diff --git a/CHANGELOG.md b/CHANGELOG.md
index 42919130..8079ed45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Session sidebar Archive/Delete menu actions now repaint from local sidebar state immediately after the server confirms the mutation, instead of waiting for the full `/api/sessions` refresh before the row disappears.
+
 ## [v0.51.134] — 2026-05-25 — Release DF (stage-batch16 — single-PR Windows path defaults)
 
 ### Fixed
diff --git a/static/sessions.js b/static/sessions.js
index 83d8c5c4..34fb99ab 100644
--- a/static/sessions.js
+++ b/static/sessions.js
@@ -1544,6 +1544,24 @@ function _sessionArchiveToast(response, session){
 function _sessionDeleteDescription(session){
   return session&&session.worktree_path?t('session_delete_worktree_desc'):t('session_delete_desc');
 }
+function _optimisticallyArchiveSessionInList(sid, archived){
+  if(!sid||!Array.isArray(_allSessions)) return;
+  let changed=false;
+  _allSessions=_allSessions.map(s=>{
+    if(!s||s.session_id!==sid) return s;
+    changed=true;
+    return {...s,archived:!!archived};
+  });
+  if(changed) renderSessionListFromCache();
+}
+function _optimisticallyRemoveSessionFromList(sid){
+  if(!sid||!Array.isArray(_allSessions)) return;
+  const before=_allSessions.length;
+  _allSessions=_allSessions.filter(s=>!s||s.session_id!==sid);
+  if(_selectedSessions&&_selectedSessions.has(sid)) _selectedSessions.delete(sid);
+  if(typeof _dropStaleOptimisticSessionRow==='function') _dropStaleOptimisticSessionRow(sid);
+  if(_allSessions.length!==before) renderSessionListFromCache();
+}
 
 function _sessionIdFromLocation(){
   if(typeof window==='undefined'||!window.location) return null;
@@ -1866,9 +1884,10 @@ function _openSessionActionMenu(session, anchorEl){
       closeSessionActionMenu();
       try{
         const response=await api('/api/session/archive',{method:'POST',body:JSON.stringify({session_id:session.session_id,archived:!session.archived})});
+        _optimisticallyArchiveSessionInList(session.session_id,!session.archived);
         session.archived=!session.archived;
         if(S.session&&S.session.session_id===session.session_id) S.session.archived=session.archived;
-        await renderSessionList();
+        void renderSessionList();
         showToast(session.archived?_sessionArchiveToast(response,session):t('session_restored'));
       }catch(err){showToast(t('session_archive_failed')+err.message);}
     }
@@ -1882,9 +1901,10 @@ function _openSessionActionMenu(session, anchorEl){
         closeSessionActionMenu();
         try{
           await api('/api/session/archive',{method:'POST',body:JSON.stringify({session_id:session.session_id,archived:true})});
+          _optimisticallyArchiveSessionInList(session.session_id,true);
           session.archived=true;
           if(S.session&&S.session.session_id===session.session_id) S.session.archived=true;
-          await renderSessionList();
+          void renderSessionList();
           showToast(t('session_hidden'));
         }catch(err){showToast(t('session_archive_failed')+err.message);}
       }
@@ -3874,6 +3894,7 @@ async function deleteSession(sid){
   let response=null;
   try{
     response=await api('/api/session/delete',{method:'POST',body:JSON.stringify({session_id:sid})});
+    _optimisticallyRemoveSessionFromList(sid);
     _clearHandoffStorageForSession(sid);
   }catch(e){setStatus(`Delete failed: ${e.message}`);return;}
   if(S.session&&S.session.session_id===sid){
@@ -3894,7 +3915,7 @@ async function deleteSession(sid){
     }
   }
   showToast(_sessionResponseRetainsWorktree(response,session)?t('session_deleted_worktree'):t('session_deleted'));
-  await renderSessionList();
+  void renderSessionList();
 }
 
 // ── Project helpers ─────────────────────────────────────────────────────
diff --git a/tests/test_session_action_menu_regression.py b/tests/test_session_action_menu_regression.py
index e3d36cdc..136b5882 100644
--- a/tests/test_session_action_menu_regression.py
+++ b/tests/test_session_action_menu_regression.py
@@ -29,3 +29,29 @@ def test_session_list_refresh_does_not_close_open_conversation_actions():
     assert "if(_renamingSid) return;" in body
     assert "if(_sessionActionMenu) return;" in body
     assert body.index("if(_sessionActionMenu) return;") < body.index("closeSessionActionMenu();")
+
+
+def test_archive_action_repaints_sidebar_before_full_refresh():
+    """Archive should hide the row from cached sidebar state before /api/sessions returns."""
+    body = _function_block(SESSIONS_JS, "_openSessionActionMenu")
+
+    api_call = "const response=await api('/api/session/archive'"
+    optimistic = "_optimisticallyArchiveSessionInList(session.session_id,!session.archived);"
+    full_refresh = "void renderSessionList();"
+
+    assert optimistic in body
+    assert body.index(api_call) < body.index(optimistic) < body.index(full_refresh)
+
+
+def test_delete_action_repaints_sidebar_before_loading_remaining_sessions():
+    """Delete should remove the row locally before loading replacement session data."""
+    body = _function_block(SESSIONS_JS, "deleteSession")
+
+    api_call = "response=await api('/api/session/delete'"
+    optimistic = "_optimisticallyRemoveSessionFromList(sid);"
+    remaining_fetch = "const remaining=await api('/api/sessions');"
+    full_refresh = "void renderSessionList();"
+
+    assert optimistic in body
+    assert body.index(api_call) < body.index(optimistic) < body.index(full_refresh)
+    assert body.index(optimistic) < body.index(remaining_fetch)