v0.127.0: a mount Felhom itself made is not 'something else' (R-220)

After a rebuild the customer's own drives could not be re-attached: candidates
returned initialize:[] attach:[] while both drives sat there, and the deploy
refused with 'choose an attached drive from the list' — a list that was empty.
Measured live three times.

Mechanism: enrolment mounts a drive TWICE, at /mnt/felhom-drives/<name> and at
the raw /mnt/<name> it creates on the host. The host survives a guest rebuild;
the controller's registry does not. So classifyClaim saw a mount outside the
managed prefix and concluded 'claimed by something else' — about our own mount.

The fix is CORROBORATED, not a widened prefix: a non-managed mountpoint is
forgiven only when the SAME device is also mounted under the managed path, a
pairing only our enrolment produces. A disk another system uses — /srv/data,
/media/x, even /mnt/someone-elses-disk — has no counterpart and is STILL
refused, with its own test and a red-proof showing an over-wide fix offering it
for formatting.

Read from /proc/mounts deliberately: the lsblk invocation is pinned verbatim in
configs/felhom-agent.sudoers, so using the plural MOUNTPOINTS would have coupled
this to a sudoers rollout. /proc/mounts is world-readable — no sudo, no new
allowlisted command, no config change.

Fail-safe: an unreadable mount table corroborates NOTHING, so the device
classifies exactly as before. 'Could not corroborate' must never read as 'ours'.

29 packages ok, vet clean, agent gates OK.

.claude/rules/backup.md

@@ -0,0 +1,46 @@
+---
+paths: ["internal/backup/**", "internal/pbs/**", "internal/pbsdr/**", "internal/dr/**"]
+---
+
+# Backup, PBS and DR
+
+`internal/backup/` is the vzdump runner, restore-test scheduler and report store. `internal/pbs/` is
+the fingerprint-pinned PBS-API client plus the verify maintenance loop. `internal/pbsdr/` and
+`internal/dr/` carry the DR tier and recipe halves.
+
+## The three PBS laws
+
+1. **Set-only.** `pvesm remove` **DELETES the encryption key**. Re-apply configuration; never remove
+   and re-add a PBS storage to change it.
+2. **Secret on stdin.** A token secret is passed on stdin, never as an argv the process table shows.
+3. **Verify the pin BEFORE consuming the secret.** A fingerprint check after the secret has been sent
+   protects nothing.
+
+## Verify is server-side, and its default skips the work
+
+The agent drives verification **remotely** via the PBS API; `proxmox-backup-client` has **no** verify
+subcommand. `POST .../verify` defaults to **`ignore-verified=true`, which SKIPS already-verified
+snapshots** — send `ignore-verified=false` to actually re-read and detect corruption. A verify that
+skipped everything reports success.
+
+## Presence is not success
+
+A timestamp recording an **attempt** is not evidence of a **result**. Where a status field travels
+beside a timestamp, the verdict must consult **both** — or the timestamp must record only successes.
+Ask of any timestamp: *what exactly must have happened for this to be set?* If the answer is "we
+tried", it cannot answer "did it work".
+
+**Corollary:** when a verdict changes which field it counts from, the alarm text changes with it.
+Leaving a message reading `last run 8h ago` while alarming on a six-day-old **success** turns a true
+alarm into one the operator dismisses.
+
+## Prune is server-side now
+
+`DatastoreBackup` carries **no** `Datastore.Prune`. Boxes set `keep_last: 0` and the off-site endpoint
+runs the prune jobs. **Box tokens stay write-only — never widen that grant** (R-89).
+
+<!--
+The ignore-verified default is the sharpest instance of the "absent log line" class in this repo: a
+verify that silently skipped every snapshot completes fast, exits clean, and reports the same shape
+as one that read every byte.
+-->

