await api('/api/dashboard/status');
+    const status=await api('/api/dashboard/status',{timeoutToast:false});
     _dashboardStatusCache=status||{running:false};
   }catch(_){
     _dashboardStatusCache={running:false};
@@ -4587,7 +4587,7 @@ async function pollSystemHealth(){
   if(document.visibilityState !== 'visible') return;
   if(!_systemHealthPanelIsVisible()) return;
   try{
-    const payload=await api('/api/system/health');
+    const payload=await api('/api/system/health',{timeoutToast:false});
     renderSystemHealth(payload);
   }catch(_){
     setSystemHealthUnavailable('Unavailable');
@@ -4653,7 +4653,7 @@ function dismissAgentHealthAlert(){
 async function pollAgentHealth(){
   if(document.visibilityState !== 'visible') return;
   try{
-    const payload=await api('/api/health/agent');
+    const payload=await api('/api/health/agent',{timeoutToast:false});
     if(payload.alive === true){
       _agentHealthLastState='alive';
       _setAgentHealthDismissed(false);
diff --git a/static/workspace.js b/static/workspace.js
index 603bdc31..5f86dafa 100644
--- a/static/workspace.js
+++ b/static/workspace.js
@@ -3,6 +3,7 @@ async function api(path,opts={}){
   const rel = path.startsWith('/') ? path.slice(1) : path;
   const url=new URL(rel,document.baseURI||location.href);
   const timeoutMs=Object.prototype.hasOwnProperty.call(opts,'timeoutMs')?opts.timeoutMs:30000;
+  const timeoutToast=opts.timeoutToast!==false;
   // Retry up to 2 times on network errors (e.g. stale keep-alive after long idle).
   // Server errors (4xx/5xx) and client-side timeouts are NOT retried.
   let lastErr;
@@ -15,6 +16,8 @@ async function api(path,opts={}){
     try{
       const fetchOpts={...opts};
       delete fetchOpts.timeoutMs;
+      delete fetchOpts.timeoutToast;
+
       const useTimeout=Number.isFinite(Number(timeoutMs))&&Number(timeoutMs)>0;
       if(useTimeout&&typeof AbortController!=='undefined'){
         controller=new AbortController();
@@ -69,7 +72,7 @@ async function api(path,opts={}){
         const err=(e&&e.name==='TimeoutError')?e:new Error('Request timed out. Please try again.');
         err.name='TimeoutError';
         err.timeout=true;
-        if(typeof showToast==='function') showToast('Request timed out. Please try again.',5000,'error');
+        if(timeoutToast&&typeof showToast==='function') showToast('Request timed out. Please try again.',5000,'error');
         throw err;
       }
       // Only retry on network errors (TypeError from fetch), not on HTTP errors
@@ -98,7 +101,7 @@ function recordClientSSEError(source, details={}){
       url_path:(typeof location!=='undefined'&&location.pathname)||'/',
       reason:details.reason||'EventSource.onerror',
     };
-    void api('/api/client-events/log',{method:'POST',body:JSON.stringify(payload),timeoutMs:3000}).catch(()=>{});
+    void api('/api/client-events/log',{method:'POST',body:JSON.stringify(payload),timeoutMs:3000,timeoutToast:false}).catch(()=>{});
   }catch(_){}
 }
 
diff --git a/tests/test_api_timeout.py b/tests/test_api_timeout.py
index 3f89f71a..f5a51fcc 100644
--- a/tests/test_api_timeout.py
+++ b/tests/test_api_timeout.py
@@ -159,13 +159,48 @@ def test_api_rejects_stalled_response_body_with_timeout():
     assert any(event.get("aborted") for event in payload["events"]), payload
 
