diff --git a/README.md b/README.md
index 21ad3d5..c0be761 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ A Kubernetes-driven Minecraft server hosting platform — one command to deploy,
 - **Web 控制面板**：浏览器中查看服务器状态、在线玩家与资源用量，管理备份与恢复。
 - **备份与恢复**：一键把整服数据（世界、配置、插件/模组，即整个 /data 卷）打包进集群内的归档库，支持从任意备份点回滚；默认安装就已启用（归档 PVC 与路径由安装器一并生成）。
 - **控制面数据库备份**：账号、服务器归属、配额与存档索引所在的数据库每天自动备份，每次升级迁移前先快照，出错可用 `felis db restore` 整库原子回滚；面板「维护与备份」页显示备份是否新鲜（见 [故障排查 §16](docs/troubleshooting.md)）。
-- **智慧回收（可选开启）**：超过 15 天无人游玩的世界自动备份后删除，释放磁盘空间；安装时设置 `FELIS_WORLDS_HOST_PATH`（k3s 默认 `/var/lib/rancher/k3s/storage`）即启用每日回收，不设置则不删任何世界。
+- **智慧回收（可选开启）**：超过 15 天无人游玩的世界自动备份后删除，释放磁盘空间；安装时设置 `FELIS_WORLDS_HOST_PATH`（k3s 默认 `/var/lib/rancher/k3s/storage`）即启用每日回收，不设置则不删任何世界。过期备份无论是否开启都会每天清理。
 - **多核心支持**：兼容 Paper、Fabric、Forge、NeoForge，经由 Velocity 代理统一入口。
 - **模组自助提交**：玩家自行上传模组包，服主审批通过后自动构建；构建产物进入镜像白名单，可直接选用为服务器镜像完成部署。
 - **Passkey 登录**：支持指纹、面容、硬件密钥等无密码认证方式。
diff --git a/cmd/felis/manifests.go b/cmd/felis/manifests.go
index 1187eed..eeed8ee 100644
--- a/cmd/felis/manifests.go
+++ b/cmd/felis/manifests.go
@@ -48,7 +48,7 @@ func cmdManifests(args []string, stdout, stderr io.Writer) int {
 	registryImage := fs.String("registry-image", "", "in-cluster registry image (default: registry 2.8.3, pinned by digest)")
 	backupPVC := fs.String("backup-pvc", "felis-backups", "name of the world-archive PVC this bundle renders in the Minecraft namespace and advertises to the backup/restore executors via FELIS_BACKUP_PVC (default: felis-backups; pass an empty value to render none, leaving backup/restore answering 503)")
 	worldsHostPath := fs.String("worlds-host-path", "", "node directory the reaper reads worlds from: each world PVC resolves as <path>/<pvc>, or as the stock local-path directory <path>/<pv-name>_<ns>_<pvc-name> (k3s storage root: /var/lib/rancher/k3s/storage); enables the reaper CronJob (requires --archive-local-path and a non-empty --backup-pvc)")
-	archiveLocalPath := fs.String("archive-local-path", "", "path the backup PVC is mounted at in the reaper CronJob; MUST equal felis.toml [archive] local_path")
+	archiveLocalPath := fs.String("archive-local-path", "", "path the backup PVC is mounted at in the reaper CronJob; MUST equal felis.toml [archive] local_path. With the backup PVC alone it renders the retention-only CronJob, which deletes backups past their expiry and never touches a world")
 	registryStorage := fs.String("registry-storage", "", "capacity the registry PVC requests (default 10Gi; k3s local-path does not enforce it)")
 	uploadsStorage := fs.String("uploads-storage", "", "capacity the uploads PVC requests (default 5Gi; k3s local-path does not enforce it)")
 	backupStorage := fs.String("backup-storage", "", "capacity the world-archive PVC requests (default 10Gi; k3s local-path does not enforce it)")
@@ -138,8 +138,22 @@ func cmdManifests(args []string, stdout, stderr io.Writer) int {
 			"<path>/<pvc>, or each candidate's archive fails and the world is preserved;\n"+
 			"  - %s.\n", *worldsHostPath, *worldsHostPath, *worldsHostPath, pin)
 	} else {
-		fmt.Fprintln(stderr, "felis manifests: note: retention reaper CronJob not rendered "+
-			"(pass --worlds-host-path and --archive-local-path — the archive PVC defaults to felis-backups — to enable it)")
+		switch {
+		case *archiveLocalPath != "" && *backupPVC == "":
+			fmt.Fprintln(stderr, "felis manifests: --archive-local-path names where the backup PVC is mounted, "+
+				"but --backup-pvc is empty (no archive store renders); drop one or the other")
+			return 2
+		case *archiveLocalPath != "":
+			fmt.Fprintln(stderr, "felis manifests: note: rendering the reaper CronJob retention-only: backups past "+
+				"their expiry are deleted daily, idle worlds are never archived or deleted "+
+				"(pass --worlds-host-path to reap them too)")
+		case *backupPVC != "":
+			fmt.Fprintln(stderr, "felis manifests: note: reaper CronJob not rendered: backups are never expired, so "+
+				"the archive store only grows until the disk fills (pass --archive-local-path, equal to felis.toml "+
+				"[archive] local_path, for the retention-only CronJob, and --worlds-host-path as well to reap idle worlds)")
+		default:
+			fmt.Fprintln(stderr, "felis manifests: note: reaper CronJob not rendered (backups are disabled)")
+		}
 	}
 
