CHANGELOG (Unreleased): the live proof the next release owes for the after-failure orphan check

v0.159.0/v0.159.1 ran the check before every snapshot-mode whole-guest backup, which takes a
metadata snapshot of the live pool. Now explainFailure (vzdump start or task failure) is its only
caller; the finding is still appended to the failed backup's error. Tests: failure = 1 call,
success = 0 calls; red-proved against the v0.159.1 runner.go (2 calls / calls=1).

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

.gitea/workflows/gates.yml

@@ -16,7 +16,16 @@
 # A failing run must reach a person — a detector nobody hears is the defect R-29 filed, rebuilt one
 # layer up. That is the last step, and it runs ONLY on failure.
 name: gates
-on: [push]
+# R-1129: `workflow_dispatch` is the manual PROOF that the failure mail can be sent. A push run is
+# unchanged by it: the proof step below is skipped on a push, and `force_alarm` is then empty.
+on:
+  push:
+  workflow_dispatch:
+    inputs:
+      force_alarm:
+        description: "Fail this run on purpose so the alarm step sends its real mail (a proof, not a gate result)"
+        type: boolean
+        default: false
 
 jobs:
   gates:
@@ -57,6 +66,22 @@ jobs:
           GITEA_BASE: http://gitea.gitea-system.svc.cluster.local:3000
         run: cd ws/felhom-agent && python3 scripts/agent_gates.py
 
+      - name: Manual proof - alarm key present, optional forced failure (dispatch only, R-1129)
+        # Runs ONLY on a manual dispatch, never on a push. It prints the key's LENGTH, never the key,
+        # so "CI can see the secret" is an observable rather than an assumption. With
+        # force_alarm=true it then fails on purpose so the alarm step below sends its real mail;
+        # the commit itself stays green, because its push run skips this step.
+        if: github.event_name == 'workflow_dispatch'
+        env:
+          RESEND_API_KEY: ${{ secrets.RESEND_API_KEY }}
+          FORCE_ALARM: ${{ github.event.inputs.force_alarm }}
+        run: |
+          python3 -c 'import os;print("RESEND_API_KEY length: %d" % len(os.environ.get("RESEND_API_KEY","")))'
+          if [ "$FORCE_ALARM" = "true" ]; then
+            echo "force_alarm=true - failing on purpose so the alarm step runs (R-1129 proof)"
+            exit 1
+          fi
+
       - name: Alarm on failure
         # THE POINT OF THE WHOLE THING. Probe P5 measured that a failed run produces NO mail, NO
         # notification row and NO log line from Gitea itself — a red tick in a web UI nobody watches
@@ -70,6 +95,8 @@ jobs:
         if: failure()
         env:
           RESEND_API_KEY: ${{ secrets.RESEND_API_KEY }}
+          # Empty on a push, so a push run's mail is exactly what it was before R-1129.
+          FORCE_ALARM: ${{ github.event.inputs.force_alarm }}
         run: |
           python3 - <<'PY'
           import json, os, sys, urllib.request, urllib.error
@@ -87,7 +114,9 @@ jobs:
           body = json.dumps({
               "from": "Felhom CI <monitoring@felhom.eu>",
               "to": ["admin@felhom.eu"],
-              "subject": "[felhom CI] gates FAILED in %s" % repo,
+              "subject": ("[felhom CI] FORCED TEST, not a real failure - gates FAILED in %s"
+                          if os.environ.get("FORCE_ALARM") == "true"
+                          else "[felhom CI] gates FAILED in %s") % repo,
               "text": (
                   "The gate entry point exited non-zero.\n\n"
                   "Repository : %s\n"

CHANGELOG.md

@@ -1,3 +1,138 @@
+## Unreleased — the orphan thin check runs only after a failed backup (R-1012 follow-up) (2026-10-17)
+
+**Not released, not vouched; the next vouched agent release carries it.** v0.159.0/v0.159.1 ran the R-1012 orphan check
+before EVERY snapshot-mode whole-guest backup, and that check takes a short metadata snapshot of the live thin pool.
+Now `BackupRunner` runs it only when the snapshot step has failed (the vzdump start or its task) — the moment the
+answer is needed. The finding is still appended in plain words to the failed backup's error, exactly as before; a
+successful backup never runs the check and keeps a clean record; stop mode and an unwired runner are unchanged. The
+`thin-orphan-check` capability text says „after a failed whole-guest backup". Tests
+`TestBackup_SnapshotFailure_NamesTheOrphan` (now: exactly 1 call, after the failure) and
+`TestBackup_ThinCheck_SilentWhenNotApplicable` (now: 0 calls on a successful backup), red-proved against the v0.159.1
+`runner.go`: failure legs „thin check ran 2 times, want 1", success leg `calls=1`. No root file, sudoers or bundle
+change. (Installer side, felhom.eu, same night: `felhom-host-install.sh --rotate-recovery-only`, R-1141.)
+**Owed by the release that carries it (not yet proven live):** one green snapshot backup with NO `felhom-thin-check`
+call in the journal, and one failed snapshot backup whose error carries the finding.
+
+## v0.159.1 — the signed decommission prunes the guest-bind record (found by v0.159.0's own live proof) (2026-10-17)
+
+**v0.159.0 is superseded — do not vouch it.** Everything of v0.159.0 below, plus: `signedjobs.DecommissionExecutor`
+drops the drive from every guest's bind record (`SetGuestBinds`, wired to the agent's `GuestBindStore`), as the
+self-serve decommission always did. Without it a drive decommissioned by an operator-signed job and then forgotten
+(R-1124) left a record the 20-second guest-bind re-assert warned about every tick („reconcile: skipping non-enrolled
+drive") — seen on demo-hp minutes after the R-1124 proof. Test `TestDecommissionExecutor_PrunesTheGuestBindRecord`,
+red-proved. Released: tag `v0.159.1`, sha256 `de8f6ad9…aff9`, bundle `2af3d27d…7cd6` (the same root files as v0.159.0).
+**Not vouched.** Delivery to a box on the v0.158.1 bundle: `agent_update 0.159.1` → `agent_config_update 0.159.0-step1`
+(sha `1d65edb3…d6cf`, published) → `agent_config_update 0.159.1` (the bundle adds `felhom-thin-check`, R16).
+
+## v0.159.0 — forget a decommissioned drive that is gone (R-1124); name an orphan thin device in a backup failure (R-1012); Go 1.27.2 (R-972) (2026-10-17)
+
+**Superseded by v0.159.1 — do not vouch.** Task: „agent release, the catalog allow-list, break-glass rotation, off-site
+history check" (felhom.eu `REPORT-agent-allowlist-rotation-2026-10-17.md`).
+
+- **Go 1.27.2 + x/crypto v0.58.0** (R-972, `37b99d7`): the first release that carries them (v0.158.1 was built with
+  go1.26.0).
+- **R-1124 — a decommissioned drive that is gone is forgotten.** `SudoHostOps.ForgetRetiredDrives` (agent start and the
+  20-second storage tick): for a Felhom drive unit whose intent is `decommissioned`, whose `/dev/disk/by-uuid` link is
+  gone and which is not mounted, `systemctl disable` + the new root verb `felhom-priv-apply unit-forget <unit>` +
+  `daemon-reload`. The unit is gone, so a later boot no longer waits for the drive and the agent stops listing it (no
+  „absent by UUID" line every 20 s). A decommissioned drive still plugged in KEEPS its unit and raw mount, so the
+  one-click re-enroll (H3) still works. `unit-forget` re-checks as root: a felhom by-UUID drive unit (not a network
+  unit), disabled, its `Where` not mounted, its by-UUID link absent — otherwise refused. Sudoers `FELHOM_MOUNT` gains the
+  one verb. Tests `TestForgetRetiredDrives_*` and `configs/test_felhom_priv_apply.py` `UnitForget`, red-proved.
+  **Live on demo-hp:** a loop-backed test drive enrolled through the local API, decommissioned by a signed job (kept
+  its unit while present), unplugged → 8 s later the unit and its wants link were removed and `GET /disks` dropped it.
+- **R-1012 — an orphan thin device is NAMED in the backup failure, never removed.** New READ-ONLY root helper
+  `felhom-thin-check <vg> <pool>` (config bundle): LVM's thin ids before and after, the pool's ids through a metadata
+  snapshot it reserves and releases (refuses — exit 3 — when someone else holds one; releases on every exit; sends no
+  other pool message). `internal/thincheck`: an orphan = in the pool and in neither LVM list, on two reads 3 s apart;
+  fails open. `BackupRunner.SetThinCheck`: before a snapshot-mode backup (a WARN when found) and again after a failure —
+  the finding is appended in plain words to the error the controller mails to the operator, pointing at the new
+  runbook `whole-guest-backup-orphan-thin.md`. Sudoers `FELHOM_THINCHECK`, capability `thin-orphan-check`. Tests
+  `internal/thincheck`, `TestBackup_SnapshotFailure_NamesTheOrphan`, `configs/test_felhom_thin_check.py`, red-proved.
+  **Live on demo-hp:** on a scratch thin pool (a loop file on `/mnt/hdd_1`, never `pve/data`) the helper listed a made
+  orphan (device 7) and refused a snapshot held by someone else; on `pve/data` it read 1, 2 = LVM's and released; a
+  normal whole-guest backup of 9201 ran the check first and finished green.
+- Released: tag `v0.159.0`, sha256 `3cfd0a25…edfed5`, bundle `40663c4f…6d681`; step bundle `0.159.0-step1`.
+
+## CI only — a manual proof that the failure mail can be sent (R-1129, 2026-10-17)
+
+No agent release; no binary changes.
+
+`.gitea/workflows/gates.yml` gains a manual `workflow_dispatch` trigger with one input, `force_alarm` (default false), and
+one step that runs ONLY on a dispatch: it prints the length of `RESEND_API_KEY` (never the key) and, with
+`force_alarm=true`, fails on purpose so the existing alarm step sends its real mail; the mail's subject then starts
+„FORCED TEST, not a real failure". A push run is unchanged: the new step is skipped and the subject is the old one. Same
+change in all four repos' workflows. Purpose: prove the failure mail now goes out after the operator set the key
+(every failed run until today ended „ALARM FAILED: RESEND_API_KEY is empty").
+
+## scripts only — the decoy suite is a gate of the full run (R-1116, 2026-10-17)
+
+No agent release; no binary changes. `scripts/test_gate_decoys.py` is now the `gate-decoys` row of `agent_gates.py`:
+the full run (which CI runs on every push), not `--fast` — it takes ~20 s in the workspace (measured: 30 cases; ~5 s in a
+CI-shaped shallow clone, also green). It was in no runner, the shape that let the catalog's R-1115 fail unseen for a
+night. It plants only in scratch clones and asks a fake Gitea on 127.0.0.1; it does not call the runner (no
+recursion). Declared in its own `COVERS`; `test_agent_gates.py` pins it (registered once, full run only, named by
+`--fast`'s SKIPPED line). Red-proved: a reuse-refs FACT case flipped to expect rc 0 turned the full run red
+(`CONVICTED: gate-decoys`); restored, green. CLAUDE.md's `--fast` sentence names it.
+
+## unreleased — Go 1.27.2 and golang.org/x/crypto v0.58.0 (R-972, 2026-10-16)
+
+**Not released, not deployed** — agent releases wait for the operator's vouch; the next vouched release carries this.
+`go.mod`: `go 1.27.2` (was 1.25.0; the shipped 0.158.1 binary was built with go1.26.0), x/crypto v0.58.0 (was v0.52.0),
+x/sys v0.49.0. `go build`, `go vet`, the full `go test ./...` and `agent_gates.py --fast` green on Go 1.27.2.
+`release-agent.sh` builds with the toolchain `go.mod` names (GOTOOLCHAIN=auto), so no script change.
+
+## scripts only — `release-agent.sh` refuses when the registry cannot say the version is new (R-1098, 2026-10-16)
+
+No agent release; no binary changes. `scripts/release-agent.sh` already refused a version whose tag exists or whose
+package answers 200. It let everything else through — a registry it could not reach (curl prints `000`) or a 500 read
+as „new". Now only a clean `404` proves the version is new; anything else refuses with the code it got. New
+`scripts/test_release_push_once.sh` (the real script, a fake `curl` and `go` on PATH; published / absent / unreachable /
+server error / tag exists), red-proved: with the 404 rule removed, the unreachable and server-error cases fail. Same rule
+as the controller `build.sh` and, since today, felhom.eu `scripts/build-hub.sh`.
+
+## v0.158.1 — security review of v0.158.0: the mkfs wrapper trusts no sibling claim; the internal-place helper fails closed (2026-10-16)
+
+**v0.158.0 is superseded — do not vouch it.** A security review of `912f7c1` found two defects; both fixed here, each test
+seen failing against the 0.158.0 script:
+- **`felhom-mkfs-guarded`**: 0.158.0 let a format through when a SIBLING part was mounted at /mnt/<name> AND under
+  /mnt/felhom-drives („Felhom's own drive"). That corroboration is a mount the agent can make itself, so a compromised agent
+  could unlock a host owner's disk — the exact case this root wrapper exists for. Removed: any mount of any node outside
+  /mnt/felhom-drives refuses again (now read from the kernel's mount table for every node; an unlistable disk refuses).
+  Consequence: the free part next to an in-use Felhom drive cannot be formatted — `CandidatePartition.Formattable` is false
+  for every part of a disk with a mounted node, and the controller does not offer it (a part with a filesystem can still be
+  USED). Pinned by configs/test_felhom_mkfs_guarded.py + partitions_test.go.
+- **`felhom-internal-place`**: a failed `lvs` listing read as „nothing promised" (a too-large place) and a `blkid` error read
+  as „no signature" (the only gate before mkfs). Now: a failed listing, a listing without the pool, or any blkid exit other
+  than 0/2 REFUSES. Three new tests, all failing against 0.158.0.
+- Released: tag `v0.158.1` (code `98f3cdd`), sha256 `20264df6…84b76a1`, bundle `c23c3d35…cb1c41b`. **Not vouched.**
+
+## v0.158.0 — the internal data place; partitions as places; add_internal_place (2026-10-16)
+
+Design: felhom.eu `architecture/16-storage-physical-identity.md` §5, §6, §7, §9 (operator rulings D3–D5; the D3 sizes
+ruled 2026-10-16 after the space check, felhom.eu `audits/storage-identity-buildB-2026-10-15/SPACE-CHECK.md`).
+
+- **The internal data place („Belső tárhely")** (`internal/localapi/internalplace.go`): when the record
+  `/var/lib/felhom-agent/internal-place.json` names a filesystem, the agent mounts it at `/mnt/belso` by fs-UUID like an
+  enrolled drive (startup + every 20 s tick) and records it `enrolled`; `GET /disks` reports it with kind `internal`.
+  It never takes `/mnt/belso` from a household drive, and eject/decommission/format of it are refused (device-mapper on
+  the system disk). Its identity is the system disk's, so build A never counts a copy to `sys_drive` as a second copy.
+- **Root helper `configs/felhom-internal-place`** (new in the bundle): `plan|create <planned GiB>` — the ruled size rule
+  (reserve max(16 GiB, 10 %) ≤ 48 GiB, made only when ≥ 20 GiB, nothing promised beyond pool − reserve), the only
+  lvcreate/mkfs of a system-disk volume; formats only a `felhom-belso` with no signature. Run by the installer (1.33.0)
+  and by the new signed op.
+- **Signed op `add_internal_place`** (old one-disk boxes, `16` §9): no parameters (the size is the rule's), destructive
+  class (operator key). Runs the helper with `create 0`, writes the record, mounts.
+- **Partitions as places** (`internal/storage/partitions.go`): `GET /disks/candidates` lists each partition of a free
+  disk as empty / filesystem / in_use. A data-bearing part's wipe id binds disk id + part number + fs-UUID
+  (`byid:<…-partN>+fsuuid:<uuid>`); both must name the same device at format time.
+- **`felhom-mkfs-guarded`** (REVERTED in v0.158.1): a SIBLING part that is Felhom's own drive no longer blocked formatting
+  the free part next to it. First tests of the wrapper: `configs/test_felhom_mkfs_guarded.py`.
+- `configs/` changed (sudoers `FELHOM_INTERNALPLACE`, the helper, the wrapper, the bundle list) — **a config-bundle job
+  is needed** with the agent update. **Not vouched** (the operator's act).
+- Released: tag `v0.158.0` (code `912f7c1`), sha256 `a3589d1d…2caba`, bundle `17066273…fb5c76`. **Superseded by v0.158.1 —
+  do not vouch** (its mkfs wrapper trusted a sibling claim the agent can fake; its helper failed open).
+
 ## v0.157.0 — every storage place knows its physical disk(s); POST /disks/same-disk (2026-10-15)
 
 Design: felhom.eu `architecture/16-storage-physical-identity.md` §3, §4, §10 (operator rulings D1–D6, 2026-10-15). Spike:

CLAUDE.md

@@ -56,7 +56,8 @@ This is in the core because breaching it is how this component stops being audit
 gate in its `GATES` table (that table is the list); the shared ones — `reuse_refs_check`,
 `instructions_gate`, `observations_gate` — are the copies in `felhom.eu/scripts/`, never copied into
 this repo (a copy recreates the drift they detect; an absent sibling clone FAILS). `--fast` selects the
-gates touching no network and no container runtime, and skips `published` (network), naming it. **A missing gate is a FAILURE, never a skip.**
+gates touching no network and no container runtime, and skips `published` (network) and `gate-decoys` (the decoy
+suite, ~20 s; R-1116), naming them — CI runs the full set. **A missing gate is a FAILURE, never a skip.**
 
 **The pre-push hook** (`.githooks/pre-push`) runs it with `--fast` and refuses a failing push. It is
 **per-clone** — switch it on once with `git config core.hooksPath .githooks`, and a manual run WARNS

CONTEXT.md

@@ -1,5 +1,16 @@
 # CONTEXT — felhom-agent working state
 
+> **2026-10-17 — v0.159.1 RELEASED (0.159.0 superseded, do not vouch).** Go 1.27.2; R-1124 a decommissioned drive that is
+> gone is forgotten (`ForgetRetiredDrives`, root verb `unit-forget`); R-1012 the read-only `felhom-thin-check` names an
+> orphan thin device in a failed backup's text; the signed decommission prunes the guest-bind record. Bundle adds a path →
+> step bundle `0.159.0-step1`. Proven on demo-hp; delivered by signed jobs on the operator's yes. Vouch: the operator's.
+
+> **2026-10-16 — v0.158.1 RELEASED and VOUCHED (storage identity build B; 0.158.0 superseded, do not vouch).** The internal
+> data place (root helper `felhom-internal-place`, the record in the state dir, mounted at /mnt/belso like a drive), the
+> signed `add_internal_place`, partitions in `/disks/candidates` (`formattable` only while nothing on the disk is mounted),
+> the partition wipe id `byid:<…-partN>+fsuuid:<uuid>`, the strict mkfs wrapper. Delivered through step bundle
+> `0.158.1-step1` (a bundle that adds a path, R16). Next: R-1093 (an empty part's probe reads the parent's partition table).
+
 > **2026-10-15 (night) — v0.157.0 RELEASED, NOT VOUCHED (storage identity build A, felhom.eu `16` §13).** Every storage
 > place carries `kind`, `physical_disks`, `identity` (+ reason) in `GET /disks` and the hub report; `POST /disks/same-disk`
 > answers the controller (v0.317.0, MinAgent 0.157.0). Computed on every read, never cached. Delivered by signed jobs to

REPORT.md

@@ -1,43 +1,41 @@
-# REPORT — v0.157.0: every storage place knows its physical disk(s); POST /disks/same-disk (2026-10-15)
+# REPORT — the orphan thin check runs only after a failed backup (unreleased) (2026-10-17, night)
 
-Written in ASD-STE100 Simplified Technical English. Design read first: felhom.eu `architecture/16-storage-physical-identity.md`
+Written in ASD-STE100 Simplified Technical English. Architecture read: felhom.eu `documentation/architecture/03-host-agent.md`
-(§3, §4, §8, §10; ACCEPTED 2026-10-15, §13 = what was built), `03-host-agent.md`. Task: storage identity build A (operator
+(the `FELHOM_THINCHECK` row), `runbooks/whole-guest-backup-orphan-thin.md`, R-1012's closing note.
-rulings D1–D6). Controller counterpart: felhom-controller v0.317.0 (MinAgent 0.157.0); hub v0.154.0 shows the fields.
+
+## In plain words
+
+- Before tonight the agent looked for an orphan thin device before **every** whole-guest backup. To look, it takes a
+  short metadata snapshot of the live disk pool. Now it looks **only when the backup's snapshot step has failed** — the
+  only moment somebody needs the answer. The operator's failure mail still names the orphan, in the same words.
+- **Not released. Not vouched.** The next agent release that the operator vouches carries it. Nothing was copied to a
+  box.
 
 ## What changed
 
-- `internal/storage/identity.go`: the physical disk(s) under a place, from `/sys`, `/run/udev/data`, `/proc/mounts` only
+- `internal/backup/runner.go`: the pre-run check (and its WARN line) is gone; `explainFailure` (after a vzdump start
-  (no block I/O). `proven`, or `unknown` with `vm` / `network` / `usb_bridge` / `weak_wwn` / `no_serial`.
+  failure or a task failure, snapshot mode only) is now the only caller. Comments say so.
-- `GET /disks` rows and the hub report's `storage_targets` gain `kind`, `physical_disks`, `identity`, `identity_reason`.
+- `internal/capability/manifest.go`: the `thin-orphan-check` text says „after a failed whole-guest backup".
-- `POST /disks/same-disk` `{a, b}` → `{different, proven, reason, a, b}`; scoped like every `/disks` call; a path the agent
+- `internal/backup/r1012_thincheck_test.go`: failure → exactly ONE call and the finding in the error; success → ZERO
-  did not mount itself is `unmapped`.
+  calls and a clean record; stop mode → zero calls; unwired → error unchanged.
-- `configs/` unchanged.
 
-## Tests and red-proofs
+## Red-proof
 
-Fixture `/sys` + udev trees for every spike case and five same-disk handler tests. Seen failing first: the LVM thin
+The new tests, run against the v0.159.1 `runner.go` (`git show HEAD:…`), then the fix restored:
-„diamond" (tmeta/tdata under one pool) read as a failure — fixed by counting a seen node once. Broken on purpose and seen
-failing: the VM rule, the vendor-less WWN rule, the own-mount rule (an absent drive), the `sys_drive` mapping.
-`python3 scripts/agent_gates.py`: all OK.
 
-## Release and delivery
+| test | failed with |
+|---|---|
+| `TestBackup_SnapshotFailure_NamesTheOrphan/{task_fails,start_fails}` | `thin check ran 2 times, want 1 (after the failure only)` |
+| `TestBackup_ThinCheck_SilentWhenNotApplicable` | `success: … Success:true … calls=1 (want no check on a successful backup, clean record)` |
 
-- `scripts/release-agent.sh 0.157.0`: tag `v0.157.0`, sha256 `addd4041…0aef`, bundle `0604bc60…397a`.
+Restored → both PASS; `git diff` on `runner.go` = the fix only.
-- Delivered by signed `agent_update` jobs to Tester 1, demo-hp and the N100 (the three test boxes). **NOT VOUCHED** — the
-  operator's act. Until the vouch, the global floor cannot declare MinAgent 0.157.0.
 
-## Live proof (method: the agent's local API on each PVE host, with the guest's own token)
+## Gates
 
-| Box | `GET /disks` | same-disk: drive vs system data |
+`go build ./... && go vet ./... && go test ./...` and `python3 scripts/agent_gates.py` — results in the session report.
-|---|---|---|
-| demo-hp | `local`/`local-lvm` proven (SATA SSD), NVMe drive proven (`eui:`), PBS `network` | different, proven |
-| N100 | system proven (SATA SSD serial), USB drive proven (the bridge passes the real serial) | different, proven |
-| Tester 1 (VM) | every place `unknown/vm` | not proven (`vm`) |
 
-On all three: system data vs `/var/lib/docker` → same disk, proven; a drive name that is not mounted → `unmapped`. The hub
+## Not live-validated
-stored the same fields (read from its database with the WAL). Evidence: felhom.eu `audits/storage-identity-buildA-2026-10-15/`.
 
-## Observations
+No agent was built or delivered (no release tonight). The changed path is the failure path; the next release's live
-
+proof should make one snapshot backup succeed (helper NOT called: no `felhom-thin-check` line in the agent journal
-1. FILED: R-1083 — scratch box 9202 has no `local_api` in its `bootstrap.json`, so it cannot use any agent call.
+and none in the sudo log for that run) and one fail (the finding in the failure text).
-2. NOT-A-FINDING: `usb_bridge` is built from the design's rule and was not seen on a real enclosure; that is R-1077, already open.

REUSE.md

@@ -15,13 +15,14 @@
 | `SudoHostOps.run` | internal/storage/hostops.go | `run(ctx, name, args...) error` | allowlisted exec with stderr-wrapped error | Every arg pre-validated via validate.go before this is called |
 | `Prober.Probe` | internal/capability/probe.go | `Probe(ctx) []Status` | live sudo-policy capability check (`sudo -n -l --`) | Needs a DIRECT runner (never the sudo-prefixing one — double-sudo); never executes probed cmds. v0.86.0: config-gated caps (`Capability.GatedBy` + `Prober.GateActive`) report `inactive`/"disabled by configuration" ONLY when healthy — broken plumbing stays degraded; the pbsdr-* gate answers from `pbsdr.Manager.DRConfigured` (marker-backed across restarts) |
 | ~~`stageTemp`~~ (REMOVED v0.146.0, R-861) | — | — | — | Nothing the agent writes is `install`ed where root reads it any more: use `felhom-priv-apply` (below) or ship a fixed file in the bundle |
-| `felhom-priv-apply` (v0.146.0, R-861) | configs/felhom-priv-apply | `felhom-priv-apply unit <name> \| dnsmasq <tmp> <name> \| wg \| sshd-config \| sshd-key \| controller-image <vmid>` (the last reads the ref on stdin, R-861 (a) A1) | ANY agent-rendered file a root program reads (systemd unit, dnsmasq drop-in, wg-quick conf, OOB sshd) — fixed source + destination, CONTENT checked against the agent's own renderers | A new renderer needs a verb + a contract test (`internal/privapplytest.Check`) feeding its REAL output; never a new `install` sudoers line |
+| `felhom-priv-apply` (v0.146.0, R-861) | configs/felhom-priv-apply | `felhom-priv-apply unit <name> \| unit-forget <name> (v0.159.0, R-1124) \| dnsmasq <tmp> <name> \| wg \| sshd-config \| sshd-key \| controller-image <vmid>` (the last reads the ref on stdin, R-861 (a) A1) | ANY agent-rendered file a root program reads (systemd unit, dnsmasq drop-in, wg-quick conf, OOB sshd) — fixed source + destination, CONTENT checked against the agent's own renderers | A new renderer needs a verb + a contract test (`internal/privapplytest.Check`) feeding its REAL output; never a new `install` sudoers line |
 | `privapplytest.Check` | internal/privapplytest/check.go | `Check(t, verb, name, content) string` | the Go↔root-checker contract: a renderer's real output must read `OK` | Skips without python3; one call per rendered shape + one refused control |
 | `BUNDLE_FILES` + `Bundle` (mode `bundle`, `--install-bundle`; mode `agent_update` v0.146.0, R-861) | configs/felhom-os-apply | the ONE table of root-owned paths + the installer of them | ANY new root-owned file the installer writes (sudoers line, wrapper, unit) — add it to the table, never a new installer fetch (R-840) | The builder (`scripts/build-config-bundle.py`) and the installer read the same table; `test_every_root_file_the_installer_writes_is_in_the_bundle` fails on a path the bundle lacks. Trust files (`/etc/felhom/os-trust.json`, `operator-signers`) are NEVER bundle paths (R17) |
 | `osupdate.ConfigUpdateExecutor` | internal/osupdate/bundle.go | signed op `agent_config_update` {agent_version, bundle_sha256} | delivering the bundle to an installed box | a courier only: the root wrapper re-verifies signature, host, nonce and sha itself |
 | `osupdate.Leg.SendUnsent` / `lockPass` (v0.144.0, R-868) | internal/osupdate/unsent.go | `(ctx) int` | an OS-pass report the agent never sent (killed mid-pass): the wrapper keeps `report-<run>-<layer>-apply.json` beside the plan; the agent deletes it once the hub has it | any new caller that runs an apply pass must hold `lockPass` (flock, across processes) — the sender must never take a running pass's copy |
 | `osupdate.LoadSavedBlock` (v0.144.0, R-866) | internal/osupdate/leg.go | `(planDir) (block, savedAt, ok)` | the hub's newest os_update block as the daemon last received it (`os-update-block.json`) | the debug pass uses it ONLY when the hub cannot be reached, and says so in its header; no saved block → no pass |
 | `dpkg_state()` / `DPKG_STATE_SCRIPT` (v0.145.0, R-876) | configs/felhom-os-apply | `audit, journal = self.dpkg_state()` | dpkg's state in ONE call: `--audit` AND the update journal | never gate a repair on `--audit` alone — a crash leaves only the journal (measured); keep it one call (R-845) |
+| `thincheck.Checker.Check` + `Describe` (v0.159.0, R-1012) | internal/thincheck/thincheck.go | `Check(ctx, vmid) []Finding` | name an ORPHAN thin device (pool holds it, LVM does not) in a whole-guest backup failure — `BackupRunner.SetThinCheck` | READ-ONLY by design: the root helper `felhom-thin-check <vg> <pool>` sends only reserve/release_metadata_snap; an orphan needs two reads; fails open (never stops a backup). The repair stays human |
 | `guesthook.SnippetReady` / `Register` (v0.146.0, R-861) | internal/guesthook/install.go | `SnippetReady(path) error` | is the pre-start hook (a FIXED file from the bundle) in place — register only then | The agent never installs the hook (Proxmox runs it as root); a missing hookscript stops a guest start, so never `Register` without `SnippetReady` |
 
 ### Disk / format safety (role gates, durable IDs, format guards)
@@ -44,7 +45,7 @@
 | `storage.IdentityResolver` / `Relation` / `MountFor` | internal/storage/identity.go | `HostPath(path) PlaceIdentity`, `Device(dev) PlaceIdentity`, `Relation(a, b) (different, proven, reason)` | physical-disk identity of a storage place (felhom.eu `16-storage-physical-identity.md` §3, v0.157.0) | Reads /sys + /run/udev/data + /proc/mounts only (no block I/O). Judge a drive ONLY on its own mount (`localapi.ownMountIdentity`) — never the containing fs, or an absent drive reads as the root disk. A shared disk key is "same, proven" even when unknown. Pinned by identity_test.go (fixture trees) + samedisk_test.go |
 | `localapi.Server.EnsureInternalPlace` / `InternalPlaceRecord` | internal/localapi/internalplace.go | `EnsureInternalPlace(ctx)` (startup + 20 s tick); `ReadInternalPlace` / `WriteInternalPlace` | the one-disk box's internal data place (felhom.eu `16` §5, v0.158.0): mounts it at /mnt/belso by fs-UUID like an enrolled drive, records it `enrolled`; the controller binds + registers it | Never takes /mnt/belso from a household drive (a foreign mount, or a unit naming another UUID, waits). Never formats/ejects (dm on the system disk → role system). The ONLY maker is the root helper `configs/felhom-internal-place` (installer + signed `add_internal_place`). Pinned by internalplace_test.go |
 | `configs/felhom-internal-place` | configs/ (bundle → /usr/local/sbin) | `plan\|create <planned GiB>` | the ruled size rule (reserve max(16, 10 %) ≤ 48 GiB; ≥ 20 GiB or nothing) + the only lvcreate/mkfs of a system-disk volume | Formats only a felhom-belso with NO signature; refuses a foreign one; never resizes/removes. Sudoers: `^(plan\|create) 0$` only. Pinned by configs/test_felhom_internal_place.py |
-| `storage.candidatePartitions` / `CandidatePartition` | internal/storage/partitions.go | `CandidateDisk.Partitions` | partitions as places (`16` §6): empty / filesystem / in_use per part of a free disk | A part with children or a member type is never listed; a raw /mnt mount counts as Felhom's only when corroborated (felhomOwnedMounts). Pinned by partitions_test.go |
+| `storage.candidatePartitions` / `CandidatePartition` | internal/storage/partitions.go | `CandidateDisk.Partitions` | partitions as places (`16` §6): empty / filesystem / in_use per part of a free disk; `Formattable` only while no node of the disk is mounted | A part with children or a member type is never listed; a raw /mnt mount counts as Felhom's only when corroborated (felhomOwnedMounts) — for LISTING only: the root mkfs wrapper trusts no such claim (v0.158.1). Pinned by partitions_test.go |
 | partition wipe id `byid:<…-partN>+fsuuid:<uuid>` | internal/storage/durable_device.go | `DeviceDurableID` / `ResolveDurableDevice` | a data-bearing PART binds disk id + part number + filesystem (`16` §6) | Both halves must resolve to the SAME device or the wipe refuses. Whole disks keep the plain id. Pinned by partition_durable_test.go |
 | `ValidateUUID/MountPath/BlockDevice/FSType/SMARTDevice/LVMName`, `UnitNameForMount` | internal/storage/validate.go | `Validate*(v) error` | EVERY arg that reaches a root shell-out | The security boundary; strict whitelists (no by-* symlinks, no dm, no traversal); `systemdEscapePath` computed in-process |
 | `ValidateNetworkMountSpec` | internal/storage/netmount.go | `ValidateNetworkMountSpec(spec) error` | NAS mount input boundary | Same discipline as validate.go; SMB requires a creds ref; mountpoint confined under `NetworkMountRoot` |
@@ -56,6 +57,7 @@
 | `SudoHostOps.EnsureMount` | internal/storage/hostops.go | `EnsureMount(ctx, MountSpec) error` | persistent by-UUID systemd .mount | Validate→render→stage→`install`→`enable --now`; idempotent |
 | `SudoHostOps.Unmount` | internal/storage/hostops.go | `Unmount(ctx, where) error` | detach a mount unit | DESTRUCTIVE — caller MUST have gated it; does not self-authorize |
 | `SudoHostOps.ReassertEnrolledMounts` | internal/storage/hostops.go | `ReassertEnrolledMounts(ctx)` | reboot remount (re-resolve by UUID) | Re-asserts unless mounted AND enabled (`shouldReassertMount`); skips absent UUIDs |
+| `SudoHostOps.ForgetRetiredDrives` (v0.159.0, R-1124) | internal/storage/forget_retired.go | `ForgetRetiredDrives(ctx, IntentReader) int` | drop the host mount unit of a DECOMMISSIONED drive that is GONE (start-up + the 20 s tick) | Only decommissioned + absent + unmounted; a present decommissioned drive keeps its unit (H3 re-enroll). The file goes only through `felhom-priv-apply unit-forget`, which re-checks all three as root |
 | `GuestBinder.AttachDrive` / `DetachDrive` | internal/localapi/intermediary.go | `AttachDrive(ctx, vmid, where) (guestPath, err)` | live drive hot-swap under `/mnt/felhom-drives` | Normalizes to EXACTLY ONE bind via `countHostMounts` (converges double-binds); force re-bind when guest can't see it |
 | `GuestBinder.EnsureSharedParent` | internal/localapi/intermediary.go | `EnsureSharedParent(ctx) error` | shared-parent bind + boot unit | make-private+make-shared ONLY on first bind — re-running orphans the guest's slave; F2-a: compares script AND unit for staleness |
 | `StablePathForRaw` / `DriveNameFromRaw` | internal/localapi/intermediary.go | `StablePathForRaw("/mnt/<n>") string` | raw host mount → stable guest path | Single source of truth both repos derive from |

