diff --git a/src/cli/App.tsx b/src/cli/App.tsx
index 3915cc4..fcb30fc 100644
--- a/src/cli/App.tsx
+++ b/src/cli/App.tsx
@@ -1899,6 +1899,8 @@ export default function App({
   // Epoch counter to force dequeue effect re-run when refs change but state doesn't
   // Incremented when userCancelledRef is reset while messages are queued
   const [dequeueEpoch, setDequeueEpoch] = useState(0);
+  // Strict lock to ensure dequeue submit path is at-most-once while onSubmit is in flight.
+  const dequeueInFlightRef = useRef(false);
 
   // Track last dequeued message for restoration on error
   // If an error occurs after dequeue, we restore this to the input field (if input is empty)
@@ -10695,7 +10697,8 @@ ${SYSTEM_REMINDER_CLOSE}
       !anySelectorOpen && // Don't dequeue while a selector/overlay is open
       !waitingForQueueCancelRef.current && // Don't dequeue while waiting for cancel
       !userCancelledRef.current && // Don't dequeue if user just cancelled
-      !abortControllerRef.current // Don't dequeue while processConversation is still active
+      !abortControllerRef.current && // Don't dequeue while processConversation is still active
+      !dequeueInFlightRef.current // Don't dequeue while previous dequeue submit is still in flight
     ) {
       // consumeItems(n) fires onDequeued → setQueueDisplay(prev => prev.slice(n)).
       const batch = tuiQueueRef.current?.consumeItems(queueLen);
@@ -10725,7 +10728,16 @@ ${SYSTEM_REMINDER_CLOSE}
 
       // Submit via normal flow — overrideContentPartsRef carries rich content parts.
       overrideContentPartsRef.current = queuedContentParts;
-      onSubmitRef.current(concatenatedMessage);
+      // Lock prevents re-entrant dequeue if deps churn before processConversation
+      // sets abortControllerRef (which is the normal long-term gate).
+      dequeueInFlightRef.current = true;
+      void onSubmitRef.current(concatenatedMessage).finally(() => {
+        dequeueInFlightRef.current = false;
+        // If more items arrived while in-flight, bump epoch so the effect re-runs.
+        if ((tuiQueueRef.current?.length ?? 0) > 0) {
+          setDequeueEpoch((e) => e + 1);
+        }
+      });
     } else if (hasAnythingQueued) {
       // Log why dequeue was blocked (useful for debugging stuck queues)
       debugLog(
diff --git a/src/tests/cli/queue-ordering-wiring.test.ts b/src/tests/cli/queue-ordering-wiring.test.ts
index 57d5559..0a0fbe2 100644
--- a/src/tests/cli/queue-ordering-wiring.test.ts
+++ b/src/tests/cli/queue-ordering-wiring.test.ts
@@ -33,7 +33,8 @@ describe("queue ordering wiring", () => {
     // Queue is now drained via QueueRuntime.consumeItems; setQueueDisplay is
     // updated automatically via the onDequeued callback — no direct setState here.
     expect(segment).toContain("tuiQueueRef.current?.consumeItems(queueLen)");
-    expect(segment).toContain("onSubmitRef.current(concatenatedMessage);");
+    expect(segment).toContain("onSubmitRef.current(concatenatedMessage)");
+    expect(segment).toContain("!dequeueInFlightRef.current");
     expect(segment).toContain("queuedOverlayAction,");
   });