 	params := platform.Params{
diff --git a/cmd/felis/manifests_test.go b/cmd/felis/manifests_test.go
index 6fd40d0..e93b774 100644
--- a/cmd/felis/manifests_test.go
+++ b/cmd/felis/manifests_test.go
@@ -90,12 +90,13 @@ func TestManifestsRendersBundle(t *testing.T) {
 		t.Error("rendered bundle must not contain ClusterRole/ClusterRoleBinding")
 	}
 	// Without the retention flags, the reaper CronJob is not rendered and the
-	// generator says so on stderr.
+	// generator says so on stderr, naming what that leaves: backups that never
+	// expire.
 	if strings.Contains(text, "kind: CronJob") {
-		t.Error("no reaper CronJob must render without --worlds-host-path")
+		t.Error("no reaper CronJob must render without --archive-local-path")
 	}
-	if !strings.Contains(errBuf.String(), "not rendered") {
-		t.Errorf("expected a 'reaper not rendered' notice on stderr, got %q", errBuf.String())
+	if !strings.Contains(errBuf.String(), "not rendered") || !strings.Contains(errBuf.String(), "never expired") {
+		t.Errorf("expected a 'reaper not rendered, backups never expired' notice on stderr, got %q", errBuf.String())
 	}
 }
 
@@ -144,6 +145,40 @@ func TestManifestsBackupPVCOptOut(t *testing.T) {
 	}
 }
 
+// TestManifestsRendersRetentionOnly: the archive store without a worlds root
+// still gets the daily CronJob, retention-only, so backups past their expiry
+// leave the store on an install that never reaps a world; the operator is told
+// which of the two it got. An archive path with the store switched off is a
+// mistake and fails loud.
+func TestManifestsRendersRetentionOnly(t *testing.T) {
+	var out, errBuf bytes.Buffer
+	code := run([]string{"manifests", "--felis-image", "reg/felis:test", "--velocity-cidr", "10.0.0.5/32",
+		"--archive-local-path", "/var/lib/felis/archives"}, &out, &errBuf)
+	if code != 0 {
+		t.Fatalf("exit code = %d, want 0; stderr=%q", code, errBuf.String())
+	}
+	text := out.String()
+	for _, want := range []string{"kind: CronJob", "name: felis-reaper", "--retention-only", "claimName: felis-backups"} {
+		if !strings.Contains(text, want) {
+			t.Errorf("retention-only bundle missing %q", want)
+		}
+	}
+	if strings.Contains(text, "kind: PersistentVolume\n") || strings.Contains(text, "--worlds-root") {
+		t.Error("a retention-only bundle must not reach for a worlds root")
+	}
+	if !strings.Contains(errBuf.String(), "retention-only") {
+		t.Errorf("stderr must say the CronJob is retention-only, got %q", errBuf.String())
+	}
+
+	out.Reset()
+	errBuf.Reset()
+	code = run([]string{"manifests", "--felis-image", "reg/felis:test", "--velocity-cidr", "10.0.0.5/32",
+		"--archive-local-path", "/var/lib/felis/archives", "--backup-pvc="}, &out, &errBuf)
+	if code != 2 || out.Len() != 0 || !strings.Contains(errBuf.String(), "--backup-pvc is empty") {
+		t.Errorf("archive path without an archive store: exit=%d out=%d bytes stderr=%q, want a fail-loud 2", code, out.Len(), errBuf.String())
+	}
+}
+
 // TestManifestsRendersReaper proves the happy path with the full retention trio:
 // a batch/v1 CronJob is emitted, named felis-reaper, mounting the backup PVC at the
 // supplied archive path.
diff --git a/cmd/felis/reaper.go b/cmd/felis/reaper.go
index f9fde57..f0196ea 100644
--- a/cmd/felis/reaper.go
+++ b/cmd/felis/reaper.go
@@ -32,11 +32,17 @@ import (
 // cadence, and RunOnce is idempotent and restart-safe, so a missed or retried
 // run simply converges. Only the tarLocal archive backend is wired in this
 // build; the snapshot backends (§19) are a later integration.
+//
+// --retention-only runs the archive-store half alone (reaper.RunRetention):
+// the CronJob an install without a worlds root gets, so backups past their
+// expiry still leave the store there. It builds no Kubernetes client and reads
+// no world.
 func cmdReaper(args []string, stdout, stderr io.Writer) int {
 	fs := flag.NewFlagSet("reaper", flag.ContinueOnError)
 	fs.SetOutput(stderr)
 	cfgPath := fs.String("config", "/etc/felis/felis.toml", "path to felis.toml")
 	worldsRoot := fs.String("worlds-root", "/worlds", "mount root under which world PVCs are visible (tarLocal: <root>/<pvc>, else the stock local-path <root>/<pv-name>_<ns>_<pvc-name>)")
+	retentionOnly := fs.Bool("retention-only", false, "only expire, read back and sweep the archive store: no server is evaluated and no world is read or deleted, so neither the worlds root nor the Kubernetes API is needed")
 	if err := fs.Parse(args); err != nil {
 		return 2
 	}
@@ -55,13 +61,16 @@ func cmdReaper(args []string, stdout, stderr io.Writer) int {
 
 	ctx := ctrl.SetupSignalHandler()
 