cmd/felhom-agent/main.go

@@ -59,6 +59,7 @@ import (
 	"gitea.dooplex.hu/admin/felhom-agent/internal/selfupdate"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/signedjobs"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/storage"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/thincheck"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/vzpartial"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/wgtunnel"
 )
@@ -1091,6 +1092,9 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		decommIntent = intentStore
 	}
 	decommExec := signedjobs.NewDecommissionExecutor(decommIntent, logger)
+	if guestBindStore != nil { // typed-nil guard, as above
+		decommExec.SetGuestBinds(guestBindStore) // v0.159.1: prune the bind record like the self-serve decommission
+	}
 
 	// Agent self-update (TASK D1): the agent_update executor downloads the operator-signed binary,
 	// verifies it against the SIGNED sha256, and hands it to the root guarded wrapper (A/B flip +
@@ -1425,6 +1429,9 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		// re-assert below sees its unit.
 		localSrv.EnsureInternalPlace(ctx)
 		if mountReasserter != nil {
+			// R-1124: a decommissioned drive that is gone loses its host mount unit first (start-up and every tick), so
+			// no later boot waits for it and the re-assert below no longer lists it.
+			mountReasserter.ForgetRetiredDrives(ctx, intentReader)
 			mountReasserter.ReassertEnrolledMounts(ctx)
 		}
 		// F9: on startup (the host's bring-up/reconcile trigger), re-assert any enrolled guest data-drive
@@ -1463,6 +1470,7 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 					// unit re-disabled at runtime), then re-assert the guest binds against the now-live mounts.
 					localSrv.EnsureInternalPlace(ctx) // `16` §5: a record written since the last tick (the signed job)
 					if mountReasserter != nil {
+						mountReasserter.ForgetRetiredDrives(ctx, intentReader) // R-1124: decommissioned + gone → unit removed
 						mountReasserter.ReassertEnrolledMounts(ctx)
 					}
 					localSrv.ReassertGuestBinds(ctx)
@@ -2061,8 +2069,12 @@ func buildLocalAPIServer(cfg config.Config, px *proxmox.Client, store *backup.St
 		},
 		Logger: logger,
 	}
+	// R-1012: an orphan thin device (a full host root during a snapshot) is NAMED in the backup failure the controller
+	// mails to the operator, through the read-only root helper. Never removed — the repair stays a human step.
+	thinChecker := &thincheck.Checker{API: px, Runner: &proxmox.ExecRunner{Mode: gaMode, SudoPath: cfg.Privileged.SudoPath}, Logger: logger}
 	for _, r := range tierRunners {
 		r.SetBeforeBackup(func(ctx context.Context, storage string, vmid int) { cleaner.Clean(ctx, storage, vmid) })
+		r.SetThinCheck(func(ctx context.Context, vmid int) string { return thincheck.Describe(thinChecker.Check(ctx, vmid)) })
 	}
 	srv.SetPartialSweep(func(ctx context.Context, vmid int) {
 		for _, t := range tierTargets {

configs/felhom-agent.sudoers

@@ -25,6 +25,7 @@
 
 Cmnd_Alias FELHOM_MOUNT = \
   /usr/local/sbin/felhom-priv-apply ^unit mnt-[A-Za-z0-9_.\\-]+\.(mount|automount)$, \
+  /usr/local/sbin/felhom-priv-apply ^unit-forget mnt-[A-Za-z0-9_.\\-]+\.mount$, \
   /usr/bin/systemctl daemon-reload, \
   /usr/bin/systemctl ^enable --now -- mnt-[A-Za-z0-9_.\\-]+\.mount$, \
   /usr/bin/systemctl ^disable -- mnt-[A-Za-z0-9_.\\-]+\.mount$, \
@@ -101,6 +102,11 @@ Cmnd_Alias FELHOM_VZPARTIAL = \
 # ruled size rule and formats ONLY that volume, ONLY when it carries no signature. The agent calls it from the signed
 # `add_internal_place` job (an old box), always with 0 GiB planned: its guest's volumes already exist. `plan` changes
 # nothing. The installer runs the helper as root itself (a new box).
+# R-1012 (agent v0.159.0): the READ-ONLY orphan-thin check before and after a whole-guest backup — lists the pool's thin
+# device ids (through a metadata snapshot it reserves and releases) next to LVM's. It sends no other pool message; the
+# repair stays a human step. Pinned by configs/test_felhom_thin_check.py.
+Cmnd_Alias FELHOM_THINCHECK = \
+  /usr/local/sbin/felhom-thin-check ^[A-Za-z0-9_+][A-Za-z0-9_.+-]{0\,63} [A-Za-z0-9_+][A-Za-z0-9_.+-]{0\,63}$
 Cmnd_Alias FELHOM_INTERNALPLACE = \
   /usr/local/sbin/felhom-internal-place ^(plan|create) 0$
 
@@ -336,4 +342,4 @@ Cmnd_Alias FELHOM_GUESTNET = \
   /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_FSTRIM, 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, FELHOM_POWEROFF, FELHOM_VZPARTIAL, FELHOM_INTERNALPLACE
+felhom-agent ALL=(root) NOPASSWD: FELHOM_MOUNT, FELHOM_DISK, FELHOM_PROVISION, FELHOM_FORMAT, FELHOM_DNSMASQ, FELHOM_GUESTHOOK, FELHOM_INTERMEDIARY, FELHOM_CONTROLLERSWAP, FELHOM_STALELOCK, FELHOM_FSTRIM, 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, FELHOM_POWEROFF, FELHOM_VZPARTIAL, FELHOM_INTERNALPLACE, FELHOM_THINCHECK

configs/felhom-internal-place

@@ -55,15 +55,19 @@ pool_gib=$(gib_floor "$pool_b")
 
 # Every thin volume promised in the pool (its virtual size) — except the place itself and vzdump's short-lived
 # snapshots (snap_*_vzdump), which exist only during a whole-box copy and are what the reserve is for.
-promised_b=0; have_lv=false
+# FAIL CLOSED: a failed or empty listing must never read as „nothing promised" (that would size the place too big).
+listing=$(lvs --noheadings --nosuffix --units b -o lv_name,pool_lv,lv_size "$VG" 2>/dev/null) || die "cannot list the volumes of $VG"
+pool_seen=false; promised_b=0; have_lv=false
 while read -r name pl size; do
 	[[ -n "${name:-}" ]] || continue
+	[[ "$name" == "$POOL" ]] && pool_seen=true
 	[[ "$pl" == "$POOL" ]] || continue
 	if [[ "$name" == "$LV_NAME" ]]; then have_lv=true; continue; fi
 	[[ "$name" =~ ^snap_.*_vzdump$ ]] && continue
 	[[ "$size" =~ ^[0-9]+$ ]] || die "cannot read the size of $VG/$name"
 	promised_b=$(( promised_b + size ))
-done < <(lvs --noheadings --nosuffix --units b -o lv_name,pool_lv,lv_size "$VG" 2>/dev/null)
+done <<< "$listing"
+$pool_seen || die "the listing of $VG does not contain the pool $POOL — refusing to guess what is promised"
 promised_gib=$(( (promised_b + 1073741823) / 1073741824 ))   # rounded UP: never promise a partial GiB twice
 
 reserve=$(( pool_gib / 10 )); (( reserve < 16 )) && reserve=16; (( reserve > 48 )) && reserve=48
@@ -79,6 +83,17 @@ is_block() { [[ "$(stat -L -c %F "$1" 2>/dev/null)" == "block special file" ]];
 fs_uuid() { blkid -p -s UUID -o value "$DEV" 2>/dev/null; }
 fs_type() { blkid -p -s TYPE -o value "$DEV" 2>/dev/null; }
 fs_label() { blkid -p -s LABEL -o value "$DEV" 2>/dev/null; }
+# has_signature: FAIL CLOSED. blkid -p exits 0 when it found something and 2 when it found NOTHING; any other result (an
+# error, an ambivalent probe, blkid missing) must never read as „empty" — that is the only gate in front of mkfs.
+has_signature() {
+	local rc=0
+	blkid -p -o value "$DEV" >/dev/null 2>&1 || rc=$?
+	case $rc in
+		0) return 0 ;;
+		2) return 1 ;;
+		*) die "cannot probe $DEV for a signature (blkid exit $rc) — refusing" ;;
+	esac
+}
 lv_gib() { gib_floor "$(lvs --noheadings --nosuffix --units b -o lv_size "$VG/$LV_NAME" 2>/dev/null | tr -d ' ')"; }
 
 if $have_lv; then
@@ -89,12 +104,12 @@ if $have_lv; then
 		echo "existing uuid=$(fs_uuid) gib=$(lv_gib)"; exit 0
 	fi
 	# A felhom-belso with NO signature: a crash between lvcreate and mkfs. Nothing can be on it — format it.
-	[[ -z "$(blkid -p -o value "$DEV" 2>/dev/null)" ]] || die "$DEV carries a signature blkid cannot name — left alone"
+	has_signature && die "$DEV carries a signature blkid cannot name — left alone"
 else
 	(( internal >= MIN_GIB )) || { echo "skipped only $internal GiB free for it (pool $pool_gib, reserve $reserve, promised $promised_gib, planned $PLANNED; needs $MIN_GIB)"; exit 0; }
 	lvcreate -q -y -V "${internal}G" -T "$VG/$POOL" -n "$LV_NAME" >/dev/null || die "lvcreate failed"
 	is_block "$DEV" || die "$DEV did not appear after lvcreate"
-	[[ -z "$(blkid -p -o value "$DEV" 2>/dev/null)" ]] || die "the new $DEV already carries a signature — left alone"
+	has_signature && die "the new $DEV already carries a signature — left alone"
 	made=created
 fi
 mkfs.ext4 -q -L "$LABEL" "$DEV" >/dev/null || die "mkfs.ext4 failed on $DEV"

configs/felhom-mkfs-guarded.sh

@@ -58,31 +58,23 @@ fi
 
 # 3) mounted OUTSIDE Felhom's own drive area = a live foreign filesystem → catastrophic. Mounts under
 #    /mnt/felhom-drives are our own drives (the agent detaches before a re-init) → allowed.
-#    Agent v0.158.0 (felhom.eu architecture/16 §6, partitions as places): a SIBLING partition that is Felhom's own
+#    Agent v0.158.0: read from the kernel's mount table for EVERY node of the disk (lsblk's MOUNTPOINT shows one mount
-#    enrolled drive is mounted TWICE — raw at /mnt/<name> and under /mnt/felhom-drives (R-220). That raw mount is
+#    per node; a bind elsewhere hid behind it), and a disk whose nodes cannot be listed REFUSES (it passed before).
-#    allowed only when the same device is ALSO mounted under /mnt/felhom-drives, a state only Felhom's enrolment
+#    Deliberately NO exemption for a sibling that is Felhom's own enrolled drive (raw /mnt/<name> + /mnt/felhom-drives):
-#    produces. The TARGET itself mounted anywhere outside /mnt/felhom-drives, or any mount elsewhere (/srv, /media,
+#    the only corroboration available here is a mount the agent itself can make, so trusting it would let a compromised
-#    /mnt/a/b), still REFUSES. Read from the kernel's mount table, every node of the disk (partitions and children).
+#    agent unlock a host owner's disk. Consequence (felhom.eu `16` §13): the free part next to an in-use Felhom drive
+#    cannot be formatted; the dashboard does not offer it.
 PROC_MOUNTS=/proc/mounts
 node_mounts() { awk -v d="$1" '$1 == d { print $2 }' "$PROC_MOUNTS"; }
 disk_nodes="$(lsblk -nrpo NAME "$whole" 2>/dev/null || true)"
 [[ -n "$disk_nodes" ]] || die "cannot list the nodes of $whole — refusing"
 while read -r node; do
   [[ -z "$node" ]] && continue
-  own=false
-  while read -r mp; do
-    case "$mp" in /mnt/felhom-drives/*) own=true ;; esac
-  done < <(node_mounts "$node")
   while read -r mp; do
     [[ -z "$mp" ]] && continue
     case "$mp" in
       /mnt/felhom-drives|/mnt/felhom-drives/*) : ;;
-      *)
+      *) die "device (or a partition) is mounted at $mp ($node)" ;;
-        if [[ "$node" != "$dev" && "$own" == true && "$mp" =~ ^/mnt/[A-Za-z0-9_][A-Za-z0-9_.-]*$ ]]; then
-          : # a sibling that is Felhom's own enrolled drive (raw mount + managed mount)
-        else
-          die "device (or a partition) is mounted at $mp ($node)"
-        fi ;;
     esac
   done < <(node_mounts "$node")
 done <<< "$disk_nodes"

configs/felhom-os-apply

@@ -191,6 +191,8 @@ BUNDLE_FILES = [
     ("/usr/local/sbin/felhom-backup-target-apply", "felhom-backup-target-apply", 0o755, "bash", "replace"),
     # R-1006 (agent v0.156.0): the only delete of backup files — a dead half-written vzdump, re-checked as root.
     ("/usr/local/sbin/felhom-vzdump-partial-clean", "felhom-vzdump-partial-clean", 0o755, "bash", "replace"),
+    # R-1012 (agent v0.159.0): the read-only orphan-thin check around a whole-guest backup (names an orphan, never removes).
+    ("/usr/local/sbin/felhom-thin-check", "felhom-thin-check", 0o755, "bash", "replace"),
     # felhom.eu architecture/16 §5 (agent v0.158.0): the internal data place — the only lvcreate/mkfs of a system-disk volume.
     ("/usr/local/sbin/felhom-internal-place", "felhom-internal-place", 0o755, "bash", "replace"),
     ("/usr/local/sbin/felhom-os-apply", "felhom-os-apply", 0o755, "python", "replace"),

configs/felhom-priv-apply

@@ -13,6 +13,8 @@ longer name the destination: each verb has a fixed source and a fixed (or strict
 
