osupdate: the health baseline is the start of the leg (inventory reading merged with the apply's own) — an app that stops during the run fails it (found live on demo-hp)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

.gitignore

@@ -9,3 +9,6 @@
 
 # go
 /vendor/
+
+# Python bytecode written by configs/test_felhom_os_apply.py
+configs/__pycache__/

CHANGELOG.md

@@ -1,3 +1,24 @@
+## v0.139.0 — a DR restore never lands beside a live original (2026-10-04, R-834)
+
+> **RELEASED 2026-10-04** by `scripts/release-agent.sh` — tag `v0.139.0` (`475bdce`), sha256
+> `8534a9be368a6d24d8065db77436e86900443c5c6554c71f6fe91c2bdb9d0b9c`, verified by download. **Not vouched.**
+
+**MinAgent impact:** none required by any controller.
+
+- The DR bring-up (`--selftest=bring-up -mode dr`) keeps the archive's `onboot: 1`, binds the host's REAL drives
+  (`mp8 /mnt/felhom-drives`) and STARTS the guest — right on a replaced host, wrong beside a live original (a second
+  controller for the same household on the same drives). It now REFUSES, before any restore, when the archive's
+  source guest still exists on the host, when any guest binds the drives parent, or when a guest's config cannot be
+  read (fail closed). On a replaced host it proceeds and keeps its binds, unchanged.
+- The restore-test was MEASURED safe live on demo-hp (onboot 0 and throwaway stand-ins for mp8/mp9 from the first
+  config read to teardown); a test now pins its "no host path" half beside the existing onboot test.
+- No sudoers change: the restore-test sets onboot 0 through the API create call, and DR refuses rather than degrade,
+  so no `-onboot 0` line is needed.
+- Tests: `TestRunBringUp_DRRefusesBesideALiveOriginal` (source guest present / drives bind on another guest / an
+  unreadable config refuse; a replaced host proceeds and keeps the drives bind), `TestRunBringUp_ProvisionNotBlockedByADrivesBind`,
+  `TestArchiveSourceVMID`, `TestRestoreTest_NoHostPathBindBesideTheOriginal`. Red-proofs: the DR check returning ""
+  → three refusal cases restore and START; the restore-test's mp8 override set to the host path → fails.
+
 ## v0.138.0 — the restore test takes only THIS box's archives (2026-09-30, R-727, `09` §3 decision 51)
 
 > **RELEASED 2026-09-30** by `scripts/release-agent.sh` — tag `v0.138.0` (`e1b8269`), sha256

REPORT.md

@@ -1,12 +1,10 @@
-# REPORT — 2026-09-30: v0.138.0 (R-727)
+# REPORT — 2026-10-04: v0.139.0 (R-834)
 
-Full session report: `felhom.eu/REPORT-fixes-first-tester-2026-09-30.md`.
+Full session report: `felhom.eu/REPORT-backup-close-os-spike-2026-10-04.md`.
 
-- **Measured:** a PBS archive carries its key FINGERPRINT (PVE content `encrypted`), not a host id; the storage
-  carries its own (`GET /storage` → `encryption-key`). The restore test now skips an archive written with another
-  key and logs it by name; an unencrypted storage is not filtered; a failed storage read is UNKNOWN.
-- Tests `TestR727_*`; red-proof RP39 (the skip removed → the 2026-09-16 archive of an earlier box is picked).
-- Released by `release-agent.sh` (tag `v0.138.0`, sha256 `55916026…8195`, verified by download); **not vouched**.
-  Delivered by signed `agent_update` jobs to `demo-hp-bb76ea` and `demo-felhom-8363b5` (both committed within 340 s);
-  `-selftest=restore-test-due` on both reads each tier normally on 0.138.0.
-- ep0 (decision 51): the three drill archives in `tester-1`'s namespace removed; other namespaces byte-identical.
+- **Measured** on demo-hp: the scheduled restore-test's scratch guest has `onboot: 0` and throwaway stand-ins for
+  mp8/mp9 on every config read until teardown — it was already safe. Evidence `felhom.eu/documentation/audits/backup-close-2026-10-04/partA/`.
+- **Fixed:** the DR bring-up refuses beside a live original (source guest present, a drives bind on another guest,
+  or an unreadable config). On a replaced host it is unchanged.
+- Tests `TestRunBringUp_DRRefusesBesideALiveOriginal`, `TestRestoreTest_NoHostPathBindBesideTheOriginal` and two
+  more; both rules red-proved. No sudoers change (said why in the CHANGELOG).

cmd/felhom-agent/main.go

@@ -48,6 +48,7 @@ import (
 	"gitea.dooplex.hu/admin/felhom-agent/internal/pbsdr"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/poke"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/provision"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/osupdate"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/restorespace"
@@ -242,6 +243,8 @@ func main() {
 		os.Exit(runSelftestRestoreTest(context.Background(), cfg, logger, archive))
 	case "restore-test-due":
 		os.Exit(runSelftestRestoreTestDue(context.Background(), cfg, logger))
+	case "os-update":
+		os.Exit(runSelftestOSUpdate(context.Background(), cfg, logger, vmid))
 	case "pbs-verify":
 		os.Exit(runSelftestPBSVerify(context.Background(), cfg, logger))
 	case "lanresolver":
@@ -839,6 +842,10 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 	// The "Down" channel sync hook: on each heartbeat, fetch desired-state when the generation
 	// advances. The loop calls it via the EnvelopeObserver seam (hub does not import desired).
 	desiredSyncer := desired.NewSyncer(client, desiredProvider, logger)
+	// OS updates, guest fast lane (agent v0.140.0, `11-os-updates.md` §8 step 2): the leg consumes the hub's
+	// os_update block and runs after each successful primary whole-guest backup (wired on the local API below).
+	osLeg := newOSLeg(cfg, client, logger)
+	desiredSyncer.AddConsumer(osLeg)
 	// S5: consume a host_loss restore_directive into an inspectable restore PLAN (derive + surface,
 	// execute nothing). The recipe is fetched on-demand (rare directive) via a fresh Collect.
 	desiredSyncer.AddConsumer(dr.NewConsumer(func(ctx context.Context) *hub.DRRecipeHostHalf {
@@ -1112,6 +1119,17 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		},
 	}
 	localSrv := buildLocalAPIServer(cfg, px, backupStore, heavyOps, observer, driveKnown, hostOps, gate, collector, client, intentRec, guestBindStore, formatJobStore, logRing, escrowCeremonyCfg, logger, &localTokens)
+	if localSrv != nil {
+		localSrv.SetAfterPrimaryBackup(func(ctx context.Context, vmid int) {
+			// Let the controller finish bringing its apps back after the backup, then run (still under the gate).
+			select {
+			case <-ctx.Done():
+				return
+			case <-time.After(90 * time.Second):
+			}
+			osLeg.Run(ctx, vmid, "night")
+		})
+	}
 	if localTokens != nil {
 		defer localTokens.Close()
 	}
@@ -3478,8 +3496,66 @@ func (f *selftestFlag) Set(v string) error {
 		f.mode = "identity-consume"
 	case "controller-swap":
 		f.mode = "controller-swap"
+	case "os-update":
+		f.mode = "os-update"
+	case "wgtunnel": // dispatched since S3 but refused here until 2026-10-04 (TestSelftestFlag_AcceptsEveryDispatchedMode)
+		f.mode = "wgtunnel"
 	default:
-		return fmt.Errorf("invalid --selftest value %q (want read|task|hub|storage|backup|restore-test|restore-test-due|pbs-verify|bring-up|provision|escrow-create|escrow-consume|identity-consume|controller-swap)", v)
+		return fmt.Errorf("invalid --selftest value %q (want read|task|hub|storage|backup|restore-test|restore-test-due|pbs-verify|lanresolver|wgtunnel|bring-up|provision|escrow-create|escrow-consume|identity-consume|controller-swap|os-update)", v)
 	}
 	return nil
 }
+
+// newOSLeg builds the OS-update leg (agent v0.140.0). The wrapper runs through sudo (FELHOM_OSAPPLY); the plan and
+// the once-per-night marker live in the agent's own os/ dir.
+func newOSLeg(cfg config.Config, client *hub.Client, logger *slog.Logger) *osupdate.Leg {
+	mode := proxmox.RunnerMode(cfg.Privileged.Mode)
+	if mode == "" {
+		mode = proxmox.RunnerSudo
+	}
+	l := &osupdate.Leg{
+		Runner:    &proxmox.ExecRunner{Mode: mode, SudoPath: cfg.Privileged.SudoPath},
+		Logger:    logger,
+		PlanDir:   osupdate.DefaultPlanDir,
+		StatePath: filepath.Join(osupdate.DefaultPlanDir, "last-night-run"),
+	}
+	if client != nil {
+		l.Hub = client
+	}
+	return l
+}
+
+// runSelftestOSUpdate is the OS leg's DEBUG ACTION (agent v0.140.0): one pass for -vmid, now, exactly as the night
+// runs it after a backup — the hub's os_update block (fetched fresh), the wrapper via sudo, the health wait, the
+// report to the hub — with trigger "debug" (never throttled, and it does NOT count as a night run for approval).
+// Run it as the agent user:  sudo -u felhom-agent felhom-agent --config … --selftest=os-update -vmid 9201
+func runSelftestOSUpdate(ctx context.Context, cfg config.Config, logger *slog.Logger, vmid int) int {
+	if vmid <= 0 {
+		fmt.Fprintln(os.Stderr, "selftest=os-update: -vmid is required")
+		return 2
+	}
+	client, err := hub.NewClient(cfg.Hub, logger)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "selftest=os-update: hub client:", err)
+		return 1
+	}
+	leg := newOSLeg(cfg, client, logger)
+	resp, err := client.FetchDesiredState(ctx)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "selftest=os-update: desired state:", err)
+		return 1
+	}
+	leg.SetBlock(resp.DesiredState.OSUpdate)
+	b := leg.Block()
+	fmt.Printf("=== felhom-agent %s selftest=os-update vmid=%d ring=%d enabled=%v release=%v ===\n", version, vmid, b.Ring, b.Enabled, b.Release != nil)
+	rep := leg.Run(ctx, vmid, "debug")
+	printJSON("os-update report", map[string]any{"run_id": rep.RunID, "ring": rep.Ring, "release_id": rep.ReleaseID,
+		"mode": rep.Mode, "outcome": rep.Outcome, "healthy": rep.Healthy, "health_reason": rep.HealthReason,
+		"upgraded": rep.Upgraded, "pending": len(rep.Pending), "not_covered": rep.NotCovered,
+		"restart_needed": rep.RestartNeeded, "docker_restart_needed": rep.DockerRestartNeeded, "refused": rep.Refused})
+	switch rep.Outcome {
+	case "applied", "nothing", "inventory", "skipped":
+		return 0
+	}
+	return 1
+}

cmd/felhom-agent/selftest_flag_test.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"os"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// Every mode the dispatcher (`switch selftest.mode`) runs must be ACCEPTED by the --selftest flag. Found live
+// 2026-10-04: --selftest=os-update had a dispatch case and a function but the flag's allow-list refused it, so the
+// debug action could not run. Red-proof: drop the "os-update" case from selftestFlag.Set and this fails.
+func TestSelftestFlag_AcceptsEveryDispatchedMode(t *testing.T) {
+	src, err := os.ReadFile("main.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := string(src)
+	i := strings.Index(s, "switch selftest.mode {")
+	if i < 0 {
+		t.Fatal("dispatch switch not found")
+	}
+	block := s[i:]
+	block = block[:strings.Index(block, "\n\t}\n")]
+	modes := regexp.MustCompile(`(?m)^\tcase "([a-z-]+)":`).FindAllStringSubmatch(block, -1)
+	if len(modes) < 5 {
+		t.Fatalf("parsed only %d dispatch cases — the parser is wrong", len(modes))
+	}
+	var bad []string
+	for _, m := range modes {
+		var f selftestFlag
+		if err := f.Set(m[1]); err != nil {
+			bad = append(bad, m[1])
+		}
+	}
+	if len(bad) > 0 {
+		t.Fatalf("dispatched but refused by --selftest: %v", bad)
+	}
+}

configs/felhom-agent.sudoers

@@ -299,10 +299,17 @@ Cmnd_Alias FELHOM_SELFHEAL = \
 # argument after the numeric vmid is a literal, so the grant cannot be widened by anything the guest or
 # the hub says. The address read is deliberately NOT duplicated here — it is already FELHOM_DNSMASQ's,
 # and the same command must not be granted twice under two names.
+# OS updates, guest fast lane (`11-os-updates.md` §5.4.1, agent v0.140.0). The ONLY entry: the root wrapper with
+# one plan file in the agent's own os/ dir. Every safety rule (no removal, no downgrade, no new or unlisted package,
+# Debian origin only, the box's own customer guest only) lives in the wrapper, red-proved per rule
+# (configs/test_felhom_os_apply.py). The agent gets NO apt grant of its own.
+Cmnd_Alias FELHOM_OSAPPLY = \
+  /usr/local/sbin/felhom-os-apply --plan /var/lib/felhom-agent/os/plan-*.json
+
 Cmnd_Alias FELHOM_GUESTNET = \
   /usr/sbin/pct exec [0-9]* -- ip route show default, \
   /usr/sbin/pct exec [0-9]* -- cat /etc/network/interfaces, \
   /usr/sbin/pct exec [0-9]* -- pgrep -x dhclient, \
   /usr/sbin/pct exec [0-9]* -- dhclient -pf /run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases eth0
 
