diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea21356..fecde6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,15 @@ updates (and the old binary's capability probe would read `controllerswap-write`
   `TestSudoersAllowsTheControllerImageVerb`, `TestFelhomOpSudoersPctIsExact`, `TestR861_WriteControllerImageUsesTheRootVerb`,
   `TestControllerSwap_WriteViaRootVerb_NoShell`. Red-proofs: `felhom.eu/documentation/audits/day-2026-10-07/C/`.
 - `README.md`: the controller-swap paragraph described the removed `tee` path — corrected.
+## Unreleased (2026-10-07) — the Proxmox package lane (R-812 option A, `09` §3 decision 163)
+
+**MinAgent impact: none** (a new layer; an older hub ignores the pve report). **The bundle carries the new
+`felhom-os-apply` — deliver it with the binary** (signed `agent_update`, then signed `agent_config_update`).
+
+- `configs/felhom-os-apply`: new layer `pve`, lane `slow` only — the host's Proxmox USERSPACE packages: origin `Proxmox Debian Repository` only (R2), never a kernel / boot / firmware / microcode name (R14, `HOST_SLOW_RE` — the kernel is R-836's lane), no removal (R4), no undo (R5), a new package only from `PVE_NEW_ALLOW` (`proxmox-firewall-data`, measured on demo-felhom; R6 otherwise), an appliance only (R12), authority = a signed `os_pve_step` or the root-owned ring-0 mark (R3). Select `pending-pve` (ring 0): installed Proxmox-origin packages with a pending upgrade. The report carries `pve_manager` (pveversion after the step).
+- `internal/pvegate` (new): the agent's own writes to /etc/pve wait while a pve step runs (pmxcfs restarts); the step waits for writes in flight (bounded, 2 min — then it fails and does not run). Wired at `proxmox.Client.doBody` (every non-GET) and `ExecRunner.RunStdin` (`WritesEtcPVE`: pct config verbs, pvesm, pveum, felhom-pbs-apply create/reconcile).
+- `internal/osupdate`: `LayerPVE`; the night leg runs the pve step in ring 0 after a healthy host step (an appliance; ring 1 never in the night leg); `PVEHealthVerdict` = the host rule + every running container keeps its id + pveversion reads the installed pve-manager; the pve report carries Proxmox userspace only (the hub's candidate set). `PVEStepExecutor` (signed `os_pve_step`, ring 1, under the heavy-op gate and the /etc/pve gate); `reconcile.ClassOSPVEStep` (destructive-class); `felhom-opsign -op os_pve_step` (params by `-params`).
+- Tests: wrapper `PVELane` (17; red first — the `pve-manager` plan was refused R12 on the old code), `pvegate` (5), `TestPVEGate_*` + `TestWritesEtcPVE`, `TestPVE_*`, `TestPVEHealthVerdict`, `TestPVEStepExecutor_*`. Red-proofs: `felhom.eu/documentation/audits/day-2026-10-07/B/`.
 
 ## v0.150.0 — the Docker step proves the engine reports a memory kill; after a restart the agent remembers the last backup per tier; three more SMART counters on the wire (R-528, R-894, R-330; `09` §3 decisions 157, 161) (2026-10-07)
 
diff --git a/REUSE.md b/REUSE.md
index 5134fba..3265fa8 100644
--- a/REUSE.md
+++ b/REUSE.md
@@ -88,6 +88,7 @@
 
 | Symbol | File | Short signature | Use for | Gotchas |
 |---|---|---|---|---|
+| `pvegate.Write` / `pvegate.Step` | internal/pvegate/pvegate.go | `Write(ctx) (release, waited, err)` / `Step(ctx) (end, err)` | R-812 option A: keep the agent's own /etc/pve writes out of a Proxmox package step (pmxcfs restarts) | Already wired at the two chokepoints — `Client.doBody` (every non-GET) and `ExecRunner.RunStdin` (`WritesEtcPVE`: pct config verbs, pvesm, pveum, felhom-pbs-apply create/reconcile). A new root CLI that writes /etc/pve goes into `WritesEtcPVE`, never its own lock. Never take `Step` around anything but the wrapper call (`Leg.runPVE`) — a `Write` inside a `Step` deadlocks until its context ends. |
 | `Client.WaitTask` | internal/proxmox/task.go | `WaitTask(ctx, upid, opts) (TaskStatus, error)` | asserting EVERY mutating op | POST 200 ≠ success; authz can fail at task exec; `AllowWarnings` opt-in |
 | `Client.Pool` | internal/proxmox/query.go | `Pool(ctx, name) (PoolInfo, error)` | felhom-pool membership (the ownership registry, A1) | Needs `Pool.Audit` at `/pool/<name>` (host-install v1.9.0+); `Pool.Allocate` does NOT satisfy the read; members can be storages (type `storage`, vmid 0) — filter them |
 | `Client` mutate wrappers (`RestoreLXC/Vzdump/DestroyLXC/Snapshot/Rollback/SetConfig/ResizeLXC/Start/Stop`) | internal/proxmox/mutate.go | return `(upid, error)` | all API mutations | Async → always pair with WaitTask; route via gate/queue, not ad-hoc |
diff --git a/cmd/felhom-agent/main.go b/cmd/felhom-agent/main.go
index a5ab4d3..ae0bd75 100644
--- a/cmd/felhom-agent/main.go
+++ b/cmd/felhom-agent/main.go
@@ -1109,6 +1109,15 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 			}
 			return release, nil
 		}}
+	// R-812 option A: a signed Proxmox package step (`11` §5.10) — ring 1; under the heavy-op gate and the /etc/pve gate.
+	pveExec := osupdate.PVEStepExecutor{Leg: osLeg, Guest: firstGuest(px),
+		Gate: func(ctx context.Context) (func(), error) {
+			release, busy, ok := heavyOps.TryAcquire("os-pve-step")
+			if !ok {
+				return nil, fmt.Errorf("busy: %s", busy)
+			}
+			return release, nil
+		}}
 	// Agent v0.143.0 (R-840): the config bundle — the box's root-owned files by a signed job; the wrapper verifies it.
 	bundleExec := osupdate.ConfigUpdateExecutor{Leg: osLeg, URLTemplate: suCfg.URLTemplate, Username: suCfg.Username, Token: suCfg.Token,
 		// The capability probe confirms from the agent's side: `sudo -l` lists every command the new sudoers grants.
@@ -1120,7 +1129,7 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 			}
 			logger.Warn("osupdate: capability probe after the config bundle", "ok", ok, "total", total, "degraded", strings.Join(names, ","))
 		}}
-	jobsRunner := signedjobs.NewRunner(client, gate, signedjobs.ExecutorChain{wipeExec, decommExec, updateExec, dockerExec, bundleExec}, cfg.Hub.HostID, logger)
+	jobsRunner := signedjobs.NewRunner(client, gate, signedjobs.ExecutorChain{wipeExec, decommExec, updateExec, dockerExec, pveExec, bundleExec}, cfg.Hub.HostID, logger)
 	loop.SetEnvelopeObserver(hub.MultiObserver(desiredSyncer, jobsRunner))
 
 	// Controller-driven escrow ceremony (v0.88.0): static config facts + the LATE-BOUND DR gate —
diff --git a/cmd/felhom-opsign/main.go b/cmd/felhom-opsign/main.go
index b213499..d62c920 100644
--- a/cmd/felhom-opsign/main.go
+++ b/cmd/felhom-opsign/main.go
@@ -43,7 +43,7 @@ func main() {
 
