diff --git a/.github/workflows/evict-orphan-caches.yml b/.github/workflows/evict-orphan-caches.yml
index 5308b30e61..6f51bc8150 100644
--- a/.github/workflows/evict-orphan-caches.yml
+++ b/.github/workflows/evict-orphan-caches.yml
@@ -23,8 +23,18 @@ name: Evict orphan Actions caches
 #
 # Defaut : tous les lundis 03:00 UTC (apres la nuit europeenne, avant
 # l'activite US). Ajustable via workflow_dispatch.
+#
+# Reouverture de #16088 (2026-09-28) : le sweep passe AUSSI a chaque push sur
+# main. Chaque merge ecrit ses overlays CodeQL (un par langue) ; mesure du
+# 28/09, 33 overlays en ~5 h (3,96 Go) avec un quota a 10,14 / 10 Go, et le
+# cache `.lake` de knot_lean evince moins de 10 h apres sa sauvegarde. Un
+# passage hebdomadaire ne suit pas cette cadence, et le cron de ce depot
+# est servi avec des heures de retard. Le script garde les 3 overlays les
+# plus recents par famille (`--keep-latest`, defaut 3) et evince le reste.
 
 on:
+  push:
+    branches: [main]
   schedule:
     - cron: "0 3 * * 1"
   workflow_dispatch:
diff --git a/scripts/ci/evict_orphan_caches.py b/scripts/ci/evict_orphan_caches.py
index ff4a56b03b..cdde254123 100644
--- a/scripts/ci/evict_orphan_caches.py
+++ b/scripts/ci/evict_orphan_caches.py
@@ -159,6 +159,15 @@ def _parse_args() -> argparse.Namespace:
         help="Evict caches whose last_accessed_at is older than this many hours "
         "(default: 24). A cache never hit has last_accessed_at == created_at.",
     )
+    p.add_argument(
+        "--keep-latest",
+        type=int,
+        default=3,
+        help="Per overlay family (config hash + lang + toolchain), keep only the "
+        "N most recent caches still classified KEEP and evict the older ones "
+        "(default: 3; 0 disables). Reopening of #16088: every overlay of main "
+        "is an ancestor of main, so the two other criteria never catch them.",
+    )
     p.add_argument(
         "--repo",
         default=os.environ.get("GITHUB_REPOSITORY", "jsboige/CoursIA"),
@@ -300,6 +309,7 @@ def _classify_cache(
     sha = m.group("sha40")
     rec["sha40"] = sha
     rec["lang"] = m.group("lang")
+    rec["family"] = f"{m.group('random8')}-{m.group('lang')}-{m.group('toolchain')}"
 
     reasons: list[str] = []
     ancestor_status = _is_ancestor(sha, remote, main_branch)
@@ -324,6 +334,34 @@ def _classify_cache(
     return rec
 
 
+def _mark_superseded(records: list[dict[str, Any]], keep_latest: int) -> None:
+    """Evict the overlays of a family beyond its `keep_latest` most recent ones.
+
+    Only records still classified KEEP are counted and touched : an overlay
+    already evicted for another reason does not take one of the kept slots,
+    and a REFUSE (undecidable ancestry) is never turned into a deletion.
+    Order is `created_at` descending ; `keep_latest <= 0` disables the rule.
+
+    Why (reopening of #16088, 2026-09-28) : each overlay of `main` carries a
+    SHA of `main`, hence an ancestor, and the quota fills in a few hours while
+    the age window is 7 days. Measured : 33 overlays kept, 3.96 GB, quota at
+    10.14 / 10 GB, and the knot_lean `.lake` cache evicted within 10 h of its
+    save -- every Lean build of that lake then ran cold.
+    """
+    if keep_latest <= 0:
+        return
+    families: dict[str, list[dict[str, Any]]] = {}
+    for r in records:
+        if r["verdict"] == "KEEP" and "family" in r:
+            families.setdefault(r["family"], []).append(r)
+    for members in families.values():
+        members.sort(key=lambda r: _parse_iso(r["created_at"]), reverse=True)
+        for r in members[keep_latest:]:
+            r.update(
+                {"verdict": "EVICT", "reason": f"superseded_beyond_latest_{keep_latest}"}
+            )
+
+
 def _print_human(records: list[dict[str, Any]], applied: bool) -> None:
     for r in records:
         verdict = r["verdict"]
@@ -379,6 +417,7 @@ def main() -> int:
         )
         for c in caches
     ]
+    _mark_superseded(records, args.keep_latest)
 
     applied = args.apply
     if applied:
diff --git a/tests/test_evict_orphan_caches.py b/tests/test_evict_orphan_caches.py
index aacd46a09f..58076194ee 100644
--- a/tests/test_evict_orphan_caches.py
+++ b/tests/test_evict_orphan_caches.py
@@ -206,6 +206,77 @@ def test_ancestor_check_unknown_refuses(self):
         self.assertEqual(rec["reason"], "ancestor_check_failed")
 