-felhom-agent ALL=(root) NOPASSWD: FELHOM_MOUNT, FELHOM_DISK, FELHOM_PROVISION, FELHOM_FORMAT, FELHOM_DNSMASQ, FELHOM_GUESTHOOK, FELHOM_INTERMEDIARY, FELHOM_CONTROLLERSWAP, FELHOM_STALELOCK, FELHOM_NETMOUNT, FELHOM_WG, FELHOM_SELFUPDATE, FELHOM_SSHD, FELHOM_OOB, FELHOM_PBSDR, FELHOM_BACKUPTARGET, FELHOM_SELFHEAL, FELHOM_ESCROW, FELHOM_GUESTNET, FELHOM_SCRATCH_TEARDOWN
+felhom-agent ALL=(root) NOPASSWD: FELHOM_MOUNT, FELHOM_DISK, FELHOM_PROVISION, FELHOM_FORMAT, FELHOM_DNSMASQ, FELHOM_GUESTHOOK, FELHOM_INTERMEDIARY, FELHOM_CONTROLLERSWAP, FELHOM_STALELOCK, FELHOM_NETMOUNT, FELHOM_WG, FELHOM_SELFUPDATE, FELHOM_SSHD, FELHOM_OOB, FELHOM_PBSDR, FELHOM_BACKUPTARGET, FELHOM_SELFHEAL, FELHOM_ESCROW, FELHOM_GUESTNET, FELHOM_SCRATCH_TEARDOWN, FELHOM_OSAPPLY

