diff --git a/CHANGELOG.md b/CHANGELOG.md
index ef3c6e5a..1f488f3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@
 
 ### Fixed
 
+- **The Settings → Extensions diagnostics panel now shows per-extension sidecar runtime status.** When an extension's loopback sidecar health response includes an optional top-level `runtime` object, the diagnostics panel parses it and renders only allowlisted scalar fields (sidecar/native-host/bridge status, last-seen time, and the loopback origin) so you can see at a glance whether an extension's helper process is running, waiting, or stale — without WebUI depending on any one extension's private payload shape. All values are status-enum-allowlisted, HTML-escaped, timestamp-validated, and origin-limited to `http://127.0.0.1`/`localhost`; a missing or malformed `runtime` object degrades cleanly, and a failed diagnostics refresh now renders the error instead of staying stuck on "Loading…". Thanks @franksong2702. (#4979)
+
 - **The "Response complete" notification now previews the final answer, not the start of the stream.** The browser/PWA completion notification body was built from the live streaming accumulator sliced to 100 chars, so it showed the *beginning* of the response (often a preamble or empty) rather than what the user actually got. It now derives the preview from the settled final answer (anchor projection → message content → raw text), strips inline thinking, normalizes whitespace, and truncates at 100 chars — and works for completions that finish while the session isn't the active pane. Thanks @claw-io. (#5036, fixes #5035)
 
 - **Onboarding now has the same searchable model picker as Settings.** A fresh install (e.g. an OpenRouter-only first run) previously showed only a small default model list in the onboarding step — no search box and no way to enter a custom model ID — so picking a model not in the short list meant finishing setup and fixing it later. Onboarding now reuses the same searchable picker (with custom-model-ID entry) that Settings uses, instead of a separate onboarding-only dropdown that could drift. The custom-provider free-text branch is unchanged, and the plain-`<select>` fallback (when the shared picker is unavailable) correctly preserves a saved/default model instead of resetting to the first option. Thanks @rodboev. (#5031, fixes #4706)
diff --git a/docs/EXTENSIONS.md b/docs/EXTENSIONS.md
index 985b5368..24b69c46 100644
--- a/docs/EXTENSIONS.md
+++ b/docs/EXTENSIONS.md
@@ -414,4 +414,9 @@ directly with `fetch(..., { credentials: 'omit', cache: 'no-store' })` and a
 short timeout. WebUI does **not** proxy sidecar requests and does not send WebUI
 cookies to sidecars. A successful HTTP response is shown as healthy, a non-OK
 HTTP response as unhealthy, and CORS/network/timeouts as unreachable or blocked;
-health response bodies are never rendered.
+raw health response bodies are never rendered. If a healthy response includes an
+optional top-level `runtime` object, the panel may parse it and render only
+allowlisted scalar fields such as `sidecar`, `native_host`, `bridge`,
+`last_seen_at`, and `webui_origin`. This keeps sidecar-specific diagnostics
+machine-readable without making WebUI depend on any one extension's private
+payload shape.
diff --git a/static/panels.js b/static/panels.js
index ddc565d6..ab9d50ff 100644
--- a/static/panels.js
+++ b/static/panels.js
@@ -8101,6 +8101,74 @@ function _extensionSidecarHealthBadge(status,label){
   return `<span class="extension-sidecar-status-badge extension-sidecar-status-${safeStatus}">${esc(label||safeStatus)}</span>`;
 }
 