-	scheme := runtime.NewScheme()
-	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
-	utilruntime.Must(v1alpha1.AddToScheme(scheme))
-	cl, err := client.New(ctrl.GetConfigOrDie(), client.Options{Scheme: scheme})
-	if err != nil {
-		fmt.Fprintf(stderr, "felis reaper: build k8s client: %v\n", err)
-		return 1
+	var cl client.Client
+	if !*retentionOnly {
+		scheme := runtime.NewScheme()
+		utilruntime.Must(clientgoscheme.AddToScheme(scheme))
+		utilruntime.Must(v1alpha1.AddToScheme(scheme))
+		cl, err = client.New(ctrl.GetConfigOrDie(), client.Options{Scheme: scheme})
+		if err != nil {
+			fmt.Fprintf(stderr, "felis reaper: build k8s client: %v\n", err)
+			return 1
+		}
 	}
 
 	archiver, err := buildArchiver(ctx, cfg, *worldsRoot, cl)
@@ -80,9 +89,13 @@ func cmdReaper(args []string, stdout, stderr io.Writer) int {
 	r := &reaper.Reaper{
 		Cfg:      rcfg,
 		Store:    reaper.NewPGStore(drv.DB()),
-		Cluster:  reaper.NewK8sCluster(cl, cfg.K8s.Namespace),
 		Archiver: archiver,
 	}
+	if *retentionOnly {
+		fmt.Fprintln(stderr, "felis reaper: retention only — no worlds root is configured, so idle worlds are neither archived nor released")
+		return reportReaperRun(r.RunRetention(ctx), stdout, stderr)
+	}
+	r.Cluster = reaper.NewK8sCluster(cl, cfg.K8s.Namespace)
 
 	// Pre-reap warnings go out by email when [smtp] is configured (the same
 	// relay and password_ref convention felis-api uses); without it the channel
@@ -248,14 +261,20 @@ func reaperConfig(cfg *config.Config) (reaper.Config, error) {
 