 
+class TestMarkSuperseded(unittest.TestCase):
+    """Reouverture #16088 (2026-09-28) : garder les N overlays les plus
+    recents par famille, evincer les autres, meme ancetres de main."""
+
+    def _rec(self, family, hours_ago, verdict="KEEP", reason="recent_and_ancestor"):
+        created = _dt.datetime(2026, 9, 28, 4, 0, tzinfo=_dt.timezone.utc) - _dt.timedelta(hours=hours_ago)
+        return {
+            "key": f"{family}-{hours_ago}",
+            "family": family,
+            "created_at": _iso(created),
+            "verdict": verdict,
+            "reason": reason,
+        }
+
+    def test_keeps_latest_n_per_family(self):
+        recs = [self._rec("py", h) for h in (5, 1, 3, 0, 4)]
+        eoc._mark_superseded(recs, 3)
+        kept = sorted(r["key"] for r in recs if r["verdict"] == "KEEP")
+        self.assertEqual(kept, ["py-0", "py-1", "py-3"])
+        evicted = [r for r in recs if r["verdict"] == "EVICT"]
+        self.assertEqual(len(evicted), 2)
+        self.assertTrue(all(r["reason"] == "superseded_beyond_latest_3" for r in evicted))
+
+    def test_families_are_independent(self):
+        recs = [self._rec("py", h) for h in (0, 1)] + [self._rec("cs", h) for h in (0, 1, 2)]
+        eoc._mark_superseded(recs, 2)
+        evicted = [r["key"] for r in recs if r["verdict"] == "EVICT"]
+        self.assertEqual(evicted, ["cs-2"])
+
+    def test_already_evicted_does_not_take_a_slot(self):
+        # Un overlay deja evince (SHA orphelin) ne compte pas parmi les N gardes.
+        recs = [
+            self._rec("py", 0, verdict="EVICT", reason="sha_not_ancestor_of_main"),
+            self._rec("py", 1),
+            self._rec("py", 2),
+        ]
+        eoc._mark_superseded(recs, 2)
+        self.assertEqual([r["verdict"] for r in recs], ["EVICT", "KEEP", "KEEP"])
+        self.assertEqual(recs[0]["reason"], "sha_not_ancestor_of_main")
+
+    def test_refuse_is_never_turned_into_eviction(self):
+        recs = [self._rec("py", h) for h in (0, 1)]
+        recs.append(self._rec("py", 2, verdict="REFUSE", reason="ancestor_check_failed"))
+        eoc._mark_superseded(recs, 1)
+        self.assertEqual(recs[2]["verdict"], "REFUSE")
+        self.assertEqual([r["verdict"] for r in recs[:2]], ["KEEP", "EVICT"])
+
+    def test_zero_disables(self):
+        recs = [self._rec("py", h) for h in range(6)]
+        eoc._mark_superseded(recs, 0)
+        self.assertTrue(all(r["verdict"] == "KEEP" for r in recs))
+
+    def test_records_without_family_are_untouched(self):
+        rec = {"key": "lake-x", "created_at": "2026-09-28T00:00:00Z",
+               "verdict": "REFUSE", "reason": "not_codeql_overlay"}
+        eoc._mark_superseded([rec], 1)
+        self.assertEqual(rec["verdict"], "REFUSE")
+
+    def test_classify_sets_family(self):
+        now = _dt.datetime.now(_dt.timezone.utc)
+        cache = {
+            "id": 1,
+            "key": TestClassifyCache.KEY_ORPHAN,
+            "size_in_bytes": 1,
+            "created_at": _iso(now),
+            "last_accessed_at": _iso(now),
+        }
+        rec = eoc._classify_cache(cache, max_age_hours=24, remote="origin", main_branch="main")
+        self.assertEqual(rec["family"], "d953d79b74456ce0-python-2.27.0")
+
+
 class TestParseIso(unittest.TestCase):
     """Compat GitHub '...Z' suffix."""