 
+def test_api_can_suppress_timeout_toast_for_background_pollers():
+    """Passive pollers need abort/reject cleanup without a user-visible toast."""
+    api_fn = _extract_js_function(_source(WORKSPACE_JS), "api")
+    script = textwrap.dedent(
+        f"""
+        const events=[];
+        global.document={{baseURI:'http://example.test/hermes/'}};
+        global.location={{href:'http://example.test/hermes/',pathname:'/hermes/',search:''}};
+        global.window={{location:global.location}};
+        global.showToast=(msg,ms,type)=>events.push({{msg:String(msg),ms,type}});
+        global.fetch=(url,opts)=>new Promise(()=>{{
+          if(opts&&opts.signal)opts.signal.addEventListener('abort',()=>events.push({{aborted:true}}));
+        }});
+        {api_fn}
+        api('/api/sessions',{{timeoutMs:20,timeoutToast:false}})
+          .then(()=>{{console.error('resolved unexpectedly');process.exit(2);}})
+          .catch(err=>{{
+            console.log(JSON.stringify({{message:String(err&&err.message||err),events}}));
+            process.exit(0);
+          }});
+        setTimeout(()=>{{console.error('api did not reject after timeoutMs');process.exit(3);}},250);
+        """
+    )
+    result = _node_eval(script, timeout=1.0)
+    assert result.returncode == 0, result.stderr or result.stdout
+    payload = json.loads(result.stdout.strip())
+    assert "timed out" in payload["message"].lower()
+    assert any(event.get("aborted") for event in payload["events"]), payload
+    assert not any("msg" in event for event in payload["events"]), payload
+
+
 def test_api_has_default_timeout_and_per_call_override_contract():
     src = _source(WORKSPACE_JS)
     body = _extract_js_function(src, "api")
     assert "timeoutMs" in body, "api() must accept opts.timeoutMs as a per-call override"
+    assert "timeoutToast" in body, "api() must let passive callers suppress timeout toasts"
+
     assert "30000" in body, "api() must default browser API calls to a 30s timeout"
     assert "AbortController" in body, "api() must abort hung fetches with AbortController"
     assert "delete fetchOpts.timeoutMs" in body, "api() must strip timeoutMs before calling fetch()"
+    assert "delete fetchOpts.timeoutToast" in body, "api() must strip timeoutToast before calling fetch()"
+
     fetch_call = re.search(r"fetch\(url\.href,\{.*?\.\.\.fetchOpts.*?\}\)", body, re.DOTALL)
     assert fetch_call, "api() must call fetch() with sanitized fetchOpts"
     assert "...opts" not in fetch_call.group(0), "api() must not spread raw opts into fetch()"
@@ -182,6 +217,23 @@ def test_update_flows_keep_explicit_longer_timeouts():
     assert "api('/api/updates/force',{method:'POST',body:JSON.stringify({target}),timeoutMs:120000})" in src
 