.claude/rules/health-checks.md

@@ -0,0 +1,26 @@
+---
+paths: ["internal/capability/**", "internal/storage/**", "internal/localapi/**", "internal/hub/**", "internal/guesthook/**"]
+---
+
+# A health check issues no block I/O
+
+No `statfs`, no `getdents`, no read, write or `fsync` — **not even behind a timeout**.
+
+A probe that touches a wedged device enters uninterruptible sleep, survives `SIGKILL`, and cannot be
+recovered until the device returns or the host reboots — so `systemctl restart` hangs too. A timeout
+protects the caller's control flow and nothing else: the blocked thread remains.
+
+**Liveness is decided from `/proc` and the kernel's own state**, never by reading or writing the
+filesystem.
+
+<!--
+Measured, R-117 spike §6.3 (felhom.eu/documentation/audits/SPIKE-r117-bind-liveness-2026-07-30.md):
+a probe stayed in D state 3m50s after kill -9; a buffered write with no fsync blocked too (O_CREAT
+needs journal access); and statfs/getdents returned HEALTHY on a namespace that EIOs every byte —
+fast, and wrong.
+
+This rule used to be duplicated verbatim in felhom-agent/CLAUDE.md with a note explaining that
+felhom.eu/CLAUDE.md "does not load in an agent-only session". That reasoning was correct before
+path-scoped rules existed. The single source is now felhom.eu/CLAUDE.md "Code quality rules"; this
+file is the scoped copy that loads exactly where health checks are written. (2026-08-06)
+-->

.claude/rules/localapi.md

@@ -0,0 +1,44 @@
+---
+paths: ["internal/localapi/**", "internal/authz/**", "internal/guesthook/**"]
+---
+
+# Local API, authz and guest hooks — the per-guest blast radius
+
+`internal/localapi/` is the narrow per-guest local API: token store, disks/format, guest binds,
+controller swap, stale-lock recovery, pinned self-signed leaf. `internal/authz/` is the operator
+signed-op verifier (SSHSIG) plus the durable nonce store. `internal/guesthook/` installs the
+pre-start self-heal hookscript.
+
+> **Overlap note:** `health-checks.md` also matches `internal/localapi/**` and
+> `internal/guesthook/**`. That is deliberate — both rules apply there and both load. Neither
+> supersedes the other.
+
+## Scoping is the whole security property
+
+This API is reachable **from inside a customer guest**. Every route must be scoped to the guest that
+called it — a route that can name another guest's id has escaped its blast radius. Fail **safe to
+protected**: an unrecognised or unresolvable caller gets less access, never more.
+
+## Replay protection must survive a restart
+
+**`authz.MemoryNonceStore` on a real host is a defect** — replay protection dies on restart. Use
+`authz.FileNonceStore`. The memory store exists for tests.
+
+## The token is a hash on disk, plaintext only at mint
+
+The store keeps **hashes**. The plaintext token exists in exactly one place, `bootstrap.json` on the
+PVE host — so a "read the token" step means reading that file, and a lost token is re-minted, never
+recovered.
+
+## Binds can brick guest boot
+
+| Do not | Because | Use |
+|---|---|---|
+| `GuestBinder.AttachBind`/`DetachBind` (per-drive `pct set -mpN`) | legacy model; a missing bind source can **brick guest boot** (C1) | `AttachDrive`/`DetachDrive` (intermediary model) |
+| `isHostMountpoint` to reconcile bind state | a boolean cannot converge stacked double-binds (the `/mnt` doubling bug) | `countHostMounts` normalization inside `AttachDrive` |
+
+<!--
+Why fail-safe-to-protected rather than fail-closed: this API also carries the recovery paths. A hard
+refusal on an unresolvable caller would make a half-broken guest unrecoverable through the very
+interface built to recover it. Less access, never none.
+-->

