diff --git a/static/messages.js b/static/messages.js
index 8f57d13a..e060486c 100644
--- a/static/messages.js
+++ b/static/messages.js
@@ -592,6 +592,54 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
   // ── Shared SSE handler wiring (used for initial connection and reconnect) ──
   let _reconnectAttempted=false;
   let _terminalStateReached=false;
+  let _deferredStreamRecoveryBound=false;
+
+  function _pageHiddenForStreamError(){
+    return (typeof document!=='undefined'&&document.visibilityState==='hidden')||
+      (typeof document!=='undefined'&&document.wasDiscarded===true);
+  }
+
+  function _reattachOrRestoreAfterDeferredStreamError(){
+    if(_terminalStateReached||_streamFinalized) return;
+    (async()=>{
+      try{
+        if(streamId){
+          const st=await api(`/api/chat/stream/status?stream_id=${encodeURIComponent(streamId)}`);
+          if(st.active){
+            setComposerStatus('Reconnected');
+            _wireSSE(new EventSource(new URL(`api/chat/stream?stream_id=${encodeURIComponent(streamId)}`,document.baseURI||location.href).href,{withCredentials:true}));
+            return;
+          }
+        }
+      }catch(_){
+        if(_deferStreamErrorIfOffline()||_pageHiddenForStreamError()) return;
+      }
+      if(await _restoreSettledSession()) return;
+      if(_deferStreamErrorIfOffline()||_pageHiddenForStreamError()) return;
+      _handleStreamError();
+    })();
+  }
+
+  function _deferStreamErrorIfPageHidden(){
+    if(!_pageHiddenForStreamError()) return false;
+    setComposerStatus('Connection paused. Reconnecting when this tab returns…');
+    if(S.session&&S.session.session_id===activeSid&&streamId) S.activeStreamId=streamId;
+    if(!_deferredStreamRecoveryBound){
+      _deferredStreamRecoveryBound=true;
+      const resume=()=>{
+        if(_pageHiddenForStreamError()) return;
+        window.removeEventListener('focus',resume);
+        window.removeEventListener('pageshow',resume);
+        document.removeEventListener('visibilitychange',resume);
+        _deferredStreamRecoveryBound=false;
+        _reattachOrRestoreAfterDeferredStreamError();
+      };
+      document.addEventListener('visibilitychange',resume);
+      window.addEventListener('focus',resume);
+      window.addEventListener('pageshow',resume);
+    }
+    return true;
+  }
 
   // Bug A fix (#631): track whether the stream has been finalized so any rAF
   // scheduled by a trailing 'token'/'reasoning' event that arrives in the same
@@ -1633,6 +1681,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
     source.addEventListener('error',async e=>{
       source.close();
       if(_deferStreamErrorIfOffline()) return;
+      if(_deferStreamErrorIfPageHidden()) return;
       if(_terminalStateReached || _streamFinalized){
         _closeSource();
         return;
@@ -1654,12 +1703,14 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
           }
           if(await _restoreSettledSession()) return;
           if(_deferStreamErrorIfOffline()) return;
+          if(_deferStreamErrorIfPageHidden()) return;
           _handleStreamError();
         },1500);
         return;
       }
       if(await _restoreSettledSession()) return;
       if(_deferStreamErrorIfOffline()) return;
+      if(_deferStreamErrorIfPageHidden()) return;
       _handleStreamError();
     });
 
diff --git a/tests/test_offline_banner.py b/tests/test_offline_banner.py
index 4942d8fe..45177975 100644
--- a/tests/test_offline_banner.py
+++ b/tests/test_offline_banner.py
@@ -70,3 +70,24 @@ def test_sse_network_error_defers_to_offline_banner_instead_of_inline_error():
     assert "if(_deferStreamErrorIfOffline()) return;" in MESSAGES_JS
     error_handler = MESSAGES_JS.split("source.addEventListener('error',async e=>{", 1)[1].split("source.addEventListener('cancel'", 1)[0]
     assert error_handler.find("_deferStreamErrorIfOffline()") < error_handler.rfind("_handleStreamError()")
+
+
+def test_sse_error_defers_while_page_hidden_until_tab_returns():
+    assert "function _deferStreamErrorIfPageHidden()" in MESSAGES_JS
+    assert "document.visibilityState==='hidden'" in MESSAGES_JS
+    assert "document.wasDiscarded===true" in MESSAGES_JS
+    assert "Connection paused. Reconnecting when this tab returns…" in MESSAGES_JS
+    assert "document.addEventListener('visibilitychange',resume)" in MESSAGES_JS
+    assert "window.addEventListener('pageshow',resume)" in MESSAGES_JS
+    error_handler = MESSAGES_JS.split("source.addEventListener('error',async e=>{", 1)[1].split("source.addEventListener('cancel'", 1)[0]
+    assert "if(_deferStreamErrorIfPageHidden()) return;" in error_handler
+    assert error_handler.find("_deferStreamErrorIfPageHidden()") < error_handler.rfind("_handleStreamError()")
+
+
+def test_deferred_hidden_stream_error_reattaches_or_restores_before_inline_error():
+    recovery_block = MESSAGES_JS.split("function _reattachOrRestoreAfterDeferredStreamError(){", 1)[1].split("function _deferStreamErrorIfPageHidden()", 1)[0]
+    assert "api(`/api/chat/stream/status?stream_id=${encodeURIComponent(streamId)}`)" in recovery_block
+    assert "if(st.active)" in recovery_block
+    assert "_wireSSE(new EventSource" in recovery_block
+    assert "if(await _restoreSettledSession()) return;" in recovery_block
+    assert recovery_block.find("if(await _restoreSettledSession()) return;") < recovery_block.rfind("_handleStreamError()")