 // buildArchiver constructs the WorldArchiver. Only tarLocal is implemented in
 // this build; the resolver maps each world PVC to its directory under worldsRoot
-// (resolveWorldDir).
+// (resolveWorldDir). A nil cl is the retention-only run, which never archives a
+// world, so its archiver resolves none.
 func buildArchiver(ctx context.Context, cfg *config.Config, worldsRoot string, cl client.Client) (backup.WorldArchiver, error) {
 	switch cfg.Archive.Store {
 	case "tarLocal":
-		return &backup.TarLocal{
-			BackupRoot: cfg.Archive.LocalPath,
-			Resolve:    resolveWorldDir(ctx, cl, cfg.K8s.Namespace, worldsRoot),
-		}, nil
+		t := &backup.TarLocal{BackupRoot: cfg.Archive.LocalPath}
+		if cl != nil {
+			t.Resolve = resolveWorldDir(ctx, cl, cfg.K8s.Namespace, worldsRoot)
+		} else {
+			t.Resolve = func(pvc string) (string, error) {
+				return "", fmt.Errorf("resolve world PVC %s: this run has no worlds root (retention only)", pvc)
+			}
+		}
+		return t, nil
 	default:
 		return nil, fmt.Errorf("[archive] store %q is not implemented in this build (only tarLocal)", cfg.Archive.Store)
 	}
diff --git a/deploy/bootstrap.sh b/deploy/bootstrap.sh
index 3fbb066..8074204 100644
--- a/deploy/bootstrap.sh
+++ b/deploy/bootstrap.sh
@@ -95,10 +95,11 @@
 #                     felis.toml [archive] local_path (default: /var/lib/felis/archives)
 #   FELIS_WORLDS_HOST_PATH node directory holding the world volumes (on the k3s this
 #                     installer provisions: /var/lib/rancher/k3s/storage). Setting it
-#                     enables the daily retention reaper, which archives and then deletes
-#                     worlds idle beyond the retention window; the reaper reads that
+#                     lets the daily reaper also archive and then delete worlds idle
+#                     for 15 days (without it the reaper only deletes backups past
+#                     their expiry and leaves every world); the reaper reads that
 #                     root as root, so it keeps k3s's own 0700 root:root
-#                     (default: unset = no reaper)
+#                     (default: unset = worlds are never reaped)
 #   FELIS_REGISTRY_STORAGE / FELIS_UPLOADS_STORAGE / FELIS_BACKUP_STORAGE capacity the
 #                     registry, uploads and world-archive PVCs request on first install
 #                     (defaults: 10Gi, 5Gi, 10Gi). An existing claim keeps its size; on
@@ -172,8 +173,8 @@ FELIS_BACKUP_STORAGE="${FELIS_BACKUP_STORAGE:-}"
 # Retention is opt-in because it DELETES worlds (after a verified archive): point this at the
 # node directory the world volumes live under. On the k3s this installer provisions that is
 # /var/lib/rancher/k3s/storage — the reaper resolves each PVC's local-path directory exactly
-# from its volumeName. Left unset, no reaper CronJob renders and archives accumulate until
-# the backup PVC fills (then backups fail loudly; nothing is deleted).
+# from its volumeName. Left unset, the reaper CronJob renders retention-only: backups past
+# their expiry are still deleted daily, and no world is ever archived or deleted.
 FELIS_WORLDS_HOST_PATH="${FELIS_WORLDS_HOST_PATH:-}"
 # k3s's local-path provisioner root. It appears with the first volume the provisioner
 # creates, which on a fresh install is after the reaper's PV has been applied.
@@ -3462,8 +3463,15 @@ deploy_bundle() {
   else
     manifest_args+=(--backup-pvc=)
   fi
-  # Retention renders only when the operator names where the worlds live; the archive path
-  # always travels with it because it must equal the [archive] local_path written above.
+  # With an archive store the reaper always renders, since backups past their expiry have
+  # to leave it; it reaps idle worlds only when the operator names where the worlds live.
+  # The archive path must equal the [archive] local_path written above.
+  if [ -n "$FELIS_BACKUP_PVC" ]; then
+    manifest_args+=(--archive-local-path "$FELIS_ARCHIVE_LOCAL_PATH")
+    if [ -z "$FELIS_WORLDS_HOST_PATH" ]; then
+      log "idle-world retention is off: the daily reaper deletes expired backups and keeps every world (set FELIS_WORLDS_HOST_PATH=${K3S_STORAGE_ROOT} to reap worlds idle for 15 days)"
+    fi
+  fi
   if [ -n "$FELIS_WORLDS_HOST_PATH" ]; then
     log "retention enabled: the daily reaper will read worlds from ${FELIS_WORLDS_HOST_PATH}"
     # The reaper reads this root as root with DAC_OVERRIDE (platform.reaperPodSecurityContext)
@@ -3478,7 +3486,7 @@ deploy_bundle() {
         warn "worlds root ${FELIS_WORLDS_HOST_PATH} does not exist yet; the reaper CronJob cannot start until it does (hostPath type Directory)"
       fi
     fi
-    manifest_args+=(--worlds-host-path "$FELIS_WORLDS_HOST_PATH" --archive-local-path "$FELIS_ARCHIVE_LOCAL_PATH")
+    manifest_args+=(--worlds-host-path "$FELIS_WORLDS_HOST_PATH")
   fi
   local size
   size="$(pvc_size "$CONTROL_NS" registry "$FELIS_REGISTRY_STORAGE" FELIS_REGISTRY_STORAGE)"
diff --git a/deploy/bootstrap_test.sh b/deploy/bootstrap_test.sh
index bbdaba3..7a1ae62 100644
--- a/deploy/bootstrap_test.sh
+++ b/deploy/bootstrap_test.sh
@@ -949,8 +949,12 @@ run_bundle_flags() { # backup-pvc worlds-host-path
 out="$(run_bundle_flags felis-backups '')"
 expect "a default install asks the renderer for the archive PVC" "--backup-pvc
 felis-backups" "$out"
+# data-durability-17: without a worlds root the reaper still renders, retention-only,
+# so backups past their expiry leave the store; it needs the archive mount for that.
+expect "a default install passes the archive mount so expired backups are deleted" "--archive-local-path
+/var/lib/felis/archives" "$out"
 case "$out" in
-  *--worlds-host-path*) echo "FAIL: no reaper flags may render without FELIS_WORLDS_HOST_PATH"; fails=$((fails + 1)) ;;
+  *--worlds-host-path*) echo "FAIL: no worlds root may render without FELIS_WORLDS_HOST_PATH"; fails=$((fails + 1)) ;;
 esac
 
 expect "a known registry size reaches the renderer" "--registry-storage
@@ -961,6 +965,9 @@ esac
 
 out="$(run_bundle_flags '' '')"
 expect "an emptied FELIS_BACKUP_PVC is the explicit no-backup shape" "--backup-pvc=" "$out"
+case "$out" in
+  *--archive-local-path*) echo "FAIL: no archive mount may be passed without an archive PVC"; fails=$((fails + 1)) ;;
+esac
 # Game server egress excludes every private range already; the node's own public
 # addresses must be excluded too or a server can dial the panel NodePort on them.
 expect "every global node address is denied to game server egress (v4)" "--server-egress-deny-cidr
diff --git a/docs/troubleshooting.md b/docs/troubleshooting.md
index 5dc3afa..cd41605 100644
--- a/docs/troubleshooting.md
+++ b/docs/troubleshooting.md
@@ -756,7 +756,16 @@ Registry manifest rendering is [GO-TESTED]; actual serving is
 