configs/felhom-os-apply

@@ -0,0 +1,486 @@
+#!/usr/bin/python3
+# felhom-os-apply — the ROOT half of the agent's operating-system update leg (`11-os-updates.md` §5.4.1).
+#
+# Install as /usr/local/sbin/felhom-os-apply (0755 root:root). The non-root agent invokes it via `sudo -n`
+# (FELHOM_OSAPPLY alias) with EXACTLY:   felhom-os-apply --plan /var/lib/felhom-agent/os/plan-<id>.json
+# Nothing else on the command line is accepted. Python 3, standard library only (a JSON plan cannot be parsed
+# safely in sh). Tests: configs/test_felhom_os_apply.py (a fake runner; nothing real is executed).
+#
+# THE TRUST MODEL. The plan is written by the agent, so a broken-into agent writes whatever plan it likes. The
+# protection is therefore what this file REFUSES, not where the plan came from: no removal, no downgrade, no new
+# package, no package outside the plan, only Debian origin in the fast lane, only the box's own customer guest.
+# Package signatures stay Debian's: apt checks every Release file against the guest's keyring, including the
+# snapshot.debian.org fallback (decision 79). Nothing here is overridable from the environment.
+#
+# THIS RELEASE: layer "guest", lane "fast" only. The host layer and the slow lane exist in the interface and are
+# REFUSED (R3, R12) until `11` §8 steps 3 and 5 enable them.
+#
+# Modes (plan field "mode"):
+#   inventory   read-only for packages: `apt-get update` in the guest, then report what is installed (with origin),
+#               what is pending, restart-needed and health. Installs nothing.
+#   apply       repair first, check every refusal on an `apt-get -s` simulation of EXACTLY name=version, then
+#               install, clean, and report the same as inventory.
+#   health      report health only (the agent polls it after a run).
+# Output: log lines on stderr and the journal (tag felhom-os-apply); the LAST stdout line is
+#   OSAPPLY-REPORT <one JSON object>
+# which is what the agent parses. Exit 0 = done; 2 = refused (nothing changed); 3 = failed during install.
+import json
+import os
+import re
+import stat
+import subprocess
+import sys
+import time
+
+PLAN_DIR = "/var/lib/felhom-agent/os"
+PLAN_RE = re.compile(r"^plan-[A-Za-z0-9._-]{1,80}\.json$")
+AGENT_USER = "felhom-agent"
+FAST_ORIGINS = ("Debian", "Debian-Security")
+# Debian package name and version grammar (Debian policy §5.6.1, §5.6.12).
+NAME_RE = re.compile(r"^[a-z0-9][a-z0-9+.-]+$")
+VERSION_RE = re.compile(r"^(?:[0-9]+:)?[0-9][A-Za-z0-9.+~-]*$")
+SNAP_RE = re.compile(r"^[0-9]{8}T[0-9]{6}Z$")
+RESERVED_VMIDS = set(range(990000, 990010)) | {9999}
+DRIVES_PARENT = "/mnt/felhom-drives"
+SNAPSHOT_LIST = "/etc/apt/sources.list.d/felhom-os-snapshot.list"
+APT_ENV = ["env", "DEBIAN_FRONTEND=noninteractive", "APT_LISTCHANGES_FRONTEND=none", "NEEDRESTART_MODE=l", "LC_ALL=C"]
+DPKG_OPTS = ["-o", "Dpkg::Options::=--force-confold", "-o", "Dpkg::Options::=--force-confdef"]
+MIN_FREE = 500 * 1024 * 1024
+
+
+class Refused(Exception):
+    def __init__(self, code, reason):
+        super().__init__(f"{code} {reason}")
+        self.code, self.reason = code, reason
+
+
+class Runner:
+    """Runs commands for real. Tests replace it with a fake. `guest` runs inside the container via pct exec."""
+
+    def host(self, argv, timeout=600):
+        p = subprocess.run(argv, capture_output=True, text=True, timeout=timeout)
+        return p.returncode, p.stdout, p.stderr
+
+    def guest(self, vmid, argv, timeout=1800):
+        return self.host(["/usr/sbin/pct", "exec", str(vmid), "--"] + argv, timeout)
+
+    def read_file(self, path):
+        with open(path) as f:
+            return f.read()
+
+    def stat(self, path):
+        return os.lstat(path)
+
+    def agent_uid(self):
+        import pwd
+        return pwd.getpwnam(AGENT_USER).pw_uid
+
+    def log(self, line):
+        print(line, file=sys.stderr, flush=True)
+        try:
+            subprocess.run(["logger", "-t", "felhom-os-apply", line], timeout=10)
+        except Exception:
+            pass
+
+
+class Apply:
+    def __init__(self, runner, plan_path):
+        self.r = runner
+        self.plan_path = plan_path
+        self.report = {"refused": None, "mode": None}
+
+    # ---------- checks ----------
+    def load_plan(self):
+        p = self.plan_path
+        d, base = os.path.dirname(p), os.path.basename(p)
+        if d != PLAN_DIR or not PLAN_RE.match(base) or ".." in p:
+            raise Refused("R1", f"the plan must be {PLAN_DIR}/plan-<id>.json, got {p!r}")
+        try:
+            st = self.r.stat(p)
+        except OSError as e:
+            raise Refused("R1", f"cannot stat the plan: {e}")
+        if not stat.S_ISREG(st.st_mode):
+            raise Refused("R1", "the plan is not a regular file (a symlink or a device is refused)")
+        if st.st_uid != self.r.agent_uid():
+            raise Refused("R1", f"the plan is not owned by {AGENT_USER}")
+        if st.st_size > 2 * 1024 * 1024:
+            raise Refused("R1", "the plan is larger than 2 MB")
+        try:
+            plan = json.loads(self.r.read_file(p))
+        except (OSError, ValueError) as e:
+            raise Refused("R1", f"the plan is not valid JSON: {e}")
+        if not isinstance(plan, dict):
+            raise Refused("R1", "the plan is not a JSON object")
+        return plan
+
+    def check_plan(self, plan):
+        mode = plan.get("mode", "apply")
+        if mode not in ("apply", "inventory", "health"):
+            raise Refused("R11", f"unknown mode {mode!r}")
+        if plan.get("layer") != "guest":
+            raise Refused("R12", f"layer {plan.get('layer')!r} is refused in this release (guest only)")
+        if plan.get("lane", "fast") != "fast":
+            raise Refused("R3", "the slow lane is refused in this release")
+        vmid = plan.get("vmid")
+        if not isinstance(vmid, int) or isinstance(vmid, bool) or vmid <= 0:
+            raise Refused("R11", f"vmid must be a positive integer, got {vmid!r}")
+        rid = plan.get("release_id", "")
+        if not isinstance(rid, str) or not re.match(r"^[A-Za-z0-9._:-]{1,80}$", rid):
+            raise Refused("R11", f"release_id {rid!r} is not a plain id")
+        if plan.get("allow_new"):
+            raise Refused("R6", "allow_new is a slow-lane field; the fast lane never adds a package")
+        pk = plan.get("packages", [])
+        if not isinstance(pk, list) or (mode == "apply" and not pk):
+            raise Refused("R11", "packages must be a non-empty list in apply mode")
+        seen = set()
+        for e in pk:
+            if not isinstance(e, dict):
+                raise Refused("R11", "every package entry must be an object")
+            n, v, o = e.get("name"), e.get("version"), e.get("origin")
+            if not isinstance(n, str) or not NAME_RE.match(n):
+                raise Refused("R11", f"package name {n!r} is not a Debian package name")
+            if not isinstance(v, str) or not VERSION_RE.match(v):
+                raise Refused("R11", f"version {v!r} of {n} is not a Debian version string")
+            if n in seen:
+                raise Refused("R11", f"package {n} is named twice")
+            seen.add(n)
+            if o not in FAST_ORIGINS:
+                raise Refused("R2", f"{n}: origin {o!r} is not Debian / Debian-Security (the fast lane, `11` C3)")
+        snap = plan.get("snapshot", "")
+        if snap and not SNAP_RE.match(snap):
+            raise Refused("R11", f"snapshot {snap!r} is not YYYYMMDDTHHMMSSZ")
+        return mode, vmid
+
+    def check_guest(self, vmid):
+        if vmid in RESERVED_VMIDS:
+            raise Refused("R10", f"vmid {vmid} is a reserved scratch vmid")
+        try:
+            conf = self.r.read_file(f"/etc/pve/lxc/{vmid}.conf")
+        except OSError:
+            raise Refused("R10", f"vmid {vmid} is not a container on this host")
+        cur = conf.split("\n[", 1)[0]  # the current config, not a snapshot section
+        binds = [l for l in cur.splitlines() if re.match(r"^mp[0-9]+: " + re.escape(DRIVES_PARENT) + r",", l)]
+        if not binds:
+            raise Refused("R10", f"vmid {vmid} does not bind {DRIVES_PARENT} — it is not this box's customer guest")
+        lock = [l for l in cur.splitlines() if l.startswith("lock:")]
+        if lock:
+            raise Refused("R9", f"vmid {vmid} is locked ({lock[0].split(':', 1)[1].strip()}) — a backup or restore is running")
+        rc, out, _ = self.r.host(["/usr/sbin/pct", "status", str(vmid)])
+        if rc != 0 or "running" not in out:
+            raise Refused("R10", f"vmid {vmid} is not running")
+
+    # ---------- guest helpers ----------
+    def g(self, argv, timeout=1800):
+        return self.r.guest(self.vmid, argv, timeout)
+
+    def installed(self):
+        rc, out, _ = self.g(["dpkg-query", "-W", "-f", "${Package}\t${Version}\t${db:Status-Abbrev}\n"])
+        res = {}
+        for l in out.splitlines():
+            parts = l.split("\t")
+            if len(parts) == 3 and parts[2].startswith("ii"):
+                res[parts[0]] = parts[1]
+        return res
+
+    def dpkg_cmp(self, a, op, b):
+        rc, _, _ = self.g(["dpkg", "--compare-versions", a, op, b])
+        return rc == 0
+
+    def madison(self, name):
+        rc, out, _ = self.g(["apt-cache", "madison", name])
+        vs = set()
+        for l in out.splitlines():
+            f = [x.strip() for x in l.split("|")]
+            if len(f) >= 3 and f[0] == name:
+                vs.add(f[1])
+        return vs
+
+    def simulate(self, args):
+        rc, out, err = self.g(APT_ENV + ["apt-get", "-s", "-q"] + args)
+        inst, remv = [], []
+        for l in out.splitlines():
+            m = re.match(r"^Inst (\S+) (?:\[([^]]*)\] )?\((\S+) (.*?) \[[a-z0-9]+\]\)", l)
+            if m:
+                inst.append({"name": m.group(1), "from": m.group(2), "to": m.group(3), "origin": m.group(4)})
+            m = re.match(r"^Remv (\S+)", l)
+            if m:
+                remv.append(m.group(1))
+        return rc, inst, remv, out + err
+
+    @staticmethod
+    def origin_name(origin):
+        # "Debian:13.7/stable, Debian-Security:13/stable-security" -> {"Debian", "Debian-Security"}
+        return {o.strip().split(":")[0] for o in origin.split(",") if o.strip()}
+
+    def free_bytes(self):
+        rc, out, _ = self.g(["df", "-B1", "--output=avail", "/"])
+        try:
+            return int(out.strip().splitlines()[-1])
+        except (ValueError, IndexError):
+            return -1
+
+    def apt_lock_held(self):
+        rc, out, _ = self.g(["fuser", "/var/lib/dpkg/lock-frontend", "/var/lib/dpkg/lock"])
+        return rc == 0 and out.strip() != ""
+
+    def health(self):
+        """The guest's signals: every container's state + health, the controller's own health, the network."""
+        rc, out, _ = self.g(["docker", "ps", "-a", "--format", "{{.Names}}\t{{.State}}\t{{.Status}}"], timeout=60)
+        cont = {}
+        for l in out.splitlines():
+            p = l.split("\t")
+            if len(p) == 3:
+                h = "healthy" if "(healthy)" in p[2] else "unhealthy" if "(unhealthy)" in p[2] else \
+                    "starting" if "(health: starting)" in p[2] else "none"
+                cont[p[0]] = {"state": p[1], "health": h}
+        nrc, _, _ = self.g(["getent", "hosts", "deb.debian.org"], timeout=30)
+        return {"docker_ok": rc == 0, "containers": cont,
+                "controller": cont.get("felhom-controller", {}).get("health", "absent"),
+                "network_ok": nrc == 0}
+
+    def restart_needed(self):
+        """Processes still mapping deleted files, OUTSIDE docker containers (C11)."""
+        script = ('for p in /proc/[0-9]*; do grep -q "(deleted)" $p/maps 2>/dev/null || continue; '
+                  'grep -q "docker" $p/cgroup 2>/dev/null && continue; echo "${p#/proc/} $(cat $p/comm 2>/dev/null)"; done')
+        rc, out, _ = self.g(["sh", "-c", script], timeout=120)
+        procs = sorted({l.split(" ", 1)[1] for l in out.splitlines() if " " in l})
+        pid1 = any(l.split(" ", 1)[0] == "1" for l in out.splitlines())
+        return procs, pid1
+
+    def inventory(self):
+        inst = self.installed()
+        names = sorted(inst)
+        origins = {}
+        for i in range(0, len(names), 200):
+            rc, out, _ = self.g(["apt-cache", "policy"] + names[i:i + 200])
+            cur, star = None, False
+            for l in out.splitlines():
+                if not l.startswith(" "):
+                    cur, star = l.rstrip(":"), False
+                    continue
+                s = l.strip()
+                if s.startswith("*** "):
+                    star = True
+                    continue
+                if star and cur and re.match(r"^[0-9-]+ ", s):
+                    if "/var/lib/dpkg/status" in s:
+                        origins.setdefault(cur, "local")
+                    else:
+                        origins[cur] = s
+                    continue
+                if star and not re.match(r"^[0-9-]+ ", s):
+                    star = False
+        # Map an index URL to an origin name the hub understands.
+        def oname(src):
+            if src in (None, "local"):
+                return "unknown"
+            if "security" in src and "debian" in src:
+                return "Debian-Security"
+            if "docker.com" in src:
+                return "Docker"
+            if "debian" in src:
+                return "Debian"
+            return "other"
+        rc, pend, remv, _ = self.simulate(["dist-upgrade"])
+        return {
+            "installed": [{"name": n, "version": inst[n], "origin": oname(origins.get(n))} for n in names],
+            "pending": [{"name": p["name"], "from": p["from"], "to": p["to"],
+                         "origin": sorted(self.origin_name(p["origin"]))} for p in pend],
+        }
+
+    # ---------- the run ----------
+    def run(self):
+        plan = self.load_plan()
+        self.mode, self.vmid = self.check_plan(plan)
+        self.report.update(mode=self.mode, release_id=plan.get("release_id"), vmid=self.vmid)
+        self.check_guest(self.vmid)
+        log = self.r.log
+        if self.mode == "health":
+            self.report["health"] = self.health()
+            return 0
+        log(f"os-apply: START release={plan.get('release_id')} layer=guest:{self.vmid} lane=fast mode={self.mode} packages={len(plan.get('packages', []))}")
+        if self.apt_lock_held():
+            raise Refused("R9", "another apt/dpkg holds the lock in the guest")
+        self.report["health_before"] = self.health()
+        if self.mode == "apply":
+            self.repair()
+        rc, out, err = self.g(APT_ENV + ["apt-get", "-q", "update"], timeout=600)
+        if rc != 0:
+            raise Refused("R7", f"apt-get update failed in the guest: {(out + err).strip().splitlines()[-1:]}")
+        if self.mode == "apply":
+            rc = self.apply(plan)
+            if rc:
+                return rc
+        procs, pid1 = self.restart_needed()
+        self.report.update(self.inventory())
+        self.report["restart_needed"] = procs
+        self.report["docker_restart_needed"] = any(p in ("dockerd", "containerd") for p in procs)
+        self.report["reboot_needed"] = pid1
+        self.report["health_after"] = self.health()
+        return 0
+
+    def repair(self):
+        rc, before, _ = self.g(["dpkg", "--audit"])
+        self.g(APT_ENV + ["dpkg", "--configure", "-a", "--force-confold"])
+        rc2, out, err = self.g(APT_ENV + ["apt-get", "-f", "install", "-y", "-q"] + DPKG_OPTS)
+        _, after, _ = self.g(["dpkg", "--audit"])
+        configured = len([l for l in before.splitlines() if l.startswith(" ")])
+        fixed = len(re.findall(r"^Setting up ", out, re.M))
+        self.report["repair"] = {"half_configured_before": configured, "fixed": fixed, "clean_after": after.strip() == ""}
+        self.r.log(f"os-apply: REPAIR configured={configured} fixed={fixed}")
+        if after.strip():
+            raise Refused("R13", "dpkg is still broken after the repair: " + after.strip().splitlines()[0])
+
+    def apply(self, plan):
+        log = self.r.log
+        inst = self.installed()
+        upgrade, already, notinst = [], 0, 0
+        for e in plan["packages"]:
+            n, v = e["name"], e["version"]
+            if n not in inst:
+                notinst += 1
+                continue
+            if not self.dpkg_cmp(v, "gt", inst[n]):
+                already += 1
+                continue
+            upgrade.append((n, v))
+        from_snap = 0
+        missing = [(n, v) for n, v in upgrade if v not in self.madison(n)]
+        if missing:
+            snap = plan.get("snapshot", "")
+            if not snap:
+                raise Refused("R7", f"{missing[0][0]}={missing[0][1]} is not downloadable and the plan names no snapshot")
+            self.add_snapshot_sources(snap)
+            still = [(n, v) for n, v in missing if v not in self.madison(n)]
+            if still:
+                self.remove_snapshot_sources()
+                raise Refused("R7", f"{still[0][0]}={still[0][1]} is not downloadable, not even from snapshot {snap}")
+            from_snap = len(missing)
+        try:
+            log(f"os-apply: PLAN upgrade={len(upgrade)} already={already} not-installed={notinst} from-snapshot={from_snap}")
+            self.report["plan"] = {"upgrade": len(upgrade), "already": already, "not_installed": notinst, "from_snapshot": from_snap}
+            if not upgrade:
+                self.report["upgraded"] = []
+                log("os-apply: DONE rc=0 seconds=0 upgraded=0 (nothing to do)")
+                return 0
+            args = ["install", "--only-upgrade", "--no-install-recommends"] + [f"{n}={v}" for n, v in upgrade]
+            rc, sim, remv, text = self.simulate(args)
+            if rc != 0:
+                tail = text.strip().splitlines()[-1] if text.strip() else ""
+                raise Refused("R7", "the simulation failed: " + tail)
+            if remv:
+                raise Refused("R4", f"the plan would remove {', '.join(remv[:5])}")
+            want = dict(upgrade)
+            for p in sim:
+                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:
+                    raise Refused("R6", f"the plan would touch {p['name']}, which is not in the plan")
+                if p["to"] != want[p["name"]]:
+                    raise Refused("R6", f"{p['name']} would go to {p['to']}, not the approved {want[p['name']]}")
+                if not self.dpkg_cmp(p["to"], "gt", p["from"]):
+                    raise Refused("R5", f"{p['name']} would be downgraded {p['from']} -> {p['to']}")
+                if not self.origin_name(p["origin"]) & set(FAST_ORIGINS):
+                    raise Refused("R2", f"{p['name']} would come from {p['origin']}, not Debian")
+            need = self.download_bytes(args)
+            free = self.free_bytes()
+            if free >= 0 and free < max(MIN_FREE, 3 * need):
+                raise Refused("R8", f"free space {free} B is below max(500 MB, 3 x download {need} B)")
+            t0 = time.time()
+            rc, out, err = self.g(APT_ENV + ["apt-get", "-y", "-q"] + DPKG_OPTS + args)
+            secs = time.time() - t0
+            # dpkg says "Installing new version of config file X" when X was NOT changed locally (the package's new
+            # version is taken), and "Configuration file 'X'" + "Keeping old config file" when it was (--force-confold
+            # keeps the local one; the package's version lands as X.dpkg-dist). Measured live 2026-10-04 (debian_version).
+            conflict = None
+            for l in (out + err).splitlines():
+                m = re.search(r"Installing new version of config file (\S+?)\s*\.\.\.", l)
+                if m:
+                    log(f"os-apply: CONFFILE updated {m.group(1)} (it was not changed locally)")
+                m = re.search(r"Configuration file '([^']+)'", l)
+                if m:
+                    conflict = m.group(1)
+                if conflict and "Keeping old config file" in l:
+                    log(f"os-apply: CONFFILE kept {conflict} (changed locally; the package's version is {conflict}.dpkg-dist)")
+                    self.report.setdefault("conffiles_kept", []).append(conflict)
+                    conflict = None
+            self.g(["apt-get", "clean"])
+            if rc != 0:
+                _, aud, _ = self.g(["dpkg", "--audit"])
+                first = aud.strip().splitlines()[0] if aud.strip() else "clean"
+                log(f"os-apply: FAILED rc={rc} step=install — dpkg state: {first}")
+                self.report["failed"] = {"rc": rc, "dpkg_audit": first, "tail": (out + err).strip().splitlines()[-3:]}
+                return 3
+            self.report["upgraded"] = [{"name": n, "version": v} for n, v in upgrade]
+            self.report["seconds"] = round(secs, 1)
+            log(f"os-apply: DONE rc=0 seconds={secs:.1f} upgraded={len(upgrade)}")
+            return 0
+        finally:
+            if from_snap:
+                self.remove_snapshot_sources()
+
+    def download_bytes(self, args):
+        rc, out, _ = self.g(APT_ENV + ["apt-get", "-s", "-o", "Debug::NoLocking=1", "--print-uris", "-q"] + args)
+        total = 0
+        for l in out.splitlines():
+            m = re.match(r"^'[^']+' \S+ ([0-9]+) ", l)
+            if m:
+                total += int(m.group(1))
+        return total
+
+    def add_snapshot_sources(self, snap):
+        rc, out, _ = self.g(["sh", "-c", ". /etc/os-release && echo $VERSION_CODENAME"])
+        code = out.strip()
+        if not re.match(r"^[a-z]+$", code):
+            raise Refused("R7", f"cannot read the guest's Debian codename ({code!r})")
+        body = (f"deb [check-valid-until=no] http://snapshot.debian.org/archive/debian/{snap} {code} main\n"
+                f"deb [check-valid-until=no] http://snapshot.debian.org/archive/debian-security/{snap} {code}-security main\n")
+        self.r.guest_write(self.vmid, SNAPSHOT_LIST, body)
+        self.r.log(f"os-apply: SNAPSHOT using snapshot.debian.org/{snap} for versions no longer published (decision 79)")
+        rc, out, err = self.g(APT_ENV + ["apt-get", "-q", "update"], timeout=600)
+        if rc != 0:
+            self.remove_snapshot_sources()
+            raise Refused("R7", "apt-get update against snapshot.debian.org failed")
+
+    def remove_snapshot_sources(self):
+        self.g(["rm", "-f", SNAPSHOT_LIST])
+        self.g(APT_ENV + ["apt-get", "-q", "update"], timeout=600)
+
+
+def guest_write(self, vmid, path, body):
+    """Write a small text file inside the guest via `pct exec … tee` (stdin), never via a shell string."""
+    p = subprocess.run(["/usr/sbin/pct", "exec", str(vmid), "--", "tee", path], input=body,
+                       capture_output=True, text=True, timeout=60)
+    if p.returncode != 0:
+        raise Refused("R7", f"could not write {path} in the guest")
+
+
+Runner.guest_write = guest_write
+
+
+def main(argv, runner=None):
+    r = runner or Runner()
+    if len(argv) != 3 or argv[1] != "--plan":
+        r.log("os-apply: REFUSED: R1 usage: felhom-os-apply --plan /var/lib/felhom-agent/os/plan-<id>.json")
+        print("OSAPPLY-REPORT " + json.dumps({"refused": {"code": "R1", "reason": "usage"}}))
+        return 2
+    a = Apply(r, argv[2])
+    try:
+        rc = a.run()
+    except Refused as e:
+        r.log(f"os-apply: REFUSED: {e.code} {e.reason}")
+        a.report["refused"] = {"code": e.code, "reason": e.reason}
+        rc = 2
+    except subprocess.TimeoutExpired as e:
+        r.log(f"os-apply: FAILED rc=124 step=timeout — {e.cmd}")
+        a.report["failed"] = {"rc": 124, "timeout": str(e.cmd)[:200]}
+        rc = 3
+    print("OSAPPLY-REPORT " + json.dumps(a.report, sort_keys=True))
+    return rc
+
+
+if __name__ == "__main__":
+    if os.geteuid() != 0:
+        print("felhom-os-apply: must run as root (via sudo)", file=sys.stderr)
+        sys.exit(2)
+    sys.exit(main(sys.argv))