 Verbs (each one sudoers line, exact-match pattern):
   unit <name>              /var/lib/felhom-agent/units/<name> -> /etc/systemd/system/<name>   (.mount | .automount)
+  unit-forget <name>       REMOVES /etc/systemd/system/<name> (R-1124): only a felhom by-UUID drive .mount unit that is
+                           disabled, not mounted, and whose drive is absent (its /dev/disk/by-uuid link is gone)
   dnsmasq <tmp> <name>     /tmp/felhom-resolver-<digits>.conf -> /etc/dnsmasq.d/felhom-<...>.conf
   wg                       /var/lib/felhom-agent/wg/wg-felhom.conf -> /etc/wireguard/wg-felhom.conf (0600)
   sshd-config              /var/lib/felhom-agent/felhom-sshd/sshd_config -> /etc/felhom-sshd/sshd_config
@@ -41,7 +43,7 @@ WG_SRC, WG_DEST = STATE + "/wg/wg-felhom.conf", "/etc/wireguard/wg-felhom.conf"
 SSHD_SRC, SSHD_DEST = STATE + "/felhom-sshd/sshd_config", "/etc/felhom-sshd/sshd_config"
 KEY_SRC, KEY_DEST = STATE + "/felhom-sshd/authorized_keys.felhom-op", "/etc/felhom-sshd/authorized_keys/felhom-op"
 MAX_BYTES = 64 * 1024
-VERBS = ("unit", "dnsmasq", "wg", "sshd-config", "sshd-key", "controller-image")
+VERBS = ("unit", "unit-forget", "dnsmasq", "wg", "sshd-config", "sshd-key", "controller-image")
 # R-861 (a) A1 (`09` §3 decision 165): the SAME pattern as the agent's controllerImageRe (internal/localapi/
 # controllerswap.go) — a compromised agent cannot hand the guest's bootstrap any other image. Pinned by
 # configs/test_felhom_priv_apply.py ControllerImage.
@@ -51,6 +53,11 @@ CONTROLLER_IMAGE_MAX = 256
 VMID_RE = re.compile(r"^[0-9]{1,9}$")
 
 UNIT_NAME_RE = re.compile(r"^mnt-[A-Za-z0-9_.\\-]+\.(mount|automount)$")
+DRIVE_UNIT_NAME_RE = re.compile(r"^mnt-[A-Za-z0-9_.\\-]+\.mount$")
+DRIVE_UNIT_MARKER = "Managed by felhom-agent"
+NET_UNIT_MARKER = "felhom network storage"
+WANTS_DIR = UNIT_DIR + "/multi-user.target.wants"
+BY_UUID_DIR = "/dev/disk/by-uuid"
 DNSMASQ_TMP_RE = re.compile(r"^/tmp/felhom-resolver-[0-9]+\.conf$")
 DNSMASQ_NAME_RE = re.compile(r"^felhom-[a-z0-9][a-z0-9._-]*\.conf$")
 SEG = r"[A-Za-z0-9_-][A-Za-z0-9_.-]*"
@@ -135,6 +142,36 @@ class Host:
     def read_stdin(self, limit):
         return sys.stdin.buffer.read(limit + 1)
 
+    # ---- unit-forget (R-1124) ----
+    def read_installed(self, path):
+        """The installed unit: None when absent; Refused when it is not a regular file (a symlink is never followed)."""
+        try:
+            fd = os.open(path, os.O_RDONLY | os.O_NOFOLLOW | os.O_CLOEXEC)
+        except FileNotFoundError:
+            return None
+        except OSError as e:
+            raise Refused("F1", f"cannot open {path}: {e.strerror}")
+        with os.fdopen(fd, "rb") as f:
+            if not stat.S_ISREG(os.fstat(f.fileno()).st_mode):
+                raise Refused("F1", f"{path} is not a regular file")
+            return f.read(MAX_BYTES + 1)
+
+    def lexists(self, path):
+        return os.path.lexists(path)
+
+    def mountpoints(self):
+        """Every mount point in /proc/self/mountinfo (field 5, octal escapes decoded)."""
+        out = set()
+        with open("/proc/self/mountinfo", "r", encoding="utf-8", errors="replace") as f:
+            for line in f:
+                parts = line.split(" ")
+                if len(parts) > 4:
+                    out.add(re.sub(r"\\([0-7]{3})", lambda m: chr(int(m.group(1), 8)), parts[4]))
+        return out
+
+    def remove(self, path):
+        os.remove(path)
+
     def write_guest_image(self, vmid, data):
         """As root: `pct exec <vmid> -- tee <the fixed file>` with the checked ref on stdin (no shell)."""
         r = subprocess.run(["/usr/sbin/pct", "exec", str(vmid), "--", "tee", CONTROLLER_IMAGE_FILE],
@@ -424,6 +461,45 @@ def controller_image(rest, host):
     return 0
 
 
+def unit_forget(rest, host):
+    """R-1124: remove ONE felhom drive mount unit that the agent has already disabled, whose drive is gone. A drive that
+    is still present or still mounted keeps its unit — this verb can only forget, never unmount or take a drive away."""
+    try:
+        if len(rest) != 1 or not DRIVE_UNIT_NAME_RE.match(rest[0]) or "/" in rest[0]:
+            raise Refused("A1", "usage: felhom-priv-apply unit-forget mnt-<escaped path>.mount")
+        name = rest[0]
+        path = os.path.join(UNIT_DIR, name)
+        data = host.read_installed(path)
+        if data is None:
+            host.log(f"felhom-priv-apply: ABSENT unit-forget {path} (nothing to remove)")
+            return 0
+        text = text_of(data, path)
+        if DRIVE_UNIT_MARKER not in text or NET_UNIT_MARKER in text:
+            raise Refused("F2", f"{name} is not a felhom drive unit")
+        check_unit(name, text)
+        s = parse_ini(text, name)
+        what, where = s["Mount"].get("What", ""), s["Mount"]["Where"]
+        mu = re.match(r"^/dev/disk/by-uuid/(.+)$", what)
+        if not mu:
+            raise Refused("F2", f"{name} is not a by-UUID drive unit")
+        if host.lexists(os.path.join(WANTS_DIR, name)):
+            raise Refused("F3", f"{name} is still enabled (disable it first)")
+        if where in host.mountpoints():
+            raise Refused("F4", f"{where} is mounted")
+        if host.lexists(os.path.join(BY_UUID_DIR, mu.group(1))):
+            raise Refused("F5", f"the drive of {name} is present (filesystem UUID {mu.group(1)})")
+    except Refused as e:
+        host.log(f"felhom-priv-apply: REFUSED [{e.rule}] unit-forget {' '.join(rest)[:120]}: {e.reason}")
+        return 2 if e.rule == "A1" else 3
+    try:
+        host.remove(path)
+    except OSError as e:
+        host.log(f"felhom-priv-apply: FAILED unit-forget {path}: {e}")
+        return 4
+    host.log(f"felhom-priv-apply: REMOVED unit-forget {path} (where={where})")
+    return 0
+
+
 def main(argv, host=None):
     host = host or Host()
     if argv == ["--self-check"]:
@@ -445,6 +521,8 @@ def main(argv, host=None):
         return 0
     if argv and argv[0] == "controller-image":
         return controller_image(argv[1:], host)
+    if argv and argv[0] == "unit-forget":
+        return unit_forget(argv[1:], host)
     try:
         verb, src, dest, mode, checker = plan(argv)
         data = host.read_source(src)

configs/felhom-thin-check

@@ -0,0 +1,74 @@
+#!/bin/bash
+# felhom-thin-check — list the thin device ids a thin pool holds next to the ones LVM knows (R-1012). READ-ONLY: it
+# names an orphan, it never removes one. Installed as /usr/local/sbin/felhom-thin-check (config bundle).
+#
+#   felhom-thin-check <vg> <pool>
+#
+# A full host root while vzdump takes its snapshot can leave a thin snapshot inside the pool that LVM no longer knows
+# (demo-hp 2026-10-14: `thin_ls` device 4, LVM only 1 and 2); from then on every snapshot backup of that guest fails
+# („Creation of new snapshot 4 of device 2 failed") and nothing said why. The repair (`dmsetup message … delete <id>`)
+# stays a HUMAN step, decided by the operator — this helper only reads.
+#
+# Reading the live pool's device list needs a metadata snapshot: the kernel's documented way to read metadata while
+# the pool is in use (`reserve_metadata_snap`, `thin_ls --metadata-snap`, `release_metadata_snap`). It changes no data
+# and no mapping; it is held for the length of one `thin_ls -o DEV` (well under a second on these pools). Rules:
+#   1. the arguments are an LVM name pair; <vg>/<pool> is a thin pool (lv_attr starts with `t`);
+#   2. only one run at a time (a lock file); a metadata snapshot that someone ELSE holds is never touched — the run
+#      refuses (exit 3) and does not release it;
+#   3. LVM's list is read before AND after the pool's, so a volume created in between is not reported as an orphan
+#      (the caller treats an id as an orphan only when it is in the pool and in neither LVM list).
+# Output, one record per line:  lvm-before <id> <lv> | pool <id> | lvm-after <id> <lv> | ok
+# Exit: 0 read, 1 refused (arguments / not a thin pool), 3 a metadata snapshot is already held or cannot be reserved,
+# 4 the pool could not be read. Pinned by configs/test_felhom_thin_check.py.
+set -u
+LVS=/usr/sbin/lvs
+DMSETUP=/usr/sbin/dmsetup
+THIN_LS=/usr/sbin/thin_ls
+LOCK=/run/lock/felhom-thin-check.lock
+NAME_RE='^[A-Za-z0-9_+][A-Za-z0-9_.+-]{0,63}$'
+
+die() { echo "felhom-thin-check: REFUSED: $1" >&2; exit "${2:-1}"; }  # $1 the reason, $2 the exit code
+
+lvm_ids() { # $1 tag → "<tag> <id> <lv>" for every thin volume of this pool
+	"$LVS" --noheadings --separator , -o lv_name,thin_id --select "pool_lv=$POOL" -- "$VG" 2>/dev/null |
+		awk -F, -v tag="$1" '{ gsub(/ /, ""); if ($2 ~ /^[0-9]+$/) print tag, $2, $1 }'
+}
+
+release() { "$DMSETUP" message "$TPOOL" 0 release_metadata_snap >/dev/null 2>&1; }
+
+main() {
+	[[ $# -eq 2 ]] || die "usage: felhom-thin-check <vg> <pool>"
+	VG=$1 POOL=$2
+	local attr held ids
+	[[ "$VG" =~ $NAME_RE && "$POOL" =~ $NAME_RE ]] || die "not an LVM name pair"
+
+	attr=$("$LVS" --noheadings -o lv_attr -- "$VG/$POOL" 2>/dev/null | tr -d ' ')
+	[[ "$attr" == t* ]] || die "$VG/$POOL is not a thin pool"
+
+	DM="${VG//-/--}-${POOL//-/--}"
+	TPOOL="$DM-tpool"
+	TMETA="/dev/mapper/${DM}_tmeta"
+
+	exec 9>"$LOCK" || die "cannot open the lock file" 4
+	flock -w 30 9 || die "another check holds the lock" 3
+
+	# Field 7 of the thin-pool status is the held metadata root: "-" when no metadata snapshot exists.
+	held=$("$DMSETUP" status "$TPOOL" 2>/dev/null | awk '$3 == "thin-pool" { print $7 }')
+	[[ -n "$held" ]] || die "cannot read the status of $TPOOL" 4
+	[[ "$held" == "-" ]] || die "a metadata snapshot of $TPOOL is already held (by someone else) — not touched" 3
+
+	lvm_ids lvm-before
+	"$DMSETUP" message "$TPOOL" 0 reserve_metadata_snap >/dev/null 2>&1 || die "could not reserve a metadata snapshot of $TPOOL" 3
+	trap release EXIT
+	trap 'release; trap - EXIT; exit 4' INT TERM HUP
+	if ! ids=$("$THIN_LS" --metadata-snap --no-headers -o DEV "$TMETA" 2>/dev/null); then
+		die "thin_ls could not read $TMETA" 4
+	fi
+	release
+	trap - EXIT INT TERM HUP
+	awk '$1 ~ /^[0-9]+$/ { print "pool", $1 }' <<<"$ids"
+	lvm_ids lvm-after
+	echo ok
+}
+
+if [[ "${BASH_SOURCE[0]}" == "$0" ]]; then main "$@"; fi

configs/test_felhom_internal_place.py

@@ -14,12 +14,16 @@ GIB = 1 << 30
 STUB_LVS = r'''#!/usr/bin/env python3
 import json, os, sys
 st = json.load(open(os.environ["IP_STATE"]))
+if st.get("lvs_fail_listing") and "lv_name,pool_lv,lv_size" in sys.argv: sys.exit(5)
 args = [a for a in sys.argv[1:] if not a.startswith("-") and a not in ("b",)]
 fields = sys.argv[sys.argv.index("-o") + 1].split(",")
 target = args[-1]
+listing = target == st["vg"]
 for lv in st["lvs"]:
     full = st["vg"] + "/" + lv["name"]
-    if target == st["vg"] or target == full:
+    if listing and st.get("hide_pool_in_listing") and lv.get("pool", "") == "":
+        continue   # a listing that silently lost the pool row (the pool's own size stays readable)
+    if listing or target == full:
         row = {"lv_name": lv["name"], "pool_lv": lv.get("pool", ""), "lv_size": str(lv["size"])}
         print("  " + " ".join(row[f] for f in fields))
 '''
@@ -35,15 +39,18 @@ if st.get("dirty_new"): st["fs"]["felhom-belso"] = {"TYPE": "", "RAW": "junk"}
 json.dump(st, open(p, "w"))
 '''
 STUB_BLKID = r'''#!/usr/bin/env python3
+# like blkid -p: exit 0 when something is found, 2 when nothing is; st["blkid_rc"] forces an error exit
 import json, os, sys
 st = json.load(open(os.environ["IP_STATE"]))
+if st.get("blkid_rc"): sys.exit(st["blkid_rc"])
 fs = st["fs"].get(os.path.basename(sys.argv[-1]), {})
 if "-s" in sys.argv:
     v = fs.get(sys.argv[sys.argv.index("-s") + 1], "")
     if v: print(v)
-else:
+    sys.exit(0 if v else 2)
-    vals = [fs.get(k, "") for k in ("TYPE", "LABEL", "UUID", "RAW") if fs.get(k)]
+vals = [fs.get(k, "") for k in ("TYPE", "LABEL", "UUID", "RAW") if fs.get(k)]
-    if vals: print("\n".join(vals))
+if vals: print("\n".join(vals))
+sys.exit(0 if vals else 2)
 '''
 STUB_MKFS = r'''#!/usr/bin/env python3
 import json, os, sys
@@ -213,5 +220,36 @@ class Create(unittest.TestCase):
             b.close()
 
 
+class FailsClosed(unittest.TestCase):
+    """A read that fails must never read as „empty" or „nothing promised". Positive control: Create (same setups)."""
+
+    def test_a_failed_volume_listing_creates_nothing(self):
+        b = Box(349, lvs_fail_listing=True)
+        try:
+            rc, out, err = b.run("create", "132")
+            self.assertEqual(rc, 1, out)
+            self.assertEqual(b.calls(), [])
+        finally:
+            b.close()
+
+    def test_a_listing_without_the_pool_creates_nothing(self):
+        b = Box(349, [thin("vm-9201-disk-1", 250)], hide_pool_in_listing=True)
+        try:
+            self.assertEqual(b.run("create", "132")[0], 1)
+            self.assertEqual(b.calls(), [])
+        finally:
+            b.close()
+
+    def test_a_blkid_error_never_reads_as_empty(self):
+        for setup in ({"lvs": [thin("felhom-belso", 183)], "fs": {}}, {}):
+            b = Box(349, **({"lvs": setup["lvs"], "fs": setup["fs"]} if setup else {}), blkid_rc=4)
+            try:
+                rc, out, err = b.run("create", "0" if setup else "132")
+                self.assertEqual(rc, 1, (setup, out))
+                self.assertNotIn("mkfs", " ".join(b.calls()), setup)
+            finally:
+                b.close()
+
+
 if __name__ == "__main__":
     unittest.main()

configs/test_felhom_mkfs_guarded.py

@@ -1,9 +1,10 @@
 #!/usr/bin/env python3
 """Tests for configs/felhom-mkfs-guarded.sh — the ONLY mkfs path the agent's sudoers permits.
 
-First tests of this wrapper (agent v0.158.0), written with its change for partitions as places (felhom.eu
+First tests of this wrapper (agent v0.158.0), written for partitions as places (felhom.eu architecture/16 §6). Every
-architecture/16 §6): a SIBLING partition that is Felhom's own enrolled drive (mounted raw at /mnt/<name> AND under
+mount of every node of the disk outside /mnt/felhom-drives refuses — INCLUDING a sibling that is Felhom's own drive
-/mnt/felhom-drives) no longer blocks formatting the empty partition next to it; every other mount still refuses.
+(its raw /mnt/<name> mount): the agent can make that corroborating mount itself, so the root wrapper must not trust
+it (security review of 912f7c1). An unlistable disk refuses.
 