 ## 10. World reaper: false-deletes and skipped backups (spec §18)
 
-The reaper is a **run-once daily CronJob batch**, not an operator controller. It
+The reaper is a **run-once daily CronJob batch**, not an operator controller.
+Every install with an archive store gets it. Without `FELIS_WORLDS_HOST_PATH`
+it runs `felis reaper --retention-only`: it deletes backups past their expiry,
+reads archives back and sweeps the store (the second half of "A failed reaper
+Job" below), never looks at a server, and its summary shows `evaluated=0`. The
+installer says so (`idle-world retention is off`). Setting the worlds root on a
+re-run turns world reaping on. [GO-TESTED: `TestRunRetentionTouchesNoWorld`,
+`TestReaperCronJob_Gating`, `TestReaperCronJob_RetentionOnlyShape`.]
+
+With a worlds root the reaper
 reaps a world only when `now - last_active_at > 15d` (`inactive_15d`); the 15-day
 deadline is **hard-fixed in code** (only `warn_before` / `retention` /
 `max_local_bytes` and the on-demand backup keys `manual_retention` /
diff --git a/internal/platform/bundle.go b/internal/platform/bundle.go
index b205409..0733b8f 100644
--- a/internal/platform/bundle.go
+++ b/internal/platform/bundle.go
@@ -39,9 +39,10 @@ type Object interface {
 // node-pressure eviction shield is the BUILT-IN system-cluster-critical
 // PriorityClass the pod templates reference (workloads.go controlPlanePriorityName),
 // not an object this bundle renders.
-// The reaper CronJob is also part of Workloads, rendered only when the retention
-// storage topology is supplied (WorldsHostPath + BackupPVC + ArchiveLocalPath —
-// workloads.go documents the gate and the shape-asserted hostPath caveat). The
+// The reaper CronJob is also part of Workloads: it reaps worlds when the full
+// storage topology is supplied (WorldsHostPath + BackupPVC + ArchiveLocalPath)
+// and only looks after the archive store when the worlds root is missing
+// (workloads.go documents both gates and the shape-asserted hostPath caveat). The
 // per-server StatefulSet is never a static manifest — the operator renders it at
 // reconcile time (internal/operator).
 func Objects(p Params) []Object {
diff --git a/internal/platform/workloads.go b/internal/platform/workloads.go
index 61911ff..10439c4 100644
--- a/internal/platform/workloads.go
+++ b/internal/platform/workloads.go
@@ -25,17 +25,20 @@ import (
 // workloads_test.go evaluates those correspondences with the SAME selector
 // machinery K8s uses, because no cluster runs here.
 //
-// The reaper CronJob (spec §18 three-clock retention) renders ONLY when the
+// The reaper CronJob (spec §18 three-clock retention) reaps worlds ONLY when the
 // storage topology is supplied — WorldsHostPath + BackupPVC + ArchiveLocalPath,
-// gated by reaperEnabled. It is opt-in-when-configured rather than always-on
+// gated by reaperEnabled. World reaping is opt-in-when-configured rather than always-on
 // because archiving idle worlds means mounting where the worlds physically live,
 // and the spec keeps that open (§18/§19: tarLocal-on-local-path is the starter,
 // Longhorn/snapshot the documented evolution, and they do not share a mount
 // model). The starter model — a node-local worlds-root, exposed through a static
 // hostPath PV and mounted read-only — is the only one coherent with the operator's per-server
 // ReadWriteOnce world PVCs (a shared RWX worlds mount would contradict them), so
-// that is what renders; when the trio is absent no CronJob is emitted, which is
-// the fail-safe choice for a workload that deletes PVCs. The reaper resolver
+// that is what renders; when the trio is absent no world is ever reaped, which is
+// the fail-safe choice for a workload that deletes PVCs. With only the archive
+// store configured (BackupPVC + ArchiveLocalPath) the CronJob still renders, in
+// a retention-only shape that expires, reads back and sweeps backups and never
+// touches a world (retentionEnabled). The reaper resolver
 // (cmd/felis/reaper.resolveWorldDir) finds worlds either as <WorldsHostPath>/<pvc>
 // or in the stock local-path layout k3s writes under its storage root
 // (<pv-name>_<ns>_<pvc-name>, read from the live PVC), so pointing
@@ -249,8 +252,11 @@ func Workloads(p Params) []Object {
 	if p.BackupPVC != "" {
 		objs = append(objs, backupPVC(p))
 	}
-	if reaperEnabled(p) {
+	switch {
+	case reaperEnabled(p):
 		objs = append(objs, worldsRootPV(p), worldsRootPVC(p), reaperCronJob(p))
+	case retentionEnabled(p):
+		objs = append(objs, reaperCronJob(p))
 	}
 	return objs
 }
@@ -289,7 +295,16 @@ const controlPlanePriorityName = "system-cluster-critical"
 // together so a partial configuration fails loudly rather than silently dropping
 // retention here.
 func reaperEnabled(p Params) bool {
-	return p.WorldsHostPath != "" && p.BackupPVC != "" && p.ArchiveLocalPath != ""
+	return p.WorldsHostPath != "" && retentionEnabled(p)
+}
+
+// retentionEnabled reports whether the archive store can be looked after: the
+// backup PVC and the path it must be mounted at. Without a worlds root the
+// same CronJob renders in its retention-only shape (see reaperCronJob), so
+// backups past their expiry still leave the store on an install that never
+// reaps worlds; without it they would pile up until the node's disk filled.
+func retentionEnabled(p Params) bool {
+	return p.BackupPVC != "" && p.ArchiveLocalPath != ""
 }
 