configs/test_felhom_os_apply.py

@@ -0,0 +1,467 @@
+#!/usr/bin/env python3
+"""Tests for configs/felhom-os-apply (`11` §5.4.1). A fake runner plays the host and the guest: nothing is executed
+for real except the local `dpkg --compare-versions` (pure, no network). Every refusal R1–R13 has a test; the red-proof
+(each test fails when its rule is removed) is `audits/os-guest-lane-2026-10-04/partB/redproof.txt`.
+
+Run: python3 configs/test_felhom_os_apply.py   (also run by internal/osupdate's Go test)
+"""
+import importlib.machinery
+import importlib.util
+import json
+import os
+import pathlib
+import re
+import stat as statmod
+import subprocess
+import unittest
+
+HERE = pathlib.Path(__file__).resolve().parent
+_loader = importlib.machinery.SourceFileLoader("osapply", os.environ.get("OSAPPLY_UNDER_TEST", str(HERE / "felhom-os-apply")))  # red-proof seam
+_spec = importlib.util.spec_from_loader("osapply", _loader)
+osapply = importlib.util.module_from_spec(_spec)
+_loader.exec_module(osapply)
+
+PLAN = "/var/lib/felhom-agent/os/plan-t1.json"
+CONF_OK = ("arch: amd64\nmp0: local-lvm:vm-9201-disk-1,mp=/var/lib/felhom,backup=1,size=70G\n"
+           "mp8: /mnt/felhom-drives,mp=/mnt/felhom-drives\nrootfs: local-lvm:vm-9201-disk-0,size=32G\n")
+DEB = "Debian:13.7/stable"
+SEC = "Debian-Security:13/stable-security"
+
+
+def dpkg_cmp(a, op, b):
+    return subprocess.run(["dpkg", "--compare-versions", a, op, b]).returncode == 0
+
+
+class St:
+    def __init__(self, mode=statmod.S_IFREG | 0o600, uid=999, size=100):
+        self.st_mode, self.st_uid, self.st_size = mode, uid, size
+
+
+class Fake:
+    """The host + one guest. `installed` / `live` (name -> versions in the live archive) / `snapshot` (versions
+    the snapshot archive adds) / `extra_sim` (lines the simulation adds) / `dpkg_audit` / `free`."""
+
+    def __init__(self):
+        self.plan = {"release_id": "os-t1", "layer": "guest", "lane": "fast", "vmid": 9201, "mode": "apply",
+                     "snapshot": "20261004T080000Z",
+                     "packages": [{"name": "libc6", "version": "2.41-12+deb13u4", "origin": "Debian"},
+                                  {"name": "openssl", "version": "3.5.7-1~deb13u3", "origin": "Debian-Security"}]}
+        self.files = {"/etc/pve/lxc/9201.conf": CONF_OK}
+        self.stats = {PLAN: St()}
+        self.installed = {"libc6": "2.41-12+deb13u3", "openssl": "3.5.6-1~deb13u1", "bash": "5.2.37-2+b9"}
+        self.live = {"libc6": {"2.41-12+deb13u4"}, "openssl": {"3.5.7-1~deb13u3"}}
+        self.snapshot = {}
+        self.snap_active = False
+        self.extra_sim = []
+        self.dpkg_audit = ""
+        self.free = 10 * 1024 ** 3
+        self.install_rc = 0
+        self.calls = []
+        self.logs = []
+        self.written = {}
+        self.status = "status: running"
+        self.lock_held = False
+
+    # Runner interface
+    def read_file(self, p):
+        if p == PLAN:
+            return json.dumps(self.plan)
+        if p not in self.files:
+            raise OSError("no such file")
+        return self.files[p]
+
+    def stat(self, p):
+        if p not in self.stats:
+            raise OSError("no such file")
+        return self.stats[p]
+
+    def agent_uid(self):
+        return 999
+
+    def log(self, line):
+        self.logs.append(line)
+
+    def host(self, argv, timeout=600):
+        self.calls.append(("host", argv))
+        if argv[1] == "status":
+            return 0, self.status + "\n", ""
+        return 1, "", "unexpected host call"
+
+    def guest_write(self, vmid, path, body):
+        self.written[path] = body
+        if path == osapply.SNAPSHOT_LIST:
+            self.snap_active = True
+
+    def avail(self, n):
+        v = set(self.live.get(n, set()))
+        if self.snap_active:
+            v |= self.snapshot.get(n, set())
+        return v
+
+    def guest(self, vmid, argv, timeout=1800):
+        self.calls.append(("guest", vmid, argv))
+        a = [x for x in argv if not re.match(r"^[A-Z_]+=", x) and x != "env"]
+        cmd = a[0]
+        if cmd == "dpkg-query":
+            return 0, "".join(f"{n}\t{v}\tii \n" for n, v in self.installed.items()), ""
+        if cmd == "dpkg" and a[1] == "--compare-versions":
+            return (0 if dpkg_cmp(a[2], a[3], a[4]) else 1), "", ""
+        if cmd == "dpkg" and a[1] == "--audit":
+            return 0, self.dpkg_audit, ""
+        if cmd == "dpkg" and a[1] == "--configure":
+            return 0, "", ""
+        if cmd == "fuser":
+            return (0, " 123", "") if self.lock_held else (1, "", "")
+        if cmd == "apt-cache" and a[1] == "madison":
+            return 0, "".join(f" {a[2]} | {v} | http://deb.debian.org trixie/main amd64 Packages\n" for v in self.avail(a[2])), ""
+        if cmd == "apt-cache" and a[1] == "policy":
+            out = ""
+            for n in a[2:]:
+                out += f"{n}:\n  Installed: {self.installed.get(n)}\n  Version table:\n *** {self.installed.get(n)} 500\n        500 http://deb.debian.org/debian trixie/main amd64 Packages\n"
+            return 0, out, ""
+        if cmd == "apt-get":
+            if "update" in a:
+                return 0, "", ""
+            if "clean" in a:
+                return 0, "", ""
+            if "-f" in a:
+                self.dpkg_audit = ""
+                return 0, "Setting up x (1) ...\n" if getattr(self, "repaired", False) else "", ""
+            if "-s" in a:
+                return self.sim(a)
+            if "install" in a:
+                if self.install_rc:
+                    return self.install_rc, "", "E: boom"
+                for x in a:
+                    if "=" in x and not x.startswith("-") and "::" not in x:
+                        n, v = x.split("=", 1)
+                        self.installed[n] = v
+                return 0, getattr(self, "install_out", "Setting up libc6 ...\n"), ""
+        if cmd == "df":
+            return 0, f"Avail\n{self.free}\n", ""
+        if cmd == "docker":
+            return 0, "felhom-controller\trunning\tUp 1 hour (healthy)\napp\trunning\tUp 1 hour (healthy)\n", ""
+        if cmd == "getent":
+            return 0, "1.2.3.4 deb.debian.org\n", ""
+        if cmd == "sh":
+            if "os-release" in a[2]:
+                return 0, "trixie\n", ""
+            return 0, "", ""
+        if cmd == "rm":
+            self.snap_active = False
+            return 0, "", ""
+        return 1, "", f"unexpected guest call {a}"
+
+    def sim(self, a):
+        if "--print-uris" in a:
+            return 0, "'http://x/libc6.deb' libc6.deb 4000000 SHA256:x\n", ""
+        if "dist-upgrade" in a:
+            return 0, "Inst bash [5.2.37-2+b9] (5.2.37-2+b10 Debian:13.7/stable [amd64])\n", ""
+        out = ""
+        for x in a:
+            if "=" in x and not x.startswith("-") and "::" not in x:
+                n, v = x.split("=", 1)
+                if v not in self.avail(n):
+                    return 100, "", f"E: Version '{v}' for '{n}' was not found"
+                origin = 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, ""
+
+
+def run(f):
+    import io
+    import contextlib
+    buf = io.StringIO()
+    with contextlib.redirect_stdout(buf):
+        rc = osapply.main(["felhom-os-apply", "--plan", PLAN], runner=f)
+    line = [l for l in buf.getvalue().splitlines() if l.startswith("OSAPPLY-REPORT ")][-1]
+    return rc, json.loads(line[len("OSAPPLY-REPORT "):])
+
+
+class Happy(unittest.TestCase):
+    def test_apply_installs_exactly_the_plan(self):
+        f = Fake()
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(f.installed["libc6"], "2.41-12+deb13u4")
+        self.assertEqual(f.installed["openssl"], "3.5.7-1~deb13u3")
+        self.assertEqual(f.installed["bash"], "5.2.37-2+b9", "a package outside the plan was changed")
+        self.assertEqual(rep["plan"]["upgrade"], 2)
+        self.assertIn("installed", rep)
+        self.assertEqual(rep["pending"][0]["name"], "bash")
+        self.assertTrue(any(l.startswith("os-apply: REPAIR ") for l in f.logs), "the repair line must always print")
+        self.assertTrue(any(l.startswith("os-apply: DONE rc=0") for l in f.logs))
+        inst = [c for c in f.calls if c[0] == "guest" and "install" in c[2] and "-s" not in c[2] and "-f" not in c[2]]
+        self.assertTrue(inst and "Dpkg::Options::=--force-confold" in inst[0][2], "must keep existing config files")
+
+    def test_already_current_is_a_no_op(self):
+        f = Fake()
+        f.installed.update(libc6="2.41-12+deb13u4", openssl="3.5.7-1~deb13u3")
+        rc, rep = run(f)
+        self.assertEqual(rc, 0)
+        self.assertEqual(rep["plan"]["upgrade"], 0)
+
+    def test_inventory_installs_nothing(self):
+        f = Fake()
+        f.plan["mode"] = "inventory"
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(f.installed["libc6"], "2.41-12+deb13u3")
+        self.assertIn("installed", rep)
+        self.assertIn("restart_needed", rep)
+
+    def test_health_mode(self):
+        f = Fake()
+        f.plan["mode"] = "health"
+        rc, rep = run(f)
+        self.assertEqual(rc, 0)
+        self.assertEqual(rep["health"]["controller"], "healthy")
+
+
+class Repair(unittest.TestCase):
+    def test_repair_runs_first_and_is_reported(self):
+        f = Fake()
+        f.dpkg_audit = "The following packages have been unpacked but not yet configured.\n perl  Larry Wall's\n"
+        f.repaired = True
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(rep["repair"]["half_configured_before"], 1)
+        self.assertEqual(rep["repair"]["fixed"], 1)
+        order = [i for i, c in enumerate(f.calls) if c[0] == "guest" and c[2][-1:] != ["update"]]
+        first_cfg = next(i for i, c in enumerate(f.calls) if c[0] == "guest" and "--configure" in c[2])
+        first_upd = next(i for i, c in enumerate(f.calls) if c[0] == "guest" and "update" in c[2])
+        self.assertLess(first_cfg, first_upd, "the repair must run before anything else touches apt")
+        self.assertTrue(order)
+
+
+class Snapshot(unittest.TestCase):
+    def test_a_replaced_version_comes_from_the_snapshot(self):
+        f = Fake()
+        f.live["openssl"] = {"3.5.7-1~deb13u4"}  # Debian moved on
+        f.snapshot["openssl"] = {"3.5.7-1~deb13u3"}
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertEqual(rep["plan"]["from_snapshot"], 1)
+        self.assertEqual(f.installed["openssl"], "3.5.7-1~deb13u3", "must install the APPROVED version, not the newer one")
+        body = f.written[osapply.SNAPSHOT_LIST]
+        self.assertIn("snapshot.debian.org/archive/debian/20261004T080000Z trixie main", body)
+        self.assertIn("debian-security/20261004T080000Z trixie-security main", body)
+        self.assertFalse(f.snap_active, "the temporary snapshot sources must be removed after the run")
+
+    def test_snapshot_does_not_have_it_either(self):
+        f = Fake()
+        f.live["openssl"] = set()
+        rc, rep = run(f)
+        self.assertEqual((rc, rep["refused"]["code"]), (2, "R7"))
+        self.assertFalse(f.snap_active)
+
+
+class Refusals(unittest.TestCase):
+    def refused(self, f, code):
+        rc, rep = run(f)
+        self.assertEqual(rc, 2, rep)
+        self.assertEqual(rep["refused"]["code"], code, rep)
+        self.assertTrue(any(l.startswith(f"os-apply: REFUSED: {code} ") for l in f.logs), f.logs)
+        inst = [c for c in f.calls if c[0] == "guest" and "install" in c[2] and "-s" not in c[2] and "-f" not in c[2]]
+        self.assertEqual(inst, [], "a refusal must install nothing")
+        return rep
+
+    def test_R1_usage(self):
+        import io
+        import contextlib
+        f = Fake()
+        with contextlib.redirect_stdout(io.StringIO()):
+            self.assertEqual(osapply.main(["felhom-os-apply", "--plan", PLAN, "--extra"], runner=f), 2)
+            self.assertEqual(osapply.main(["felhom-os-apply", "--plan"], runner=f), 2)
+
+    def test_R1_path_outside_the_plan_dir(self):
+        import io
+        import contextlib
+        f = Fake()
+        with contextlib.redirect_stdout(io.StringIO()):
+            rc = osapply.main(["felhom-os-apply", "--plan", "/tmp/plan-x.json"], runner=f)
+        self.assertEqual(rc, 2)
+        self.assertTrue(any("R1" in l for l in f.logs))
+
+    def test_R1_symlink(self):
+        f = Fake()
+        f.stats[PLAN] = St(mode=statmod.S_IFLNK | 0o777)
+        self.refused(f, "R1")
+
+    def test_R1_not_owned_by_the_agent(self):
+        f = Fake()
+        f.stats[PLAN] = St(uid=0)
+        self.refused(f, "R1")
+
+    def test_R2_non_debian_origin_in_the_plan(self):
+        f = Fake()
+        f.plan["packages"][0]["origin"] = "Proxmox"
+        self.refused(f, "R2")
+
+    def test_R2_non_debian_origin_in_the_simulation(self):
+        f = Fake()
+        f.installed["libc6"] = "2.41-12+deb13u3"
+        orig = f.sim
+
+        def sim(a):
+            rc, out, err = orig(a)
+            return rc, out.replace("Debian:13.7/stable", "Proxmox Debian Repository:stable"), err
+        f.sim = sim
+        self.refused(f, "R2")
+
+    def test_R3_slow_lane(self):
+        f = Fake()
+        f.plan["lane"] = "slow"
+        self.refused(f, "R3")
+
+    def test_R4_removal(self):
+        f = Fake()
+        f.extra_sim = ["Remv bash [5.2.37-2+b9]"]
+        self.refused(f, "R4")
+
+    def test_R5_downgrade(self):
+        f = Fake()
+        f.installed["libc6"] = "2.41-12+deb13u4"
+        f.plan["packages"] = [{"name": "openssl", "version": "3.5.7-1~deb13u3", "origin": "Debian-Security"}]
+        f.extra_sim = ["Inst openssl [3.5.6-1~deb13u1] (3.5.5-1 Debian:13.7/stable [amd64])"]
+        orig = f.sim
+
+        def sim(a):  # the simulation answers with a LOWER version than installed
+            rc, out, err = orig(a)
+            return rc, "\n".join(l for l in out.splitlines() if not l.startswith("Inst openssl [3.5.6-1~deb13u1] (3.5.7")) + "\n", err
+        f.sim = sim
+        f.plan["packages"][0]["version"] = "3.5.7-1~deb13u3"
+        rep = run(f)[1]
+        # The plan asks 3.5.7; the simulation goes to 3.5.5: that is BOTH a wrong version (R6) and a downgrade.
+        self.assertIn(rep["refused"]["code"], ("R5", "R6"))
+
+    def test_R5_downgrade_exact(self):
+        f = Fake()
+        f.plan["packages"] = [{"name": "openssl", "version": "3.5.7-1~deb13u3", "origin": "Debian-Security"}]
+        f.installed["openssl"] = "3.5.6-1~deb13u1"
+        orig = f.sim
+
+        def sim(a):
+            rc, out, err = orig(a)
+            return rc, out.replace("[3.5.6-1~deb13u1]", "[3.5.8-1]"), err
+        f.sim = sim
+        self.refused(f, "R5")
+
+    def test_R6_new_package(self):
+        f = Fake()
+        f.extra_sim = ["Inst newthing (1.0 Debian:13.7/stable [amd64])"]
+        self.refused(f, "R6")
+
+    def test_R6_unlisted_package(self):
+        f = Fake()
+        f.extra_sim = ["Inst bash [5.2.37-2+b9] (5.2.37-2+b10 Debian:13.7/stable [amd64])"]
+        self.refused(f, "R6")
+
+    def test_R6_allow_new_is_slow_lane(self):
+        f = Fake()
+        f.plan["allow_new"] = ["proxmox-kernel-x"]
+        self.refused(f, "R6")
+
+    def test_R7_not_downloadable_and_no_snapshot(self):
+        f = Fake()
+        f.live["openssl"] = set()
+        f.plan["snapshot"] = ""
+        self.refused(f, "R7")
+
+    def test_R8_free_space(self):
+        f = Fake()
+        f.free = 100 * 1024 * 1024
+        self.refused(f, "R8")
+
+    def test_R9_guest_locked_by_a_backup(self):
+        f = Fake()
+        f.files["/etc/pve/lxc/9201.conf"] = CONF_OK + "lock: backup\n"
+        self.refused(f, "R9")
+
+    def test_R9_apt_lock_held(self):
+        f = Fake()
+        f.lock_held = True
+        self.refused(f, "R9")
+
+    def test_R10_not_the_boxs_own_guest(self):
+        f = Fake()
+        f.files["/etc/pve/lxc/9201.conf"] = CONF_OK.replace("mp8: /mnt/felhom-drives,", "mp8: /mnt/hdd_1/scratch,")
+        self.refused(f, "R10")
+
+    def test_R10_reserved_vmid(self):
+        f = Fake()
+        f.plan["vmid"] = 990003
+        self.refused(f, "R10")
+
+    def test_R10_bind_only_in_a_snapshot_section(self):
+        f = Fake()
+        f.files["/etc/pve/lxc/9201.conf"] = "rootfs: x\n[snap1]\nmp8: /mnt/felhom-drives,mp=/mnt/felhom-drives\n"
+        self.refused(f, "R10")
+
+    def test_R10_not_running(self):
+        f = Fake()
+        f.status = "status: stopped"
+        self.refused(f, "R10")
+
+    def test_R11_duplicate(self):
+        f = Fake()
+        f.plan["packages"].append(dict(f.plan["packages"][0]))
+        self.refused(f, "R11")
+
+    def test_R11_bad_version_string(self):
+        f = Fake()
+        f.plan["packages"][0]["version"] = "1.0; rm -rf /"
+        self.refused(f, "R11")
+
+    def test_R11_bad_name(self):
+        f = Fake()
+        f.plan["packages"][0]["name"] = "--purge"
+        self.refused(f, "R11")
+
+    def test_R12_host_layer(self):
+        f = Fake()
+        f.plan["layer"] = "host"
+        self.refused(f, "R12")
+
+    def test_R13_repair_does_not_fix_it(self):
+        f = Fake()
+        f.dpkg_audit = "The following packages are broken\n perl\n"
+        orig = f.guest
+
+        def guest(vmid, argv, timeout=1800):
+            rc, out, err = orig(vmid, argv, timeout)
+            if "-f" in argv:
+                f.dpkg_audit = "The following packages are broken\n perl\n"
+            return rc, out, err
+        f.guest = guest
+        self.refused(f, "R13")
+
+
+class Conffiles(unittest.TestCase):
+    # dpkg's two shapes, measured live 2026-10-04: an unchanged file is UPDATED; a locally changed one is KEPT.
+    def test_updated_vs_kept(self):
+        f = Fake()
+        f.install_out = ("Installing new version of config file /etc/debian_version ...\n"
+                         "Configuration file '/etc/ssh/sshd_config'\n ==> Modified (by you or by a script) since installation.\n"
+                         " ==> Keeping old config file as default.\n")
+        rc, rep = run(f)
+        self.assertEqual(rc, 0, rep)
+        self.assertIn("os-apply: CONFFILE updated /etc/debian_version (it was not changed locally)", f.logs)
+        self.assertTrue(any(l.startswith("os-apply: CONFFILE kept /etc/ssh/sshd_config") for l in f.logs), f.logs)
+        self.assertEqual(rep["conffiles_kept"], ["/etc/ssh/sshd_config"])
+        self.assertFalse(any("kept /etc/debian_version" in l for l in f.logs), "an updated file must not be reported as kept")
+
+
+class Failure(unittest.TestCase):
+    def test_install_failure_is_rc3_with_dpkg_state(self):
+        f = Fake()
+        f.install_rc = 100
+        rc, rep = run(f)
+        self.assertEqual(rc, 3)
+        self.assertEqual(rep["failed"]["rc"], 100)
+        self.assertTrue(any(l.startswith("os-apply: FAILED rc=100 step=install") for l in f.logs))
+
+
+if __name__ == "__main__":
+    unittest.main()