.claude/rules/proxmox.md

@@ -0,0 +1,44 @@
+---
+paths: ["internal/proxmox/**", "internal/reconcile/**", "internal/signedjobs/**"]
+---
+
+# Proxmox — the API contract, and how destructive work is gated
+
+`internal/proxmox/` is the API-first `Client` plus the fenced root-CLI `Privileged`.
+`internal/reconcile/` is the reconcile engine, reversibility gate, op journal and crash recovery.
+`internal/signedjobs/` holds the operator-signed destructive executors (wipe, decommission).
+
+## A 200 on the POST is not success
+
+**Every mutating op is async**: it returns a **UPID**, and `WaitTask` must assert
+`exitstatus == "OK"`. Authorization can fail at *task execution* long after the HTTP call returned
+200. Treating the POST's status as the result is how a failed destroy reads as a successful one.
+
+## The privsep token gotcha
+
+A `--privsep 1` token's rights are the **intersection** of the backing user's permissions **and** the
+token's own ACLs. The role must be granted on **both** or every call 403s. The same intersection rule
+bites on PBS (`token ∩ user`).
+
+## TLS
+
+**SHA-256 leaf-cert pinning** against the self-signed host cert. **No insecure default**, ever. The
+pin is the raw leaf-DER sha — the SAN is never checked, so a cert rotation changes the pin and the
+agent must be re-pinned.
+
+## The destructive path — never the direct call
+
+| Do not | Because | Use |
+|---|---|---|
+| `Client.DestroyLXC` / `Vzdump` / `SetConfig` ad-hoc | skips classification, signature, per-guest serialization, crash recovery | `reconcile.Engine` paths / `RunSignedJob`; queue via `Queue.Submit` |
+| add a method to `proxmox.Privileged` | breaks the 3-exception root-CLI fence (`routing_test.go`) | `proxmox.Runner` + a new sudoers `Cmnd_Alias` + `validate.go`-style checks |
+| treat `ListLXC` output as "guests we own" | audit A1 — pre-v0.62.0 the stale-lock reaper did exactly this, contained only by the pool-scoped token | intersect with `Client.Pool` membership (`staleLockController.Guests()`); **fail safe on read failure** |
+
+Full trap table: `REUSE.md` §3. Every guest joins the `felhom` pool — `VM.Audit` comes from the
+`/pool` grant, not from a per-guest ACL.
+
+<!--
+The fence is not stylistic. It is what makes this component auditable: two types, one of which can
+only speak HTTP and one of which can only shell out, with a test asserting neither crosses. A single
+convenience method on Privileged that also makes an HTTP call would end that property silently.
+-->

.claude/rules/storage.md

@@ -0,0 +1,49 @@
+---
+paths: ["internal/storage/**", "internal/escrow/**"]
+---
+
+# Storage and escrow — format safety and zero-knowledge recovery
+
+`internal/storage/` is the storage observer, durable IDs, role/claim classifiers, `SudoHostOps` and
+the watchdog. `internal/escrow/` is the PBS-key escrow with its zero-knowledge recovery code.
+
+> **Overlap note:** `health-checks.md` also matches `internal/storage/**`. Deliberate — both rules
+> apply there and both load.
+
+## Never format the device you inspected
+
+**AGENT-001 is a TOCTOU:** acting on the caller's `req.Device` (or any remembered `/dev` path) after
+inspection lets `/dev` re-enumeration retarget the node to a **different physical disk**. Format the
+**re-resolved** device — `Server.reresolveWipe` / `reresolveBlank`.
+
+**Never exec raw `mkfs.*`** (including `Binaries.MkfsExt4`/`MkfsXfs`): sudoers no longer allowlists
+raw mkfs, and going direct bypasses the claim filter and the wrapper's re-checks. Use
+`SudoHostOps.Format`, which routes through `felhom-mkfs-guarded`.
+
+## The two durable-ID schemes refuse each other
+
+They are not interchangeable, and each returns a `binding_mismatch` for the other's scheme:
+
+| Purpose | Scheme | Resolver |
+|---|---|---|
+| wipe confirmation | `byid:` / `byuuid:` | `ResolveDurableDevice`, `DiskInfo.WipeDurableID` |
+| enrolled-storage remount | `uuid:` | `ResolveStorageDevice` |
+
+Using `DiskInfo.DurableID` (a `uuid:`) as a wipe-confirmation id is F20-BUG2.
+
+## Drive data is never taken by force
+
+Plain `umount` only — **never `-l`, never `-f`**, and never any format operation under
+`/mnt/felhom-drives`.
+
+## Escrow is zero-knowledge, and a fetch failure is not a wrong code
+
+The server holds no client key; a no-key restore fails with `missing key`. **A fetch failure must
+never be reported as a wrong recovery code** — that told a customer their correct code was bad, in
+hundredths of a second, when checking a code actually takes about one. Distinguish "we could not
+reach the store" from "the code did not match", always.
+
+<!--
+The escrow recovery-code "flake" was a REAL defect, not a flake. "Known flake, re-run" needs evidence
+before it is said out loud — that phrase cost this project a real finding once.
+-->