 HOW IT RUNS ANYWHERE: the wrapper is copied with five literal host paths replaced (each replacement is asserted, so a
 drifted wrapper fails here instead of silently testing nothing): /proc/mounts → a fake mount table, the block-device
@@ -110,8 +111,12 @@ class Partitions(unittest.TestCase):
         finally:
             d.close()
 
-    def test_the_empty_part_next_to_felhoms_own_drive_is_formatted(self):
+    def test_a_free_part_on_an_unmounted_disk_is_formatted(self):
-        self.check(OWN_SDB1)
+        self.check([])   # positive control for every refusal below
+
+    def test_the_free_part_next_to_felhoms_own_drive_is_refused(self):
+        # The agent could make the „corroborating" managed mount itself: the root wrapper does not trust it.
+        self.check(OWN_SDB1, want_ok=False)
 
     def test_a_sibling_mounted_raw_only_is_refused(self):
         self.check([("/dev/sdb1", "/mnt/hdd_1")], want_ok=False)
@@ -131,9 +136,9 @@ class Partitions(unittest.TestCase):
 
     def test_the_catastrophic_cases_still_refuse(self):
         self.check([("/dev/sdb1", "/")], want_ok=False)                     # system disk
-        self.check(OWN_SDB1, nodes=disk_sdb(sdb1_fstype="LVM2_member"), want_ok=False)  # a member signature
+        self.check([], nodes=disk_sdb(sdb1_fstype="LVM2_member"), want_ok=False)  # a member signature
-        self.check(OWN_SDB1, pvs="/dev/sdb1", want_ok=False)                # an LVM PV (pvs)
+        self.check([], pvs="/dev/sdb1", want_ok=False)                      # an LVM PV (pvs)
-        self.check(OWN_SDB1, ro="1", want_ok=False)                         # read-only
+        self.check([], ro="1", want_ok=False)                               # read-only
 
 
 if __name__ == "__main__":

configs/test_felhom_priv_apply.py

@@ -376,5 +376,67 @@ class ControllerImage(unittest.TestCase):
         self.assertIn("controller-image", buf.getvalue())
 
 
+class UnitForget(unittest.TestCase):
+    """R-1124: the agent forgets a decommissioned drive whose disk is gone — the root half removes its unit file, and
+    ONLY a felhom by-UUID drive unit that is disabled, not mounted, and whose /dev/disk/by-uuid link is absent.
+    RED-PROOF: on the pre-R-1124 wrapper `unit-forget` is not a verb (A1 usage, rc 2) — the removal case fails."""
+    NAME = "mnt-hdd_1.mount"
+    PATH = "/etc/systemd/system/mnt-hdd_1.mount"
+    UUID_LINK = "/dev/disk/by-uuid/91d2dc2d-2d28-4929-9bdd-3e11fa2f41ae"
+
+    def host(self, text=LOCAL_UNIT, kind="file", links=(), mounted=()):
+        h = FakeHost()
+        h.installed = {} if text is None else {self.PATH: (kind, text.encode())}
+        h.links, h.mounted, h.removed = set(links), set(mounted), []
+        h.read_installed = lambda p: (None if p not in h.installed else
+                                      (_ for _ in ()).throw(pa.Refused("F1", f"{p} is not a regular file"))
+                                      if h.installed[p][0] != "file" else h.installed[p][1])
+        h.lexists = lambda p: p in h.links
+        h.mountpoints = lambda: set(h.mounted)
+        h.remove = lambda p: h.removed.append(p)
+        return h
+
+    def test_an_absent_disabled_unmounted_drive_unit_is_removed(self):
+        h = self.host()
+        self.assertEqual(run(h, "unit-forget", self.NAME), 0, h.logs)
+        self.assertEqual(h.removed, [self.PATH])
+
+    def test_already_gone_is_fine(self):
+        h = self.host(text=None)
+        self.assertEqual(run(h, "unit-forget", self.NAME), 0, h.logs)
+        self.assertEqual(h.removed, [])
+
+    def refused(self, h, rule, *argv):
+        rc = run(h, *(argv or ("unit-forget", self.NAME)))
+        self.assertIn(rc, (2, 3), h.logs)
+        self.assertEqual(h.removed, [], h.logs)
+        self.assertTrue(any(f"[{rule}]" in l for l in h.logs), h.logs)
+
+    def test_F5_a_present_drive_keeps_its_unit(self):
+        self.refused(self.host(links=[self.UUID_LINK]), "F5")
+
+    def test_F4_a_mounted_drive_keeps_its_unit(self):
+        self.refused(self.host(mounted=["/mnt/hdd_1"]), "F4")
+
+    def test_F3_an_enabled_unit_is_not_removed(self):
+        self.refused(self.host(links=["/etc/systemd/system/multi-user.target.wants/" + self.NAME]), "F3")
+
+    def test_F2_a_network_unit_or_a_foreign_unit_is_not_removed(self):
+        self.refused(self.host(text=LOCAL_UNIT.replace("Managed by felhom-agent", "Written by someone")), "F2")
+        net = LOCAL_UNIT.replace("# Managed by felhom-agent", "# Managed by felhom-agent felhom network storage")
+        self.refused(self.host(text=net), "F2")
+
+    def test_F1_a_symlinked_unit_is_not_followed(self):
+        self.refused(self.host(kind="symlink"), "F1")
+
+    def test_A1_names(self):
+        for argv in (("unit-forget", "mnt-hdd_1.automount"), ("unit-forget", "sshd.service"),
+                     ("unit-forget", "../mnt-hdd_1.mount"), ("unit-forget",), ("unit-forget", self.NAME, "x")):
+            self.refused(self.host(), "A1", *argv)
+
+    def test_U3_a_unit_whose_name_lies_about_where_is_not_removed(self):
+        self.refused(self.host(text=LOCAL_UNIT.replace("Where=/mnt/hdd_1", "Where=/mnt/other")), "U3")
+
+
 if __name__ == "__main__":
     unittest.main(verbosity=2)

configs/test_felhom_thin_check.py

@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+"""Tests for configs/felhom-thin-check (R-1012): it lists the thin pool's device ids next to LVM's and NEVER removes
+anything. Fake `lvs`, `dmsetup` and `thin_ls` record every call; nothing real is touched. Each refusal has a positive
+control (the healthy read), so a test cannot pass because the helper refuses everything.
+Run: python3 configs/test_felhom_thin_check.py   (also run by internal/thincheck's Go test)
+"""
+import os, pathlib, re, subprocess, tempfile, unittest
+
+HELPER = pathlib.Path(__file__).resolve().parent / "felhom-thin-check"
+
+
+class Box:
+    def __init__(self, pool_ids=(1, 2), lvm=(("vm-9201-disk-0", 1), ("vm-9201-disk-1", 2)), attr="twi-aotz--",
+                 held="-", reserve_rc=0, thin_ls_rc=0):
+        self.t = tempfile.TemporaryDirectory()
+        r = pathlib.Path(self.t.name)
+        self.log = r / "calls"
+        self.log.write_text("")
+        lvm_lines = "\\n".join(f"  {n},{i}" for n, i in lvm)
+        pool_lines = "\\n".join(str(i) for i in pool_ids)
+        self.bins = {}
+        for name, body in {
+            "lvs": f'''case "$*" in *lv_attr*) echo "  {attr}";; *thin_id*) printf "{lvm_lines}\\n";; esac''',
+            "dmsetup": f'''case "$1" in
+  status) echo "0 112975872 thin-pool 585 6860/262144 517080/882624 {held} rw discard_passdown queue_if_no_space - 1024";;
+  message) [ "$4" = reserve_metadata_snap ] && exit {reserve_rc}; exit 0;;
+esac''',
+            "thin_ls": f'''[ {thin_ls_rc} -ne 0 ] && exit {thin_ls_rc}; printf "{pool_lines}\\n"''',
+        }.items():
+            p = r / name
+            p.write_text(f'#!/bin/bash\necho "{name} $*" >> "{self.log}"\n{body}\n')
+            p.chmod(0o755)
+            self.bins[name] = p
+        self.lock = r / "lock"
+
+    def run(self, *args):
+        script = (f'source "{HELPER}"; LVS="{self.bins["lvs"]}"; DMSETUP="{self.bins["dmsetup"]}"; '
+                  f'THIN_LS="{self.bins["thin_ls"]}"; LOCK="{self.lock}"; main "$@"')
+        r = subprocess.run(["bash", "-c", script, "x", *args], capture_output=True, text=True)
+        return r.returncode, r.stdout, r.stderr
+
+    def calls(self):
+        return self.log.read_text().splitlines()
+
+
+def messages(calls):
+    return [c.split()[-1] for c in calls if c.startswith("dmsetup message")]
+
+
+class Reads(unittest.TestCase):
+    def test_healthy_pool_lists_both_sides_and_releases(self):
+        b = Box()
+        rc, out, err = b.run("pve", "data")
+        self.assertEqual(rc, 0, err)
+        self.assertEqual(out.splitlines(), ["lvm-before 1 vm-9201-disk-0", "lvm-before 2 vm-9201-disk-1",
+                                            "pool 1", "pool 2",
+                                            "lvm-after 1 vm-9201-disk-0", "lvm-after 2 vm-9201-disk-1", "ok"])
+        self.assertEqual(messages(b.calls()), ["reserve_metadata_snap", "release_metadata_snap"])
+        self.assertIn("thin_ls --metadata-snap --no-headers -o DEV /dev/mapper/pve-data_tmeta", b.calls())
+
+    def test_the_2026_10_14_orphan_is_listed(self):
+        rc, out, _ = Box(pool_ids=(1, 2, 4)).run("pve", "data")
+        self.assertEqual(rc, 0)
+        self.assertIn("pool 4", out.splitlines())
+
+    def test_dashed_names_map_to_the_device_mapper_name(self):
+        b = Box()
+        rc, _, err = b.run("felhom-scratch", "thin-pool")
+        self.assertEqual(rc, 0, err)
+        self.assertIn("dmsetup status felhom--scratch-thin--pool-tpool", b.calls())
+
+
+class Refuses(unittest.TestCase):
+    def refused(self, box, rc_want, *args):
+        rc, out, err = box.run(*args)
+        self.assertEqual(rc, rc_want, (out, err))
+        self.assertNotIn("ok", out.splitlines())
+        return box.calls()
+
+    def test_arguments(self):
+        for args in (("pve",), ("pve", "data", "x"), ("pve;id", "data"), ("-pve", "data"), ("pve", "../data"),
+                     ("pve", "da ta")):
+            calls = self.refused(Box(), 1, *args)
+            self.assertEqual(calls, [], args)
+
+    def test_not_a_thin_pool(self):
+        calls = self.refused(Box(attr="Vwi-aotz--"), 1, "pve", "vm-9201-disk-1")
+        self.assertEqual(messages(calls), [])
+
+    def test_a_snapshot_someone_else_holds_is_never_touched(self):
+        b = Box(held="1234")
+        rc, _, err = b.run("pve", "data")
+        self.assertEqual(rc, 3)
+        self.assertEqual(messages(b.calls()), [])  # neither reserve nor release
+        # the reason line ends with the reason, not the exit code (found live on demo-hp 2026-10-17)
+        self.assertTrue(err.strip().endswith("not touched"), err)
+
+    def test_reserve_failure_does_not_release(self):
+        calls = self.refused(Box(reserve_rc=1), 3, "pve", "data")
+        self.assertEqual(messages(calls), ["reserve_metadata_snap"])
+
+    def test_thin_ls_failure_still_releases(self):
+        calls = self.refused(Box(thin_ls_rc=1), 4, "pve", "data")
+        self.assertEqual(messages(calls), ["reserve_metadata_snap", "release_metadata_snap"])
+
+
+class NeverDeletes(unittest.TestCase):
+    def test_the_only_pool_messages_are_reserve_and_release(self):
+        src = HELPER.read_text()
+        sent = re.findall(r'"\$DMSETUP" message "\$TPOOL" 0 (\S+)', src)
+        self.assertEqual(sorted(set(sent)), ["release_metadata_snap", "reserve_metadata_snap"])
+        for word in ("delete", "lvremove", "thin_repair", "create_thin", "create_snap", " rm "):
+            code = "\n".join(l for l in src.splitlines() if not l.lstrip().startswith("#"))
+            self.assertNotIn(word, code, word)
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)

go.mod

@@ -1,7 +1,8 @@
 module gitea.dooplex.hu/admin/felhom-agent
 
-go 1.25.0
+go 1.27.2
 
-require golang.org/x/crypto v0.52.0
+require (
-
+	golang.org/x/crypto v0.58.0
-require golang.org/x/sys v0.45.0 // indirect
+	golang.org/x/sys v0.49.0
+)

go.sum

@@ -1,6 +1,6 @@
-golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
+golang.org/x/crypto v0.58.0 h1:COkYLr4k7nDI4r6QtMML2AfzeIswWHAJthLS6K/M/54=
-golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
+golang.org/x/crypto v0.58.0/go.mod h1:Xh+kl5A+M0gMiWDytH2Hhr5Z7WbNCpv/eB/EFgfSk+w=
-golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
+golang.org/x/sys v0.49.0 h1:XbzkgYJHdqh/8m2Uu0W/dQv8nktxx4BFHp1M0gROTXA=
-golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.49.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
-golang.org/x/term v0.43.0 h1:S4RLU2sB31O/NCl+zFN9Aru9A/Cq2aqKpTZJ6B+DwT4=
+golang.org/x/term v0.47.0 h1:cpyOwQkr2Nzxe2p6KnrTG7Ei2wtzjsuSjhpXXepZ/BM=
-golang.org/x/term v0.43.0/go.mod h1:lrhlHNdQJHO+1qVYiHfFKVuVioJIheAc3fBSMFYEIsk=
+golang.org/x/term v0.47.0/go.mod h1:efAfAuG6RKABvg1ArGebRkvX6LXul14SM67o2e4mUCY=

internal/backup/r1012_thincheck_test.go

@@ -0,0 +1,67 @@
+package backup
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// R-1012: a snapshot backup that fails carries the orphan finding in its error — the text the controller mails to
+// the operator (`whole_guest_backup_failed`). The check runs ONCE, after the failure — never before the run.
+// RED-PROOF (P1/redproof-thincheck.txt): with explainFailure's append removed this test fails. RED-PROOF (2026-10-17
+// night, felhom-agent REPORT.md): with the v0.159.0 pre-run check restored, calls = 2 and this test fails.
+func TestBackup_SnapshotFailure_NamesTheOrphan(t *testing.T) {
+	const why = "probable cause: thin pool pve/data holds device 4 that LVM does not know"
+	for name, api := range map[string]*fakeBackupAPI{
+		"task fails":  {vzdumpUPID: "UPID:x", waitErr: errors.New("task failed: job errors")},
+		"start fails": {vzdumpErr: errors.New("vzdump: 500")},
+	} {
+		t.Run(name, func(t *testing.T) {
+			r := NewBackupRunner(api, "local", "", "", "", quiet())
+			calls := 0
+			r.SetThinCheck(func(context.Context, int) string { calls++; return why })
+			rec, err := r.Backup(context.Background(), 9201)
+			if err == nil || rec.Success {
+				t.Fatalf("want a failure, got %+v", rec)
+			}
+			if !strings.Contains(rec.Error, why) {
+				t.Fatalf("the failure does not name the orphan: %q", rec.Error)
+			}
+			if calls != 1 {
+				t.Fatalf("thin check ran %d times, want 1 (after the failure only)", calls)
+			}
+		})
+	}
+}
+
+// A successful backup never runs the check (it takes a metadata snapshot of the live pool, and nobody needs the answer)
+// and keeps a clean record; a stop-mode backup takes no snapshot, so the check never runs; an unwired runner behaves
+// exactly as before. RED-PROOF (2026-10-17 night): with the v0.159.0 pre-run check restored, the success leg fails
+// with calls=1.
+func TestBackup_ThinCheck_SilentWhenNotApplicable(t *testing.T) {
+	ok := &fakeBackupAPI{vzdumpUPID: "UPID:x",
+		content: []proxmox.StorageContent{{VolID: "local:backup/vzdump-lxc-9201-x", Content: "backup", VMID: 9201, Size: 100, CTime: 1}}}
+	r := NewBackupRunner(ok, "local", "", "", "", quiet())
+	calls := 0
+	r.SetThinCheck(func(context.Context, int) string { calls++; return "probable cause: x" })
+	rec, err := r.Backup(context.Background(), 9201)
+	if err != nil || !rec.Success || rec.Error != "" || calls != 0 {
+		t.Fatalf("success: err=%v rec=%+v calls=%d (want no check on a successful backup, clean record)", err, rec, calls)
+	}
+
+	stop := NewBackupRunner(&fakeBackupAPI{vzdumpUPID: "UPID:x", waitErr: errors.New("boom")}, "local", proxmox.ModeStop, "", "", quiet())
+	calls = 0
+	stop.SetThinCheck(func(context.Context, int) string { calls++; return "probable cause: x" })
+	rec, _ = stop.Backup(context.Background(), 9201)
+	if calls != 0 || strings.Contains(rec.Error, "probable cause") {
+		t.Fatalf("stop mode: calls=%d error=%q", calls, rec.Error)
+	}
+
+	plain := NewBackupRunner(&fakeBackupAPI{vzdumpUPID: "UPID:x", waitErr: errors.New("boom")}, "local", "", "", "", quiet())
+	if rec, _ := plain.Backup(context.Background(), 9201); rec.Error != "boom" {
+		t.Fatalf("unwired: error = %q, want the task error unchanged", rec.Error)
+	}
+}

internal/backup/runner.go

@@ -61,8 +61,13 @@ type BackupRunner struct {
 	// beforeBackup runs just before the space preflight (R-1006): it removes a dead half-written vzdump of this guest on
 	// this target, so a leftover from a power cut cannot hold the space this backup needs. nil = nothing.
 	beforeBackup func(ctx context.Context, storage string, vmid int)
-	logger       *slog.Logger
+	// thinCheck (R-1012) names an orphan thin device in the guest's pools in plain words ("" = none / not checked). It
-	now          func() time.Time
+	// runs ONLY when a snapshot-mode vzdump has failed (start or task), so the failure the controller mails to the
+	// operator says why; a successful backup never runs it (it takes a metadata snapshot of the live pool). It never
+	// removes anything. nil = not wired.
+	thinCheck func(ctx context.Context, vmid int) string
+	logger    *slog.Logger
+	now       func() time.Time
 	// rejected remembers the volids already announced by warnRejectedArchiveOnce, so an incomplete
 	// archive is reported ONCE rather than on every 5-minute due-check. Bounded in practice: one
 	// entry per aborted upload, and a process restart clears it. Guarded by rejectedMu because the
@@ -110,6 +115,22 @@ func (r *BackupRunner) SetBeforeBackup(fn func(ctx context.Context, storage stri
 	r.beforeBackup = fn
 }
 