 func run() error {
 	var (
-		op        = flag.String("op", "", "op class to sign, e.g. storage_wipe | guest_destroy | decommission | agent_update | os_docker_step | agent_config_update")
+		op        = flag.String("op", "", "op class to sign, e.g. storage_wipe | guest_destroy | decommission | agent_update | os_docker_step | os_pve_step | agent_config_update")
 		host      = flag.String("host", "", "target host_id (anti-retarget — the op runs ONLY on this host)")
 		guest     = flag.String("guest", "", "target guest_id (\"\" = host-scoped op)")
 		keyID     = flag.String("key-id", "", "key id of the signing key (must match a pinned agent signer)")
diff --git a/configs/felhom-os-apply b/configs/felhom-os-apply
index 3ac7397..6e2b044 100755
--- a/configs/felhom-os-apply
+++ b/configs/felhom-os-apply
@@ -21,6 +21,11 @@
 # or, for an unsigned ring-0 step, the root-owned TRUST_FILE saying `"ring0_slow_lane": true` (set by hand on the demo
 # boxes only). The agent's own config is NOT trusted for either: the agent can write it. A Docker step also needs
 # `live-restore` ON (R15) — without it every container restarts.
+# Agent v0.151.0 (R-812 option A, `09` §3 decision 163) adds the layer "pve": the HOST's Proxmox USERSPACE packages,
+# lane "slow" only, origin "Proxmox Debian Repository" only, never a kernel / boot / firmware / microcode name (R14 —
+# the kernel is R-836's lane), no removal, no undo, a NEW package only from PVE_NEW_ALLOW, an appliance only (R12), and
+# the same authority as the Docker step (R3: a signed `os_pve_step`, or the root-owned ring-0 mark). Select
+# "pending-pve" (ring 0): every installed Proxmox-origin package with a pending upgrade, minus HOST_SLOW_RE.
 #
 # Modes (plan field "mode"):
 #   inventory   `apt-get update`, then report what is installed (with origin), what is pending, and health.
@@ -100,6 +105,12 @@ HOST_SERVICES = ["pveproxy", "pvedaemon", "pvestatd", "pve-cluster", "felhom-age
 DOCKER_NAMES = ("containerd.io", "docker-buildx-plugin", "docker-ce", "docker-ce-cli", "docker-ce-rootless-extras",
                 "docker-compose-plugin")
 DOCKER_ORIGIN = "Docker CE"
+# The Proxmox package lane (R-812 option A): the origin apt prints for download.proxmox.com, and the ONLY new packages
+# a pve step may add (measured on demo-felhom 2026-10-07: a full upgrade adds proxmox-firewall-data and the kernel;
+# the kernel is refused by R14 whatever this list says).
+PVE_ORIGIN = "Proxmox Debian Repository"
+PVE_NEW_ALLOW = ("proxmox-firewall-data",)
+PVE_SIGNED_OP = "os_pve_step"
 # ROOT-OWNED trust anchors (the installer writes them; the demo boxes got them by hand, R-840). Never the agent's config.
 TRUST_FILE = "/etc/felhom/os-trust.json"          # {"host_id": "...", "ring0_slow_lane": false}
 TRUST_SIGNERS = "/etc/felhom/operator-signers"    # ssh allowed_signers: <key_id> namespaces="felhom-op-v1" <key>
@@ -434,12 +445,14 @@ class Apply:
                 raise Refused("R11", "bundle is a host-layer mode")
             return mode, "host", 0, "bundle"
         layer = plan.get("layer")
-        if layer not in ("guest", "host", "docker"):
-            raise Refused("R12", f"layer {layer!r} is not guest, host or docker")
+        if layer not in ("guest", "host", "docker", "pve"):
+            raise Refused("R12", f"layer {layer!r} is not guest, host, docker or pve")
         lane = plan.get("lane", "fast")
         if layer == "docker" and lane != "slow":
             raise Refused("R3", "the Docker engine is the slow lane (`11` §5.8); a fast-lane Docker plan is refused")
-        if layer != "docker" and lane != "fast":
+        if layer == "pve" and lane != "slow":
+            raise Refused("R3", "the Proxmox packages are the slow lane (`11` §5.10); a fast-lane pve plan is refused")
+        if layer not in ("docker", "pve") and lane != "fast":
             raise Refused("R3", f"the {layer} layer has no slow lane in this release (kernel, Proxmox: `11` §8 step 6)")
         if mode == "facts" and layer != "host":
             raise Refused("R11", "facts is a host-layer mode (it reads the host and the guest)")
@@ -447,7 +460,7 @@ class Apply:
             raise Refused("R11", "live-restore-on is a guest-layer mode")
         if mode == "oom-check" and layer != "docker":
             raise Refused("R11", "oom-check is a docker-layer mode (it checks the guest's Docker engine)")
-        if plan.get("undo") and layer != "docker":
+        if plan.get("undo") and layer != "docker":  # the pve layer has no undo in this release (R-812 option A)
             raise Refused("R5", "an undo (downgrade) exists only for the Docker layer, inside a signed job")
         vmid = plan.get("vmid")
         if not isinstance(vmid, int) or isinstance(vmid, bool) or vmid <= 0:
@@ -458,17 +471,19 @@ class Apply:
         if plan.get("allow_new"):
             raise Refused("R6", "allow_new is a slow-lane field; the fast lane never adds a package")
         select = plan.get("select", "listed")
-        if select not in ("listed", "pending-fast", "pending-docker"):
+        if select not in ("listed", "pending-fast", "pending-docker", "pending-pve"):
             raise Refused("R11", f"unknown select {select!r}")
         if (select == "pending-docker") != (layer == "docker" and select != "listed"):
             if select == "pending-docker" or layer == "docker":
                 raise Refused("R11", f"select {select!r} does not fit layer {layer!r}")
+        if (select == "pending-pve") != (layer == "pve" and select != "listed"):
+            raise Refused("R11", f"select {select!r} does not fit layer {layer!r}")
         pk = plan.get("packages", [])
         if not isinstance(pk, list):
             raise Refused("R11", "packages must be a list")
         if mode == "apply" and select == "listed" and not pk:
             raise Refused("R11", "packages must be a non-empty list in apply mode (select listed)")
-        if select in ("pending-fast", "pending-docker") and pk:
+        if select in ("pending-fast", "pending-docker", "pending-pve") and pk:
             raise Refused("R11", f"select {select} takes no package list")
         seen = set()
         for e in pk:
@@ -488,6 +503,12 @@ class Apply:
                 continue
             if n in DOCKER_NAMES:
                 raise Refused("R2", f"{n} is a Docker package — the slow lane (`11` §5.8), never in a {layer} plan")
+            if layer == "pve":
+                if o != PVE_ORIGIN:
+                    raise Refused("R2", f"{n}: origin {o!r} is not {PVE_ORIGIN!r} (the pve layer)")
+                if HOST_SLOW_RE.match(n):
+                    raise Refused("R14", f"{n} is a kernel / boot / firmware package — never the pve lane (R-836)")
+                continue
             if o not in FAST_ORIGINS:
                 raise Refused("R2", f"{n}: origin {o!r} is not Debian / Debian-Security (the fast lane, `11` C3)")
             if layer == "host" and HOST_SLOW_RE.match(n):
@@ -630,12 +651,13 @@ class Apply:
         now = self.r.now()
         self.r.write_nonces({k: v for k, v in seen.items() if v > now})
 
-    def docker_authority(self, plan):
-        """R3 for the docker layer: returns (who, undo). A signed job binds the EXACT package list and the undo flag."""
+    def docker_authority(self, plan, op_name=SIGNED_OP):
+        """R3 for the docker (and, op_name os_pve_step, the pve) layer: returns (who, undo). A signed job binds the EXACT
+        package list and the undo flag."""
         trust = self.load_trust()
         signed = plan.get("signed")
         if signed:
-            params = self.verify_signed(signed, trust)
+            params = self.verify_signed(signed, trust, op_name=op_name)
             want = sorted(f"{e.get('name')}={e.get('version')}" for e in params.get("packages") or [])
             got = sorted(f"{e['name']}={e['version']}" for e in plan.get("packages", []))
             if not want or want != got:
@@ -649,7 +671,7 @@ class Apply:
             raise Refused("R3", "an undo (downgrade) needs a signed operator job")
         if trust.get("ring0_slow_lane") is True:
             return "ring0", False
-        raise Refused("R3", "a Docker step needs a signed operator job (ring 1) or this box's root-owned ring-0 mark")
+        raise Refused("R3", f"a {self.layer} slow-lane step needs a signed operator job (ring 1) or this box's root-owned ring-0 mark")
 
     def live_restore(self):
         rc, out, _ = self.g(["docker", "info", "--format", "{{.LiveRestoreEnabled}}"], timeout=60)
@@ -795,8 +817,8 @@ class Apply:
 
     # ---------- target helpers ----------
     def x(self, argv, timeout=1800):
-        """Run in the TARGET layer: the guest via pct exec, or the host directly."""
-        if self.layer == "host":
+        """Run in the TARGET layer: the guest via pct exec, or the host directly (host and pve)."""
+        if self.layer in ("host", "pve"):
             return self.r.host(argv, timeout)
         return self.r.guest(self.vmid, argv, timeout)  # guest and docker both live in the customer guest
 
@@ -891,7 +913,7 @@ class Apply:
     def restart_needed(self):
         """Processes still mapping deleted files, OUTSIDE containers (C11). Guest: outside docker; host: outside the
         LXC guests (the host's /proc shows guest processes too)."""
-        skip = RESTART_SKIP_CGROUP["host" if self.layer == "host" else "guest"]
+        skip = RESTART_SKIP_CGROUP["host" if self.layer in ("host", "pve") else "guest"]
         script = ('for p in /proc/[0-9]*; do grep -q "(deleted)" $p/maps 2>/dev/null || continue; '
                   'grep -q "%s" $p/cgroup 2>/dev/null && continue; echo "${p#/proc/} $(cat $p/comm 2>/dev/null)"; done' % skip)
         rc, out, _ = self.x(["sh", "-c", script], timeout=120)
@@ -965,7 +987,7 @@ class Apply:
             return Bundle(self).from_plan(plan)
         if self.mode == "agent_update":
             return self.agent_update(plan)
-        if self.layer == "host":
+        if self.layer in ("host", "pve"):
             self.check_appliance()
         self.check_guest(self.vmid)
         log = self.r.log
@@ -976,6 +998,9 @@ class Apply:
             self.report["oom_check"] = self.oom_check()
             return 0
         self.who, self.allow_downgrade = ("fast", False)
+        if self.layer == "pve" and self.mode == "apply":
+            self.who, self.allow_downgrade = self.docker_authority(plan, op_name=PVE_SIGNED_OP)
+            self.report["authority"] = self.who
         if self.layer == "docker" and self.mode == "apply":
             self.who, self.allow_downgrade = self.docker_authority(plan)
             if self.live_restore() != "true":
@@ -988,7 +1013,7 @@ class Apply:
         log(f"os-apply: START release={plan.get('release_id')} layer={self.layer}" +
             (f":{self.vmid}" if self.layer != "host" else "") +
             f" lane={plan.get('lane', 'fast')} mode={self.mode} select={self.select} packages={len(plan.get('packages', []))}" +
-            (f" authority={self.who}{' UNDO' if self.allow_downgrade else ''}" if self.layer == "docker" else ""))
+            (f" authority={self.who}{' UNDO' if self.allow_downgrade else ''}" if self.layer in ("docker", "pve") else ""))
         if self.apt_lock_held():
             raise Refused("R9", f"another apt/dpkg holds the lock on the {self.layer}")
         self.report["health_before"] = self.health()
@@ -1012,6 +1037,8 @@ class Apply:
         if self.layer == "docker":
             rc_v, out_v, _ = self.g(["docker", "version", "--format", "{{.Server.Version}}"], timeout=60)
             self.report["docker_engine"] = out_v.strip() if rc_v == 0 and out_v.strip() else "unknown"
+        if self.layer == "pve":
+            self.report["pve_manager"] = self.pve_manager()
         self.report["reboot_scanned"] = "reboot_needed" in self.report
         self.report["health_after"] = self.health()
         if self.layer == "docker" and self.mode == "apply":
@@ -1161,10 +1188,26 @@ class Apply:
         return [{"name": p["name"], "version": p["to"], "origin": DOCKER_ORIGIN} for p in pend
                 if p["from"] is not None and p["name"] in DOCKER_NAMES and self.origin_name(p["origin"]) == {DOCKER_ORIGIN}]
 