CHANGELOG.md

@@ -1,3 +1,103 @@
+## v0.127.0 — a mount Felhom itself made is not "something else" (2026-08-06, R-220)
+
+**After a rebuild the customer's own drives could not be re-attached, and the refusal named an action
+they could not perform.** `GET /api/disks/candidates` returned `initialize: [], attach: []` while both
+drives sat there, and the deploy refused with *"choose an attached drive from the list"* — a list that
+was empty. Measured live **three times**: CAMPAIGN-11 Phase 1, and twice on the R-201 re-walk.
+
+**The mechanism.** Enrolment mounts a drive **twice** — at the managed `/mnt/felhom-drives/<name>` and
+at the raw `/mnt/<name>` it creates on the host. **The host survives a guest rebuild; the controller's
+registry does not.** So `classifyClaim` saw a mount outside the managed prefix and correctly concluded
+"claimed by something else" — about Felhom's own mount.
+
+**The fix is CORROBORATED, not a widened prefix.** A mountpoint outside `/mnt/felhom-drives` is
+forgiven **only when the same device is ALSO mounted under the managed path** — a pairing that only
+Felhom's own enrolment produces. A disk another system is using, at `/srv/data` or `/media/x` or even
+`/mnt/someone-elses-disk`, has no such counterpart and **is still refused**. That fence has its own
+test, and its red-proof shows an over-wide fix offering `/mnt/someone-elses-disk` for formatting.
+
+**Read from `/proc/mounts`, deliberately.** The lsblk invocation is pinned **verbatim** in
+`configs/felhom-agent.sudoers` (`lsblk -J -o NAME,FSTYPE,PTTYPE,MOUNTPOINT /dev/*`), so switching it to
+the plural `MOUNTPOINTS` would have meant shipping a sudoers change with the binary — a far larger
+blast radius than this finding warrants. `/proc/mounts` is world-readable: **no sudo, no new allowlisted
+command, no config change.**
+
+**Fail-safe:** an unreadable mount table corroborates **nothing**, so the device classifies exactly as
+it did before this change — refused. "We could not corroborate" must never read as "it is ours".
+
+Tests: `claim_r220_test.go` — the own-drive case, the foreign-mount fence over four paths, and the
+corroboration itself (both mounts required; a lone raw mount vouches for nothing; another device's
+managed mount does not vouch for this one; an unreadable table corroborates nothing).
+**Red-proofs:** removing the exemption refuses the customer's own drive again
+(*"device is mounted at /mnt/adatok (sdb)"*); over-widening it to any `/mnt/*` path breaks the fence.
+
+## docs — CLAUDE.md becomes a core plus path-scoped rules (2026-08-06, R-229 leg (b)) — no version bump
+
+**Documentation only. No Go changed, nothing built, nothing deployed.** `go build`/`vet`/`test` green
+and unchanged.
+
+**175 -> 99 effective lines** (207 -> 103 raw, 14,093 -> 6,267 bytes). The release/publish-train
+section was the largest block and the `felhom-build-deploy` skill already carries the procedure, so
+the core points at it instead of restating a table that drifts from the script. The package layout
+went the same way as the controller's: `REUSE.md` and the tree are its home, and the per-package
+annotations that were doing real work moved into the rule file for the area they describe rather than
+being deleted.
+
+**New:** `.claude/rules/{proxmox,localapi,backup,storage}.md`, all `paths:`-scoped, all <=46 effective
+lines, joining the existing `health-checks.md`.
+
+**Kept in the core deliberately** — it is the only part re-injected after `/compact`: the root-CLI
+fence and its three named exceptions (breaching it is how this component stops being auditable), the
+destructive-op gate, the prove-ownership rule from audit A1, the gate entry point, the F9
+live-validation fence, trunk-based with its revert-and-report escape hatch, and the end-of-session
+checklist.
+
+**Glob overlap, stated rather than silently resolved:** `health-checks.md` matches
+`internal/{localapi,guesthook}/**` and `internal/storage/**`, which `localapi.md` and `storage.md`
+also match. Both rules load in those directories and neither supersedes the other; each new file says
+so in its own text so a reader who sees two rules fire is not left guessing which wins.
+
+## docs — the "CI is still owed" claim was stale; corrected (2026-08-06, R-229 part 2) — no version bump
+
+**One sentence, no code.** This file asserted that continuous integration was still owed
+(`felhom.eu` `OPEN-ITEMS.md` R-168). **R-168 was CLOSED on 2026-08-02** — a Gitea Actions runner
+re-runs each repo's gate entry point on every push and emails the operator on failure. Found while
+confirming this session's own push by run ID, which is the check that caught it.
+
+The same stale sentence was in four instruction files across all four repos and is corrected in all
+four. In `felhom-agent/CLAUDE.md` it **contradicted the same file's release section**, which already
+said R-168 mails the failure — a contradiction inside one instruction file, which is the exact class
+the R-229 work exists to find.
+
+## docs — expired and contradictory blocks removed from CLAUDE.md (2026-08-06, R-229) — no version bump
+
+**Documentation and gate registration only. No Go changed, nothing built, nothing deployed.**
+
+Surgical corrections; the file was deliberately **not** restructured (that is deferred, R-229).
+
+- **Deleted the expired TEMPORARY block.** It read *"felhom-pve is at a remote site (until
+  ~2026-08-02) … Delete this block on return"* and was still being read as current fact on
+  **2026-08-06**, four days past its own deadline — while `felhom-controller/CLAUDE.md` asserted the
+  opposite. The location-independence fact worth keeping (`localapi` binds `169.254.253.1:8443` on
+  `vmbr9` since the R-50 island migration) moved to an HTML comment.
+- **Every component version literal is gone** from effective text, including
+  `felhom-agent --version → 0.115.0` and the `go.mod` Go directive. Versions change several times a
+  day; ask the hub's `/hosts` + `/configs` or the box.
+- The drill-VM claim and the host addresses now point at `documentation/operations/nodes.md`, which
+  already stated both correctly. **This file's drill-VM claim was the correct one** — confirmed by
+  `qm list` on demo-hp.
+- The R-115/R-188/R-186 release **narratives** moved to an HTML comment and to the
+  `felhom-build-deploy` skill; the **directives** stayed (never hand-roll the build; the
+  build → tag → publish → push order; reproducible `-trimpath -buildvcs=false`).
+- The health-check block-I/O rule became `.claude/rules/health-checks.md`, scoped to the five
+  packages where health checks are written. It had been duplicated from `felhom.eu/CLAUDE.md` *with a
+  note explaining that that file does not load in an agent-only session* — correct reasoning, made
+  obsolete by path-scoped rules.
+
+`agent_gates.py` now registers **`instructions`** (shared, `felhom.eu/scripts/`, never copied).
+
+Full accounting: `felhom.eu/documentation/audits/LEDGER-instruction-trim-2026-08-06.md`.
+
 ## v0.126.0 — a fetch failure is not a wrong recovery code (2026-08-06, R-224)
 