 // APIDeployment renders the felis-api Deployment (spec §7). It runs as the
@@ -600,37 +615,26 @@ func OperatorDeployment(p Params) *appsv1.Deployment {
 // pod loud if the worlds-root is absent, rather than silently creating an empty dir
 // and archiving nothing.
 //
-// Pre-conditions are the caller's: reaperCronJob assumes reaperEnabled(p) — it
-// dereferences WorldsHostPath / BackupPVC / ArchiveLocalPath without re-checking.
+// Retention only. With no WorldsHostPath the same CronJob runs `felis reaper
+// --retention-only`: it expires, reads back and sweeps the archive store and
+// never looks at a server. It then mounts no worlds root, reads no SMTP
+// password (it sends no warnings) and gets no service account token, since it
+// never calls the K8s API. It keeps the reaper's root + DAC_OVERRIDE identity:
+// the archives it reads back and deletes were written by that identity, and by
+// the backup Jobs.
+//
+// Pre-conditions are the caller's: reaperCronJob assumes retentionEnabled(p) —
+// it dereferences BackupPVC / ArchiveLocalPath without re-checking.
 func reaperCronJob(p Params) *batchv1.CronJob {
 	p = p.withDefaults()
 	labels := controlPlanePodLabels(ComponentReaper)
-
 	container := corev1.Container{
 		Name:    ComponentReaper,
 		Image:   p.FelisImage,
 		Command: []string{felisBinaryPath, "reaper"},
-		Args: []string{
-			"--config", configFilePath,
-			"--worlds-root", worldsMountPath,
-		},
-		// The [smtp] relay password for pre-reap warning emails — same optional
-		// Secret felis-api reads. Namespace caveat: a secretKeyRef is
-		// namespace-local, so this resolves against the minecraft-ns felis-smtp
-		// mirror that the "configure email" screen refreshes (the felis-config
-		// mirror it also refreshes is what puts [smtp] in this pod's config).
-		// Absent Secret ⇒ empty env ⇒ the reaper logs suppressed warnings
-		// instead of stamping them (never a failed pod).
-		Env: []corev1.EnvVar{
-			{Name: SMTPPasswordEnv, ValueFrom: &corev1.EnvVarSource{SecretKeyRef: &corev1.SecretKeySelector{
-				LocalObjectReference: corev1.LocalObjectReference{Name: SMTPSecretName},
-				Key:                  SMTPSecretPasswordKey,
-				Optional:             boolPtr(true),
-			}}},
-		},
+		Args:    []string{"--config", configFilePath, "--retention-only"},
 		VolumeMounts: []corev1.VolumeMount{
 			{Name: configVolume, MountPath: configMountPath, ReadOnly: true},
-			{Name: worldsVolume, MountPath: worldsMountPath, ReadOnly: true},
 			{Name: backupVolume, MountPath: p.ArchiveLocalPath},
 			{Name: tmpVolume, MountPath: "/tmp"},
 		},
@@ -645,14 +649,6 @@ func reaperCronJob(p Params) *batchv1.CronJob {
 				Secret: &corev1.SecretVolumeSource{SecretName: configSecretName},
 			},
 		},
-		{
-			Name: worldsVolume,
-			VolumeSource: corev1.VolumeSource{
-				PersistentVolumeClaim: &corev1.PersistentVolumeClaimVolumeSource{
-					ClaimName: worldsRootName(p), ReadOnly: true,
-				},
-			},
-		},
 		{
 			Name: backupVolume,
 			VolumeSource: corev1.VolumeSource{
@@ -662,6 +658,34 @@ func reaperCronJob(p Params) *batchv1.CronJob {
 		{Name: tmpVolume, VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}}},
 	}
 
+	if p.WorldsHostPath != "" {
+		container.Args = []string{"--config", configFilePath, "--worlds-root", worldsMountPath}
+		// The [smtp] relay password for pre-reap warning emails — same optional
+		// Secret felis-api reads. Namespace caveat: a secretKeyRef is
+		// namespace-local, so this resolves against the minecraft-ns felis-smtp
+		// mirror that the "configure email" screen refreshes (the felis-config
+		// mirror it also refreshes is what puts [smtp] in this pod's config).
+		// Absent Secret ⇒ empty env ⇒ the reaper logs suppressed warnings
+		// instead of stamping them (never a failed pod).
+		container.Env = []corev1.EnvVar{
+			{Name: SMTPPasswordEnv, ValueFrom: &corev1.EnvVarSource{SecretKeyRef: &corev1.SecretKeySelector{
+				LocalObjectReference: corev1.LocalObjectReference{Name: SMTPSecretName},
+				Key:                  SMTPSecretPasswordKey,
+				Optional:             boolPtr(true),
+			}}},
+		}
+		container.VolumeMounts = append(container.VolumeMounts,
+			corev1.VolumeMount{Name: worldsVolume, MountPath: worldsMountPath, ReadOnly: true})
+		volumes = append(volumes, corev1.Volume{
+			Name: worldsVolume,
+			VolumeSource: corev1.VolumeSource{
+				PersistentVolumeClaim: &corev1.PersistentVolumeClaimVolumeSource{
+					ClaimName: worldsRootName(p), ReadOnly: true,
+				},
+			},
+		})
+	}
+
 	return &batchv1.CronJob{
 		TypeMeta: metav1.TypeMeta{APIVersion: "batch/v1", Kind: "CronJob"},
 		// The CronJob lives in the MINECRAFT namespace: a Pod can only mount PVCs
@@ -771,7 +795,8 @@ func worldsRootPVC(p Params) *corev1.PersistentVolumeClaim {
 // reaperPodSpec is the reaper Job's pod template. It lives apart from the CronJob
 // literal only so the optional node pin is one visible branch: with ReaperNode
 // set the pod carries a kubernetes.io/hostname selector, keeping the reaper on
-// the node that actually holds the worlds hostPath on a multi-node cluster.
+// the node that actually holds the worlds hostPath on a multi-node cluster. The
+// retention-only shape gets no service account token: it never calls the API.
 func reaperPodSpec(p Params, container corev1.Container, volumes []corev1.Volume) corev1.PodSpec {
 	spec := corev1.PodSpec{
 		ServiceAccountName: SAReaper,
@@ -784,6 +809,9 @@ func reaperPodSpec(p Params, container corev1.Container, volumes []corev1.Volume
 	if p.ReaperNode != "" {
 		spec.NodeSelector = map[string]string{"kubernetes.io/hostname": p.ReaperNode}
 	}
+	if p.WorldsHostPath == "" {
+		spec.AutomountServiceAccountToken = boolPtr(false)
+	}
 	return spec
 }
 