+    def pending_pve(self):
+        """Ring 0 (select pending-pve): the newest pending version of each INSTALLED Proxmox-origin package, never a
+        kernel / boot / firmware / microcode name (HOST_SLOW_RE, R-836's lane), never another origin."""
+        rc, pend, remv, _ = self.simulate(["dist-upgrade"])
+        return [{"name": p["name"], "version": p["to"], "origin": PVE_ORIGIN} for p in pend
+                if p["from"] is not None and not HOST_SLOW_RE.match(p["name"]) and p["name"] not in DOCKER_NAMES
+                and self.origin_name(p["origin"]) == {PVE_ORIGIN}]
+
+    def pve_manager(self):
+        """pveversion's pve-manager version ("unknown" when it cannot be read)."""
+        rc, out, _ = self.r.host(["pveversion"], 60)
+        m = re.match(r"^pve-manager/([^/\s]+)", out.strip()) if rc == 0 else None
+        return m.group(1) if m else "unknown"
+
     def origin_ok(self, origin):
         o = self.origin_name(origin)
         if self.layer == "docker":
             return o == {DOCKER_ORIGIN}
+        if self.layer == "pve":
+            return o == {PVE_ORIGIN}
         return bool(o & set(FAST_ORIGINS))
 
     def apply(self, plan):
@@ -1173,6 +1216,8 @@ class Apply:
             packages = plan["packages"]
         elif self.select == "pending-docker":
             packages = self.pending_docker()
+        elif self.select == "pending-pve":
+            packages = self.pending_pve()
         else:
             packages = self.pending_fast()
         cmp_op = "ne" if self.allow_downgrade else "gt"
@@ -1221,6 +1266,11 @@ class Apply:
                 raise Refused("R4", f"the plan would remove {', '.join(remv[:5])}")
             want = dict(upgrade)
             for p in sim:
+                if p["from"] is None and self.layer == "pve" and p["name"] in PVE_NEW_ALLOW and self.origin_ok(p["origin"]) \
+                        and not HOST_SLOW_RE.match(p["name"]):
+                    self.r.log(f"os-apply: NEW {p['name']}={p['to']} (on the pve lane's allow-list)")
+                    self.report.setdefault("added", []).append({"name": p["name"], "version": p["to"]})
+                    continue
                 if p["from"] is None:
                     raise Refused("R6", f"the plan would add a package that is not installed: {p['name']}")
                 if p["name"] not in want:
@@ -1231,7 +1281,7 @@ class Apply:
                     raise Refused("R5", f"{p['name']} would be downgraded {p['from']} -> {p['to']}")
                 if not self.origin_ok(p["origin"]):
                     raise Refused("R2", f"{p['name']} would come from {p['origin']}, not the {self.layer} layer's origin")
-                if self.layer == "host" and HOST_SLOW_RE.match(p["name"]):
+                if self.layer in ("host", "pve") and HOST_SLOW_RE.match(p["name"]):
                     raise Refused("R14", f"{p['name']} is a kernel / boot / firmware package — the host's slow lane")
             need = self.download_bytes(args)
             free = self.free_bytes()
diff --git a/configs/test_felhom_os_apply.py b/configs/test_felhom_os_apply.py
index c9e1805..0b40aa3 100644
--- a/configs/test_felhom_os_apply.py
+++ b/configs/test_felhom_os_apply.py
@@ -232,6 +232,8 @@ class Fake:
             return (0, self.daemon_json, "") if self.daemon_json is not None else (1, "", "No such file")
         if cmd == "cat" and a[1] == "/etc/debian_version":
             return 0, "13.7\n", ""
+        if cmd == "pveversion":
+            return 0, f"pve-manager/{self.installed.get('pve-manager', '9.2.2')}/abcdef (running kernel: 7.0.14-20-pve)\n", ""
         if cmd == "uname":
             return 0, "7.0.14-20-pve\n", ""
         if cmd == "apt-mark":
@@ -284,7 +286,7 @@ class Fake:
                 n, v = x.split("=", 1)
                 if v not in self.avail(n):
                     return 100, "", f"E: Version '{v}' for '{n}' was not found"
-                origin = "Docker CE:trixie" if n in osapply.DOCKER_NAMES else SEC if n == "openssl" else DEB
+                origin = getattr(self, "origins", {}).get(n) or ("Docker CE:trixie" if n in osapply.DOCKER_NAMES else SEC if n == "openssl" else DEB)
                 out += f"Inst {n} [{self.installed[n]}] ({v} {origin} [amd64])\n"
         out += "".join(l + "\n" for l in self.extra_sim)
         return 0, out, ""
@@ -1324,5 +1326,155 @@ class OOMCheck(unittest.TestCase):
         self.assertEqual((rc, rep["refused"]["code"]), (2, "R11"), rep)
 
 
+PVE = "Proxmox Debian Repository:stable"
+PVE_SET = [{"name": "pve-manager", "version": "9.2.21", "origin": "Proxmox Debian Repository"},
+           {"name": "libpve-common-perl", "version": "9.1.9", "origin": "Proxmox Debian Repository"}]
+
+
+def pve_fake(signed=None, ring0=False):
+    f = Fake()
+    f.installed.update({"pve-manager": "9.2.2", "libpve-common-perl": "9.1.1", "proxmox-kernel-helper": "9.0.4"})
+    f.live["pve-manager"] = {"9.2.21", "9.2.2"}
+    f.live["libpve-common-perl"] = {"9.1.9", "9.1.1"}
+    f.origins = {"pve-manager": PVE, "libpve-common-perl": PVE, "proxmox-kernel-helper": PVE, "shim-signed": PVE,
+                 "proxmox-firewall-data": PVE}
+    f.plan = {"release_id": "os-pve-t1", "layer": "pve", "lane": "slow", "vmid": 9201, "mode": "apply",
+              "packages": [dict(p) for p in PVE_SET]}
+    if ring0:
+        f.files[osapply.TRUST_FILE] = json.dumps({"host_id": "demo-hp-bb76ea", "ring0_slow_lane": True})
+    if signed is not None:
+        f.plan["signed"] = signed
+    return f
+
+
+class PVELane(unittest.TestCase):
+    """R-812 option A (`09` §3 decision 163): the host's Proxmox USERSPACE packages, slow lane, no kernel / boot /
+    firmware / microcode (R14), no removal, a new package only from PVE_NEW_ALLOW. Red-proof: audits/day-2026-10-07/B/."""
+
+    def refused(self, f, code):
+        rc, rep = run(f)
+        self.assertEqual(rc, 2, rep)
+        self.assertEqual(rep["refused"]["code"], code, rep)
+        self.assertEqual(f.installed["pve-manager"], "9.2.2", "nothing may be installed on a refusal")
+        return rep
+
+    # THE RED TEST (design-R-812 §5): before the pve layer existed this plan was refused R12.
+    def test_pve_manager_plan_is_installed_on_the_host(self):
+        f = pve_fake(signed=signed_job(packages=PVE_SET, op="os_pve_step"))
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(f.installed["pve-manager"], "9.2.21")
+        self.assertEqual(rep["authority"], "signed")
+        self.assertEqual(rep["pve_manager"], "9.2.21", "pveversion after the step is reported")
+        inst = [c for c in f.calls if c[0] == "host" and "install" in c[1] and "-s" not in c[1] and "-f" not in c[1]
+                and "--print-uris" not in c[1]]
+        self.assertTrue(inst, "the pve layer installs on the HOST")
+        self.assertFalse([c for c in f.calls if c[0] == "guest" and "install" in c[2]], "nothing installed in the guest")
+        self.assertEqual(sorted(rep["health_after"]["host_services"]), sorted(osapply.HOST_SERVICES))
+
+    def test_kernel_in_a_pve_plan_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.plan["packages"].append({"name": "proxmox-kernel-7.0", "version": "7.0.14-20", "origin": "Proxmox Debian Repository"})
+        self.refused(f, "R14")
+
+    def test_shim_in_a_pve_plan_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.plan["packages"].append({"name": "shim-signed", "version": "1.47+pmx1", "origin": "Proxmox Debian Repository"})
+        self.refused(f, "R14")
+
+    def test_kernel_pulled_in_by_the_simulation_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.installed["proxmox-kernel-helper"] = "9.0.4"
+        f.extra_sim = ["Inst proxmox-kernel-helper [9.0.4] (9.0.6 Proxmox Debian Repository:stable [all])"]
+        self.refused(f, "R6")  # not in the plan — refused before the name check; R14 below when it IS in the plan
+        g = pve_fake(ring0=True)
+        g.live["proxmox-kernel-helper"] = {"9.0.6"}
+        g.plan["packages"] = [dict(PVE_SET[0])]
+        g.extra_sim = ["Inst proxmox-kernel-helper [9.0.4] (9.0.6 Proxmox Debian Repository:stable [all])"]
+        # a kernel-helper the plan did not name is R6; the R14 name check covers a listed one (test above)
+        self.refused(g, "R6")
+
+    def test_debian_package_in_a_pve_plan_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.plan["packages"].append({"name": "libc6", "version": "2.41-12+deb13u4", "origin": "Debian"})
+        self.refused(f, "R2")
+
+    def test_debian_origin_in_the_pve_simulation_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.origins["libpve-common-perl"] = DEB
+        self.refused(f, "R2")
+
+    def test_docker_package_in_a_pve_plan_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.plan["packages"].append({"name": "docker-ce", "version": "5:29.8.2-1~debian.13~trixie", "origin": "Proxmox Debian Repository"})
+        self.refused(f, "R2")
+
+    def test_pve_in_the_fast_lane_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.plan["lane"] = "fast"
+        self.refused(f, "R3")
+
+    def test_no_authority_is_refused(self):
+        self.refused(pve_fake(), "R3")
+
+    def test_docker_signed_op_does_not_authorize_a_pve_step(self):
+        self.refused(pve_fake(signed=signed_job(packages=PVE_SET, op="os_docker_step")), "R3")
+
+    def test_pve_on_a_byo_box_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.files[osapply.INSTALL_STATE] = json.dumps({"mode": "byo"})
+        self.refused(f, "R12")
+
+    def test_unlisted_new_package_is_refused(self):
+        f = pve_fake(ring0=True)
+        f.extra_sim = ["Inst proxmox-new-thing (1.0 Proxmox Debian Repository:stable [all])"]
+        self.refused(f, "R6")
+
+    def test_allow_listed_new_package_is_accepted(self):
+        f = pve_fake(ring0=True)
+        f.extra_sim = ["Inst proxmox-firewall-data (0.1 Proxmox Debian Repository:stable [all])"]
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(f.installed["pve-manager"], "9.2.21")
+
+    def test_allow_new_is_never_an_open_door_in_the_fast_lane(self):
+        f = Fake()
+        f.plan["layer"] = "host"
+        f.extra_sim = ["Inst proxmox-firewall-data (0.1 Proxmox Debian Repository:stable [all])"]
+        rc, rep = run(f)
+        self.assertEqual((rc, rep["refused"]["code"]), (2, "R6"), rep)
+
+    def test_undo_is_refused(self):
+        f = pve_fake(signed=signed_job(packages=PVE_SET, op="os_pve_step"))
+        f.plan["undo"] = True
+        self.refused(f, "R5")
+
+    def test_ring0_pending_pve_takes_only_installed_proxmox_userspace(self):
+        f = pve_fake(ring0=True)
+        f.plan["select"], f.plan["packages"] = "pending-pve", []
+        f.installed.update({"linux-image-amd64": "6.12.1", "tailscale": "1.102.2"})
+        f.pending_sim = [
+            "Inst pve-manager [9.2.2] (9.2.21 Proxmox Debian Repository:stable [amd64])",
+            "Inst libpve-common-perl [9.1.1] (9.1.9 Proxmox Debian Repository:stable [all])",
+            "Inst proxmox-kernel-helper [9.0.4] (9.0.6 Proxmox Debian Repository:stable [all])",
+            "Inst proxmox-kernel-7.0.14-20-pve-signed (7.0.14-20 Proxmox Debian Repository:stable [amd64])",
+            "Inst proxmox-firewall-data (0.1 Proxmox Debian Repository:stable [all])",
+            "Inst libc6 [2.41-12+deb13u3] (2.41-12+deb13u4 Debian:13.7/stable [amd64])",
+            "Inst tailscale [1.102.2] (1.102.5 Tailscale:pkgs.tailscale.com [amd64])",
+        ]
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(rep["authority"], "ring0")
+        self.assertEqual(sorted(u["name"] for u in rep["upgraded"]), ["libpve-common-perl", "pve-manager"],
+                         "pending-pve: installed, Proxmox-origin, never kernel/boot/firmware, never Debian or other origins")
+        self.assertEqual(f.installed["libc6"], "2.41-12+deb13u3")
+
+    def test_select_pending_pve_needs_the_pve_layer(self):
+        f = Fake()
+        f.plan["layer"], f.plan["select"], f.plan["packages"] = "host", "pending-pve", []
+        rc, rep = run(f)
+        self.assertEqual((rc, rep["refused"]["code"]), (2, "R11"), rep)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/internal/osupdate/leg.go b/internal/osupdate/leg.go
index 6d18b4a..49f029e 100644
--- a/internal/osupdate/leg.go
+++ b/internal/osupdate/leg.go
@@ -20,6 +20,7 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
+	"regexp"
 	"sort"
 	"strings"
 	"sync"
@@ -27,6 +28,7 @@ import (
 
