diff --git a/hermes_cli/gateway.py b/hermes_cli/gateway.py
index 8ac557a797..00335ac22f 100644
--- a/hermes_cli/gateway.py
+++ b/hermes_cli/gateway.py
@@ -1765,11 +1765,37 @@ def _reaper_candidate_is_supervisor_owned(pid: int) -> bool:
     return False
 
 
-def _reap_unsupervised_gateway_orphans(extra_exclude: set | None = None) -> bool:
+def _gateway_process_age_s(pid: int) -> float:
+    """Seconds since ``pid`` started, or ``0.0`` when undeterminable (never negative).
+
+    A probe failure must not widen a reap, so an unknown age reads as "too young to
+    touch" under a positive grace and is irrelevant when the grace is 0.
+    """
+    try:
+        import psutil  # type: ignore
+        import time as _time
+
+        return max(0.0, _time.time() - float(psutil.Process(int(pid)).create_time()))
+    except Exception:
+        return 0.0
+
+
+def _reap_unsupervised_gateway_orphans(
+    extra_exclude: set | None = None, *, min_age_s: float = 0.0,
+) -> bool:
     """Kill no-supervisor gateway orphans the pidfile/runtime record can't see. On WSL/no-systemd hosts
     the restart fallback runs the gateway in-process under a ``gateway restart`` argv; a stale pidfile
     then lets a live orphan keep the webhook port while a restart stacks a duplicate. No-op where a
-    supervisor exists (there ``gateway restart`` is a transient command). ``extra_exclude``: already killed."""
+    supervisor exists (there ``gateway restart`` is a transient command). ``extra_exclude``: already killed.
+
+    ``min_age_s`` spares a candidate younger than the grace: a gateway claims
+    ``gateway.pid``/``gateway.lock`` only after imports + runner setup, so a process
+    that a previous Desktop generation (or a concurrent ``gateway start``) just launched
+    is scan-visible but not yet record-visible, and the argv sweep cannot tell it from
+    a corpse. Reaping it writes a planned-stop marker it consumes seconds later — a clean
+    exit 0 with no supervisor to revive it (#122533). Only the Desktop boot sweep passes a
+    grace (it is the one caller that races a launch); stop/restart keep reaping at once.
+    """
     try:
         supervised_host = supports_systemd_services()
     except Exception:
@@ -1801,6 +1827,8 @@ def _reap_unsupervised_gateway_orphans(extra_exclude: set | None = None) -> bool
         ]
     except Exception:
         return False
+    if min_age_s > 0:
+        orphans = [p for p in orphans if _gateway_process_age_s(p) >= min_age_s]
     if not orphans:
         return False
 
diff --git a/hermes_cli/web_server.py b/hermes_cli/web_server.py
index b14c72001b..7721ac8f71 100644
--- a/hermes_cli/web_server.py
+++ b/hermes_cli/web_server.py
@@ -241,10 +241,18 @@ async def _lifespan(app: "FastAPI"):
         # one that would race the same credential (#77276). Runs
         # unconditionally; protection of a healthy standalone gateway lives
         # INSIDE the reaper (registration probed with cleanup_stale=False).
+        # The grace covers the one race this call site creates: a gateway launched
+        # moments ago by the previous Desktop generation (or a concurrent start)
+        # is scan-visible but has not claimed gateway.pid/gateway.lock yet, and the
+        # argv sweep would reap it — writing a planned-stop marker that the booting
+        # gateway consumes seconds later, exiting 0 with no supervisor to revive it
+        # (#122533). Same rule the serve-process reaper applies to an unrecorded
+        # sibling (hermes_cli.dashboard_procs._REAP_MIN_AGE_SECONDS).
         try:
+            from hermes_cli.dashboard_procs import _REAP_MIN_AGE_SECONDS
             from hermes_cli.gateway import _reap_unsupervised_gateway_orphans
 
-            _reap_unsupervised_gateway_orphans()
+            _reap_unsupervised_gateway_orphans(min_age_s=_REAP_MIN_AGE_SECONDS)
         except Exception:
             _log.exception("Desktop startup: orphan gateway reap failed")