 **A hub the agent could not reach was reported to the customer as a bad recovery code.** Measured live

CLAUDE.md

@@ -1,216 +1,103 @@
 # CLAUDE.md — `felhom-agent`
 
-> Loads when Claude Code touches this repo. Stable orientation only — **current state lives in
-> `CONTEXT.md` and the top of `CHANGELOG.md`**, never here. Cross-repo orientation: workspace-root
-> `/mnt/5_hdd/felhom.eu/git/CLAUDE.md`.
+> Stable orientation only — **current state lives in `CONTEXT.md` and the top of `CHANGELOG.md`**,
+> never here. Cross-repo conventions (artifact taxonomy, access, clean-tree gate, secrets,
+> CHANGELOG/REPORT): workspace-root `/mnt/5_hdd/felhom.eu/git/CLAUDE.md`. Path-scoped detail:
+> `.claude/rules/`.
 
 ## What this repo is
 
-`felhom-agent` is the operator-tier **host agent** that runs on each Proxmox host and owns **all**
-Proxmox interaction: provision/restore guests, host storage, backup/restore orchestration, the hub
-control loop, and a narrow per-guest local API. It is the **most privilege-sensitive** component.
+The operator-tier **host agent**, one per Proxmox host, owning **all** Proxmox interaction:
+provision/restore guests, host storage, backup/restore orchestration, the hub control loop, and a
+narrow per-guest local API. It is the **most privilege-sensitive component in the system**.
 
-- Renamed former `proxmox-controller` repo.
-- **Distinct from `felhom-controller`** — that is the *in-guest* controller (Docker-only, no Proxmox
-  creds). Do not confuse them.
-- Control plane, not data plane: if the agent dies, apps keep serving; only management degrades.
+- Renamed from `proxmox-controller`.
+- **Distinct from `felhom-controller`** — that is the *in-guest* controller, Docker-only, holding no
+  Proxmox credentials. Do not confuse them.
+- **Control plane, not data plane:** if the agent dies, apps keep serving; only management degrades.
+- Pure Go stdlib + `golang.org/x/crypto`. No web frameworks.
 