+function _extensionRuntimeStatusValue(value){
+  const normalized=String(value||'').trim().toLowerCase();
+  return ['running','connected','waiting','stale','unloaded','stopped','not_registered','unknown'].includes(normalized)
+    ? normalized
+    : 'unknown';
+}
+
+function _extensionRuntimeStatusLabel(value){
+  const normalized=_extensionRuntimeStatusValue(value);
+  if(normalized==='not_registered') return 'not registered';
+  return normalized.replace(/_/g,' ');
+}
+
+function _extensionRuntimeLastSeen(value){
+  const text=String(value??'').trim();
+  if(!/^\d+(?:\.\d+)?$/.test(text)) return '';
+  const raw=Number(text);
+  if(!Number.isFinite(raw)||raw<=0) return '';
+  const seconds=raw>1000000000000?raw/1000:raw;
+  const now=Math.floor(Date.now()/1000);
+  if(seconds>now+300) return '';
+  const age=Math.max(0,Math.floor(now-seconds));
+  if(age<5) return 'just now';
+  if(age<60) return `${age}s ago`;
+  const minutes=Math.floor(age/60);
+  if(minutes<60) return `${minutes}m ago`;
+  const hours=Math.floor(minutes/60);
+  if(hours<24) return `${hours}h ago`;
+  return `${Math.floor(hours/24)}d ago`;
+}
+
+function _extensionRuntimeOrigin(value){
+  const text=String(value||'').trim();
+  if(!text) return '';
+  try{
+    const parsed=new URL(text);
+    if(parsed.protocol==='http:'&&(parsed.hostname==='127.0.0.1'||parsed.hostname==='localhost')){
+      return parsed.origin;
+    }
+  }catch(_e){}
+  return '';
+}
+
+function _extensionRuntimeRows(runtime){
+  if(!runtime||typeof runtime!=='object') return [];
+  const rows=[];
+  if(Object.prototype.hasOwnProperty.call(runtime,'sidecar')){
+    rows.push(['Sidecar',_extensionRuntimeStatusLabel(runtime.sidecar)]);
+  }
+  if(Object.prototype.hasOwnProperty.call(runtime,'native_host')){
+    rows.push(['Native host',_extensionRuntimeStatusLabel(runtime.native_host)]);
+  }
+  if(Object.prototype.hasOwnProperty.call(runtime,'bridge')){
+    rows.push(['Bridge',_extensionRuntimeStatusLabel(runtime.bridge)]);
+  }
+  const lastSeen=_extensionRuntimeLastSeen(runtime.last_seen_at);
+  if(lastSeen) rows.push(['Last update',lastSeen]);
+  const origin=_extensionRuntimeOrigin(runtime.webui_origin);
+  if(origin) rows.push(['WebUI origin',origin]);
+  return rows;
+}
+
+function _extensionRuntimeDetails(runtime){
+  const rows=_extensionRuntimeRows(runtime);
+  if(!rows.length) return '';
+  return rows.map(([label,value])=>`<div><span>${esc(label)}</span><code>${esc(value)}</code></div>`).join('');
+}
+
 function _extensionSidecarCard(sidecars){
   const list=Array.isArray(sidecars)?sidecars:[];
   const body=list.length?`<div class="extension-sidecar-list">${list.map((sidecar,index)=>{
@@ -8122,6 +8190,7 @@ function _extensionSidecarCard(sidecars){
         <div><span>Health path</span><code>${esc(healthPath)}</code></div>
         <div><span>Health URL</span><code>${esc(healthUrl)}</code></div>
       </div>
+      <div class="extension-sidecar-runtime" data-sidecar-runtime-index="${index}" hidden></div>
     </div>`;
   }).join('')}</div>`:'<div class="extension-url-empty">No loopback sidecars declared.</div>';
   return `
@@ -8143,10 +8212,24 @@ function _setExtensionSidecarHealth(index,status,label){
   if(el) el.innerHTML=_extensionSidecarHealthBadge(status,label);
 }
 
+function _setExtensionSidecarRuntime(index,runtime){
+  const el=document.querySelector(`[data-sidecar-runtime-index="${index}"]`);
+  if(!el) return;
+  const details=_extensionRuntimeDetails(runtime);
+  if(!details){
+    el.hidden=true;
+    el.innerHTML='';
+    return;
+  }
+  el.hidden=false;
+  el.innerHTML=details;
+}
+
 async function _checkExtensionSidecarHealth(sidecar,index,seq){
   const healthUrl=sidecar&&sidecar.health_url;
   if(!healthUrl){
     _setExtensionSidecarHealth(index,'blocked','unreachable / blocked');
+    _setExtensionSidecarRuntime(index,null);
     return;
   }
   let controller=null;
@@ -8158,11 +8241,22 @@ async function _checkExtensionSidecarHealth(sidecar,index,seq){
     }
     const res=await fetch(healthUrl,{credentials:'omit',cache:'no-store',signal:controller?controller.signal:undefined});
     if(seq!==_extensionsSidecarMonitorSeq) return;
-    if(res.ok) _setExtensionSidecarHealth(index,'healthy','healthy');
-    else _setExtensionSidecarHealth(index,'unhealthy','unhealthy');
+    if(res.ok){
+      _setExtensionSidecarHealth(index,'healthy','healthy');
+      let body=null;
+      try{
+        body=await res.json();
+      }catch(_e){}
+      if(seq!==_extensionsSidecarMonitorSeq) return;
+      _setExtensionSidecarRuntime(index,body&&typeof body==='object'?body.runtime:null);
+    }else{
+      _setExtensionSidecarHealth(index,'unhealthy','unhealthy');
+      _setExtensionSidecarRuntime(index,null);
+    }
   }catch(_e){
     if(seq!==_extensionsSidecarMonitorSeq) return;
     _setExtensionSidecarHealth(index,'blocked','unreachable / blocked');
+    _setExtensionSidecarRuntime(index,null);
   }finally{
     if(timeoutId) clearTimeout(timeoutId);
   }
@@ -8287,18 +8381,27 @@ async function handleExtensionToggle(btn){
   }
 }
 