+// SetThinCheck wires the R-1012 orphan check (see BackupRunner.thinCheck).
+func (r *BackupRunner) SetThinCheck(fn func(ctx context.Context, vmid int) string) { r.thinCheck = fn }
+
+// explainFailure appends the orphan finding to a failed snapshot-mode backup's error — the only place the check runs, so
+// it sees the pool as the failure left it. Bounded, so a stuck helper cannot hold the job.
+func (r *BackupRunner) explainFailure(ctx context.Context, vmid int, rec *hub.Backup) {
+	if r.thinCheck == nil || r.mode != proxmox.ModeSnapshot {
+		return
+	}
+	cctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 2*time.Minute)
+	defer cancel()
+	if why := r.thinCheck(cctx, vmid); why != "" {
+		rec.Error = rec.Error + " — " + why
+	}
+}
+
 // localPruneSpec returns the `--prune-backups` spec to apply to THIS backup, or "" to skip pruning. It
 // applies the configured retention ONLY when the target is a non-PBS storage — PBS offsite retention is a
 // separate lifecycle and must never be pruned by the per-run flag (§9). Fail-safe: if the target's type
@@ -201,12 +222,15 @@ func (r *BackupRunner) backup(ctx context.Context, vmid int, onSnapshot func())
 		return rec, fmt.Errorf("backup: %s", rec.Error)
 	}
 
+	// R-1012: no orphan check here. It takes a metadata snapshot of the live pool, and its answer is only needed when the
+	// snapshot step has failed — explainFailure runs it then (pinned by TestBackup_ThinCheck_SilentWhenNotApplicable).
 	upid, err := r.api.Vzdump(ctx, proxmox.VzdumpOptions{
 		VMID: vmid, Storage: r.target, Mode: r.mode, Notes: r.notes,
 		PruneBackups: r.localPruneSpec(ctx), // local target → keep-last=N; PBS/unknown → "" (no prune)
 	})
 	if err != nil {
 		rec.Error = err.Error()
+		r.explainFailure(ctx, vmid, &rec)
 		rec.DurationSeconds = time.Since(start).Seconds()
 		return rec, fmt.Errorf("backup: vzdump vmid %d: %w", vmid, err)
 	}
@@ -220,6 +244,7 @@ func (r *BackupRunner) backup(ctx context.Context, vmid int, onSnapshot func())
 		}
 		if _, err := r.api.WaitTask(ctx, upid, proxmox.WaitOptions{Timeout: r.waitTimeout}); err != nil {
 			rec.Error = err.Error()
+			r.explainFailure(ctx, vmid, &rec)
 			rec.DurationSeconds = time.Since(start).Seconds()
 			return rec, fmt.Errorf("backup: vzdump task vmid %d: %w", vmid, err)
 		}

internal/capability/manifest.go

@@ -91,9 +91,11 @@ var manifest = []Capability{
 	{"disk-mkfs-xfs", "guarded format (xfs)", "/usr/local/sbin/felhom-mkfs-guarded", []string{"/dev/sda", "xfs"}, false, ""},
 	{"disk-smart", "disk SMART health read", "/usr/sbin/smartctl", []string{"-a", "-j", "/dev/sda"}, false, ""},
 	{"disk-lvs", "thin-pool usage read", "/usr/sbin/lvs", []string{"--reportformat", "json", "--units", "b", "-o", "lv_name,data_percent,metadata_percent", "--", "pve/data"}, false, ""},
+	{"thin-orphan-check", "orphan thin device check after a failed whole-guest backup (read-only, R-1012)", "/usr/local/sbin/felhom-thin-check", []string{"pve", "data"}, false, ""},
 
 	// ---- Storage mount units (watchdog re-mount) ----
 	{"mount-unit-install", "fs-UUID mount unit install (root content check, R-861)", "/usr/local/sbin/felhom-priv-apply", []string{"unit", "mnt-felhom\\x2dx.mount"}, false, ""},
+	{"mount-unit-forget", "decommissioned-drive unit removal (root check, R-1124)", "/usr/local/sbin/felhom-priv-apply", []string{"unit-forget", "mnt-felhom\\x2dx.mount"}, false, ""},
 	{"mount-daemon-reload", "systemd reload after unit write", "/usr/bin/systemctl", []string{"daemon-reload"}, false, ""},
 	{"mount-unit-enable", "mount unit enable", "/usr/bin/systemctl", []string{"enable", "--now", "--", "mnt-felhom\\x2dx.mount"}, false, ""},
 	{"mount-unit-disable", "mount unit disable", "/usr/bin/systemctl", []string{"disable", "--", "mnt-felhom\\x2dx.mount"}, false, ""},

internal/signedjobs/decommission.go

@@ -39,9 +39,21 @@ type decommissionParams struct {
 // none is wanted, because a drive can legitimately be decommissioned while physically ABSENT.
 type DecommissionExecutor struct {
 	intent IntentDecommissioner
+	binds  GuestBindPruner // optional (v0.159.1): drop the drive from every guest's bind record, as the self-serve path does
 	logger *slog.Logger
 }
 
+// GuestBindPruner is the per-guest enrolled-bind record (*localapi.GuestBindStore). The self-serve decommission prunes
+// the drive from it; the signed one did not, so a forgotten drive (R-1124) left a record the 20-second guest-bind
+// re-assert warned about forever ("skipping non-enrolled drive"), measured on demo-hp 2026-10-17.
+type GuestBindPruner interface {
+	Guests() map[int][]string
+	Remove(vmid int, durableID string) error
+}
+
+// SetGuestBinds wires the bind record (nil-safe: no record, nothing pruned).
+func (d *DecommissionExecutor) SetGuestBinds(b GuestBindPruner) { d.binds = b }
+
 // NewDecommissionExecutor wires the executor to the agent's intent store.
 func NewDecommissionExecutor(intent IntentDecommissioner, logger *slog.Logger) *DecommissionExecutor {
 	if logger == nil {
@@ -75,6 +87,20 @@ func (d *DecommissionExecutor) Execute(_ context.Context, op string, params json
 	if err := d.intent.SetDecommissioned(p.DurableID); err != nil {
 		return fmt.Errorf("decommission: record intent for %q: %w", p.DurableID, err)
 	}
+	if d.binds != nil {
+		for vmid, ids := range d.binds.Guests() {
+			for _, id := range ids {
+				if id != p.DurableID {
+					continue
+				}
+				if err := d.binds.Remove(vmid, id); err != nil {
+					d.logger.Warn("decommission: guest-bind record not pruned", "vmid", vmid, "durable_id", id, "err", err)
+				} else {
+					d.logger.Info("decommission: drive removed from the guest's bind record", "vmid", vmid, "durable_id", id)
+				}
+			}
+		}
+	}
 	d.logger.Warn("decommission: operator-signed decommission complete (drive will never auto-mount)", "durable_id", p.DurableID)
 	return nil
 }

internal/signedjobs/decommission_test.go

@@ -89,3 +89,37 @@ func TestExecutorChain_DispatchesToOwner(t *testing.T) {
 		t.Errorf("want ErrNoExecutor for an unowned op, got %v", err)
 	}
 }
+
+type fakeBinds struct{ m map[int][]string }
+
+func (f *fakeBinds) Guests() map[int][]string { return f.m }
+func (f *fakeBinds) Remove(vmid int, id string) error {
+	var kept []string
+	for _, x := range f.m[vmid] {
+		if x != id {
+			kept = append(kept, x)
+		}
+	}
+	f.m[vmid] = kept
+	return nil
+}
+
+// v0.159.1: the signed decommission drops the drive from EVERY guest's bind record, as the self-serve path does — and
+// only that drive. RED-PROOF (felhom.eu audits/agent-allowlist-rotation-2026-10-17/P1/redproof-bindprune.txt): with
+// the prune loop removed, the record still holds the drive and this test fails.
+func TestDecommissionExecutor_PrunesTheGuestBindRecord(t *testing.T) {
+	fd := &fakeDecommissioner{}
+	fb := &fakeBinds{m: map[int][]string{9201: {"uuid:keep", "uuid:gone"}, 9202: {"uuid:gone"}}}
+	ex := NewDecommissionExecutor(fd, nil)
+	ex.SetGuestBinds(fb)
+	params, _ := json.Marshal(decommissionParams{DurableID: "uuid:gone"})
+	if err := ex.Execute(context.Background(), opDecommission, params); err != nil {
+		t.Fatal(err)
+	}
+	if got := fb.m[9201]; len(got) != 1 || got[0] != "uuid:keep" {
+		t.Fatalf("9201 record = %v, want [uuid:keep]", got)
+	}
+	if got := fb.m[9202]; len(got) != 0 {
+		t.Fatalf("9202 record = %v, want empty", got)
+	}
+}

internal/storage/forget_retired.go

@@ -0,0 +1,85 @@
+package storage
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ForgetRetiredDrives (R-1124) removes the host mount unit of every DECOMMISSIONED drive that is physically gone, so a
+// later host boot no longer waits for it and the agent stops listing it (RegistryKnownTargets and
+// ReassertEnrolledMounts both enumerate the units — no unit, no entry, no „absent by UUID" line every 20 s).
+//
+// Only a drive that is BOTH decommissioned (the operator's or the customer's permanent removal) AND absent (its
+// /dev/disk/by-uuid link does not resolve) AND not mounted is forgotten. A decommissioned drive that is still plugged in
+// keeps its unit and its raw host mount — that is what makes the one-click re-enroll (H3) work, and decommission stays a
+// logical retire (`03` §storage). The intent record stays `decommissioned`: a forgotten drive that comes back is a new
+// candidate, never auto-mounted. The root half (`felhom-priv-apply unit-forget`) re-checks every one of these conditions
+// and refuses otherwise. Called at agent start, on the 20-second storage tick, and right after a decommission. Best
+// effort per unit; returns how many units it removed. Pinned by TestForgetRetiredDrives_*.
+func (h *SudoHostOps) ForgetRetiredDrives(ctx context.Context, intent IntentReader) int {
+	if intent == nil {
+		return 0 // no intent store → we cannot know a drive was retired; forget nothing
+	}
+	entries, err := os.ReadDir(h.unitDir)
+	if err != nil {
+		h.logger.Warn("storage: forget retired drives — cannot read unit dir", "dir", h.unitDir, "err", err)
+		return 0
+	}
+	mounted := map[string]bool{}
+	if ms, merr := h.host.Mounts(); merr == nil {
+		for _, m := range ms {
+			mounted[m.MountPoint] = true
+		}
+	} else {
+		h.logger.Warn("storage: forget retired drives — mount table unreadable; forgetting nothing", "err", merr)
+		return 0
+	}
+	removed := 0
+	for _, e := range entries {
+		name := e.Name()
+		if !strings.HasSuffix(name, ".mount") {
+			continue
+		}
+		data, rerr := os.ReadFile(filepath.Join(h.unitDir, name))
+		if rerr != nil {
+			continue
+		}
+		spec, ok := parseFelhomMountUnit(string(data))
+		if !ok {
+			continue // not one of our by-UUID drive units (network units are refused by the parser)
+		}
+		durableID := "uuid:" + spec.UUID
+		if intent.Get(durableID) != IntentDecommissioned {
+			continue
+		}
+		if mounted[spec.Where] {
+			h.logger.Debug("storage: decommissioned drive still mounted — keeping its unit", "where", spec.Where)
+			continue
+		}
+		if _, derr := ResolveStorageDevice(durableID); derr == nil {
+			h.logger.Debug("storage: decommissioned drive is present — keeping its unit (re-enroll stays one click)", "where", spec.Where)
+			continue
+		}
+		if h.unitEnabled(name) {
+			if err := h.run(ctx, h.bins.Systemctl, "disable", "--", name); err != nil {
+				h.logger.Warn("storage: forget retired drive — disable failed", "where", spec.Where, "unit", name, "err", err)
+				continue
+			}
+		}
+		if err := h.run(ctx, h.bins.PrivApply, "unit-forget", name); err != nil {
+			h.logger.Warn("storage: forget retired drive — unit removal refused or failed", "where", spec.Where, "unit", name, "err", err)
+			continue
+		}
+		removed++
+		h.logger.Info("storage: forgot a decommissioned drive that is gone — its mount unit is removed",
+			"name", spec.Name, "where", spec.Where, "uuid", spec.UUID, "unit", name)
+	}
+	if removed > 0 {
+		if err := h.run(ctx, h.bins.Systemctl, "daemon-reload"); err != nil {
+			h.logger.Warn("storage: daemon-reload after forgetting retired drives failed", "err", err)
+		}
+	}
+	return removed
+}