 	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
 )
 
 // WrapperPath is the pinned sudoers vector (configs/felhom-agent.sudoers FELHOM_OSAPPLY).
@@ -40,8 +42,21 @@ const (
 	LayerGuest  = "guest"
 	LayerHost   = "host"
 	LayerDocker = "docker" // the guest's Docker engine set — slow lane (`11` §5.8)
+	// LayerPVE is the HOST's Proxmox userspace packages — slow lane (R-812 option A, `09` §3 decision 163, `11` §5.10):
+	// ring 0 in the night leg after a healthy host step, ring 1 only inside a signed os_pve_step. Never a kernel.
+	LayerPVE = "pve"
 )
 
+// PVEOrigin is the origin apt prints for download.proxmox.com (the wrapper's PVE_ORIGIN); InstalledPVEOrigin is how
+// the wrapper's inventory names the same source.
+const (
+	PVEOrigin          = "Proxmox Debian Repository"
+	InstalledPVEOrigin = "Proxmox"
+)
+
+// hostSlowRE mirrors the wrapper's HOST_SLOW_RE: kernel, boot, firmware and microcode names never ride the pve lane.
+var hostSlowRE = regexp.MustCompile(`^(linux-(image|headers|kbuild|modules|base)|proxmox-kernel|proxmox-default-kernel|pve-kernel|pve-firmware|firmware-|grub|shim|systemd-boot|intel-microcode|amd64-microcode|efibootmgr)`)
+
 // DockerNames are the six packages of the Docker engine set (the wrapper's DOCKER_NAMES).
 var DockerNames = map[string]bool{"containerd.io": true, "docker-buildx-plugin": true, "docker-ce": true,
 	"docker-ce-cli": true, "docker-ce-rootless-extras": true, "docker-compose-plugin": true}
@@ -109,6 +124,8 @@ type WrapperReport struct {
 	// OOMCheck (R-528, `09` decision 157): the docker layer's memory-kill check, {result, oom_killed, oom_event,
 	// exit_code, image, detail}. Carried to the hub UNCHANGED; the agent never reads it.
 	OOMCheck json.RawMessage `json:"oom_check"`
+	// PVEManager: the pve layer — pveversion's pve-manager version after the step ("unknown" = unreadable).
+	PVEManager string `json:"pve_manager"`
 	// R-868 (v0.144.0): the agent's ids, echoed from the plan, so a report kept on disk can be sent without the
 	// agent process that started the pass. ReleaseID / VMID were always in the report.
 	RunID     string `json:"run_id"`
@@ -149,6 +166,8 @@ type Report struct {
 	// OOMCheck: docker layer — the wrapper's oom_check object, byte-for-byte (R-528; the hub decides approval on it).
 	// Pinned by TestDocker_OOMCheckReachesTheHubUnchanged and TestR868_KeptCopyCarriesTheOOMCheck.
 	OOMCheck json.RawMessage `json:"oom_check,omitempty"`
+	// PVEManager: pve layer — pve-manager's version after the step (the hub's System page; R-812 option A).
+	PVEManager string `json:"pve_manager,omitempty"`
 
 	unsent string // R-868: the wrapper's kept copy of this pass's report — deleted once the hub has it
 }
@@ -386,6 +405,36 @@ func EngineOf(pkgVersion string) string {
 	return v
 }
 
+// PVEHealthVerdict is THE Proxmox-package-step health rule (R-812 option A; pinned by TestPVEHealthVerdict): the host
+// rule (every host service active, the guest running and healthy, the tunnel running), plus every container running at
+// the start still runs as the SAME container (a Proxmox step must not restart the household's apps), plus pveversion
+// now reports the pve-manager the step installed (wantPVE "" = pve-manager was not in the step).
+func PVEHealthVerdict(before, after *Health, tunnel, wantPVE, gotPVE string) (bool, string) {
+	if ok, why := HostHealthVerdict(before, after, tunnel); !ok {
+		return false, why
+	}
+	if before != nil && before.Guest != nil && after.Guest != nil {
+		names := make([]string, 0, len(before.Guest.Containers))
+		for n := range before.Guest.Containers {
+			names = append(names, n)
+		}
+		sort.Strings(names)
+		for _, n := range names {
+			b := before.Guest.Containers[n]
+			if b.State != "running" || b.ID == "" {
+				continue
+			}
+			if a := after.Guest.Containers[n]; a.ID != b.ID {
+				return false, n + " is a new container (id changed) — the Proxmox step restarted the household's app"
+			}
+		}
+	}
+	if wantPVE != "" && gotPVE != wantPVE {
+		return false, "pveversion reads pve-manager " + gotPVE + ", not " + wantPVE
+	}
+	return true, ""
+}
+
 // DockerHealthVerdict is THE Docker-step health rule (`11` §5.8; pinned by TestDockerHealthVerdict): the guest rule,
 // plus every container running at the start still runs as the SAME container (same id — a changed id means the
 // household's apps restarted, which `live-restore` exists to prevent), plus the engine now reports the version the step
@@ -451,7 +500,7 @@ func (l *Leg) call(ctx context.Context, runID string, plan map[string]any) (Wrap
 
 // Pass is one leg's reports; an empty Layer means the step did not run.
 type Pass struct {
-	Guest, Host, Docker Report
+	Guest, Host, Docker, PVE Report
 }
 
 // Run is one pass: the guest layer, then (on an appliance, after a good guest step) the host layer, then (ring 0
@@ -479,13 +528,44 @@ func (l *Leg) Run(ctx context.Context, vmid int, trigger string) Pass {
 		if err := l.EnsureLiveRestore(ctx, g.RunID, vmid); err != nil {
 			p.Docker = l.finish(ctx, lg, Report{RunID: g.RunID, Layer: LayerDocker, Trigger: trigger, Ring: 0, VMID: vmid,
 				Mode: "apply", Outcome: "failed", HealthReason: "live-restore could not be turned on: " + err.Error()})
-			return p
+		} else {
+			p.Docker = l.runLayer(ctx, g.RunID, LayerDocker, vmid, trigger, blk, dockerOpts{})
 		}
-		p.Docker = l.runLayer(ctx, g.RunID, LayerDocker, vmid, trigger, blk, dockerOpts{})
+	}
+	// R-812 option A: the Proxmox package step — ring 0, an appliance, after a HEALTHY host step (it is a host change).
+	// A Docker step's outcome does not gate it (the Docker set lives in the guest). Pinned by TestPVE_*.
+	switch {
+	case blk.Ring != 0 || !blk.Enabled:
+		lg.Info("osupdate: pve step skipped — ring 1 takes a Proxmox set only inside a signed operator job (`11` §5.10)", "ring", blk.Ring, "enabled", blk.Enabled)
+	case !l.Appliance || h.Layer == "" || !okStep(h):
+		lg.Info("osupdate: pve step skipped — no healthy host step this pass (an appliance only)", "appliance", l.Appliance, "host_outcome", h.Outcome)
+	default:
+		p.PVE = l.runPVE(ctx, g.RunID, vmid, trigger, blk, dockerOpts{})
 	}
 	return p
 }
 