-async function loadExtensionsPanel(){
+async function loadExtensionsPanel(opts){
   const target=$('extensionsDiagnostics');
   const copyBtn=$('extensionsCopyDiagnosticsBtn');
   if(!target) return;
-  if(copyBtn) copyBtn.disabled=true;
+  // Only preserve REAL rendered diagnostics across a refresh — never the
+  // "Loading…" / error placeholders, or a failed refresh would leave the panel
+  // stuck on "Loading extension diagnostics…" instead of rendering the error.
+  const preserveExisting=!!(
+    opts&&opts.preserveExisting&&target.innerHTML.trim()
+    &&!target.querySelector('.extensions-loading,.extensions-error')
+  );
+  if(copyBtn&&!preserveExisting) copyBtn.disabled=true;
   const seq=++_extensionsSidecarMonitorSeq;
-  target.innerHTML='<div class="extensions-loading">Loading extension diagnostics…</div>';
+  if(!preserveExisting) target.innerHTML='<div class="extensions-loading">Loading extension diagnostics…</div>';
   try{
     const data=await api('/api/extensions/status');
     if(seq!==_extensionsSidecarMonitorSeq) return;
     _renderExtensionsPanel(data,seq);
   }catch(e){
+    if(seq!==_extensionsSidecarMonitorSeq) return;
+    if(preserveExisting&&target.innerHTML.trim()) return;
     _extensionsStatusData=null;
     if(copyBtn) copyBtn.disabled=true;
     target.innerHTML='<div class="extensions-error">Failed to load extension diagnostics: '+esc(e.message||String(e))+'</div>';
@@ -8314,6 +8417,7 @@ function switchExtensionsTab(tab){
   document.querySelectorAll('[data-extensions-pane]').forEach(pane=>{
     pane.hidden=pane.dataset.extensionsPane!==tab;
   });
+  if(tab==='diagnostics') loadExtensionsPanel({preserveExisting:true});
   if(tab==='gallery'&&!_extensionsGalleryLoaded) loadExtensionsGallery();
 }
 
diff --git a/static/style.css b/static/style.css
index 8d238c6d..8e0b13d1 100644
--- a/static/style.css
+++ b/static/style.css
@@ -4736,6 +4736,11 @@ main.main > #mainPlugin{display:none;}
 .extension-sidecar-fields>div{display:flex;align-items:flex-start;gap:8px;min-width:0;font-size:12px;color:var(--muted);}
 .extension-sidecar-fields span{flex:0 0 82px;}
 .extension-sidecar-fields code{font-family:var(--font-mono);font-size:11px;color:var(--text);overflow-wrap:anywhere;word-break:break-word;}
+.extension-sidecar-runtime{display:grid;grid-template-columns:repeat(auto-fit,minmax(132px,1fr));gap:6px;margin-top:9px;padding-top:9px;border-top:1px solid var(--border);}
+.extension-sidecar-runtime[hidden]{display:none!important;}
+.extension-sidecar-runtime>div{display:flex;flex-direction:column;gap:2px;min-width:0;border:1px solid var(--border);border-radius:7px;background:var(--card-bg,var(--sidebar-bg));padding:6px 8px;}
+.extension-sidecar-runtime span{font-size:10.5px;color:var(--muted);font-weight:600;text-transform:uppercase;letter-spacing:0;}
+.extension-sidecar-runtime code{font-family:var(--font-mono);font-size:11px;color:var(--text);overflow-wrap:anywhere;word-break:break-word;}
 .extension-sidecar-status-badge{display:inline-flex;align-items:center;white-space:nowrap;border-radius:999px;padding:2px 7px;font-size:10.5px;font-weight:700;font-family:var(--font-mono);line-height:1.45;background:var(--code-bg);color:var(--muted);}
 .extension-sidecar-status-healthy{background:rgba(34,197,94,.14);color:#22c55e;}
 .extension-sidecar-status-unhealthy{background:rgba(245,158,11,.14);color:#f59e0b;}
diff --git a/tests/test_extensions_settings_panel.py b/tests/test_extensions_settings_panel.py
index 0890ef2b..ca7853ea 100644
--- a/tests/test_extensions_settings_panel.py
+++ b/tests/test_extensions_settings_panel.py
@@ -96,6 +96,13 @@ def test_extensions_panel_fetches_status_endpoint_without_mutating_settings():
     assert "extensions-error" in load_block
 