internal/storage/forget_retired_test.go

@@ -0,0 +1,155 @@
+package storage
+
+import (
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+)
+
+// forgetRunner records every privileged call and plays the root half of `felhom-priv-apply unit-forget`: the unit file
+// disappears from the unit dir, so the CONSEQUENCE (the drive is no longer listed) is observable, not just the calls.
+type forgetRunner struct {
+	unitDir string
+	calls   [][]string
+}
+
+func (r *forgetRunner) RunStdin(ctx context.Context, _ io.Reader, name string, args ...string) ([]byte, []byte, error) {
+	return r.Run(ctx, name, args...)
+}
+
+func (r *forgetRunner) Run(_ context.Context, name string, args ...string) ([]byte, []byte, error) {
+	r.calls = append(r.calls, append([]string{name}, args...))
+	if len(args) == 2 && args[0] == "unit-forget" {
+		_ = os.Remove(filepath.Join(r.unitDir, args[1]))
+	}
+	return nil, nil, nil
+}
+
+type forgetCase struct {
+	intent   DriveIntent
+	present  bool // the by-uuid link resolves
+	mounted  bool
+	enabled  bool // the wants-symlink exists
+	mountErr bool
+}
+
+const forgetUUID = "4ebfd36d-87d3-4b63-839e-a5a710fc799a"
+
+func runForget(t *testing.T, c forgetCase, intent IntentReader) (int, *forgetRunner, *RegistryKnownTargets, string) {
+	t.Helper()
+	unitDir := t.TempDir()
+	unit := "mnt-media_a.mount"
+	writeUnit(t, unitDir, unit, renderMountUnit(MountSpec{Name: forgetUUID, UUID: forgetUUID, Where: "/mnt/media_a", FSType: "ext4"}))
+	if c.enabled {
+		if err := os.MkdirAll(filepath.Join(unitDir, "multi-user.target.wants"), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.Symlink(filepath.Join(unitDir, unit), filepath.Join(unitDir, "multi-user.target.wants", unit)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	devRoot := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(devRoot, "by-uuid"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if c.present {
+		dev := filepath.Join(devRoot, "sdz1")
+		if err := os.WriteFile(dev, nil, 0o600); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.Symlink(dev, filepath.Join(devRoot, "by-uuid", forgetUUID)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	withDevDiskRoot(t, devRoot)
+	hr := &fakeHostReader{}
+	if c.mounted {
+		hr.mounts = []Mount{{MountPoint: "/mnt/media_a", FSType: "ext4"}}
+	}
+	if c.mountErr {
+		hr.mountsErr = os.ErrPermission
+	}
+	rr := &forgetRunner{unitDir: unitDir}
+	ops := NewSudoHostOps(SudoHostOpsConfig{Runner: rr, Bins: Binaries{}.withDefaults(), UnitDir: unitDir,
+		StageDir: t.TempDir(), Host: hr, Logger: quietLogger()})
+	if intent == nil {
+		intent = &fakeIntent{m: map[string]DriveIntent{"uuid:" + forgetUUID: c.intent}}
+	}
+	n := ops.ForgetRetiredDrives(context.Background(), intent)
+	return n, rr, NewRegistryKnownTargets(unitDir, intent, quietLogger()), unitDir
+}
+
+// The R-1124 case: decommissioned, then unplugged. The unit is disabled and removed through the root checker, systemd
+// is reloaded, and the CONSEQUENCE — the agent no longer lists the drive — holds. RED-PROOF (P1/redproof-forget.txt):
+// with ForgetRetiredDrives' body replaced by `return 0` this test fails (the drive is still listed).
+func TestForgetRetiredDrives_DecommissionedAndGone_UnitRemovedAndNotListed(t *testing.T) {
+	n, rr, known, _ := runForget(t, forgetCase{intent: IntentDecommissioned, enabled: true}, nil)
+	if n != 1 {
+		t.Fatalf("removed = %d, want 1 (calls %v)", n, rr.calls)
+	}
+	pa := Binaries{}.withDefaults()
+	want := [][]string{
+		{pa.Systemctl, "disable", "--", "mnt-media_a.mount"},
+		{pa.PrivApply, "unit-forget", "mnt-media_a.mount"},
+		{pa.Systemctl, "daemon-reload"},
+	}
+	if !reflect.DeepEqual(rr.calls, want) {
+		t.Fatalf("calls = %v\nwant    %v", rr.calls, want)
+	}
+	got, err := known.Known(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 0 {
+		t.Fatalf("the forgotten drive is still listed: %+v", got)
+	}
+}
+
+// Already disabled (the Tester 1 shape after a manual disable): no disable call, the removal still runs.
+func TestForgetRetiredDrives_AlreadyDisabled_NoDisableCall(t *testing.T) {
+	n, rr, _, _ := runForget(t, forgetCase{intent: IntentDecommissioned}, nil)
+	pa := Binaries{}.withDefaults()
+	want := [][]string{{pa.PrivApply, "unit-forget", "mnt-media_a.mount"}, {pa.Systemctl, "daemon-reload"}}
+	if n != 1 || !reflect.DeepEqual(rr.calls, want) {
+		t.Fatalf("n=%d calls=%v want %v", n, rr.calls, want)
+	}
+}
+
+// Everything that must KEEP its unit: a decommissioned drive still plugged in (re-enroll is one click — H3), one still
+// mounted, an enrolled or ejected drive that is merely absent (it comes back), a drive with no recorded intent, and an
+// unreadable mount table. No privileged call at all, and the drive stays listed where it was listed.
+// RED-PROOF: with the present-drive check removed, the "present" case calls unit-forget and fails.
+func TestForgetRetiredDrives_KeepsEveryOtherUnit(t *testing.T) {
+	for name, c := range map[string]forgetCase{
+		"decommissioned but present": {intent: IntentDecommissioned, present: true, enabled: true},
+		"decommissioned but mounted": {intent: IntentDecommissioned, mounted: true},
+		"enrolled and absent":        {intent: IntentEnrolled},
+		"ejected and absent":         {intent: IntentEjected},
+		"no intent":                  {intent: IntentNew},
+		"mount table unreadable":     {intent: IntentDecommissioned, mountErr: true},
+	} {
+		t.Run(name, func(t *testing.T) {
+			n, rr, _, unitDir := runForget(t, c, nil)
+			if n != 0 || len(rr.calls) != 0 {
+				t.Fatalf("n=%d calls=%v — this unit must be kept", n, rr.calls)
+			}
+			if _, err := os.Stat(filepath.Join(unitDir, "mnt-media_a.mount")); err != nil {
+				t.Fatalf("unit file gone: %v", err)
+			}
+		})
+	}
+}
+
+// No intent store on the host (open failure): nothing is known to be retired, so nothing is forgotten.
+func TestForgetRetiredDrives_NilIntent_ForgetsNothing(t *testing.T) {
+	unitDir := t.TempDir()
+	writeUnit(t, unitDir, "mnt-media_a.mount", renderMountUnit(MountSpec{Name: "x", UUID: forgetUUID, Where: "/mnt/media_a"}))
+	rr := &forgetRunner{unitDir: unitDir}
+	ops := NewSudoHostOps(SudoHostOpsConfig{Runner: rr, UnitDir: unitDir, StageDir: t.TempDir(), Host: &fakeHostReader{}, Logger: quietLogger()})
+	if n := ops.ForgetRetiredDrives(context.Background(), nil); n != 0 || len(rr.calls) != 0 {
+		t.Fatalf("n=%d calls=%v", n, rr.calls)
+	}
+}

internal/storage/partitions.go

@@ -13,7 +13,8 @@ import (
 // A disk that passed the WHOLE-disk unclaimed filter (classifyClaim: not the system disk, no LVM/ZFS/RAID/LUKS/swap
 // member on any node, no foreign mount on any node) also lists its partitions, each with its own state:
 //
-//	empty       no filesystem, no children           → „format this part" (self-serve: the agent's probe says blank)
+//	empty       no filesystem, no children           → „format this part" (self-serve: the agent's probe says blank) —
+//	                                                   only while NO part of the disk is mounted (Formattable)
 //	filesystem  ext4/xfs (mountable) or another fs   → „use this part" when mountable; „format this part" only through
 //	                                                   the customer-confirmed data-bearing path (the agent's own probe)
 //	in_use      already Felhom's own drive           → shown, never offered (it is a registered drive already)
@@ -32,6 +33,10 @@ type CandidatePartition struct {
 	Mountable bool   `json:"mountable"`
 	DurableID string `json:"durable_id,omitempty"` // uuid:<fs-uuid> — the attach key ("" when empty)
 	MountedAt string `json:"mounted_at,omitempty"` // in_use: Felhom's own mount
+	// Formattable is false when ANY node of the disk is mounted (another part in use): the root mkfs wrapper refuses
+	// every mount outside /mnt/felhom-drives on the disk and deliberately does not trust a sibling that claims to be
+	// Felhom's own (a compromised agent could fake that). Such a part can still be USED (attach erases nothing).
+	Formattable bool `json:"formattable"`
 }
 
 const (
@@ -55,6 +60,19 @@ func candidatePartitions(lsblkJSON []byte, wholeName string, sizeOf func(string)
 		if d.Name != wholeName {
 			continue
 		}
+		diskMounted := d.MountPoint != ""
+		var walk func(n lsblkDev)
+		walk = func(n lsblkDev) {
+			if n.MountPoint != "" {
+				diskMounted = true
+			}
+			for _, c := range n.Children {
+				walk(c)
+			}
+		}
+		for _, c := range d.Children {
+			walk(c)
+		}
 		for _, p := range d.Children {
 			if len(p.Children) > 0 || memberFSTypes[p.FSType] {
 				continue // LVM/mapper on it, or a member: not a place (the disk filter refuses these anyway)
@@ -74,6 +92,7 @@ func candidatePartitions(lsblkJSON []byte, wholeName string, sizeOf func(string)
 					c.DurableID = "uuid:" + u
 				}
 			}
+			c.Formattable = c.State != PartInUse && !diskMounted
 			out = append(out, c)
 		}
 	}

internal/storage/partitions_test.go

@@ -71,3 +71,21 @@ func TestPartitions_UncorroboratedMountIsNotOffered(t *testing.T) {
 		}
 	}
 }
+
+// The root wrapper refuses any format on a disk with a mounted node (and trusts no „it is Felhom's own" claim), so a
+// part next to a mounted one is never offered for formatting — only for use. Positive control: an unmounted disk.
+func TestPartitions_FormattableOnlyWhenNothingOnTheDiskIsMounted(t *testing.T) {
+	m := listParts(map[string]bool{"/mnt/films": true})
+	for dev, p := range m {
+		if p.Formattable {
+			t.Fatalf("%s: a part of a disk with a mounted part must not be formattable: %+v", dev, p)
+		}
+	}
+	free := `{"blockdevices":[{"name":"sdc","fstype":null,"mountpoint":null,"children":[
+	  {"name":"sdc1","fstype":null,"mountpoint":null},{"name":"sdc2","fstype":"ext4","mountpoint":null}]}]}`
+	got := candidatePartitions([]byte(free), "sdc", func(string) int64 { return 1 << 30 }, func(string) int { return 1 },
+		func(string) (string, bool) { return "u", true }, nil)
+	if len(got) != 2 || !got[0].Formattable || !got[1].Formattable {
+		t.Fatalf("parts of an unmounted disk are formattable, got %+v", got)
+	}
+}

internal/thincheck/thincheck.go

@@ -0,0 +1,243 @@
+// Package thincheck finds an ORPHAN thin device: one the LVM thin pool holds that LVM itself no longer knows (R-1012).
+//
+// A full host root while vzdump takes its storage snapshot can leave such a device behind (demo-hp 2026-10-14: the
+// pool held devices 1, 2 and 4; LVM knew 1 and 2). From then on every snapshot backup of that guest fails at the
+// snapshot step („Creation of new snapshot 4 of device 2 failed") and nothing in the product said why. This package
+// NAMES the orphan, in plain words, in the backup's failure — it never removes one: the repair
+// (`dmsetup message <pool>-tpool 0 "delete <id>"`) stays a human step, decided by the operator (`03` whole-guest
+// backup; runbook `whole-guest-backup-orphan-thin.md`).
+//
+// The device list comes from the root helper `felhom-thin-check <vg> <pool>` (config bundle), which reads the pool
+// through a metadata snapshot and LVM's list before and after. An id is an orphan only when the pool holds it and
+// NEITHER LVM list names it, on two reads a few seconds apart — so a volume being created at that moment is never
+// reported.
+package thincheck
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// HelperPath is where the config bundle installs the root helper.
+const HelperPath = "/usr/local/sbin/felhom-thin-check"
+
+// Pool names one LVM thin pool.
+type Pool struct{ VG, Pool string }
+
+func (p Pool) String() string { return p.VG + "/" + p.Pool }
+
+// Reading is one helper run, parsed.
+type Reading struct {
+	PoolIDs   []int
+	LVMBefore map[int]string
+	LVMAfter  map[int]string
+}
+
+// Parse reads the helper's output. ok=false unless the closing "ok" line is there (a cut-off run is no reading).
+func Parse(out string) (Reading, bool) {
+	r := Reading{LVMBefore: map[int]string{}, LVMAfter: map[int]string{}}
+	done := false
+	for _, line := range strings.Split(out, "\n") {
+		f := strings.Fields(line)
+		switch {
+		case len(f) == 1 && f[0] == "ok":
+			done = true
+		case len(f) == 2 && f[0] == "pool":
+			if id, err := strconv.Atoi(f[1]); err == nil {
+				r.PoolIDs = append(r.PoolIDs, id)
+			}
+		case len(f) == 3 && (f[0] == "lvm-before" || f[0] == "lvm-after"):
+			id, err := strconv.Atoi(f[1])
+			if err != nil {
+				continue
+			}
+			if f[0] == "lvm-before" {
+				r.LVMBefore[id] = f[2]
+			} else {
+				r.LVMAfter[id] = f[2]
+			}
+		}
+	}
+	return r, done
+}
+
+// Orphans returns the ids the pool holds that neither LVM list names, sorted.
+func (r Reading) Orphans() []int {
+	var out []int
+	for _, id := range r.PoolIDs {
+		_, b := r.LVMBefore[id]
+		_, a := r.LVMAfter[id]
+		if !b && !a {
+			out = append(out, id)
+		}
+	}
+	sort.Ints(out)
+	return out
+}
+
+// Runner is the privileged exec surface (proxmox.ExecRunner in sudo mode).
+type Runner interface {
+	Run(ctx context.Context, name string, args ...string) ([]byte, []byte, error)
+}
+
+// StorageLister is the read the checker needs to map a guest's volumes to their thin pools (*proxmox.Client).
+type StorageLister interface {
+	GuestConfig(ctx context.Context, vmid int) (proxmox.GuestConfig, error)
+	ListStorage(ctx context.Context) ([]proxmox.Storage, error)
+}
+
+// Checker runs the check for one guest's pools.
+type Checker struct {
+	API    StorageLister
+	Runner Runner
+	Helper string        // "" → HelperPath
+	Pause  time.Duration // between the two reads when the first finds an orphan; 0 → 3 s
+	Logger *slog.Logger
+}
+
+// Finding is one pool with orphans.
+type Finding struct {
+	Pool    Pool
+	Orphans []int
+}
+
+// PoolsOf maps the guest's volume-backed disks (rootfs, mpN) to the lvmthin pools they live on.
+func (c *Checker) PoolsOf(ctx context.Context, vmid int) ([]Pool, error) {
+	cfg, err := c.API.GuestConfig(ctx, vmid)
+	if err != nil {
+		return nil, err
+	}
+	stores, err := c.API.ListStorage(ctx)
+	if err != nil {
+		return nil, err
+	}
+	thin := map[string]Pool{}
+	for _, s := range stores {
+		if s.Type == "lvmthin" && s.VGName != "" && s.ThinPool != "" {
+			thin[s.Storage] = Pool{VG: s.VGName, Pool: s.ThinPool}
+		}
+	}
+	vols := []string{cfg.RootFS}
+	mps := cfg.MountPoints()
+	keys := make([]string, 0, len(mps))
+	for k := range mps {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	for _, k := range keys {
+		vols = append(vols, mps[k])
+	}
+	seen := map[Pool]bool{}
+	var out []Pool
+	for _, v := range vols {
+		store, _, ok := strings.Cut(strings.Split(v, ",")[0], ":")
+		if !ok || strings.HasPrefix(store, "/") {
+			continue // a bind mount (a path) is no volume
+		}
+		if p, isThin := thin[store]; isThin && !seen[p] {
+			seen[p] = true
+			out = append(out, p)
+		}
+	}
+	return out, nil
+}
+
+// read runs the helper once.
+func (c *Checker) read(ctx context.Context, p Pool) (Reading, error) {
+	helper := c.Helper
+	if helper == "" {
+		helper = HelperPath
+	}
+	out, stderr, err := c.Runner.Run(ctx, helper, p.VG, p.Pool)
+	if err != nil {
+		return Reading{}, fmt.Errorf("felhom-thin-check %s: %w: %s", p, err, strings.TrimSpace(string(stderr)))
+	}
+	r, ok := Parse(string(out))
+	if !ok {
+		return Reading{}, fmt.Errorf("felhom-thin-check %s: the output has no closing ok line", p)
+	}
+	return r, nil
+}
+
+// Check returns the pools of vmid that hold an orphan (two reads, intersected). A pool that cannot be read is logged
+// and left out: the check FAILS OPEN — it explains a failure, it never stops a backup.
+func (c *Checker) Check(ctx context.Context, vmid int) []Finding {
+	logger := c.Logger
+	if logger == nil {
+		logger = slog.Default()
+	}
+	pools, err := c.PoolsOf(ctx, vmid)
+	if err != nil {
+		logger.Warn("thincheck: cannot map the guest's disks to thin pools — not checked", "vmid", vmid, "err", err)
+		return nil
+	}
+	pause := c.Pause
+	if pause <= 0 {
+		pause = 3 * time.Second
+	}
+	var found []Finding
+	for _, p := range pools {
+		first, err := c.read(ctx, p)
+		if err != nil {
+			logger.Warn("thincheck: thin pool not read — not checked", "vmid", vmid, "pool", p.String(), "err", err)
+			continue
+		}
+		o1 := first.Orphans()
+		if len(o1) == 0 {
+			logger.Debug("thincheck: thin pool and LVM agree", "vmid", vmid, "pool", p.String(), "devices", len(first.PoolIDs))
+			continue
+		}
+		select {
+		case <-ctx.Done():
+			return found
+		case <-time.After(pause):
+		}
+		second, err := c.read(ctx, p)
+		if err != nil {
+			logger.Warn("thincheck: second read failed — not reported", "vmid", vmid, "pool", p.String(), "err", err)
+			continue
+		}
+		in2 := map[int]bool{}
+		for _, id := range second.Orphans() {
+			in2[id] = true
+		}
+		var both []int
+		for _, id := range o1 {
+			if in2[id] {
+				both = append(both, id)
+			}
+		}
+		if len(both) > 0 {
+			found = append(found, Finding{Pool: p, Orphans: both})
+			logger.Warn("thincheck: ORPHAN thin device(s) in the pool — LVM does not know them; NOT removed (a human step)",
+				"vmid", vmid, "pool", p.String(), "orphans", both)
+		}
+	}
+	return found
+}
+
+// Describe is the operator sentence for a backup failure. Plain words; names the pool and the ids; says nothing was
+// removed and where the repair is written down.
+func Describe(f []Finding) string {
+	if len(f) == 0 {
+		return ""
+	}
+	var parts []string
+	for _, x := range f {
+		ids := make([]string, len(x.Orphans))
+		for i, id := range x.Orphans {
+			ids[i] = strconv.Itoa(id)
+		}
+		parts = append(parts, fmt.Sprintf("thin pool %s holds device %s that LVM does not know", x.Pool, strings.Join(ids, ", ")))
+	}
+	return "probable cause: " + strings.Join(parts, "; ") +
+		" (an orphan snapshot, usually left when the host disk filled during a backup). Snapshot backups on this pool " +
+		"fail until an operator removes it; Felhom did not remove anything. Repair: runbook whole-guest-backup-orphan-thin.md"
+}

