fix: clear stale busy state before send

static/messages.js

@@ -190,6 +190,32 @@ let _sendInProgress = false;
 let _sendInProgressSid = null;  // session_id of the in-flight send
 const _sessionTitleProvisionalBySid = new Map();
 
+function _clearStaleBusyStateBeforeSend({compressionRunning=false}={}){
+  if(!S||!S.busy||compressionRunning) return false;
+  const session=S.session||{};
+  const sid=session.session_id||'';
+  const hasRuntimeConfirmation=Boolean(
+    S.activeStreamId||
+    session.active_stream_id||
+    session.pending_user_message||
+    session.pending_started_at
+  );
+  if(hasRuntimeConfirmation) return false;
+  if(typeof INFLIGHT==='object'&&INFLIGHT&&sid&&INFLIGHT[sid]){
+    delete INFLIGHT[sid];
+    if(typeof clearInflightState==='function') clearInflightState(sid);
+  }
+  S.activeStreamId=null;
+  if(session) session.active_stream_id=null;
+  if(typeof setBusy==='function') setBusy(false);
+  else S.busy=false;
+  if(typeof setComposerStatus==='function') setComposerStatus('');
+  if(typeof setStatus==='function') setStatus('');
+  if(typeof updateSendBtn==='function') updateSendBtn();
+  if(sid&&typeof clearOptimisticSessionStreaming==='function') clearOptimisticSessionStreaming(sid);
+  return true;
+}
+
 function _sessionTitleLooksDefaultOrProvisional(titleText, provisionalText){
   const title=String(titleText||'').replace(/\s+/g,' ').trim();
   if(!title||title==='Untitled'||title==='New Chat')return true;
@@ -262,6 +288,7 @@ async function send(){
   }
 
   const compressionRunning=typeof isCompressionUiRunning==='function'&&isCompressionUiRunning();
+  _clearStaleBusyStateBeforeSend({compressionRunning});
   // If busy or a manual compression is still running, handle based on busy_input_mode
   if(S.busy||compressionRunning){
     if(text){

tests/test_inflight_send_start_race.py

@@ -51,6 +51,21 @@ def test_stale_inflight_purge_preserves_current_send_before_stream_id_exists():
     assert skip_idx < delete_idx, "the current-send skip must run before any purge deletion"
 
 
+def test_send_clears_stale_busy_state_before_queue_branch():
+    """A stale client-only busy flag must not divert a new user turn into the invisible queue."""
+    body = _function_body(MESSAGES_JS, "send")
+
+    assert "_clearStaleBusyStateBeforeSend" in body, (
+        "send() should reconcile client-only stale busy state before deciding busy/queue mode"
+    )
+    reconcile_idx = body.index("_clearStaleBusyStateBeforeSend")
+    busy_branch_idx = body.index("if(S.busy||compressionRunning)")
+    chat_start_idx = body.index("api('/api/chat/start'")
+    assert reconcile_idx < busy_branch_idx < chat_start_idx, (
+        "stale busy reconciliation must run before the queue branch and before /api/chat/start"
+    )
+
+
 def test_server_absent_optimistic_first_turn_rows_are_not_kept_forever():
     """A local first-turn sidebar row must expire when /api/chat/start never persisted it."""
     body = _function_body(SESSIONS_JS, "_mergeOptimisticFirstTurnSessions")