internal/capability/manifest.go

@@ -123,6 +123,9 @@ var manifest = []Capability{
 	{"dnsmasq-install", "dnsmasq package install", "/usr/bin/apt-get", []string{"install", "-y", "-q", "dnsmasq"}, false, ""},
 	{"dnsmasq-write", "dnsmasq drop-in write", "/usr/bin/install", []string{"-m", "0644", "/tmp/felhom-resolver-x.conf", "/etc/dnsmasq.d/felhom-x.conf"}, false, ""},
 	{"dnsmasq-enable", "dnsmasq enable", "/usr/bin/systemctl", []string{"enable", "--now", "dnsmasq"}, false, ""},
+
+	// ---- OS updates, guest fast lane (`11` §5.4.1; the wrapper holds every rule) ----
+	{"osapply-run", "OS update wrapper (guest fast lane)", "/usr/local/sbin/felhom-os-apply", []string{"--plan", "/var/lib/felhom-agent/os/plan-x.json"}, false, ""},
 	{"dnsmasq-reload", "dnsmasq reload", "/usr/bin/systemctl", []string{"reload", "dnsmasq"}, false, ""},
 	{"dnsmasq-restart", "dnsmasq restart (LAN-DNS self-heal)", "/usr/bin/systemctl", []string{"restart", "dnsmasq"}, false, ""},
 	{"dnsmasq-rm", "dnsmasq drop-in remove (decommission)", "/usr/bin/rm", []string{"-f", "/etc/dnsmasq.d/felhom-x.conf"}, false, ""},

internal/hub/client.go

@@ -425,3 +425,27 @@ func (c *Client) FetchRetainedIdentityEscrow(ctx context.Context) (*RetainedEscr
 	}
 	return &out, nil
 }
+
+// PostOSReport sends the OS-update leg's report after every run (hub v0.130.0): POST /api/v1/hosts/{id}/os-report.
+// Per-host key, self-scoped on the hub. Errors are typed like RegisterWG's and never include the bearer.
+func (c *Client) PostOSReport(ctx context.Context, body []byte) error {
+	if c.hostID == "" {
+		return fmt.Errorf("hub: PostOSReport requires a configured host_id")
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/api/v1/hosts/"+c.hostID+"/os-report", bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("hub: building os-report request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+c.apiKey)
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return &TransportError{Err: err}
+	}
+	defer resp.Body.Close()
+	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 64<<10))
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return &HTTPError{StatusCode: resp.StatusCode, BodyTail: tail(raw, 256)}
+	}
+	return nil
+}

internal/hub/osupdate_contract_test.go

@@ -0,0 +1,30 @@
+package hub
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+)
+
+// The os_update block is a cross-repo contract: testdata/desired-state-osupdate.golden.json is byte-identical with
+// felhom.eu/hub/internal/api/testdata (the hub's TestOSUpdate_DesiredBlockMatchesTheGolden proves the hub SERVES
+// it). Here: the agent DECODES every field. A renamed json tag on either side fails one of the two tests.
+func TestOSUpdateGolden_Decodes(t *testing.T) {
+	raw, err := os.ReadFile("testdata/desired-state-osupdate.golden.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var resp DesiredStateResponse
+	if err := json.Unmarshal(raw, &resp); err != nil {
+		t.Fatal(err)
+	}
+	o := resp.DesiredState.OSUpdate
+	if o == nil || o.Ring != 1 || !o.Enabled || o.Release == nil {
+		t.Fatalf("os_update = %+v", o)
+	}
+	r := o.Release
+	if r.ID != "os-20261004-120000" || r.Snapshot != "20261004T120000Z" || len(r.Packages) != 2 ||
+		r.Packages[1].Name != "openssl" || r.Packages[1].Version != "3.5.7-1~deb13u3" || r.Packages[1].Origin != "Debian-Security" {
+		t.Fatalf("release = %+v", r)
+	}
+}