-## Read before writing code
+## Doing X → read Y
 
-- **`REUSE.md`** — canonical helpers, format-safety guards, traps, seams. Check it first; update it
-  in the same commit that changes a shared helper or pattern.
-- `CONTEXT.md` (current state + open threads) and the top `CHANGELOG.md` entry (authoritative history).
-- Design doc: `felhom.eu/documentation/architecture/03-host-agent.md` (locked). Platform facts:
-  `felhom.eu/documentation/proxmox-platform.md` + `tests/phase{0,1-2,3,4}-findings.md`.
+| Doing | Read |
+|---|---|
+| writing any new code | `REUSE.md` — helpers, format-safety guards, traps, seams |
+| needing current state / open threads | `CONTEXT.md` + the top `CHANGELOG.md` entry |
+| Proxmox, reconcile or signed jobs | loads itself: `.claude/rules/proxmox.md` |
+| local API, authz or guest hooks | loads itself: `.claude/rules/localapi.md` |
+| backup, PBS or DR | loads itself: `.claude/rules/backup.md` |
+| storage or escrow | loads itself: `.claude/rules/storage.md` |
+| writing a health check | loads itself: `.claude/rules/health-checks.md` |
+| **release, build, publish, deploy, verify a version** | the **`felhom-build-deploy`** skill — **never hand-roll it** |
+| writing or reviewing a test, fixing a bug | the **`felhom-testing`** skill |
+| host addresses, break-glass, node facts | `felhom.eu/documentation/operations/nodes.md` — never restate them |
+| which box may I break | `felhom.eu/documentation/runbooks/target-selection.md` |
+| what version is live anywhere | ask the hub (`/hosts`, `/configs`) or the box — **never a doc** |
+| the authoritative design | `felhom.eu/documentation/architecture/03-host-agent.md` (locked) |
 
-## Layout (verified against the tree)
+## The root-CLI fence — API-first, exactly three exceptions
 
