diff --git a/hermes_cli/gateway_client.py b/hermes_cli/gateway_client.py
index 1eaf0d48a0..4e88b54993 100644
--- a/hermes_cli/gateway_client.py
+++ b/hermes_cli/gateway_client.py
@@ -51,6 +51,8 @@ class GatewayClientError(ValueError):
 
 DISCONNECTED = ("Gateway disconnected; turn outcome is unknown. "
                 "Resume the printed session ID to check whether it completed or was interrupted; do not resend the work.")
+# A request refused before it reached any socket: nothing is in doubt, so never DISCONNECTED.
+NOT_SENT = "Gateway disconnected before the request was sent; nothing was sent."
 
 
 class GatewayRPCError(GatewayClientError):
@@ -214,6 +216,10 @@ class GatewayClient:
         """Send one request and await its answer; ``_timeout`` (seconds, never sent on the wire)
         overrides ``DEFAULT_RPC_TIMEOUT`` for a verb that legitimately takes longer (``math.inf``: no
         deadline; the answer, a hang-up or the caller's cancel ends the wait)."""
+        if self.reader is not None and self.reader.done():
+            # The reader ended (the socket closed, e.g. a keepalive timeout, or it gave up): no answer
+            # could arrive, so nothing is sent and the caller may safely send again.
+            raise GatewayClientError(NOT_SENT)
         self.sequence += 1
         rid = self.sequence
         future = asyncio.get_running_loop().create_future()
diff --git a/hermes_cli/gateway_connection.py b/hermes_cli/gateway_connection.py
index 525ef5ac6f..fe3a5c1cf1 100644
--- a/hermes_cli/gateway_connection.py
+++ b/hermes_cli/gateway_connection.py
@@ -16,13 +16,11 @@ import queue
 import threading
 import time
 
-from hermes_cli.gateway_client import (DEFAULT_RPC_TIMEOUT, DISCONNECTED, RESUME_KEY_MISMATCH, GatewayClientError,
-                                       GatewayRPCError)
+from hermes_cli.gateway_client import (DEFAULT_RPC_TIMEOUT, DISCONNECTED, NOT_SENT, RESUME_KEY_MISMATCH,
+                                       GatewayClientError, GatewayRPCError)
 
 logger = logging.getLogger(__name__)
 
-# A request refused before it reached any socket: nothing is in doubt, so never DISCONNECTED.
-NOT_SENT = "Gateway disconnected before the request was sent; nothing was sent."
 # ``session.resume`` refusals that mean "this viewer may not open that session": the caller keeps the
 # session it is on instead of adopting the target (startup resume, bare -c fallback).
 RESUME_REFUSALS = frozenset({"not_found", "permission_denied"})
diff --git a/tests/hermes_cli/test_gateway_client_rpc.py b/tests/hermes_cli/test_gateway_client_rpc.py
index 83e50e8036..3ebdb7f19f 100644
--- a/tests/hermes_cli/test_gateway_client_rpc.py
+++ b/tests/hermes_cli/test_gateway_client_rpc.py
@@ -4,7 +4,7 @@ import json
 
 import pytest
 
-from hermes_cli.gateway_client import GatewayClient, GatewayClientError, GatewayRPCError
+from hermes_cli.gateway_client import NOT_SENT, GatewayClient, GatewayClientError, GatewayRPCError
 
 
 class _Socket:
@@ -89,3 +89,26 @@ async def test_send_on_a_dead_socket_is_a_client_error_not_a_raw_websockets_one(
         with pytest.raises(GatewayClientError, match='turn outcome is unknown'):
             await client.rpc('subagent.list', session_id='s')
         assert client.pending == {}
+
+
+@pytest.mark.asyncio
+async def test_a_request_after_the_reader_ended_is_not_sent():
+    """The keepalive timeout closes the socket and ends the reader before the dock's next poll: that
+    send is never written (websockets refuses a send on a closed socket), so the caller is told
+    nothing was sent, not that a turn's outcome is unknown."""
+    sent = []
+
+    class _Closed(_Socket):
+        async def send(self, raw):
+            sent.append(raw)
+
+        async def __anext__(self):
+            raise StopAsyncIteration  # the socket closed: iteration ends
+
+    async with GatewayClient(_Closed(lambda req: None)) as client:
+        await asyncio.sleep(0)  # let the reader see the close
+        assert client.reader.done()
+        with pytest.raises(GatewayClientError) as refused:
+            await client.rpc('prompt.submit', session_id='s')
+        assert str(refused.value) == NOT_SENT
+        assert sent == [] and client.pending == {}