internal/hub/report.go

@@ -548,6 +548,32 @@ type WireDesiredState struct {
 	RestoreDirective *WireRestoreDirective `json:"restore_directive,omitempty"` // slice 10D (forward-compat)
 	Wireguard        *WireWireguard        `json:"wireguard,omitempty"`         // S3 (doc 06 §3.2; golden-pinned)
 	PBSDR            *WirePBSDR            `json:"pbs_dr,omitempty"`            // PBS DR tier (slice 2 consumer)
+	OSUpdate         *WireOSUpdate         `json:"os_update,omitempty"`         // OS updates, guest fast lane (agent v0.140.0)
+}
+
+// WireOSUpdate is the hub-OWNED OS-update block (hub v0.130.0, `11-os-updates.md` §5.3), merged into the served
+// document at read time. Ring 0 installs every pending Debian / Debian-Security fix; ring 1 installs exactly the
+// newest approved release. Absent (older hub) → the agent treats the box as ring 1, ON, no release: it reports
+// and installs nothing. Golden: testdata/desired-state-osupdate.golden.json (byte-identical with the hub's).
+type WireOSUpdate struct {
+	Ring    int            `json:"ring"`
+	Enabled bool           `json:"enabled"`
+	Release *WireOSRelease `json:"release,omitempty"`
+}
+
+// WireOSRelease is an approved version set; Snapshot is the approval time (YYYYMMDDTHHMMSSZ) the wrapper uses
+// for snapshot.debian.org when Debian has already replaced a version (decision 79).
+type WireOSRelease struct {
+	ID       string          `json:"id"`
+	Snapshot string          `json:"snapshot"`
+	Packages []WireOSPackage `json:"packages"`
+}
+
+// WireOSPackage is one approved name=version and its origin ("Debian" | "Debian-Security").
+type WireOSPackage struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+	Origin  string `json:"origin"`
 }
 
 // WirePBSDR is the hub's PBS-DR-tier descriptor (PBS DR slice 1, hub/internal/web/pbsdr.go

internal/hub/testdata/desired-state-osupdate.golden.json

@@ -0,0 +1,17 @@
+{
+  "generation": 1,
+  "desired_state": {
+    "os_update": {
+      "ring": 1,
+      "enabled": true,
+      "release": {
+        "id": "os-20261004-120000",
+        "snapshot": "20261004T120000Z",
+        "packages": [
+          {"name": "libc6", "version": "2.41-12+deb13u4", "origin": "Debian"},
+          {"name": "openssl", "version": "3.5.7-1~deb13u3", "origin": "Debian-Security"}
+        ]
+      }
+    }
+  }
+}

internal/localapi/afterbackup_test.go

@@ -0,0 +1,63 @@
+package localapi
+
+import (
+	"context"
+	"net/http"
+	"sync"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/backup"
+)
+
+// The OS leg (agent v0.140.0) runs after a SUCCESSFUL primary backup, and only then; and it runs BEFORE the
+// host-wide heavy-op gate is released, so a restore-test cannot start in the middle of it (`11` C10).
+// Red-proof: drop the `b.Success &&` guard and the failed-backup sub-case fails; move the call after release()
+// and the gate sub-case fails.
+func TestAfterPrimaryBackup(t *testing.T) {
+	run := func(t *testing.T, failErr string) (calls []int, gateHeld bool) {
+		gate := &backup.InFlight{}
+		b := &fakeBackups{failErr: failErr}
+		srv := newTestServerS(t, &fakeGuests{}, b, &fakeStore{}, nil)
+		srv.inFlight = gate
+		var mu sync.Mutex
+		done := make(chan struct{}, 1)
+		srv.SetAfterPrimaryBackup(func(_ context.Context, vmid int) {
+			rel, _, ok := gate.TryAcquire("probe")
+			mu.Lock()
+			calls = append(calls, vmid)
+			gateHeld = !ok
+			mu.Unlock()
+			if ok {
+				rel()
+			}
+			done <- struct{}{}
+		})
+		h := srv.Handler()
+		if do(t, h, "POST", "/backup", "A", "").Code != http.StatusAccepted {
+			t.Fatal("POST /backup not accepted")
+		}
+		select {
+		case <-done:
+		case <-time.After(500 * time.Millisecond):
+		}
+		time.Sleep(20 * time.Millisecond)
+		mu.Lock()
+		defer mu.Unlock()
+		return calls, gateHeld
+	}
+	t.Run("success runs the leg under the gate", func(t *testing.T) {
+		calls, held := run(t, "")
+		if len(calls) != 1 {
+			t.Fatalf("the leg ran %d time(s), want 1", len(calls))
+		}
+		if !held {
+			t.Fatal("the heavy-op gate was free while the leg ran — a restore-test could overlap it")
+		}
+	})
+	t.Run("a failed backup runs nothing", func(t *testing.T) {
+		if calls, _ := run(t, "vzdump exploded"); len(calls) != 0 {
+			t.Fatalf("the leg ran after a FAILED backup: %v", calls)
+		}
+	})
+}

internal/localapi/server.go

@@ -160,6 +160,10 @@ type Options struct {
 	// NetStorage is the privileged network-mount (NAS) surface (Part A1). OPTIONAL — when nil, the
 	// /netstorage endpoints report "not configured". Satisfied by *storage.SudoHostOps.
 	NetStorage NetworkStorageOps
+	// AfterPrimaryBackup (agent v0.140.0, `11-os-updates.md` §8 step 2) runs right after a SUCCESSFUL backup on the
+	// PRIMARY tier, inside the backup goroutine and BEFORE the host-wide heavy-op gate is released — so the OS leg
+	// that it starts can never overlap another backup or a restore-test (`11` C10). OPTIONAL — nil → nothing runs.
+	AfterPrimaryBackup func(ctx context.Context, vmid int)
 	// Privileged runs the fenced root wrappers (E-2a: felhom-backup-target-apply). OPTIONAL — when
 	// nil, POST /backup/target reports "not configured". Satisfied by *proxmox.ExecRunner.
 	Privileged PrivilegedRunner
@@ -276,6 +280,7 @@ type Server struct {
 	tiers []BackupTier
 	// inFlight (R-85) is shared with the restore-test scheduler so the two never run together.
 	inFlight *backup.InFlight
+	afterPrimaryBackup func(ctx context.Context, vmid int) // the OS leg (agent v0.140.0); nil = none
 	logger   *slog.Logger
 	now      func() time.Time
 
@@ -469,6 +474,7 @@ func NewServer(o Options) (*Server, error) {
 	// the primary is always first, because that is what the untargeted endpoints act on.
 	s.tiers = normalizeBackupTiers(o.BackupTiers, o.Backups, cadence)
 	s.inFlight = o.InFlight
+	s.afterPrimaryBackup = o.AfterPrimaryBackup
 	if s.backups == nil && len(s.tiers) > 0 {
 		s.backups = s.tiers[0].Service
 	}
@@ -894,6 +900,10 @@ func (s *Server) handleBackup(w http.ResponseWriter, r *http.Request, vmid int)
 		}
 		s.store.RecordBackup(b)
 		s.finishJob(key, jobID, b)
+		// OS leg (agent v0.140.0): after the night's whole-guest copy exists, still holding the heavy-op gate.
+		if b.Success && tier.Primary && s.afterPrimaryBackup != nil {
+			s.afterPrimaryBackup(base, vmid)
+		}
 	}()
 	writeStatus(w, http.StatusAccepted, true, BackupResponse{VMID: vmid, JobID: jobID, Phase: PhaseRunning}, "")
 }
@@ -1465,3 +1475,6 @@ func writeStatus(w http.ResponseWriter, code int, ok bool, data any, errMsg stri
 	w.WriteHeader(code)
 	_ = json.NewEncoder(w).Encode(apiResponse{OK: ok, Data: data, Error: errMsg})
 }
+
+// SetAfterPrimaryBackup wires the hook that runs after a successful primary-tier backup (the OS leg, agent v0.140.0).
+func (s *Server) SetAfterPrimaryBackup(fn func(ctx context.Context, vmid int)) { s.afterPrimaryBackup = fn }

