diff --git a/scripts/compose-drift-watch.py b/scripts/compose-drift-watch.py
index ba0373541..a8d76584e 100755
--- a/scripts/compose-drift-watch.py
+++ b/scripts/compose-drift-watch.py
@@ -112,6 +112,23 @@
 #     happens to carry a top-level compose.yml (this repo's own), which is
 #     what made it look like a stack directory to a naive glob.
 KNOWN_NON_PROJECT_DIRS = {"honeypot-arcane", "apiary"}
+# #3129: llm-worker is still a manifest entry with a persistent restart
+# policy (not retired), but its single container has been deliberately kept
+# down since #3023 -- it was issuing a competing /api/chat against the same
+# Ollama instance the #1947 benchmark sweep needs cold, so the sweep owner
+# gated it off until the benchmark run releases it. That is an operator
+# decision, not the "torn down" shape retired_projects() (and #3040's Gate 1
+# below) exist to tell apart from real drift. #3040's own scope asked for
+# exactly this mechanism -- "Retired/intentionally-absent services need an
+# explicit allowlist with a reason, the same shape isolation-audit.sh
+# already uses for its known-gap WARN tier" -- so this is the allowlist that
+# issue specified, keyed by project name so it only ever silences this
+# specific, documented absence. Do not add a second entry here
+# without an equally-documented operator decision: that is exactly the
+# blanket "no sibling, don't alarm" rule #3040 removed.
+EXPECTED_ABSENT_WHILE = {
+    "llm-worker": "#3023 sweep-owner-gated for the #1947 benchmark run; stays down until the operator releases it",
+}
 
 
 def fail(msg: str) -> "None":
@@ -554,6 +571,15 @@ def sweep(stacks_root: Path, entries: list[dict], retired: set[str] | None) -> t
         if not missing:
             continue
 
+        # #3129: an operator-gated deliberate absence, distinct from both
+        # "retired" (no manifest entry at all) and ordinary drift. Checked
+        # before the sibling logic below since llm-worker structurally never
+        # has a sibling either way -- this is not a re-run of #3040's removed
+        # blanket rule, it only matches the one named project in
+        # EXPECTED_ABSENT_WHILE.
+        if name in EXPECTED_ABSENT_WHILE:
+            continue
+
         # #3040: the old rule suppressed *every* project with no sibling
         # currently running, on the theory that "the whole stack isn't
         # deployed" is self-evident and doesn't need an alarm. That's true
diff --git a/scripts/tests/test_compose_drift_watch_sweep.py b/scripts/tests/test_compose_drift_watch_sweep.py
index edb50ef2f..8c38c0b30 100644
--- a/scripts/tests/test_compose_drift_watch_sweep.py
+++ b/scripts/tests/test_compose_drift_watch_sweep.py
@@ -65,15 +65,46 @@ def _mkproject(self, name: str) -> None:
         (d / "compose.yml").write_text("services: {}\n")
 
     def test_single_service_project_missing_container_alarms(self) -> None:
+        # #3129: llm-worker itself moved into EXPECTED_ABSENT_WHILE (see
+        # below), so this general "single-service project alarms" pin now
+        # uses a different real single-service manifest entry instead.
+        self._mkproject("auth-events-worker")
+        configs = {"auth-events-worker": ({"auth-events-worker": "unless-stopped"}, [])}
+        with mock.patch.object(cdw.subprocess, "run", side_effect=_fake_compose_run(configs)):
+            findings, unresolved = cdw.sweep(self.stacks_root, entries=[], retired=set())
+        self.assertEqual(unresolved, [])
+        self.assertEqual(len(findings), 1)
+        self.assertEqual(findings[0]["project"], "auth-events-worker")
+        self.assertEqual(findings[0]["service"], "auth-events-worker")
+        self.assertEqual(findings[0]["siblings_running"], [])
+
+    def test_expected_absent_project_stays_quiet(self) -> None:
+        # #3129: llm-worker is still in the manifest (not retired) with a
+        # persistent restart policy, but its one container has been
+        # deliberately down since #3023. EXPECTED_ABSENT_WHILE must silence
+        # exactly this named project without reopening #3040's blanket
+        # "no sibling, don't alarm" rule for anything else.
         self._mkproject("llm-worker")
         configs = {"llm-worker": ({"llm-worker": "unless-stopped"}, [])}
         with mock.patch.object(cdw.subprocess, "run", side_effect=_fake_compose_run(configs)):
             findings, unresolved = cdw.sweep(self.stacks_root, entries=[], retired=set())
+        self.assertEqual(findings, [])
         self.assertEqual(unresolved, [])
+
+    def test_unlisted_single_service_project_still_alarms_next_to_expected_absent(self) -> None:
+        # Control for the above: a different single-service project with the
+        # same zero-container, no-sibling shape as llm-worker must still
+        # alarm -- EXPECTED_ABSENT_WHILE only matches its one named key.
+        self._mkproject("llm-worker")
+        self._mkproject("ml-worker")
+        configs = {
+            "llm-worker": ({"llm-worker": "unless-stopped"}, []),
+            "ml-worker": ({"ml-worker": "unless-stopped"}, []),
+        }
+        with mock.patch.object(cdw.subprocess, "run", side_effect=_fake_compose_run(configs)):
+            findings, _ = cdw.sweep(self.stacks_root, entries=[], retired=set())
         self.assertEqual(len(findings), 1)
-        self.assertEqual(findings[0]["project"], "llm-worker")
-        self.assertEqual(findings[0]["service"], "llm-worker")
-        self.assertEqual(findings[0]["siblings_running"], [])
+        self.assertEqual(findings[0]["project"], "ml-worker")
 
     def test_fully_retired_project_down_stays_quiet(self) -> None:
         self._mkproject("wordpot")