 
+def test_passive_background_polls_suppress_timeout_toasts():
+    """Passive refreshes should be best-effort and not emit generic timeout toasts."""
+    workspace = _source(WORKSPACE_JS)
+    sessions = _source(SESSIONS_JS)
+    ui = _source(UI_JS)
+    panels = _source(PANELS_JS)
+
+    assert "api('/api/client-events/log',{method:'POST',body:JSON.stringify(payload),timeoutMs:3000,timeoutToast:false})" in workspace
+    assert "api('/api/sessions' + allProfilesQS,{timeoutToast:false})" in sessions
+    assert "api('/api/projects' + allProfilesQS,{timeoutToast:false})" in sessions
+    assert "api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=0&resolve_model=0`,{timeoutToast:false})" in sessions
+    assert "api('/api/dashboard/status',{timeoutToast:false})" in ui
+    assert "api('/api/system/health',{timeoutToast:false})" in ui
+    assert "api('/api/health/agent',{timeoutToast:false})" in ui
+    assert "api(`/api/crons/status?job_id=${encodeURIComponent(jobId)}`,{timeoutToast:false})" in panels
+
+
 def test_new_session_inflight_cleanup_still_runs_after_api_rejects():
     """newSession() must keep its finally cleanup path so timeout rejections unpin the UI."""
     src = _source(SESSIONS_JS)
diff --git a/tests/test_dashboard_link_ui.py b/tests/test_dashboard_link_ui.py
index 787b869d..8c55f4c1 100644
--- a/tests/test_dashboard_link_ui.py
+++ b/tests/test_dashboard_link_ui.py
@@ -25,7 +25,7 @@ def test_dashboard_rail_item_sits_between_insights_and_settings_spacer():
 def test_dashboard_frontend_fetches_status_with_sixty_second_cache():
     assert "DASHBOARD_STATUS_TTL_MS=60000" in UI_JS
     assert "function refreshDashboardStatus" in UI_JS
-    assert "api('/api/dashboard/status')" in UI_JS
+    assert "api('/api/dashboard/status',{timeoutToast:false})" in UI_JS
     assert "setInterval(refreshDashboardStatus,DASHBOARD_STATUS_TTL_MS)" in UI_JS
     assert 'fetch("/api/dashboard/status"' not in UI_JS
     assert "fetch('/api/dashboard/status'" not in UI_JS
diff --git a/tests/test_issue1611_session_profile_filtering.py b/tests/test_issue1611_session_profile_filtering.py
index c3a6d8d5..6c277187 100644
--- a/tests/test_issue1611_session_profile_filtering.py
+++ b/tests/test_issue1611_session_profile_filtering.py
@@ -134,10 +134,10 @@ def test_static_sessions_js_uses_all_profiles_query_when_toggle_on():
     assert "_showAllProfiles ? '?all_profiles=1' : ''" in src, (
         "Expected fetch path to flip on the toggle state"
     )
-    assert "api('/api/sessions' + allProfilesQS)" in src, (
+    assert "api('/api/sessions' + allProfilesQS,{timeoutToast:false})" in src, (
         "Expected /api/sessions fetch to use the variant query"
     )
-    assert "api('/api/projects' + allProfilesQS)" in src, (
+    assert "api('/api/projects' + allProfilesQS,{timeoutToast:false})" in src, (
         "Expected /api/projects fetch to use the variant query"
     )
 
diff --git a/tests/test_issue693_system_health_panel.py b/tests/test_issue693_system_health_panel.py
index 1161dc0a..81b58438 100644
--- a/tests/test_issue693_system_health_panel.py
+++ b/tests/test_issue693_system_health_panel.py
@@ -159,7 +159,7 @@ def test_system_health_panel_markup_and_styles_live_under_insights_not_top_chrom
 
 def test_system_health_frontend_polls_visible_and_renders_progress_labels():
     assert "const SYSTEM_HEALTH_INTERVAL_MS=5000" in UI_JS
-    assert "api('/api/system/health')" in UI_JS
+    assert "api('/api/system/health',{timeoutToast:false})" in UI_JS
     assert "document.visibilityState !== 'visible'" in UI_JS
     assert "document.querySelector('main.main.showing-insights')" in UI_JS
     assert "document.addEventListener('visibilitychange',_syncSystemHealthMonitorVisibility)" in UI_JS
diff --git a/tests/test_issue716_agent_heartbeat.py b/tests/test_issue716_agent_heartbeat.py
index b0cdb0a7..201b3741 100644
--- a/tests/test_issue716_agent_heartbeat.py
+++ b/tests/test_issue716_agent_heartbeat.py
@@ -184,7 +184,7 @@ def test_agent_health_banner_markup_and_styles_exist():
 
 def test_agent_health_frontend_polls_only_visible_and_distinguishes_states():
     assert "const AGENT_HEALTH_INTERVAL_MS=30000" in UI_JS
-    assert "api('/api/health/agent')" in UI_JS
+    assert "api('/api/health/agent',{timeoutToast:false})" in UI_JS
     assert "document.visibilityState !== 'visible'" in UI_JS
     assert "document.addEventListener('visibilitychange',_syncAgentHealthMonitorVisibility)" in UI_JS
     assert "if(payload.alive === true)" in UI_JS