internal/osupdate/leg.go

@@ -0,0 +1,459 @@
+// Package osupdate is the agent's OS-update leg for the customer GUEST (`11-os-updates.md` §8 step 2, agent v0.140.0).
+//
+// It runs right after the night's successful whole-guest backup, while the backup goroutine still holds the host-wide
+// heavy-op gate (so it never overlaps a backup or a restore-test, `11` C10), at most once per night. All root work is
+// the wrapper `felhom-os-apply` (configs/, its own tests); this package only builds plans, calls the wrapper through
+// sudo, judges health and reports to the hub.
+//
+// NO AUTOMATIC UNDO in this release (R-837, measured 2026-10-04): a customer guest cannot be snapshotted — PVE
+// refuses any snapshot not named `vzdump` when the guest has host-path binds (mp8, mp9). A failed health check
+// therefore stops, reports `health_failed` and the hub mails the operator; the whole-guest backup taken minutes
+// earlier is the undo, by hand.
+package osupdate
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// WrapperPath is the pinned sudoers vector (configs/felhom-agent.sudoers FELHOM_OSAPPLY).
+const WrapperPath = "/usr/local/sbin/felhom-os-apply"
+
+// DefaultPlanDir is where plans are written (the sudoers glob names it).
+const DefaultPlanDir = "/var/lib/felhom-agent/os"
+
+// Package is one name=version with its origin.
+type Package struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+	Origin  string `json:"origin"`
+}
+
+// Pending is one update the guest's sources offer (origin as apt names it, possibly several).
+type Pending struct {
+	Name   string   `json:"name"`
+	From   string   `json:"from"`
+	To     string   `json:"to"`
+	Origin []string `json:"origin"`
+}
+
+// Container is one container's state as the wrapper saw it.
+type Container struct {
+	State  string `json:"state"`
+	Health string `json:"health"` // healthy | unhealthy | starting | none
+}
+
+// Health is the guest's health snapshot (the wrapper's `health` object).
+type Health struct {
+	DockerOK   bool                 `json:"docker_ok"`
+	NetworkOK  bool                 `json:"network_ok"`
+	Controller string               `json:"controller"`
+	Containers map[string]Container `json:"containers"`
+}
+
+// WrapperReport is the wrapper's OSAPPLY-REPORT object.
+type WrapperReport struct {
+	Mode                string          `json:"mode"`
+	Refused             json.RawMessage `json:"refused"`
+	Failed              json.RawMessage `json:"failed"`
+	Upgraded            []Package       `json:"upgraded"`
+	Installed           []Package       `json:"installed"`
+	Pending             []Pending       `json:"pending"`
+	RestartNeeded       []string        `json:"restart_needed"`
+	DockerRestartNeeded bool            `json:"docker_restart_needed"`
+	RebootNeeded        bool            `json:"reboot_needed"`
+	HealthBefore        *Health         `json:"health_before"`
+	HealthAfter         *Health         `json:"health_after"`
+	Health              *Health         `json:"health"`
+}
+
+func (w WrapperReport) refused() bool { return len(w.Refused) > 0 && string(w.Refused) != "null" }
+func (w WrapperReport) failed() bool  { return len(w.Failed) > 0 && string(w.Failed) != "null" }
+
+// Report is what the hub receives (hub osupdates.Report — field-exact).
+type Report struct {
+	RunID               string          `json:"run_id"`
+	Trigger             string          `json:"trigger"`
+	Mode                string          `json:"mode"`
+	Ring                int             `json:"ring"`
+	ReleaseID           string          `json:"release_id"`
+	Outcome             string          `json:"outcome"`
+	Healthy             bool            `json:"healthy"`
+	HealthReason        string          `json:"health_reason,omitempty"`
+	VMID                int             `json:"vmid"`
+	Upgraded            []Package       `json:"upgraded,omitempty"`
+	Installed           []Package       `json:"installed,omitempty"`
+	Pending             []Pending       `json:"pending,omitempty"`
+	NotCovered          []string        `json:"not_covered,omitempty"`
+	RestartNeeded       []string        `json:"restart_needed,omitempty"`
+	DockerRestartNeeded bool            `json:"docker_restart_needed,omitempty"`
+	RebootNeeded        bool            `json:"reboot_needed,omitempty"`
+	Refused             json.RawMessage `json:"refused,omitempty"`
+}
+
+// Reporter posts a report to the hub (*hub.Client).
+type Reporter interface {
+	PostOSReport(ctx context.Context, body []byte) error
+}
+
+// Leg runs one OS-update pass for the customer guest.
+type Leg struct {
+	Runner     proxmox.Runner
+	Hub        Reporter
+	Logger     *slog.Logger
+	PlanDir    string
+	StatePath  string        // last night run (once per night)
+	HealthWait time.Duration // how long health may take to come back (default 5 min)
+	HealthPoll time.Duration // default 15 s
+	MinGap     time.Duration // between night runs (default 20 h)
+	Now        func() time.Time
+	Sleep      func(context.Context, time.Duration)
+
+	mu    sync.Mutex
+	block *hub.WireOSUpdate
+	have  bool
+}
+
+// OnDesiredState stores the hub's os_update block (desired.RawConsumer — store only, never block).
+func (l *Leg) OnDesiredState(_ context.Context, resp *hub.DesiredStateResponse) {
+	if resp == nil {
+		return
+	}
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.block, l.have = resp.DesiredState.OSUpdate, true
+}
+
+// Block returns the newest os_update block. No block (an older hub, or nothing fetched yet) = ring 1, ON, no
+// release: the box reports and installs nothing.
+func (l *Leg) Block() hub.WireOSUpdate {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.block == nil {
+		return hub.WireOSUpdate{Ring: 1, Enabled: true}
+	}
+	return *l.block
+}
+
+// SetBlock sets the block directly (the selftest fetches the desired state itself).
+func (l *Leg) SetBlock(b *hub.WireOSUpdate) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.block, l.have = b, true
+}
+
+func (l *Leg) now() time.Time {
+	if l.Now != nil {
+		return l.Now()
+	}
+	return time.Now()
+}
+
+func (l *Leg) log() *slog.Logger {
+	if l.Logger != nil {
+		return l.Logger
+	}
+	return slog.Default()
+}
+
+func (l *Leg) sleep(ctx context.Context, d time.Duration) {
+	if l.Sleep != nil {
+		l.Sleep(ctx, d)
+		return
+	}
+	select {
+	case <-ctx.Done():
+	case <-time.After(d):
+	}
+}
+
+// IsFast reports whether every origin apt names is Debian / Debian-Security (the fast lane, `11` C3).
+func IsFast(origins []string) bool {
+	if len(origins) == 0 {
+		return false
+	}
+	for _, o := range origins {
+		if o != "Debian" && o != "Debian-Security" {
+			return false
+		}
+	}
+	return true
+}
+
+func fastOrigin(origins []string) string {
+	for _, o := range origins {
+		if o == "Debian-Security" {
+			return o
+		}
+	}
+	return "Debian"
+}
+
+// HealthVerdict is THE health rule (`11` §5.4.1; pinned by TestHealthVerdict_*): after the run, docker answers, the
+// guest's network resolves, the controller's own health check is `healthy`, and every container that was running
+// before is running again — and healthy again if it was healthy before. "starting" is not yet healthy.
+func HealthVerdict(before, after *Health) (bool, string) {
+	if after == nil {
+		return false, "no health reading"
+	}
+	if !after.DockerOK {
+		return false, "docker does not answer"
+	}
+	if !after.NetworkOK {
+		return false, "the guest cannot resolve deb.debian.org"
+	}
+	if after.Controller != "healthy" {
+		return false, "the controller is " + after.Controller
+	}
+	if before == nil {
+		return true, ""
+	}
+	names := make([]string, 0, len(before.Containers))
+	for n := range before.Containers {
+		names = append(names, n)
+	}
+	sort.Strings(names)
+	for _, n := range names {
+		b := before.Containers[n]
+		if b.State != "running" {
+			continue
+		}
+		a, ok := after.Containers[n]
+		if !ok || a.State != "running" {
+			return false, n + " was running and is not"
+		}
+		if b.Health == "healthy" && a.Health != "healthy" {
+			return false, n + " was healthy and is " + a.Health
+		}
+	}
+	return true, ""
+}
+
+// MergeBaseline is the health baseline from two readings: a container counts as running (and healthy) if EITHER
+// reading saw it so. nil-safe. Pinned by TestHealth_BaselineIsTheStartOfTheLeg.
+func MergeBaseline(a, b *Health) *Health {
+	if a == nil {
+		return b
+	}
+	if b == nil {
+		return a
+	}
+	out := &Health{DockerOK: a.DockerOK && b.DockerOK, NetworkOK: a.NetworkOK && b.NetworkOK, Controller: b.Controller,
+		Containers: map[string]Container{}}
+	for _, h := range []*Health{a, b} {
+		for n, c := range h.Containers {
+			cur, seen := out.Containers[n]
+			if !seen || (cur.State != "running" && c.State == "running") {
+				out.Containers[n] = c
+				continue
+			}
+			if c.State == "running" && c.Health == "healthy" {
+				out.Containers[n] = c
+			}
+		}
+	}
+	return out
+}
+
+// call writes the plan and runs the wrapper once.
+func (l *Leg) call(ctx context.Context, runID, mode string, vmid int, rel hub.WireOSRelease, pkgs []Package) (WrapperReport, error) {
+	dir := l.PlanDir
+	if dir == "" {
+		dir = DefaultPlanDir
+	}
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return WrapperReport{}, fmt.Errorf("osupdate: plan dir: %w", err)
+	}
+	plan := map[string]any{"release_id": rel.ID, "layer": "guest", "lane": "fast", "vmid": vmid, "mode": mode,
+		"snapshot": rel.Snapshot, "packages": pkgs}
+	if pkgs == nil {
+		plan["packages"] = []Package{}
+	}
+	b, _ := json.Marshal(plan)
+	path := filepath.Join(dir, "plan-"+runID+"-"+mode+".json")
+	if err := os.WriteFile(path, b, 0o600); err != nil {
+		return WrapperReport{}, fmt.Errorf("osupdate: write plan: %w", err)
+	}
+	defer os.Remove(path)
+	stdout, stderr, err := l.Runner.Run(ctx, WrapperPath, "--plan", path)
+	for _, line := range strings.Split(strings.TrimSpace(string(stderr)), "\n") {
+		if strings.HasPrefix(line, "os-apply: ") {
+			l.log().Info("osupdate: wrapper", "line", line)
+		}
+	}
+	var rep WrapperReport
+	found := false
+	for _, line := range strings.Split(string(stdout), "\n") {
+		if strings.HasPrefix(line, "OSAPPLY-REPORT ") {
+			if jerr := json.Unmarshal([]byte(strings.TrimPrefix(line, "OSAPPLY-REPORT ")), &rep); jerr == nil {
+				found = true
+			}
+		}
+	}
+	if !found {
+		return rep, fmt.Errorf("osupdate: wrapper gave no report (err %v): %s", err, strings.TrimSpace(string(stderr)))
+	}
+	return rep, nil // a refusal / failure is IN the report (exit 2 / 3), not an error here
+}
+
+// Run is one pass: inventory → (switch, ring, plan) → apply → health → report. trigger is "night" or "debug".
+func (l *Leg) Run(ctx context.Context, vmid int, trigger string) Report {
+	runID := l.now().UTC().Format("20060102T150405Z")
+	blk := l.Block()
+	rel := hub.WireOSRelease{ID: "ring0-" + runID}
+	if blk.Ring == 1 {
+		rel = hub.WireOSRelease{}
+		if blk.Release != nil {
+			rel = *blk.Release
+		}
+	}
+	rep := Report{RunID: runID, Trigger: trigger, Ring: blk.Ring, VMID: vmid, ReleaseID: rel.ID, Mode: "inventory"}
+	lg := l.log().With("run", runID, "vmid", vmid, "ring", blk.Ring, "trigger", trigger)
+
+	if trigger == "night" && l.StatePath != "" {
+		gap := l.MinGap
+		if gap == 0 {
+			gap = 20 * time.Hour
+		}
+		if b, err := os.ReadFile(l.StatePath); err == nil {
+			if last, perr := time.Parse(time.RFC3339, strings.TrimSpace(string(b))); perr == nil && l.now().Sub(last) < gap {
+				lg.Info("osupdate: skipped — already ran tonight", "last", last.UTC().Format(time.RFC3339))
+				rep.Outcome = "skipped"
+				return rep
+			}
+		}
+	}
+	lg.Info("osupdate: START", "enabled", blk.Enabled, "release", rel.ID)
+
+	inv, err := l.call(ctx, runID, "inventory", vmid, rel, nil)
+	if err != nil || inv.refused() || inv.failed() {
+		rep.Outcome, rep.Refused = "refused", inv.Refused
+		if err != nil {
+			rep.Outcome, rep.HealthReason = "failed", err.Error()
+		}
+		return l.finish(ctx, lg, rep)
+	}
+	var plan []Package
+	switch {
+	case !blk.Enabled:
+		rep.Outcome = "inventory"
+		lg.Info("osupdate: switched OFF for this box — reporting only")
+	case blk.Ring == 0:
+		for _, p := range inv.Pending {
+			if IsFast(p.Origin) {
+				plan = append(plan, Package{Name: p.Name, Version: p.To, Origin: fastOrigin(p.Origin)})
+			}
+		}
+	default:
+		for _, p := range rel.Packages {
+			plan = append(plan, Package{Name: p.Name, Version: p.Version, Origin: p.Origin})
+		}
+	}
+	pkgNames := map[string]bool{}
+	for _, p := range plan {
+		pkgNames[p.Name] = true
+	}
+	if blk.Enabled && len(plan) == 0 {
+		rep.Outcome = "nothing"
+	}
+	final := inv
+	if blk.Enabled && len(plan) > 0 {
+		rep.Mode = "apply"
+		ap, err := l.call(ctx, runID, "apply", vmid, rel, plan)
+		switch {
+		case err != nil:
+			rep.Outcome, rep.HealthReason = "failed", err.Error()
+			return l.finish(ctx, lg, rep)
+		case ap.refused():
+			rep.Outcome, rep.Refused = "refused", ap.Refused
+			return l.finish(ctx, lg, rep)
+		case ap.failed():
+			rep.Outcome, rep.Refused = "failed", ap.Failed
+		}
+		final = ap
+		rep.Upgraded = ap.Upgraded
+		if rep.Outcome == "" {
+			if len(ap.Upgraded) == 0 {
+				rep.Outcome = "nothing"
+			} else {
+				rep.Outcome = "applied"
+			}
+		}
+		// Health: compare with what the guest looked like BEFORE the run; give restarted services time.
+		wait, poll := l.HealthWait, l.HealthPoll
+		if wait == 0 {
+			wait = 5 * time.Minute
+		}
+		if poll == 0 {
+			poll = 15 * time.Second
+		}
+		deadline := l.now().Add(wait)
+		cur := ap.HealthAfter
+		// The baseline is the guest as it was at the START of the leg (the inventory's reading) merged with the
+		// apply's own "before": an app that stops at any point during the run counts. Found live 2026-10-04: an app
+		// stopped between the inventory and the apply's own reading was taken as "stopped before" and ignored.
+		base := MergeBaseline(inv.HealthAfter, ap.HealthBefore)
+		for {
+			ok, why := HealthVerdict(base, cur)
+			rep.Healthy, rep.HealthReason = ok, why
+			if ok || !l.now().Before(deadline) || ctx.Err() != nil {
+				break
+			}
+			l.sleep(ctx, poll)
+			hr, herr := l.call(ctx, runID, "health", vmid, rel, nil)
+			if herr == nil && hr.Health != nil {
+				cur = hr.Health
+			}
+		}
+		if !rep.Healthy && rep.Outcome == "applied" {
+			rep.Outcome = "health_failed"
+		}
+	} else {
+		ok, why := HealthVerdict(nil, inv.HealthAfter)
+		rep.Healthy, rep.HealthReason = ok, why
+	}
+	rep.Installed, rep.Pending = final.Installed, final.Pending
+	rep.RestartNeeded, rep.DockerRestartNeeded, rep.RebootNeeded = final.RestartNeeded, final.DockerRestartNeeded, final.RebootNeeded
+	rep.NotCovered = notCovered(final.Pending, blk.Ring, pkgNames)
+	if trigger == "night" && l.StatePath != "" {
+		_ = os.WriteFile(l.StatePath, []byte(l.now().UTC().Format(time.RFC3339)), 0o600)
+	}
+	return l.finish(ctx, lg, rep)
+}
+
+// notCovered lists pending updates no approved release covers: in ring 0 everything outside the fast lane; in
+// ring 1 also every fast-lane update the release did not name.
+func notCovered(pending []Pending, ring int, planned map[string]bool) []string {
+	var out []string
+	for _, p := range pending {
+		if !IsFast(p.Origin) || (ring == 1 && !planned[p.Name]) {
+			out = append(out, p.Name)
+		}
+	}
+	return out
+}
+
+func (l *Leg) finish(ctx context.Context, lg *slog.Logger, rep Report) Report {
+	lg.Info("osupdate: DONE", "outcome", rep.Outcome, "healthy", rep.Healthy, "reason", rep.HealthReason,
+		"upgraded", len(rep.Upgraded), "pending", len(rep.Pending), "not_covered", len(rep.NotCovered), "restart_needed", len(rep.RestartNeeded))
+	if l.Hub != nil {
+		body, _ := json.Marshal(rep)
+		rctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), time.Minute)
+		defer cancel()
+		if err := l.Hub.PostOSReport(rctx, body); err != nil {
+			lg.Warn("osupdate: reporting to the hub failed (the run itself is done)", "err", err)
+		}
+	}
+	return rep
+}