+// pveDrainWait bounds how long a pve step waits for the agent's own /etc/pve writes in flight (pvegate).
+var pveDrainWait = 2 * time.Minute
+
+// runPVE runs the pve layer while holding pvegate: the agent's own /etc/pve writes wait until it ends.
+func (l *Leg) runPVE(ctx context.Context, runID string, vmid int, trigger string, blk hub.WireOSUpdate, do dockerOpts) Report {
+	lg := l.log().With("run", runID, "layer", LayerPVE, "vmid", vmid, "trigger", trigger)
+	dctx, cancel := context.WithTimeout(ctx, pveDrainWait)
+	end, err := pvegate.Step(dctx)
+	cancel()
+	if err != nil {
+		return l.finish(ctx, lg, Report{RunID: runID, Layer: LayerPVE, Trigger: trigger, Ring: blk.Ring, VMID: vmid, Mode: "apply",
+			ReleaseID: do.releaseID, Outcome: "failed", HealthReason: "an agent write to /etc/pve did not finish in time (pvegate): " + err.Error()})
+	}
+	lg.Info("osupdate: pve step holds the /etc/pve write gate — the agent's own writes wait until it ends")
+	defer func() {
+		end()
+		lg.Info("osupdate: pve step released the /etc/pve write gate")
+	}()
+	return l.runLayer(ctx, runID, LayerPVE, vmid, trigger, blk, do)
+}
+
 // dockerOpts is a signed Docker step (DockerStepExecutor); the zero value is ring 0's unsigned "pending-docker".
 type dockerOpts struct {
 	releaseID string
@@ -571,7 +651,7 @@ func (l *Leg) runLayer(ctx context.Context, runID, layer string, vmid int, trigg
 		wire = blk.HostRelease
 	}
 	lane := "fast"
-	if layer == LayerDocker {
+	if layer == LayerDocker || layer == LayerPVE {
 		lane = "slow"
 		if do.signed != nil {
 			rel = hub.WireOSRelease{ID: do.releaseID}
@@ -604,6 +684,13 @@ func (l *Leg) runLayer(ctx context.Context, runID, layer string, vmid int, trigg
 		}
 	case layer == LayerDocker:
 		plan["select"] = "pending-docker" // ring 0: the wrapper checks the box's ROOT-OWNED ring-0 mark itself
+	case layer == LayerPVE && do.signed != nil:
+		plan["packages"], plan["signed"] = do.packages, do.signed
+		for _, p := range do.packages {
+			planned[p.Name] = true
+		}
+	case layer == LayerPVE:
+		plan["select"] = "pending-pve" // ring 0: the same root-owned mark; the wrapper picks installed Proxmox userspace
 	case !blk.Enabled:
 		plan["mode"] = "inventory"
 		lg.Info("osupdate: switched OFF for this box — reporting only")
@@ -637,6 +724,7 @@ func (l *Leg) runLayer(ctx context.Context, runID, layer string, vmid int, trigg
 	rep.Upgraded, rep.PassSeconds = wr.Upgraded, wr.PassSeconds
 	rep.DockerEngine, rep.Authority, rep.Undo = wr.DockerEngine, wr.Authority, wr.Undo
 	rep.OOMCheck = rawOrNil(wr.OOMCheck)
+	rep.PVEManager = wr.PVEManager
 	if rep.Outcome == "" {
 		switch {
 		case rep.Mode == "inventory" && !blk.Enabled:
@@ -654,21 +742,27 @@ func (l *Leg) runLayer(ctx context.Context, runID, layer string, vmid int, trigg
 	}
 	// Health: compare with the start of the pass; give restarted services time (only after an install).
 	cur := wr.HealthAfter
-	wantEngine := ""
+	wantEngine, wantPVE := "", ""
 	for _, u := range wr.Upgraded {
 		if u.Name == "docker-ce" {
 			wantEngine = EngineOf(u.Version)
 		}
+		if u.Name == "pve-manager" {
+			wantPVE = u.Version
+		}
 	}
 	verdict := func(h *Health) (bool, string) {
 		if layer == LayerDocker {
 			return DockerHealthVerdict(wr.HealthBefore, h, wantEngine, wr.DockerEngine)
 		}
-		if layer == LayerHost {
+		if layer == LayerHost || layer == LayerPVE {
 			t := hub.TunnelUnknown
 			if l.Tunnel != nil {
 				t, _ = l.Tunnel.Status(ctx)
 			}
+			if layer == LayerPVE {
+				return PVEHealthVerdict(wr.HealthBefore, h, t, wantPVE, wr.PVEManager)
+			}
 			return HostHealthVerdict(wr.HealthBefore, h, t)
 		}
 		return HealthVerdict(wr.HealthBefore, h)
@@ -708,6 +802,10 @@ func (l *Leg) runLayer(ctx context.Context, runID, layer string, vmid int, trigg
 		// the docker report carries the engine set only (the guest report already carries the Debian packages)
 		rep.Installed, rep.Pending = onlyDocker(wr.Installed), onlyDockerPending(wr.Pending)
 		rep.NotCovered = nil
+	} else if layer == LayerPVE {
+		// the pve report carries the Proxmox userspace set only — the hub's candidate is built from it
+		rep.Installed, rep.Pending = onlyPVE(wr.Installed), onlyPVEPending(wr.Pending)
+		rep.NotCovered = nil
 	} else {
 		rep.NotCovered = notCovered(wr.Pending, blk.Ring, planned)
 	}
@@ -732,6 +830,33 @@ func onlyDocker(in []Package) []Package {
 	return out
 }
 
+// onlyPVE keeps the installed Proxmox-origin packages the pve lane may touch (never a kernel / boot / firmware name).
+func onlyPVE(in []Package) []Package {
+	var out []Package
+	for _, p := range in {
+		if (p.Origin == InstalledPVEOrigin || p.Origin == PVEOrigin) && !hostSlowRE.MatchString(p.Name) && !DockerNames[p.Name] {
+			out = append(out, p)
+		}
+	}
+	return out
+}
+
+func onlyPVEPending(in []Pending) []Pending {
+	var out []Pending
+	for _, p := range in {
+		if p.From == "" || hostSlowRE.MatchString(p.Name) || DockerNames[p.Name] {
+			continue
+		}
+		for _, o := range p.Origin {
+			if o == PVEOrigin {
+				out = append(out, p)
+				break
+			}
+		}
+	}
+	return out
+}
+
 func onlyDockerPending(in []Pending) []Pending {
 	var out []Pending
 	for _, p := range in {
diff --git a/internal/osupdate/leg_test.go b/internal/osupdate/leg_test.go
index 739b35e..e21512d 100644
--- a/internal/osupdate/leg_test.go
+++ b/internal/osupdate/leg_test.go
@@ -13,16 +13,18 @@ import (
 	"time"
 
 	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
 )
 
 // fakeWrapper plays /usr/local/sbin/felhom-os-apply: it reads the plan the leg wrote and answers per layer and mode.
 type fakeWrapper struct {
-	t         *testing.T
-	pending   []Pending
-	applyRep  map[string]WrapperReport // per layer
-	healthSeq map[string][]*Health     // per layer: answers to successive "health" calls
-	plans     []map[string]any
-	keep      bool // R-868: like the real wrapper, keep an apply report beside the plan
+	t           *testing.T
+	pending     []Pending
+	applyRep    map[string]WrapperReport // per layer
+	healthSeq   map[string][]*Health     // per layer: answers to successive "health" calls
+	plans       []map[string]any
+	keep        bool // R-868: like the real wrapper, keep an apply report beside the plan
+	pveGateHeld bool
 }
 