diff --git a/internal/platform/workloads_test.go b/internal/platform/workloads_test.go
index e6a44d3..1fdc67f 100644
--- a/internal/platform/workloads_test.go
+++ b/internal/platform/workloads_test.go
@@ -2,6 +2,7 @@ package platform
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -785,40 +786,83 @@ func reaperParams() Params {
 	return p
 }
 
-// TestReaperCronJob_Gating proves the reaper renders iff all three storage
-// coordinates are present: an incomplete configuration must produce NO CronJob
-// (the partial-flag mistake is rejected at the CLI; here the renderer fails safe).
+// TestReaperCronJob_Gating proves the reaper reaps iff all three storage
+// coordinates are present, and that the archive store alone (backup PVC + its
+// mount path) still renders the CronJob in its retention-only shape, with no
+// worlds-root pair: backups must expire on an install that never reaps worlds.
+// Anything less renders none (the partial-flag mistake is rejected at the CLI;
+// here the renderer fails safe).
 func TestReaperCronJob_Gating(t *testing.T) {
 	cases := []struct {
-		name   string
-		mutate func(p *Params)
-		want   bool
+		name       string
+		mutate     func(p *Params)
+		reap, cron bool
 	}{
-		{"none", func(p *Params) {}, false},
-		{"worlds only", func(p *Params) { p.WorldsHostPath = "/w" }, false},
-		{"worlds+backup", func(p *Params) { p.WorldsHostPath = "/w"; p.BackupPVC = "b" }, false},
-		{"worlds+archive", func(p *Params) { p.WorldsHostPath = "/w"; p.ArchiveLocalPath = "/a" }, false},
-		{"backup+archive (no worlds)", func(p *Params) { p.BackupPVC = "b"; p.ArchiveLocalPath = "/a" }, false},
-		{"all three", func(p *Params) { p.WorldsHostPath = "/w"; p.BackupPVC = "b"; p.ArchiveLocalPath = "/a" }, true},
+		{"none", func(p *Params) {}, false, false},
+		{"worlds only", func(p *Params) { p.WorldsHostPath = "/w" }, false, false},
+		{"worlds+backup", func(p *Params) { p.WorldsHostPath = "/w"; p.BackupPVC = "b" }, false, false},
+		{"worlds+archive", func(p *Params) { p.WorldsHostPath = "/w"; p.ArchiveLocalPath = "/a" }, false, false},
+		{"backup+archive (no worlds)", func(p *Params) { p.BackupPVC = "b"; p.ArchiveLocalPath = "/a" }, false, true},
+		{"all three", func(p *Params) { p.WorldsHostPath = "/w"; p.BackupPVC = "b"; p.ArchiveLocalPath = "/a" }, true, true},
 	}
 	for _, c := range cases {
 		t.Run(c.name, func(t *testing.T) {
 			p := testParams()
 			c.mutate(&p)
-			if got := reaperEnabled(p); got != c.want {
-				t.Errorf("reaperEnabled = %v, want %v", got, c.want)
+			if got := reaperEnabled(p); got != c.reap {
+				t.Errorf("reaperEnabled = %v, want %v", got, c.reap)
 			}
-			cj := findCronJob(Workloads(p))
-			if c.want && cj == nil {
-				t.Error("CronJob must be in Workloads when enabled")
+			objs := Workloads(p)
+			cj := findCronJob(objs)
+			if c.cron != (cj != nil) {
+				t.Fatalf("CronJob rendered = %v, want %v", cj != nil, c.cron)
 			}
-			if !c.want && cj != nil {
-				t.Error("CronJob must NOT be in Workloads when disabled")
+			var pv bool
+			for _, o := range objs {
+				if _, ok := o.(*corev1.PersistentVolume); ok {
+					pv = true
+				}
+			}
+			if pv != c.reap {
+				t.Errorf("worlds-root PV rendered = %v, want %v", pv, c.reap)
+			}
+			if cj != nil {
+				_, ctr := cronPodSpec(t, cj)
+				if got := contains(ctr.Args, "--retention-only"); got == c.reap {
+					t.Errorf("args = %v: --retention-only must be passed exactly when no world is reaped", ctr.Args)
+				}
 			}
 		})
 	}
 }
 