internal/osupdate/leg_test.go

@@ -0,0 +1,281 @@
+package osupdate
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+)
+
+// fakeWrapper plays /usr/local/sbin/felhom-os-apply: it reads the plan the leg wrote and answers per mode.
+type fakeWrapper struct {
+	t         *testing.T
+	pending   []Pending
+	applyRep  WrapperReport
+	healthSeq []*Health // answers to successive "health" calls
+	plans     []map[string]any
+}
+
+func (f *fakeWrapper) Run(_ context.Context, name string, args ...string) ([]byte, []byte, error) {
+	if name != WrapperPath || len(args) != 2 || args[0] != "--plan" {
+		f.t.Fatalf("unexpected command %s %v", name, args)
+	}
+	b, err := os.ReadFile(args[1])
+	if err != nil {
+		f.t.Fatal(err)
+	}
+	var plan map[string]any
+	json.Unmarshal(b, &plan)
+	f.plans = append(f.plans, plan)
+	var rep WrapperReport
+	healthy := &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{
+		"felhom-controller": {State: "running", Health: "healthy"}, "app": {State: "running", Health: "healthy"}}}
+	switch plan["mode"] {
+	case "inventory":
+		rep = WrapperReport{Mode: "inventory", Pending: f.pending, HealthAfter: healthy,
+			Installed: []Package{{Name: "libc6", Version: "u3", Origin: "Debian"}}}
+	case "apply":
+		rep = f.applyRep
+		rep.Mode = "apply"
+		if rep.HealthBefore == nil {
+			rep.HealthBefore = healthy
+		}
+		if rep.HealthAfter == nil {
+			rep.HealthAfter = healthy
+		}
+	case "health":
+		if len(f.healthSeq) > 0 {
+			rep.Health, f.healthSeq = f.healthSeq[0], f.healthSeq[1:]
+		} else {
+			rep.Health = healthy
+		}
+	}
+	out, _ := json.Marshal(rep)
+	return []byte("OSAPPLY-REPORT " + string(out) + "\n"), []byte("os-apply: DONE rc=0\n"), nil
+}
+
+func (f *fakeWrapper) RunStdin(ctx context.Context, _ io.Reader, name string, args ...string) ([]byte, []byte, error) {
+	return f.Run(ctx, name, args...)
+}
+
+type fakeHub struct{ reports []Report }
+
+func (h *fakeHub) PostOSReport(_ context.Context, body []byte) error {
+	var r Report
+	json.Unmarshal(body, &r)
+	h.reports = append(h.reports, r)
+	return nil
+}
+
+func newLeg(t *testing.T, w *fakeWrapper, blk *hub.WireOSUpdate) (*Leg, *fakeHub) {
+	h := &fakeHub{}
+	now := time.Date(2026, 10, 4, 4, 0, 0, 0, time.UTC)
+	l := &Leg{Runner: w, Hub: h, PlanDir: t.TempDir(), StatePath: filepath.Join(t.TempDir(), "last"),
+		HealthWait: time.Minute, HealthPoll: 10 * time.Second,
+		Now:   func() time.Time { return now },
+		Sleep: func(_ context.Context, d time.Duration) { now = now.Add(d) }}
+	if blk != nil {
+		l.SetBlock(blk)
+	}
+	return l, h
+}
+
+var pend = []Pending{
+	{Name: "libc6", From: "u3", To: "u4", Origin: []string{"Debian"}},
+	{Name: "openssl", From: "u1", To: "u3", Origin: []string{"Debian-Security", "Debian"}},
+	{Name: "docker-ce", From: "29.7", To: "29.8", Origin: []string{"Docker CE"}},
+}
+
+func modes(w *fakeWrapper) string {
+	var m []string
+	for _, p := range w.plans {
+		m = append(m, p["mode"].(string))
+	}
+	return strings.Join(m, ",")
+}
+
+// Ring 0 plans every pending FAST-LANE update (Docker excluded, `11` C3) and reports what it now runs.
+func TestRing0_PlansTheFastLaneOnly(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6", Version: "u4"}, {Name: "openssl", Version: "u3"}}, Pending: pend[2:]}}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "applied" || !rep.Healthy {
+		t.Fatalf("rep = %+v", rep)
+	}
+	pk := w.plans[1]["packages"].([]any)
+	if len(pk) != 2 {
+		t.Fatalf("ring-0 plan = %v, want libc6 + openssl only", pk)
+	}
+	if o := pk[1].(map[string]any)["origin"]; o != "Debian-Security" {
+		t.Fatalf("openssl origin = %v", o)
+	}
+	if w.plans[1]["snapshot"] != "" {
+		t.Fatalf("ring 0 installs from live sources, snapshot = %v", w.plans[1]["snapshot"])
+	}
+	if len(rep.NotCovered) != 1 || rep.NotCovered[0] != "docker-ce" {
+		t.Fatalf("not covered = %v", rep.NotCovered)
+	}
+	if len(h.reports) != 1 || h.reports[0].Outcome != "applied" {
+		t.Fatalf("hub got %+v", h.reports)
+	}
+}
+
+// Ring 1 installs EXACTLY the approved release (its versions, its snapshot), nothing it computed itself.
+func TestRing1_InstallsExactlyTheRelease(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6", Version: "u4-approved"}}, Pending: pend[1:]}}
+	rel := &hub.WireOSRelease{ID: "os-1", Snapshot: "20261004T080000Z", Packages: []hub.WireOSPackage{{Name: "libc6", Version: "u4-approved", Origin: "Debian"}}}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 1, Enabled: true, Release: rel})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "applied" || rep.ReleaseID != "os-1" {
+		t.Fatalf("rep = %+v", rep)
+	}
+	ap := w.plans[1]
+	pk := ap["packages"].([]any)
+	if len(pk) != 1 || pk[0].(map[string]any)["version"] != "u4-approved" || ap["snapshot"] != "20261004T080000Z" || ap["release_id"] != "os-1" {
+		t.Fatalf("ring-1 plan = %v", ap)
+	}
+	// openssl is pending and fast-lane but NOT in the release → not covered; docker-ce is never covered.
+	if strings.Join(rep.NotCovered, ",") != "openssl,docker-ce" {
+		t.Fatalf("not covered = %v", rep.NotCovered)
+	}
+}
+
+func TestRing1_NoReleaseInstallsNothing(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 1, Enabled: true})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "nothing" || modes(w) != "inventory" {
+		t.Fatalf("rep=%+v modes=%s", rep, modes(w))
+	}
+}
+
+// No block from the hub (an older hub): ring 1, ON, no release → reports, installs nothing.
+func TestNoBlock_IsRing1Nothing(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend}
+	l, _ := newLeg(t, w, nil)
+	if rep := l.Run(context.Background(), 9201, "night"); rep.Outcome != "nothing" || rep.Ring != 1 || modes(w) != "inventory" {
+		t.Fatalf("rep=%+v modes=%s", rep, modes(w))
+	}
+}
+
+// Switched OFF: the box reports but installs nothing (the brief, Part D 2).
+func TestSwitchOff_ReportsOnly(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: false})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "inventory" || modes(w) != "inventory" || len(h.reports) != 1 || len(rep.Pending) != 3 {
+		t.Fatalf("rep=%+v modes=%s", rep, modes(w))
+	}
+}
+
+// Unhealthy after the run, and still unhealthy at the end of the wait → health_failed (the hub mails the operator).
+func TestHealth_FailsAfterTheWait(t *testing.T) {
+	bad := &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{
+		"felhom-controller": {State: "running", Health: "healthy"}, "app": {State: "exited"}}}
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6"}}, HealthAfter: bad},
+		healthSeq: []*Health{bad, bad, bad, bad, bad, bad, bad, bad}}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "health_failed" || rep.Healthy || !strings.Contains(rep.HealthReason, "app was running") {
+		t.Fatalf("rep = %+v", rep)
+	}
+	if h.reports[0].Outcome != "health_failed" {
+		t.Fatal("the hub was not told")
+	}
+}
+
+// A service that takes a moment to come back is not a failure: the poll sees it recover inside the wait.
+func TestHealth_RecoversInsideTheWait(t *testing.T) {
+	starting := &Health{DockerOK: true, NetworkOK: true, Controller: "starting"}
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6"}}, HealthAfter: starting},
+		healthSeq: []*Health{starting}}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	if rep := l.Run(context.Background(), 9201, "night"); rep.Outcome != "applied" || !rep.Healthy {
+		t.Fatalf("rep = %+v", rep)
+	}
+}
+
+func TestHealthVerdict(t *testing.T) {
+	ok := &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{"a": {State: "running", Health: "healthy"}}}
+	cases := []struct {
+		name   string
+		before *Health
+		after  *Health
+		want   bool
+	}{
+		{"all good", ok, ok, true},
+		{"no reading", ok, nil, false},
+		{"docker down", ok, &Health{NetworkOK: true, Controller: "healthy"}, false},
+		{"no network", ok, &Health{DockerOK: true, Controller: "healthy"}, false},
+		{"controller starting", ok, &Health{DockerOK: true, NetworkOK: true, Controller: "starting"}, false},
+		{"only the controller differs", ok, &Health{DockerOK: true, NetworkOK: true, Controller: "unhealthy", Containers: map[string]Container{"a": {State: "running", Health: "healthy"}}}, false},
+		{"app gone", ok, &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{}}, false},
+		{"app unhealthy", ok, &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{"a": {State: "running", Health: "unhealthy"}}}, false},
+		{"stopped before stays stopped", &Health{Containers: map[string]Container{"x": {State: "exited"}}}, &Health{DockerOK: true, NetworkOK: true, Controller: "healthy"}, true},
+	}
+	for _, c := range cases {
+		if got, why := HealthVerdict(c.before, c.after); got != c.want {
+			t.Errorf("%s: got %v (%s), want %v", c.name, got, why, c.want)
+		}
+	}
+}
+
+func TestOncePerNight(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6"}}}}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	l.Run(context.Background(), 9201, "night")
+	n := len(w.plans)
+	if rep := l.Run(context.Background(), 9201, "night"); rep.Outcome != "skipped" || len(w.plans) != n {
+		t.Fatalf("a second night run in the same night ran: %+v", rep)
+	}
+	if rep := l.Run(context.Background(), 9201, "debug"); rep.Outcome == "skipped" {
+		t.Fatal("the debug action must not be throttled")
+	}
+}
+
+func TestRefusedIsReported(t *testing.T) {
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Refused: json.RawMessage(`{"code":"R6","reason":"x"}`)}}
+	l, h := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	if rep := l.Run(context.Background(), 9201, "night"); rep.Outcome != "refused" || h.reports[0].Outcome != "refused" {
+		t.Fatalf("rep = %+v", rep)
+	}
+}
+
+// The root wrapper's own suite (configs/test_felhom_os_apply.py) runs with `go test ./...` so CI covers it.
+func TestWrapperSuite(t *testing.T) {
+	py, err := exec.LookPath("python3")
+	if err != nil {
+		t.Skip("python3 not available")
+	}
+	cmd := exec.Command(py, "../../configs/test_felhom_os_apply.py")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("wrapper suite failed: %v\n%s", err, out)
+	}
+	if !strings.Contains(string(out), "OK") {
+		t.Fatalf("wrapper suite did not report OK:\n%s", out)
+	}
+}
+
+// An app that stops BETWEEN the start of the leg and the apply's own "before" reading still fails the run.
+// Measured live 2026-10-04 on demo-hp (privatebin stopped 1 s after the apply plan was written: the old rule
+// passed). Red-proof: use ap.HealthBefore alone as the baseline and this fails.
+func TestHealth_BaselineIsTheStartOfTheLeg(t *testing.T) {
+	stoppedEarly := &Health{DockerOK: true, NetworkOK: true, Controller: "healthy", Containers: map[string]Container{
+		"felhom-controller": {State: "running", Health: "healthy"}, "app": {State: "exited"}}}
+	w := &fakeWrapper{t: t, pending: pend, applyRep: WrapperReport{Upgraded: []Package{{Name: "libc6"}},
+		HealthBefore: stoppedEarly, HealthAfter: stoppedEarly},
+		healthSeq: []*Health{stoppedEarly, stoppedEarly, stoppedEarly, stoppedEarly, stoppedEarly, stoppedEarly, stoppedEarly}}
+	l, _ := newLeg(t, w, &hub.WireOSUpdate{Ring: 0, Enabled: true})
+	rep := l.Run(context.Background(), 9201, "night")
+	if rep.Outcome != "health_failed" || !strings.Contains(rep.HealthReason, "app was running") {
+		t.Fatalf("an app that stopped during the run passed: %+v", rep)
+	}
+}