internal/thincheck/thincheck_test.go

@@ -0,0 +1,184 @@
+package thincheck
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"log/slog"
+	"os/exec"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"strings"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// The helper's output on demo-hp 2026-10-14, before the repair: the pool held 1, 2 and 4; LVM knew 1 and 2
+// (audits/power-cut-fixes-2026-10-14/E/thin-ls.txt).
+const orphanOut = `lvm-before 1 vm-9201-disk-0
+lvm-before 2 vm-9201-disk-1
+pool 1
+pool 2
+pool 4
+lvm-after 1 vm-9201-disk-0
+lvm-after 2 vm-9201-disk-1
+ok
+`
+
+const healthyOut = `lvm-before 1 vm-9201-disk-0
+lvm-before 2 vm-9201-disk-1
+pool 1
+pool 2
+lvm-after 1 vm-9201-disk-0
+lvm-after 2 vm-9201-disk-1
+ok
+`
+
+func quiet() *slog.Logger { return slog.New(slog.NewTextHandler(io.Discard, nil)) }
+
+func TestParse_TheOrphanOf20261014(t *testing.T) {
+	r, ok := Parse(orphanOut)
+	if !ok {
+		t.Fatal("a complete reading was not accepted")
+	}
+	if got := r.Orphans(); !reflect.DeepEqual(got, []int{4}) {
+		t.Fatalf("orphans = %v, want [4]", got)
+	}
+	h, _ := Parse(healthyOut)
+	if got := h.Orphans(); len(got) != 0 {
+		t.Fatalf("a healthy pool reported orphans %v", got)
+	}
+}
+
+// A volume LVM created WHILE the pool was read appears only in the after-list: never an orphan.
+func TestOrphans_AVolumeCreatedDuringTheReadIsNotAnOrphan(t *testing.T) {
+	r, _ := Parse(strings.Replace(orphanOut, "lvm-after 2 vm-9201-disk-1\n", "lvm-after 2 vm-9201-disk-1\nlvm-after 4 snap_vm-9201-disk-1_vzdump\n", 1))
+	if got := r.Orphans(); len(got) != 0 {
+		t.Fatalf("orphans = %v, want none", got)
+	}
+}
+
+// A run cut off before its closing "ok" (the helper died, the output is partial) is no reading at all.
+func TestParse_NoClosingLineIsNoReading(t *testing.T) {
+	if _, ok := Parse(strings.TrimSuffix(orphanOut, "ok\n")); ok {
+		t.Fatal("a cut-off run was accepted as a reading")
+	}
+}
+
+type fakeAPI struct {
+	cfg    proxmox.GuestConfig
+	stores []proxmox.Storage
+}
+
+func (f *fakeAPI) GuestConfig(context.Context, int) (proxmox.GuestConfig, error) { return f.cfg, nil }
+func (f *fakeAPI) ListStorage(context.Context) ([]proxmox.Storage, error)        { return f.stores, nil }
+
+func guest9201() *fakeAPI {
+	extra := map[string]json.RawMessage{
+		"mp0": json.RawMessage(`"local-lvm:vm-9201-disk-1,mp=/var/lib/felhom,backup=1,size=20G"`),
+		"mp8": json.RawMessage(`"/mnt/felhom-drives,mp=/mnt/felhom-drives"`),
+		"mp9": json.RawMessage(`"local:9201/vm-9201-disk-2.raw,mp=/x"`),
+	}
+	return &fakeAPI{
+		cfg: proxmox.GuestConfig{RootFS: "local-lvm:vm-9201-disk-0,size=8G", Extra: extra},
+		stores: []proxmox.Storage{
+			{Storage: "local", Type: "dir", Path: "/var/lib/vz"},
+			{Storage: "local-lvm", Type: "lvmthin", VGName: "pve", ThinPool: "data"},
+			{Storage: "felhom-pbs", Type: "pbs"},
+		},
+	}
+}
+
+type seqRunner struct {
+	outs  []string
+	errs  []error
+	calls [][]string
+}
+
+func (r *seqRunner) Run(_ context.Context, name string, args ...string) ([]byte, []byte, error) {
+	r.calls = append(r.calls, append([]string{name}, args...))
+	i := len(r.calls) - 1
+	var err error
+	if i < len(r.errs) {
+		err = r.errs[i]
+	}
+	if i < len(r.outs) {
+		return []byte(r.outs[i]), nil, err
+	}
+	return nil, nil, err
+}
+
+func TestPoolsOf_RootfsAndVolumeMountpointsOnly(t *testing.T) {
+	c := &Checker{API: guest9201(), Runner: &seqRunner{}, Logger: quiet()}
+	pools, err := c.PoolsOf(context.Background(), 9201)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(pools, []Pool{{VG: "pve", Pool: "data"}}) {
+		t.Fatalf("pools = %v, want [pve/data] once (bind mounts and dir volumes are not thin)", pools)
+	}
+}
+
+// The consequence: an orphan seen on BOTH reads becomes a finding whose sentence names the pool and the id, and says
+// nothing was removed. The only command ever run is the read-only helper with <vg> <pool>.
+// RED-PROOF (P1/redproof-thincheck.txt): with Orphans() returning nil this test fails.
+func TestCheck_OrphanOnBothReads_IsNamed(t *testing.T) {
+	rr := &seqRunner{outs: []string{orphanOut, orphanOut}}
+	c := &Checker{API: guest9201(), Runner: rr, Pause: 1, Logger: quiet()}
+	f := c.Check(context.Background(), 9201)
+	if len(f) != 1 || f[0].Pool.String() != "pve/data" || !reflect.DeepEqual(f[0].Orphans, []int{4}) {
+		t.Fatalf("findings = %+v", f)
+	}
+	want := [][]string{{HelperPath, "pve", "data"}, {HelperPath, "pve", "data"}}
+	if !reflect.DeepEqual(rr.calls, want) {
+		t.Fatalf("calls = %v, want only the read-only helper twice", rr.calls)
+	}
+	d := Describe(f)
+	for _, s := range []string{"thin pool pve/data holds device 4 that LVM does not know", "Felhom did not remove anything",
+		"whole-guest-backup-orphan-thin.md"} {
+		if !strings.Contains(d, s) {
+			t.Fatalf("Describe = %q, missing %q", d, s)
+		}
+	}
+}
+
+// An id that is gone on the second read (a volume mid-creation) is not reported; a healthy pool is read ONCE.
+func TestCheck_TransientOrHealthy_NothingReported(t *testing.T) {
+	rr := &seqRunner{outs: []string{orphanOut, healthyOut}}
+	if f := (&Checker{API: guest9201(), Runner: rr, Pause: 1, Logger: quiet()}).Check(context.Background(), 9201); len(f) != 0 {
+		t.Fatalf("a transient id was reported: %+v", f)
+	}
+	rr = &seqRunner{outs: []string{healthyOut}}
+	if f := (&Checker{API: guest9201(), Runner: rr, Logger: quiet()}).Check(context.Background(), 9201); len(f) != 0 || len(rr.calls) != 1 {
+		t.Fatalf("healthy: findings %+v, calls %v", f, rr.calls)
+	}
+	if Describe(nil) != "" {
+		t.Fatal("no finding must describe as empty")
+	}
+}
+
+// The helper refusing (a metadata snapshot held by someone else, exit 3) or failing: no finding, no panic — the check
+// fails open; it explains a failure, it never stops a backup.
+func TestCheck_HelperRefuses_FailsOpen(t *testing.T) {
+	rr := &seqRunner{errs: []error{errors.New("exit status 3")}}
+	if f := (&Checker{API: guest9201(), Runner: rr, Logger: quiet()}).Check(context.Background(), 9201); len(f) != 0 {
+		t.Fatalf("findings = %+v", f)
+	}
+}
+
+// The root helper's own tests (configs/test_felhom_thin_check.py) run with the Go suite.
+func TestRootHelperPythonSuite(t *testing.T) {
+	py, err := exec.LookPath("python3")
+	if err != nil {
+		t.Skip("python3 not found")
+	}
+	_, file, _, _ := runtime.Caller(0)
+	script := filepath.Join(filepath.Dir(file), "..", "..", "configs", "test_felhom_thin_check.py")
+	out, err := exec.Command(py, script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("helper suite failed: %v\n%s", err, out)
+	}
+}

scripts/agent_gates.py

@@ -15,6 +15,9 @@ Gates (all must pass; **non-zero exit on any failure**):
                      or because someone is offline on a train. CI runs the FULL set for exactly this
                      reason: it is the machine that can afford a network check, and it is the half
                      that emails when something is wrong.
+  …  gate-decoys     the decoy suite (test_gate_decoys.py): every gate here still convicts its decoys
+                     (R-1116). ~20 s in the workspace, so the full run only: not the hook, but CI
+                     runs the full set on every push. Scratch clones and a local fake Gitea only.
 
 WHY THIS FILE EXISTS, WITH ONE GATE (2026-08-02, R-29 leg (b)).
 
@@ -58,6 +61,12 @@ GATES = [
     ("release-complete", os.path.join(ROOT, "scripts", "check-release-complete.py"), [], True),
     # R-389 — a REPORT.md observation with no register row behind it. Fast: stdlib file reads.
     ("observations", SHARED_OBSERVATIONS, [ROOT], True),
+    # R-1116 (2026-10-17) — the gates' OWN decoy suite. It was in no runner, the shape that let the catalog's
+    # R-1115 fail unseen for a night. Full run only: ~20 s in the workspace (measured, 30 cases; ~5 s in a
+    # CI-shaped clone, where the shared gates have fewer siblings to search), too slow for the hook — and CI
+    # runs the FULL set, so every push is still judged by it. It plants only in scratch clones and asks a fake
+    # Gitea on 127.0.0.1 (never the network, never the real tree); it does not call this runner (no recursion).
+    ("gate-decoys", os.path.join(ROOT, "scripts", "test_gate_decoys.py"), [], False),
 ]
 
 VERDICT = {0: "OK", 1: "FAILED", 2: "INCONCLUSIVE"}

scripts/release-agent.sh

@@ -69,6 +69,10 @@ fi
 existing="$(curl -fsS -o /dev/null -w '%{http_code}' \
     "$GITEA_BASE/api/packages/$GITEA_OWNER/generic/felhom-agent/$VERSION/felhom-agent" 2>/dev/null || true)"
 [[ "$existing" != "200" ]] || die "version $VERSION is ALREADY PUBLISHED — bump the version instead"
+# R-1098 (2026-10-16): only a clean 404 proves the version is new. Until now a registry that could not be reached
+# (curl prints 000) or answered anything else passed this check — „I could not ask" is not that proof.
+# Test: scripts/test_release_push_once.sh.
+[[ "$existing" == "404" ]] || die "could not establish whether $VERSION is published (registry answered HTTP '${existing:-none}') — refusing"
 
 # ── 3. Build ────────────────────────────────────────────────────────────────────────────────────
 BIN="$(mktemp -t felhom-agent-XXXXXX)"

scripts/test_agent_gates.py

@@ -57,6 +57,20 @@ class AgentGatesTest(unittest.TestCase):
         finally:
             shutil.rmtree(tmp, ignore_errors=True)
 
+    def test_decoy_suite_is_a_full_run_gate(self):
+        """R-1116: the decoy suite is a gate of the FULL run (which CI runs on every push), and --fast
+        names it as skipped (~20 s, too slow for the hook)."""
+        sys.dont_write_bytecode = True  # no __pycache__ left in scripts/ (not gitignored here)
+        sys.path.insert(0, os.path.join(ROOT, "scripts"))
+        import agent_gates as mod
+        rows = [g for g in mod.GATES if g[0] == "gate-decoys"]
+        self.assertEqual(len(rows), 1, "gate-decoys is not registered exactly once")
+        self.assertEqual(os.path.basename(rows[0][1]), "test_gate_decoys.py")
+        self.assertFalse(rows[0][3], "gate-decoys must not be --fast")
+        self.assertEqual([g[0] for g in mod.GATES if not g[3]], ["published", "gate-decoys"])
+        self.assertIn("--fast SKIPPED (deliberate periodic runs, never in a hook): published, gate-decoys",
+                      self.out)
+
     def test_unknown_argument_is_rejected(self):
         p = subprocess.run([sys.executable, ENTRY, "--nope"], cwd=ROOT,
                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT)

scripts/test_gate_decoys.py

@@ -66,6 +66,9 @@ COVERS = {
                     "inside an HTML comment (R-426)",
     "observations": "R-419 in THIS repo's REPORT.md: an Observations note SAYING it carries no marker - vs the "
                     "two genuine markers (R-426)",
+    "gate-decoys": "this suite, run as a gate of agent_gates.py's full run, which CI runs on every push (R-1116): "
+                   "every case above is a decoy of its own gate, and ONE case that stops convicting turns the run "
+                   "red - red-proved 2026-10-17 by flipping a reuse-refs FACT case to expect rc 0",
 }
 
 fails = []

scripts/test_release_push_once.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# test_release_push_once.sh — release-agent.sh releases a version only when the registry says it is NEW (R-1098).
+#
+# The REAL release-agent.sh runs from a copy inside a scratch git repo (so its tag check reads scratch tags), with
+# RELEASE_ALLOW_DIRTY=1 (the clean-tree gate has its own history) and a fake `curl` and `go` first on PATH: curl answers
+# the package probe as FAKE_MODE says, and `go` stops the run right after the check, so nothing is built or published.
+#   published (200)        -> refused, "ALREADY PUBLISHED"
+#   absent (404)           -> passes the check, reaches the build
+#   unreachable (000)      -> refused, "could not establish"
+#   server error (500)     -> refused, "could not establish"
+#   the tag already exists -> refused, "already exists"
+# Run: bash scripts/test_release_push_once.sh   (exit 0 all cases right · 1 a case wrong)
+set -uo pipefail
+HERE="$(cd "$(dirname "$0")" && pwd)"
+WS="$(mktemp -d)"; trap 'rm -rf "${WS:?}"' EXIT
+fails=0; ran=0
+mkdir -p "$WS/bin" "$WS/repo/scripts"
+cp "$HERE/release-agent.sh" "$WS/repo/scripts/release-agent.sh"
+(cd "$WS/repo" && git init -q -b main && git -c user.name=t -c user.email=t@t commit -q --allow-empty -m init)
+cat > "$WS/bin/curl" <<'FAKE'
+#!/bin/bash
+case "${FAKE_MODE}" in
+  published) printf 200; exit 0 ;;
+  absent)    printf 404; exit 22 ;;
+  down)      printf 000; exit 7 ;;
+  error)     printf 500; exit 22 ;;
+esac
+FAKE
+printf '#!/bin/sh\necho "FAKE-GO-REACHED $*"; exit 1\n' > "$WS/bin/go"
+chmod +x "$WS/bin/curl" "$WS/bin/go"
+run() {  # name, mode, expected rc, required fragment, forbidden fragment
+    local out rc
+    out=$(cd "$WS/repo" && FAKE_MODE="$2" RELEASE_ALLOW_DIRTY=1 GITEA_USER=u GITEA_TOKEN=t PATH="$WS/bin:$PATH" \
+          bash scripts/release-agent.sh 9.9.9 2>&1); rc=$?
+    ran=$((ran+1))
+    if [[ "$rc" != "$3" ]] || ! grep -qi -- "$4" <<<"$out" || { [[ -n "$5" ]] && grep -qi -- "$5" <<<"$out"; }; then
+        fails=$((fails+1)); echo "  FAIL $1 (exit $rc)"; echo "$out" | tail -4 | sed 's/^/        /'; return
+    fi
+    echo "  ok   $1"
+}
+echo "release-agent.sh — a version is released once, and only when the registry says it is new"
+run "published (200) -> refused"   published 1 "ALREADY PUBLISHED"     "FAKE-GO-REACHED"
+run "absent (404) -> proceeds"     absent    1 "FAKE-GO-REACHED"       "could not establish"
+run "unreachable (000) -> refused" down      1 "could not establish"   "FAKE-GO-REACHED"
+run "server error (500) -> refused" error    1 "could not establish"   "FAKE-GO-REACHED"
+(cd "$WS/repo" && git tag v9.9.9)
+run "the tag exists -> refused"    absent    1 "already exists"        "FAKE-GO-REACHED"
+echo
+if [[ $fails -eq 0 ]]; then echo "all $ran cases behaved"; exit 0; fi
+echo "$fails of $ran cases FAILED"; exit 1