 
+def test_extensions_diagnostics_tab_refreshes_runtime_status():
+    tab_block = _function_block("switchExtensionsTab", extra=900)
+
+    assert "if(tab==='diagnostics') loadExtensionsPanel({preserveExisting:true});" in tab_block
+    assert "if(tab==='gallery'&&!_extensionsGalleryLoaded) loadExtensionsGallery();" in tab_block
+
+
 def test_extensions_panel_renders_sanitized_status_payload():
     render_block = _between("function _renderExtensionsPanel", "async function loadExtensionsPanel")
     warning_block = _function_block("_extensionWarningList", extra=900)
@@ -128,10 +135,13 @@ def test_extensions_panel_renders_sanitized_status_payload():
 
 
 def test_extensions_panel_renders_loopback_sidecar_monitor_safely():
+    runtime_block = _between("function _extensionRuntimeStatusValue", "function _extensionSidecarCard")
     sidecar_block = _between("function _extensionSidecarCard", "function _setExtensionSidecarHealth")
+    runtime_setter_block = _between("function _setExtensionSidecarRuntime", "async function _checkExtensionSidecarHealth")
     monitor_block = _between("async function _checkExtensionSidecarHealth", "function _renderExtensionsPanel")
     render_block = _between("function _renderExtensionsPanel", "async function loadExtensionsPanel")
     load_block = _between("async function loadExtensionsPanel", "async function copyExtensionsDiagnostics")
+    load_catch_block = load_block[load_block.index("}catch(e){"):]
 
     assert "Loopback sidecars" in sidecar_block
     assert "No loopback sidecars declared." in sidecar_block
@@ -140,17 +150,37 @@ def test_extensions_panel_renders_loopback_sidecar_monitor_safely():
     assert "esc(origin)" in sidecar_block
     assert "esc(healthPath)" in sidecar_block
     assert "esc(healthUrl)" in sidecar_block
+    assert 'data-sidecar-runtime-index="${index}"' in sidecar_block
     assert "fetch(healthUrl,{credentials:'omit',cache:'no-store'" in monitor_block
     assert "function _monitorExtensionSidecars(sidecars,seq)" in monitor_block
     assert "const seq=_extensionsSidecarMonitorSeq" not in monitor_block
     assert "_monitorExtensionSidecars(sidecars,seq)" in render_block
     assert "function _renderExtensionsPanel(data,seq)" in render_block
     assert "const seq=++_extensionsSidecarMonitorSeq" in load_block
+    assert "opts&&opts.preserveExisting&&target.innerHTML.trim()" in load_block
+    # A failed refresh must NOT be preserved as "existing content": the Loading/
+    # error placeholders are excluded so a fetch error always renders the error
+    # instead of leaving the panel stuck on "Loading extension diagnostics…".
+    assert "!target.querySelector('.extensions-loading,.extensions-error')" in load_block
+    assert "if(!preserveExisting) target.innerHTML" in load_block
+    assert "loadExtensionsPanel({preserveExisting:true})" in load_block
     assert "if(seq!==_extensionsSidecarMonitorSeq) return;" in load_block
+    assert "if(seq!==_extensionsSidecarMonitorSeq) return;" in load_catch_block
+    assert "if(preserveExisting&&target.innerHTML.trim()) return;" in load_catch_block
     assert "_renderExtensionsPanel(data,seq)" in load_block
     assert "res.ok" in monitor_block
     assert "res.text" not in monitor_block
-    assert "res.json" not in monitor_block
+    assert "body=await res.json()" in monitor_block
+    assert "_setExtensionSidecarRuntime(index,body&&typeof body==='object'?body.runtime:null)" in monitor_block
+    assert "String(value??'').trim()" in runtime_block
+    assert r"/^\d+(?:\.\d+)?$/.test(text)" in runtime_block
+    assert "seconds>now+300" in runtime_block
+    assert "runtime.sidecar" in runtime_block
+    assert "runtime.native_host" in runtime_block
+    assert "runtime.bridge" in runtime_block
+    assert "runtime.last_seen_at" in runtime_block
+    assert "runtime.webui_origin" in runtime_block
+    assert "el.innerHTML=details" in runtime_setter_block
     assert "api('/api/settings'" not in monitor_block
     assert "api('/extensions/" not in monitor_block
     assert "sidecar/*" not in monitor_block
@@ -196,6 +226,7 @@ def test_extensions_styles_are_scoped_to_extensions_panel():
     assert ".extension-installed-list" in STYLE_CSS
     assert ".extension-toggle-btn" in STYLE_CSS
     assert ".extension-sidecar-list" in STYLE_CSS
+    assert ".extension-sidecar-runtime" in STYLE_CSS
     assert ".extension-sidecar-status-badge" in STYLE_CSS
 
 
@@ -222,6 +253,8 @@ def test_extensions_docs_mentions_settings_panel_without_install_or_proxy_claims
     assert "sanitized loopback sidecars" in diagnostics_section
     assert "credentials: 'omit'" in diagnostics_section
     assert "does **not** proxy sidecar requests" in diagnostics_section
+    assert "optional top-level `runtime` object" in diagnostics_section
+    assert "allowlisted scalar fields" in diagnostics_section
     assert "do **not**" in diagnostics_section
     assert "return `HERMES_WEBUI_EXTENSION_DIR`" in diagnostics_section
     assert "override state-file path" in diagnostics_section