+// TestReaperCronJob_RetentionOnlyShape pins what the store-only run is left
+// with: the config and the archive store, and nothing that reaches a world or
+// the API — no worlds mount, no SMTP password, no service account token.
+func TestReaperCronJob_RetentionOnlyShape(t *testing.T) {
+	p := reaperParams()
+	p.WorldsHostPath = ""
+	ps, c := cronPodSpec(t, reaperCronJob(p))
+	if want := []string{"--config", configFilePath, "--retention-only"}; !reflect.DeepEqual(c.Args, want) {
+		t.Errorf("args = %v, want %v", c.Args, want)
+	}
+	if volumeByName(ps.Volumes, worldsVolume) != nil || mountByName(c.VolumeMounts, worldsVolume) != nil {
+		t.Error("a retention-only run must not mount a worlds root")
+	}
+	if m := mountByName(c.VolumeMounts, backupVolume); m == nil || m.MountPath != p.ArchiveLocalPath || m.ReadOnly {
+		t.Errorf("backup must be mounted read-write at ArchiveLocalPath %q, got %+v", p.ArchiveLocalPath, m)
+	}
+	if len(c.Env) != 0 {
+		t.Errorf("env = %v, want none (it sends no warnings)", c.Env)
+	}
+	if ps.AutomountServiceAccountToken == nil || *ps.AutomountServiceAccountToken {
+		t.Error("a retention-only run never calls the API and must not mount a service account token")
+	}
+	if c.SecurityContext == nil || c.SecurityContext.Capabilities == nil || len(c.SecurityContext.Capabilities.Add) != 1 || c.SecurityContext.Capabilities.Add[0] != "DAC_OVERRIDE" {
+		t.Error("it reads back and deletes archives other identities wrote, so it keeps DAC_OVERRIDE")
+	}
+}
+
 // TestReaperCronJob_NodePin proves the optional multi-node pin: no selector by
 // default (the single-node starter), and exactly the kubernetes.io/hostname
 // selector when ReaperNode names the node holding the worlds hostPath.
diff --git a/internal/reaper/reaper.go b/internal/reaper/reaper.go
index 4dd5633..dc1ed20 100644
--- a/internal/reaper/reaper.go
+++ b/internal/reaper/reaper.go
@@ -413,12 +413,27 @@ func (r *Reaper) RunOnce(ctx context.Context) (Summary, error) {
 		}
 	}
 
-	r.expireBackups(ctx, now, &sum)
-	r.verifyBackups(ctx, now, &sum)
-	r.sweepArchives(ctx, now, &sum)
+	r.retain(ctx, now, &sum)
 	return sum, nil
 }
 
+// RunRetention is the archive-store half of RunOnce on its own: backups past
+// their expiry are deleted, archives are read back, and leftovers are swept,
+// while no server is looked at and no world is touched. It needs no Cluster,
+// which is what lets it run where the worlds are out of reach (an install with
+// no worlds root): backups still leave the store when they expire there.
+func (r *Reaper) RunRetention(ctx context.Context) Summary {
+	var sum Summary
+	r.retain(ctx, r.now(), &sum)
+	return sum
+}
+
+func (r *Reaper) retain(ctx context.Context, now time.Time, sum *Summary) {
+	r.expireBackups(ctx, now, sum)
+	r.verifyBackups(ctx, now, sum)
+	r.sweepArchives(ctx, now, sum)
+}
+
 // evaluate handles one server: exemption, reap, or warning. A returned error
 // means the server was skipped (counted by the caller); nil covers the normal
 // outcomes including "exempt" and "warned".
diff --git a/internal/reaper/reaper_test.go b/internal/reaper/reaper_test.go
index dc2aa61..3493fe7 100644
--- a/internal/reaper/reaper_test.go
+++ b/internal/reaper/reaper_test.go
@@ -1222,3 +1222,30 @@ func TestReapFinishesInterruptedReap(t *testing.T) {
 		t.Fatalf("owner %q audits %+v", st.byName["lambda"].OwnerID, st.audits)
 	}
 }
+
+// data-durability-17: with no worlds root the store is still looked after.
+// RunRetention expires, reads back and sweeps without listing a server or
+// reaching the cluster (nil here, so any call would panic).
+func TestRunRetentionTouchesNoWorld(t *testing.T) {
+	r, st, _, ar := newReaper(DefaultConfig(),
+		Candidate{Name: "idle", OwnerID: "user-1", LastActiveAt: idleBy(40 * Day)})
+	r.Cluster = nil
+	st.listErr = errors.New("servers must not be listed")
+	ca := checking(r, ar)
+	ca.sweepRemoved = []string{"/archives/.x-1.tar.gz.partial"}
+	st.backups = []*fakeBackup{
+		{id: "gone", server: "s1", ref: "ref-gone", size: 5, status: "present", createdAt: idleBy(120 * Day), expires: idleBy(1 * Day)},
+		{id: "keep", server: "s2", ref: "ref-keep", size: 5, status: "present", createdAt: idleBy(10 * Day), expires: testNow.Add(80 * Day)},
+	}
+
+	sum := r.RunRetention(context.Background())
+	if sum.Evaluated != 0 || sum.WorldsReaped != 0 || ar.archives != 0 {
+		t.Fatalf("retention looked at servers: %+v", sum)
+	}
+	if sum.BackupsExpired != 1 || sum.Verified != 1 || sum.Swept != 1 || sum.Failed() {
+		t.Fatalf("summary = %+v, want 1 expired, 1 read back, 1 swept", sum)
+	}
+	if len(ar.deletes) != 1 || ar.deletes[0] != "ref-gone" {
+		t.Fatalf("deleted archives = %v, want [ref-gone]", ar.deletes)
+	}
+}