diff --git a/static/sessions.js b/static/sessions.js
index 01015ef0..9f653f1b 100644
--- a/static/sessions.js
+++ b/static/sessions.js
@@ -4357,8 +4357,21 @@ let _lastSessionListRenderSig = null;
 function _sessionListRenderSignature(){
   try{
     const search=($('sessionSearch')&&$('sessionSearch').value)||'';
+    const sessionKeys = [
+      'session_id','id','display_name','title','created_at','started_at',
+      'updated_at','last_message_at','last_activity','message_count',
+      'actual_message_count','is_streaming','streaming','status','pinned',
+      'archived','project_id','source','session_source','generation',
+      '_lineage_root_id','_lineage_tip_id','_compression_segment_count',
+    ];
+    const sessionsSlim = Array.isArray(_allSessions) ? _allSessions.map(s => {
+      if(!s || typeof s !== 'object') return s;
+      const out={};
+      sessionKeys.forEach(k=>{ if(Object.prototype.hasOwnProperty.call(s,k)) out[k]=s[k]; });
+      return out;
+    }) : _allSessions;
     return JSON.stringify([
-      _allSessions,
+      sessionsSlim,
       _allProjects,
       _activeSessionIdForSidebar(),
       search,
diff --git a/tests/test_webui_external_refresh_frontend.py b/tests/test_webui_external_refresh_frontend.py
index 4d4ff68e..17022f6e 100644
--- a/tests/test_webui_external_refresh_frontend.py
+++ b/tests/test_webui_external_refresh_frontend.py
@@ -122,6 +122,19 @@ def test_session_event_profile_filter_tolerates_default_root_aliases():
     assert "S.activeProfileIsDefault = !!data.is_default;" in PANELS_JS
 
 
+def test_session_list_render_signature_ignores_non_display_session_fields():
+    start = SESSIONS_JS.find("function _sessionListRenderSignature()")
+    assert start != -1
+    block = SESSIONS_JS[start:start + 1500]
+    assert "const sessionKeys = [" in block
+    assert "const sessionsSlim = Array.isArray(_allSessions)" in block
+    assert "sessionKeys.forEach" in block
+    assert "_allSessions," not in block
+    assert "message_count" in block
+    assert "last_message_at" in block
+    assert "_compression_segment_count" in block
+
+
 def test_pwa_pull_to_refresh_refreshes_session_list_not_page_when_available():
     assert "window.refreshSessionList('pull', {force:true, refreshActive:true})" in UI_JS
     assert "Promise.resolve(window.refreshSessionList('pull', {force:true, refreshActive:true})).catch(()=>{}).finally(_ptrReset)" in UI_JS