 func yes() *bool { b := true; return &b }
@@ -50,9 +52,12 @@ func (f *fakeWrapper) Run(_ context.Context, name string, args ...string) ([]byt
 	f.plans = append(f.plans, plan)
 	layer := plan["layer"].(string)
 	ok := guestOK()
-	if layer == LayerHost {
+	if layer == LayerHost || layer == LayerPVE {
 		ok = hostOK()
 	}
+	if layer == LayerPVE && plan["mode"] == "apply" {
+		f.pveGateHeld = pvegate.Stepping() // R-812: the /etc/pve write gate must be held while the pve step runs
+	}
 	var rep WrapperReport
 	switch plan["mode"] {
 	case "inventory":
@@ -160,8 +165,8 @@ func TestRing0_OneCallPerLayer(t *testing.T) {
 	if g.Outcome != "applied" || !g.Healthy || ho.Outcome != "applied" || !ho.Healthy {
 		t.Fatalf("guest %+v\nhost %+v", g, ho)
 	}
-	if calls(w) != "guest:apply,host:apply,guest:live-restore-on,docker:apply" {
-		t.Fatalf("calls = %s, want one apply per layer, guest first, then live-restore and the ring-0 docker step", calls(w))
+	if calls(w) != "guest:apply,host:apply,guest:live-restore-on,docker:apply,pve:apply" {
+		t.Fatalf("calls = %s, want one apply per layer, guest first, then live-restore, the ring-0 docker step and the pve step", calls(w))
 	}
 	for _, p := range w.plans[:2] {
 		if p["select"] != "pending-fast" || p["snapshot"] != "" || len(p["packages"].([]any)) != 0 {
@@ -171,7 +176,7 @@ func TestRing0_OneCallPerLayer(t *testing.T) {
 	if len(g.NotCovered) != 1 || g.NotCovered[0] != "docker-ce" {
 		t.Fatalf("not covered = %v", g.NotCovered)
 	}
-	if len(h.reports) != 3 || h.reports[0].Layer != LayerGuest || h.reports[1].Layer != LayerHost || h.reports[2].Layer != LayerDocker {
+	if len(h.reports) != 4 || h.reports[0].Layer != LayerGuest || h.reports[1].Layer != LayerHost || h.reports[2].Layer != LayerDocker || h.reports[3].Layer != LayerPVE {
 		t.Fatalf("hub got %+v", h.reports)
 	}
 }
@@ -389,7 +394,7 @@ func TestHostReport_CarriesRebootScanned(t *testing.T) {
 	}}
 	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
 	run2(l, "night")
-	if len(h.reports) != 3 || !h.reports[1].RebootScanned || !h.reports[1].RebootNeeded || h.reports[0].RebootScanned {
+	if len(h.reports) != 4 || !h.reports[1].RebootScanned || !h.reports[1].RebootNeeded || h.reports[0].RebootScanned {
 		t.Fatalf("hub got %+v", h.reports)
 	}
 }
@@ -436,7 +441,12 @@ func TestDocker_Ring0PlanAndReport(t *testing.T) {
 		DockerEngine: "29.8.2", Authority: "ring0"}}}
 	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
 	p := l.Run(context.Background(), 9201, "night")
-	dp := w.plans[len(w.plans)-1]
+	var dp map[string]any
+	for _, x := range w.plans {
+		if x["layer"] == "docker" {
+			dp = x
+		}
+	}
 	if dp["layer"] != "docker" || dp["lane"] != "slow" || dp["select"] != "pending-docker" {
 		t.Fatalf("docker plan = %v", dp)
 	}
diff --git a/internal/osupdate/pve_test.go b/internal/osupdate/pve_test.go
new file mode 100644
index 0000000..7b8e5f7
--- /dev/null
+++ b/internal/osupdate/pve_test.go
@@ -0,0 +1,152 @@
+package osupdate
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/signedjobs"
+)
+
+// ---- the Proxmox package step (R-812 option A, `09` §3 decision 163, `11` §5.10) ----
+
+// Ring 0: after a healthy host step the leg runs the pve layer — slow lane, select pending-pve — while holding the
+// /etc/pve write gate; the report carries only Proxmox userspace packages and pve-manager's version.
+//
+// COMPANION RED-PROOF (observed): call runLayer instead of runPVE in Run → "the /etc/pve write gate was not held".
+func TestPVE_Ring0PlanGateAndReport(t *testing.T) {
+	w := &fakeWrapper{t: t, applyRep: map[string]WrapperReport{LayerPVE: {
+		Upgraded: []Package{{Name: "pve-manager", Version: "9.2.21"}},
+		Installed: []Package{{Name: "pve-manager", Version: "9.2.21", Origin: "Proxmox"},
+			{Name: "proxmox-kernel-helper", Version: "9.0.4", Origin: "Proxmox"}, {Name: "libc6", Version: "u4", Origin: "Debian"}},
+		Pending: []Pending{{Name: "qemu-server", From: "9.0.1", To: "9.0.9", Origin: []string{PVEOrigin}},
+			{Name: "proxmox-kernel-7.0", From: "7.0.2", To: "7.0.14", Origin: []string{PVEOrigin}},
+			{Name: "libc6", From: "u3", To: "u4", Origin: []string{"Debian"}}},
+		PVEManager: "9.2.21", Authority: "ring0"}}}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	p := l.Run(context.Background(), 9201, "night")
+	var pp map[string]any
+	for _, x := range w.plans {
+		if x["layer"] == LayerPVE {
+			pp = x
+		}
+	}
+	if pp == nil || pp["lane"] != "slow" || pp["select"] != "pending-pve" {
+		t.Fatalf("pve plan = %v (calls %s)", pp, calls(w))
+	}
+	if !w.pveGateHeld {
+		t.Fatal("the /etc/pve write gate was not held while the pve step ran")
+	}
+	if pvegate.Stepping() {
+		t.Fatal("the gate must be released after the step")
+	}
+	r := p.PVE
+	if r.Outcome != "applied" || !r.Healthy || r.PVEManager != "9.2.21" {
+		t.Fatalf("pve report = %+v", r)
+	}
+	if len(r.Installed) != 1 || r.Installed[0].Name != "pve-manager" || len(r.Pending) != 1 || r.Pending[0].Name != "qemu-server" {
+		t.Fatalf("the pve report must carry Proxmox userspace only: installed=%v pending=%v", r.Installed, r.Pending)
+	}
+	if h.reports[len(h.reports)-1].Layer != LayerPVE {
+		t.Fatalf("the hub must get the pve report: %+v", h.reports)
+	}
+}
+
+// Ring 1 never takes a Proxmox step in the night leg.
+func TestPVE_Ring1NightLegNeverSteps(t *testing.T) {
+	w := &fakeWrapper{t: t}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 1, Enabled: true})
+	if p := l.Run(context.Background(), 9201, "night"); p.PVE.Layer != "" || strings.Contains(calls(w), "pve") {
+		t.Fatalf("ring 1 took a pve step: %s", calls(w))
+	}
+}
+
+// No healthy host step (a BYO box, or an unhealthy host step) → no pve step.
+func TestPVE_SkippedWithoutAHealthyHostStep(t *testing.T) {
+	w := &fakeWrapper{t: t}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	l.Appliance = false
+	if p := l.Run(context.Background(), 9201, "night"); p.PVE.Layer != "" || strings.Contains(calls(w), "pve") {
+		t.Fatalf("a BYO box took a pve step: %s", calls(w))
+	}
+	w2 := &fakeWrapper{t: t}
+	l2, _ := newLeg(t, w2, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	l2.Tunnel = fakeTunnel{"stopped"} // the host step reads unhealthy
+	w2.applyRep = map[string]WrapperReport{LayerHost: {Upgraded: []Package{{Name: "libc6", Version: "u4"}}}}
+	if p := l2.Run(context.Background(), 9201, "night"); p.PVE.Layer != "" || strings.Contains(calls(w2), "pve") {
+		t.Fatalf("a pve step ran after an unhealthy host step: %s", calls(w2))
+	}
+}
+
+// A write in flight that never finishes makes the pve step give up (failed), never run without the gate.
+func TestPVE_GivesUpWhenAWriteDoesNotFinish(t *testing.T) {
+	old := pveDrainWait
+	pveDrainWait = 50_000_000 // 50 ms
+	defer func() { pveDrainWait = old }()
+	rel, _, _ := pvegate.Write(context.Background())
+	defer rel()
+	w := &fakeWrapper{t: t}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	p := l.Run(context.Background(), 9201, "night")
+	if p.PVE.Outcome != "failed" || strings.Contains(calls(w), "pve") {
+		t.Fatalf("the pve step must fail without a wrapper call: %+v calls=%s", p.PVE, calls(w))
+	}
+}
+
+// THE pve health rule. COMPANION RED-PROOF (observed): drop the container-id loop or the pve-manager check in
+// PVEHealthVerdict → the matching case below fails.
+func TestPVEHealthVerdict(t *testing.T) {
+	before, after := hostOK(), hostOK()
+	before.Guest.Containers["app"] = Container{State: "running", Health: "healthy", ID: "a1"}
+	after.Guest.Containers["app"] = Container{State: "running", Health: "healthy", ID: "a1"}
+	if ok, why := PVEHealthVerdict(before, after, hub.TunnelRunning, "9.2.21", "9.2.21"); !ok {
+		t.Fatalf("healthy step read unhealthy: %s", why)
+	}
+	if ok, _ := PVEHealthVerdict(before, after, hub.TunnelRunning, "9.2.21", "9.2.2"); ok {
+		t.Fatal("pveversion still on the old pve-manager must fail")
+	}
+	after.Guest.Containers["app"] = Container{State: "running", Health: "healthy", ID: "b2"}
+	if ok, why := PVEHealthVerdict(before, after, hub.TunnelRunning, "", "9.2.2"); ok || !strings.Contains(why, "id changed") {
+		t.Fatalf("an app restarted by the Proxmox step must fail, got ok=%v %q", ok, why)
+	}
+}
+
+// The signed executor hands the RAW envelope and the exact list to the wrapper's pve layer.
+func TestPVEStepExecutor_PassesTheSignedEnvelope(t *testing.T) {
+	w := &fakeWrapper{t: t, applyRep: map[string]WrapperReport{LayerPVE: {
+		Upgraded: []Package{{Name: "pve-manager", Version: "9.2.21"}}, PVEManager: "9.2.21", Authority: "signed"}}}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 1, Enabled: true})
+	e := PVEStepExecutor{Leg: l, Guest: func(context.Context) (int, error) { return 9201, nil }}
+	params, _ := json.Marshal(PVEStepParams{ReleaseID: "os-pve-1", Packages: []Package{{Name: "pve-manager", Version: "9.2.21", Origin: PVEOrigin}}})
+	ctx := signedjobs.WithSignedOp(context.Background(), &reconcile.SignedOp{Blob: []byte(`{"op":"os_pve_step"}`), Sig: []byte("SIG")})
+	if err := e.Execute(ctx, OpPVEStep, params); err != nil {
+		t.Fatal(err)
+	}
+	pp := w.plans[len(w.plans)-1]
+	sg, _ := pp["signed"].(map[string]any)
+	if pp["layer"] != LayerPVE || pp["lane"] != "slow" || pp["release_id"] != "os-pve-1" || sg == nil ||
+		sg["blob_b64"] != base64.StdEncoding.EncodeToString([]byte(`{"op":"os_pve_step"}`)) || sg["sig"] != "SIG" {
+		t.Fatalf("pve plan = %v", pp)
+	}
+	if !w.pveGateHeld || calls(w) != "pve:apply" || len(h.reports) != 1 || h.reports[0].Trigger != "signed" {
+		t.Fatalf("gate=%v calls=%s reports=%+v", w.pveGateHeld, calls(w), h.reports)
+	}
+	if err := e.Execute(context.Background(), OpPVEStep, params); err == nil {
+		t.Fatal("no envelope must refuse")
+	}
+	if err := e.Execute(context.Background(), OpDockerStep, params); err != signedjobs.ErrNoExecutor {
+		t.Fatalf("another op must pass through the chain: %v", err)
+	}
+}
+
+// os_pve_step is never benign.
+func TestPVEStep_IsDestructiveClass(t *testing.T) {
+	if reconcile.Classify(reconcile.ClassOSPVEStep, reconcile.Provenance{}) != reconcile.Destructive {
+		t.Fatal("os_pve_step must be destructive-class (signed, operational key)")
+	}
+}
diff --git a/internal/osupdate/pvejob.go b/internal/osupdate/pvejob.go
new file mode 100644
index 0000000..bb28e08
--- /dev/null
+++ b/internal/osupdate/pvejob.go
@@ -0,0 +1,85 @@
+package osupdate
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/signedjobs"
+)
+
+// OpPVEStep is the signed op class of a Proxmox package step (R-812 option A, `11` §5.10): a ring-1 box takes an
+// approved Proxmox set only through it. No undo in this release. CC may sign it until the first paying customer.
+const OpPVEStep = "os_pve_step"
+
+// PVEStepParams are the signed params. The wrapper compares Packages with the plan byte-for-byte.
+type PVEStepParams struct {
+	ReleaseID string    `json:"release_id"`
+	Packages  []Package `json:"packages"`
+	VMID      int       `json:"vmid,omitempty"`
+}
+
+// PVEStepExecutor runs a verified os_pve_step (signedjobs.Executor) under the host-wide heavy-op gate (Gate) and the
+// /etc/pve write gate (inside runPVE).
+type PVEStepExecutor struct {
+	Leg   *Leg
+	Guest func(ctx context.Context) (int, error)
+	Gate  func(ctx context.Context) (release func(), err error)
+}
+
+// Execute implements signedjobs.Executor.
+func (e PVEStepExecutor) Execute(ctx context.Context, op string, params json.RawMessage) error {
+	if op != OpPVEStep {
+		return signedjobs.ErrNoExecutor
+	}
+	so, ok := signedjobs.SignedOpFrom(ctx)
+	if !ok {
+		return fmt.Errorf("os_pve_step: no signed envelope in the context — the wrapper could not verify it")
+	}
+	var p PVEStepParams
+	if err := json.Unmarshal(params, &p); err != nil || len(p.Packages) == 0 {
+		return fmt.Errorf("os_pve_step: params must name the Proxmox set: %v", err)
+	}
+	vmid := p.VMID
+	if vmid == 0 {
+		if e.Guest == nil {
+			return fmt.Errorf("os_pve_step: no vmid and no guest finder")
+		}
+		v, err := e.Guest(ctx)
+		if err != nil {
+			return fmt.Errorf("os_pve_step: find the customer guest: %w", err)
+		}
+		vmid = v
+	}
+	if e.Gate != nil {
+		release, err := e.Gate(ctx)
+		if err != nil {
+			return fmt.Errorf("os_pve_step: heavy-op gate busy (a backup or restore-test runs): %w", err)
+		}
+		defer release()
+	}
+	rep := e.Leg.RunPVESigned(ctx, vmid, p, so.Blob, string(so.Sig))
+	switch rep.Outcome {
+	case "applied", "nothing":
+		if rep.Healthy {
+			return nil
+		}
+	}
+	return fmt.Errorf("os_pve_step: %s (%s) %s", rep.Outcome, rep.HealthReason, string(rep.Refused))
+}
+
+// RunPVESigned is one signed Proxmox step (ring 1): the pve layer with the signed envelope, which the wrapper verifies
+// itself, holding the /etc/pve write gate.
+func (l *Leg) RunPVESigned(ctx context.Context, vmid int, p PVEStepParams, blob []byte, sig string) Report {
+	unlock := l.lockPass(true)
+	defer unlock()
+	l.sendUnsentLocked(ctx) // R-868
+	runID := l.now().UTC().Format("20060102T150405Z")
+	rid := p.ReleaseID
+	if rid == "" {
+		rid = "signed-" + runID
+	}
+	return l.runPVE(ctx, runID, vmid, "signed", l.Block(), dockerOpts{releaseID: rid, packages: p.Packages,
+		signed: map[string]string{"blob_b64": base64.StdEncoding.EncodeToString(blob), "sig": sig}})
+}
diff --git a/internal/osupdate/unsent.go b/internal/osupdate/unsent.go
index 5a23c5c..656d945 100644
--- a/internal/osupdate/unsent.go
+++ b/internal/osupdate/unsent.go
@@ -145,21 +145,28 @@ func (l *Leg) reportFromKept(ctx context.Context, wr WrapperReport, path string)
 	rep.Upgraded, rep.PassSeconds = wr.Upgraded, wr.PassSeconds
 	rep.DockerEngine, rep.Authority, rep.Undo = wr.DockerEngine, wr.Authority, wr.Undo
 	rep.OOMCheck = rawOrNil(wr.OOMCheck)
-	wantEngine := ""
+	rep.PVEManager = wr.PVEManager
+	wantEngine, wantPVE := "", ""
 	for _, u := range wr.Upgraded {
 		if u.Name == "docker-ce" {
 			wantEngine = EngineOf(u.Version)
 		}
+		if u.Name == "pve-manager" {
+			wantPVE = u.Version
+		}
 	}
 	verdict := func(h *Health) (bool, string) {
 		switch wr.Layer {
 		case LayerDocker:
 			return DockerHealthVerdict(wr.HealthBefore, h, wantEngine, wr.DockerEngine)
-		case LayerHost:
+		case LayerHost, LayerPVE:
 			t := hub.TunnelUnknown
 			if l.Tunnel != nil {
 				t, _ = l.Tunnel.Status(ctx)
 			}
+			if wr.Layer == LayerPVE {
+				return PVEHealthVerdict(wr.HealthBefore, h, t, wantPVE, wr.PVEManager)
+			}
 			return HostHealthVerdict(wr.HealthBefore, h, t)
 		}
 		return HealthVerdict(wr.HealthBefore, h)
@@ -167,7 +174,7 @@ func (l *Leg) reportFromKept(ctx context.Context, wr WrapperReport, path string)
 	ok, why := verdict(wr.HealthAfter)
 	if !ok && len(wr.Upgraded) > 0 && wr.VMID > 0 {
 		lane := "fast"
-		if wr.Layer == LayerDocker {
+		if wr.Layer == LayerDocker || wr.Layer == LayerPVE {
 			lane = "slow"
 		}
 		if hr, err := l.call(ctx, "kept-"+runID, map[string]any{"release_id": "kept", "layer": wr.Layer, "lane": lane,
@@ -187,6 +194,8 @@ func (l *Leg) reportFromKept(ctx context.Context, wr WrapperReport, path string)
 	rep.RebootScanned = wr.RebootScanned
 	if wr.Layer == LayerDocker {
 		rep.Installed, rep.Pending = onlyDocker(wr.Installed), onlyDockerPending(wr.Pending)
+	} else if wr.Layer == LayerPVE {
+		rep.Installed, rep.Pending = onlyPVE(wr.Installed), onlyPVEPending(wr.Pending)
 	} else {
 		planned := map[string]bool{}
 		for _, u := range wr.Upgraded {
diff --git a/internal/proxmox/client.go b/internal/proxmox/client.go
index f9c273b..e368c59 100644
--- a/internal/proxmox/client.go
+++ b/internal/proxmox/client.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
 	"io"
 	"net/http"
 	"net/url"
@@ -105,6 +106,15 @@ func (c *Client) do(ctx context.Context, method, path string, body io.Reader, ou
 // doBody is the single HTTP chokepoint: builds the request, sets auth, executes,
 // maps non-2xx to APIError, and decodes the data envelope.
 func (c *Client) doBody(ctx context.Context, method, path string, body io.Reader, contentType string, out any) error {
+	// R-812 option A: every non-GET call may write /etc/pve — it waits while a Proxmox package step restarts pmxcfs
+	// (pvegate). Pinned by TestPVEGate_ClientWriteWaitsGetDoesNot.
+	if method != http.MethodGet {
+		release, _, gerr := pvegate.Write(ctx)
+		if gerr != nil {
+			return fmt.Errorf("proxmox: %s %s held back by a Proxmox package step: %w", method, path, gerr)
+		}
+		defer release()
+	}
 	req, err := http.NewRequestWithContext(ctx, method, c.base+path, body)
 	if err != nil {
 		return fmt.Errorf("proxmox: building request: %w", err)
diff --git a/internal/proxmox/privileged.go b/internal/proxmox/privileged.go
index 4cb0997..c6f178d 100644
--- a/internal/proxmox/privileged.go
+++ b/internal/proxmox/privileged.go
@@ -4,8 +4,10 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
 	"io"
 	"os/exec"
+	"path/filepath"
 	"strconv"
 )
 
@@ -59,6 +61,15 @@ func (r *ExecRunner) Run(ctx context.Context, name string, args ...string) ([]by
 // RunStdin is Run with the process stdin fed from stdin (nil = no stdin). The sudo-prefix/mode
 // handling is identical to Run — kept here so both paths share one place.
 func (r *ExecRunner) RunStdin(ctx context.Context, stdin io.Reader, name string, args ...string) ([]byte, []byte, error) {
+	// R-812 option A: a root CLI that writes /etc/pve waits while a Proxmox package step runs (pvegate).
+	// Pinned by TestPVEGate_ExecRunnerPctSetWaits / TestWritesEtcPVE.
+	if WritesEtcPVE(name, args) {
+		release, _, gerr := pvegate.Write(ctx)
+		if gerr != nil {
+			return nil, nil, fmt.Errorf("proxmox: %s held back by a Proxmox package step: %w", name, gerr)
+		}
+		defer release()
+	}
 	var cmd *exec.Cmd
 	if r.Mode == RunnerSudo {
 		sudo := r.SudoPath
@@ -77,6 +88,28 @@ func (r *ExecRunner) RunStdin(ctx context.Context, stdin io.Reader, name string,
 	return stdout.b, stderr.b, err
 }
 
+// WritesEtcPVE reports whether a root command writes /etc/pve: `pct` with a config-changing verb, `pvesm`, `pveum`,
+// and the PBS storage wrapper's create / reconcile verbs. `pct exec|status|list|config` and every other command do not
+// (the os-update wrapper itself must never wait on the gate its own step holds). Pinned by TestWritesEtcPVE.
+func WritesEtcPVE(name string, args []string) bool {
+	base := filepath.Base(name)
+	switch base {
+	case "pvesm", "pveum":
+		return true
+	case "pct":
+		if len(args) == 0 {
+			return false
+		}
+		switch args[0] {
+		case "set", "create", "destroy", "restore", "unlock", "resize", "snapshot", "delsnapshot", "rollback", "move-volume", "start", "stop", "reboot", "shutdown":
+			return true
+		}
+	case "felhom-pbs-apply":
+		return len(args) > 0 && (args[0] == "create" || args[0] == "reconcile")
+	}
+	return false
+}
+
 // Privileged is the root-CLI backend.
 type Privileged struct {
 	runner Runner
diff --git a/internal/proxmox/pvegate_test.go b/internal/proxmox/pvegate_test.go
new file mode 100644
index 0000000..49f1d7f
--- /dev/null
+++ b/internal/proxmox/pvegate_test.go
@@ -0,0 +1,92 @@
+package proxmox
+
+import (
+	"context"
+	"net/http"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/pvegate"
+)
+
+// R-812 option A: while a Proxmox package step holds the gate, a non-GET API call waits and a GET does not.
+//
+// COMPANION RED-PROOF (observed): delete the pvegate.Write block in doBody → this fails with "a PUT reached the API
+// while the Proxmox step held the gate". Restored. (audits/day-2026-10-07/B/red-pvegate-chokepoints.txt)
+func TestPVEGate_ClientWriteWaitsGetDoesNot(t *testing.T) {
+	d := &mockDoer{fn: func(*http.Request) (*http.Response, error) { return jsonResp(200, `{"data":null}`), nil }}
+	c := newTestClient(d)
+	end, err := pvegate.Step(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.get(context.Background(), "/nodes", nil); err != nil {
+		t.Fatalf("a GET must not wait on the gate: %v", err)
+	}
+	if d.calls != 1 {
+		t.Fatalf("the GET must reach the API, calls=%d", d.calls)
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	defer cancel()
+	err = c.postForm(ctx, http.MethodPut, "/nodes/x/lxc/9201/config", nil, nil)
+	if d.calls != 1 {
+		end()
+		t.Fatal("a PUT reached the API while the Proxmox step held the gate")
+	}
+	if err == nil {
+		end()
+		t.Fatal("a PUT held back past its deadline must fail")
+	}
+	end()
+	if err := c.postForm(context.Background(), http.MethodPut, "/nodes/x/lxc/9201/config", nil, nil); err != nil || d.calls != 2 {
+		t.Fatalf("after the step the PUT must go through (err=%v calls=%d)", err, d.calls)
+	}
+}
+
+// A root `pct set` waits on the gate; `pct exec` does not.
+//
+// COMPANION RED-PROOF (observed): delete the WritesEtcPVE block in RunStdin → this fails with "pct set ran while the
+// Proxmox step held the gate". Restored.
+func TestPVEGate_ExecRunnerPctSetWaits(t *testing.T) {
+	r := &ExecRunner{Mode: RunnerDirect}
+	end, err := pvegate.Step(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer end()
+	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	defer cancel()
+	start := time.Now()
+	_, _, err = r.Run(ctx, "/nonexistent/pct", "set", "9201", "-mp8", "/x")
+	if err == nil || time.Since(start) < 90*time.Millisecond {
+		t.Fatalf("pct set ran while the Proxmox step held the gate (err=%v after %s)", err, time.Since(start))
+	}
+	start = time.Now()
+	_, _, _ = r.Run(context.Background(), "/nonexistent/pct", "exec", "9201", "--", "true")
+	if time.Since(start) > 80*time.Millisecond {
+		t.Fatal("pct exec must not wait on the gate")
+	}
+}
+
+func TestWritesEtcPVE(t *testing.T) {
+	for _, c := range []struct {
+		name string
+		args []string
+		want bool
+	}{
+		{"pct", []string{"set", "9201", "-mp8", "x"}, true},
+		{"/usr/sbin/pct", []string{"create", "9201"}, true},
+		{"pct", []string{"exec", "9201", "--", "true"}, false},
+		{"pct", []string{"status", "9201"}, false},
+		{"pvesm", []string{"add", "dir", "x"}, true},
+		{"pveum", []string{"acl", "modify"}, true},
+		{"/usr/local/sbin/felhom-pbs-apply", []string{"reconcile"}, true},
+		{"/usr/local/sbin/felhom-pbs-apply", []string{"read"}, false},
+		{"/usr/local/sbin/felhom-os-apply", []string{"--plan", "x"}, false},
+		{"pct", nil, false},
+	} {
+		if got := WritesEtcPVE(c.name, c.args); got != c.want {
+			t.Errorf("WritesEtcPVE(%s %v) = %v, want %v", c.name, c.args, got, c.want)
+		}
+	}
+}
diff --git a/internal/pvegate/pvegate.go b/internal/pvegate/pvegate.go
new file mode 100644
index 0000000..301b434
--- /dev/null
+++ b/internal/pvegate/pvegate.go
@@ -0,0 +1,104 @@
+// Package pvegate keeps the agent's own writes to /etc/pve out of the way of a Proxmox package step (R-812 option A,
+// `09` §3 decision 163, `11` §5.10).
+//
+// WHY. A `pve` step upgrades pve-cluster / pve-manager / qemu-server / pve-container; their postinst scripts restart
+// pmxcfs (the FUSE filesystem behind /etc/pve) and the API daemons. A write that lands while pmxcfs restarts fails or,
+// worse, half-lands (design-R-812 §3 A, "can go wrong"). Backups and restore-tests are already kept out by the
+// host-wide heavy-op gate; this gate covers everything else the agent writes: every non-GET Proxmox API call
+// (proxmox.Client.doBody) and every root CLI that writes /etc/pve (proxmox.ExecRunner — `pct set|create|…`, `pvesm`,
+// `pveum`, `felhom-pbs-apply create|reconcile`).
+//
+// THE RULE. Write waits while a step runs (bounded by its own context). Step marks the step and then waits until every
+// write already in flight has finished; it never waits forever (its context bounds it, and the caller gives up and
+// does not run the step). One step at a time. Pinned by pvegate_test.go and, at the two chokepoints, by
+// proxmox TestPVEGate_*.
+package pvegate
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"time"
+)
+
+var (
+	mu       sync.Mutex
+	inFlight int
+	stepping bool
+	stepDone chan struct{}
+)
+
+// ErrStepRunning is returned by Step when another step already holds the gate.
+var ErrStepRunning = errors.New("pvegate: a Proxmox package step is already running")
+
+// Write marks one /etc/pve write in flight, first waiting while a Proxmox package step runs. The returned release must
+// be called when the write has finished. waited reports how long the write was held back.
+func Write(ctx context.Context) (release func(), waited time.Duration, err error) {
+	start := time.Now()
+	for {
+		mu.Lock()
+		if !stepping {
+			inFlight++
+			mu.Unlock()
+			var once sync.Once
+			return func() {
+				once.Do(func() {
+					mu.Lock()
+					inFlight--
+					mu.Unlock()
+				})
+			}, time.Since(start), nil
+		}
+		ch := stepDone
+		mu.Unlock()
+		select {
+		case <-ch:
+		case <-ctx.Done():
+			return nil, time.Since(start), ctx.Err()
+		}
+	}
+}
+
+// Step marks a Proxmox package step and waits until every /etc/pve write already in flight has finished. On error the
+// gate is released again and the step must not run. end releases the gate and lets the held-back writes go.
+func Step(ctx context.Context) (end func(), err error) {
+	mu.Lock()
+	if stepping {
+		mu.Unlock()
+		return nil, ErrStepRunning
+	}
+	stepping = true
+	done := make(chan struct{})
+	stepDone = done
+	mu.Unlock()
+	var once sync.Once
+	end = func() {
+		once.Do(func() {
+			mu.Lock()
+			stepping = false
+			close(done)
+			mu.Unlock()
+		})
+	}
+	for {
+		mu.Lock()
+		n := inFlight
+		mu.Unlock()
+		if n == 0 {
+			return end, nil
+		}
+		select {
+		case <-ctx.Done():
+			end()
+			return nil, ctx.Err()
+		case <-time.After(50 * time.Millisecond):
+		}
+	}
+}
+
+// Stepping reports whether a Proxmox package step holds the gate (for logs).
+func Stepping() bool {
+	mu.Lock()
+	defer mu.Unlock()
+	return stepping
+}
diff --git a/internal/pvegate/pvegate_test.go b/internal/pvegate/pvegate_test.go
new file mode 100644
index 0000000..7383fce
--- /dev/null
+++ b/internal/pvegate/pvegate_test.go
@@ -0,0 +1,104 @@
+package pvegate
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+// A write that starts while a step runs waits until the step ends.
+//
+// COMPANION RED-PROOF (observed): make Write ignore `stepping` → this fails with "the write went through while the
+// Proxmox step held the gate". Restored. (audits/day-2026-10-07/B/red-pvegate.txt)
+func TestWrite_WaitsWhileAStepRuns(t *testing.T) {
+	end, err := Step(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := make(chan time.Time, 1)
+	go func() {
+		rel, _, err := Write(context.Background())
+		if err == nil {
+			rel()
+		}
+		got <- time.Now()
+	}()
+	select {
+	case <-got:
+		end()
+		t.Fatal("the write went through while the Proxmox step held the gate")
+	case <-time.After(150 * time.Millisecond):
+	}
+	ended := time.Now()
+	end()
+	select {
+	case at := <-got:
+		if at.Before(ended) {
+			t.Fatal("the write finished before the step ended")
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("the write never went through after the step ended")
+	}
+}
+
+// A step waits for a write already in flight before it starts.
+func TestStep_WaitsForAWriteInFlight(t *testing.T) {
+	rel, _, err := Write(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	started := make(chan struct{})
+	go func() {
+		end, err := Step(context.Background())
+		if err == nil {
+			close(started)
+			end()
+		}
+	}()
+	select {
+	case <-started:
+		rel()
+		t.Fatal("the step started while a write was in flight")
+	case <-time.After(150 * time.Millisecond):
+	}
+	rel()
+	select {
+	case <-started:
+	case <-time.After(2 * time.Second):
+		t.Fatal("the step never started after the write finished")
+	}
+}
+
+// A step that cannot drain the writes in time gives up and releases the gate (it never waits forever).
+func TestStep_GivesUpAndReleases(t *testing.T) {
+	rel, _, _ := Write(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	defer cancel()
+	if _, err := Step(ctx); err == nil {
+		t.Fatal("the step must give up while a write is in flight past its deadline")
+	}
+	if Stepping() {
+		t.Fatal("a step that gave up must release the gate")
+	}
+	rel()
+}
+
+// A write held back past its own deadline returns the context's error.
+func TestWrite_HonoursItsContext(t *testing.T) {
+	end, _ := Step(context.Background())
+	defer end()
+	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+	defer cancel()
+	if _, _, err := Write(ctx); err == nil {
+		t.Fatal("a write held back past its deadline must fail")
+	}
+}
+
+// One step at a time.
+func TestStep_OneAtATime(t *testing.T) {
+	end, _ := Step(context.Background())
+	defer end()
+	if _, err := Step(context.Background()); err != ErrStepRunning {
+		t.Fatalf("a second step must be refused, got %v", err)
+	}
+}
diff --git a/internal/reconcile/classify.go b/internal/reconcile/classify.go
index b4cd3c8..029e83b 100644
--- a/internal/reconcile/classify.go
+++ b/internal/reconcile/classify.go
@@ -52,6 +52,10 @@ const (
 	// (signed, operational key) like agent_update; the root wrapper re-verifies the same signature itself.
 	ClassOSDockerStep OpClass = "os_docker_step"
 
+	// A Proxmox package step on the host (R-812 option A, `11` §5.10) — ring 1. Destructive-class (signed, operational
+	// key) like os_docker_step; the root wrapper re-verifies the same signature itself.
+	ClassOSPVEStep OpClass = "os_pve_step"
+
 	// The config bundle (agent v0.143.0, R-840, `11` §5.4.2): the box's ROOT-OWNED files (sudoers, wrappers, units).
 	// Destructive-class (signed, operational key) like agent_update; the root wrapper re-verifies the signature itself.
 	ClassAgentConfigUpdate OpClass = "agent_config_update"
@@ -123,7 +127,7 @@ func Classify(class OpClass, prov Provenance) Disposition {
 		return Destructive
 	case ClassKeyRotation:
 		return Destructive
-	case ClassAgentUpdate, ClassOSDockerStep, ClassAgentConfigUpdate:
+	case ClassAgentUpdate, ClassOSDockerStep, ClassOSPVEStep, ClassAgentConfigUpdate:
 		// Never benign — no agent-internal provenance can make replacing the agent binary
 		// unsigned-safe (a compromised process must not be able to self-bless an update).
 		return Destructive