-```
-cmd/felhom-agent/    main + flags + --selftest modes + the daemon entry
-cmd/felhom-opsign/   offline operator signing CLI (SSHSIG)
-internal/authz/      operator signed-op verifier (SSHSIG) + durable FileNonceStore
-internal/backup/     vzdump backup runner + restore-test scheduler + report store
-internal/capability/ live sudo-policy capability probe (degradation visibility)
-internal/config/     JSON config + FELHOM_AGENT_* env overlay; secrets redacted (Redacted())
-internal/desired/    hub desired-state syncer (envelope observer)
-internal/escrow/     PBS-key escrow (zero-knowledge recovery code)
-internal/guesthook/  pre-start self-heal hookscript install
-internal/hub/        daemon: HostReport collector + Bearer client + resilient Loop
-internal/lanresolver/ split-horizon DNS on guest IP change (dnsmasq RESTART, not reload)
-internal/localapi/   per-guest local API: token store, disks/format, guest binds, controller swap,
-                     stale-lock recovery, pinned self-signed leaf
-internal/log/        slog setup
-internal/pbs/        PBS-API client (fingerprint-pinned) + verify maintenance loop
-internal/provision/  guest bootstrap back-half (token mint → bootstrap.json → pct bind)
-internal/proxmox/    API-first Client + fenced root-CLI Privileged + UPID WaitTask
-internal/reconcile/  reconcile engine + reversibility gate + op journal + crash recovery
-internal/signedjobs/ operator-signed destructive executors (wipe, decommission)
-internal/storage/    storage observer + durable ids + role/claim classifiers + SudoHostOps + watchdog
-```
-
-## Build / run
-
-- Module `gitea.dooplex.hu/admin/felhom-agent`; binary `felhom-agent` (`cmd/felhom-agent/`).
-- **Pure Go stdlib + `golang.org/x/crypto` only** — no web frameworks. `go.mod` directive go 1.25.0;
-  DooPlex (192.168.0.180, where CC runs) has the Go toolchain and is on the same LAN as the demo
-  host — build and run live tests locally.
-- Version via `-ldflags "-X main.version=<v>"`; `--version` flag. Bump on meaningful changes + CHANGELOG entry.
-- **Full build/deploy/publish runbook: use the `felhom-build-deploy` skill.** Summary:
-
-> **Clean-tree gate before any build:** `git status --porcelain` must be empty and
-> `git rev-parse HEAD` must equal `git rev-parse origin/main` in the repo being built. An unpushed
-> change does not exist — never build a dirty or unpushed tree. The `git pull` in the build step
-> stays (it is a no-op when you work in this tree, and load-bearing if anything was pushed from
-> elsewhere).
-
-> **RELEASING IS ONE COMMAND, AND IT PUBLISHES (R-115).** There used to be a raw `go build` line
-> here and a *separate* "Publish" row, so publishing was a step someone had to remember — and it was
-> **forgotten three times in five days**, the last leaving agent v0.120.0 deployed on both demo hosts
-> and undownloadable, where a documented-path reinstall would have silently downgraded them while
-> reporting success. Do not hand-roll the build: the script also creates the `v<version>` git TAG
-> that `felhom-host-install.sh` fetches this version's sixteen config files from (R-183), and it
-> verifies by an **independent download** rather than trusting the publish step's own output.
-> `scripts/publish-agent.sh` still exists and is still correct — the release script CALLS it rather
-> than reimplementing it.
->
-> **THE ORDER IS build → tag LOCALLY → publish → push tag, and each step protects something (R-188,
-> R-186).** The tag is created before the publish so the build and the tag describe the same commit;
-> it is *pushed* after, because the push is what wakes CI (`on: [push]`) and a tag visible before its
-> package makes the published-versions gate correctly fail a correct release — it did, on roughly
-> every second release, and R-168 sends that failure to you by mail. The invariant the old order
-> protected is asserted directly instead: the gate now also refuses a **published version with no
-> tag**. If the push fails after a successful publish the script says so loudly and prints the
-> one-line recovery; if the *publish* fails it removes the local-only tag so a retry is clean.
->
-> **A RELEASED BINARY IS INDEPENDENTLY VERIFIABLE (R-186).** The build uses `-trimpath
-> -buildvcs=false` so the same source produces the same bytes whether or not the tag exists yet —
-> before this, a rebuild could not reproduce the sha you were vouching. To check any published
-> version yourself:
->
-> ```bash
-> V=0.122.0
-> git checkout "v$V" && go build -trimpath -buildvcs=false -ldflags "-X main.version=$V" \
->     -o /tmp/felhom-agent-check ./cmd/felhom-agent
-> sha256sum /tmp/felhom-agent-check
-> curl -fsSL "https://gitea.dooplex.hu/api/packages/admin/generic/felhom-agent/$V/felhom-agent" | sha256sum
-> ```
->
-> The two hashes must match. `publish-agent.sh`'s fallback build uses the **same** flags — it used to
-> force `CGO_ENABLED=0` and produce a 74 KB-smaller binary for the same version; if either build line
-> ever changes, change both or one version name means two binaries again.
-
-| Step | Where | One-liner |
-|---|---|---|
-| **Release** (build + tag + publish + verify) | DooPlex (local) | `GITEA_USER=admin GITEA_TOKEN=<tok> scripts/release-agent.sh <ver>` — refuses a dirty/unpushed tree and refuses to re-release an existing version |
-| Copy | local → felhom-pve | `scp /tmp/felhom-agent-<v> felhom-pve:/tmp/` (one hop) |
-| Deploy | felhom-pve | backup `.bak-<old>` → `install -m0755` → `systemctl restart felhom-agent` (non-root `felhom-agent` user, config `/etc/felhom-agent/agent.json`) |
-| Ship configs | felhom-pve | sudoers (`/etc/sudoers.d/felhom-agent`) + guarded-mkfs wrapper WITH the binary when `configs/` changed |
-| **Verify** (anyone, any time) | anywhere with the repo + Go | `git checkout v<ver> && go build -trimpath -buildvcs=false -ldflags "-X main.version=<ver>" -o /tmp/a ./cmd/felhom-agent && sha256sum /tmp/a` — must equal `curl -fsSL <pkg-url> \| sha256sum` |
-| **Vouch** | hub operator UI | Configs → Day-0 artifacts. **Deliberately NOT automated** — vouching is what points machines at a version, and it stays your act (prove-then-vouch) |
-| Verify | felhom-pve | `felhom-agent --version` + journal (clean ReassertGuestBinds, no capability degradation) |
-
-## Proxmox model (the load-bearing rules)
+This is in the core because breaching it is how this component stops being auditable.
 
 - **API-first** via a scoped `FelhomAgent` token. Raw root-CLI is **fenced to exactly 3 exceptions**:
-  keyctl `pct create` (golden image), USB mount/fstab, SMART/sensors. `Client` never shells out;
-  `Privileged` never makes HTTP calls (asserted by `routing_test.go`). Keep that fence.
-- **Every mutating op is async** → returns a UPID → `WaitTask` asserts `exitstatus == "OK"`. A 200 on
-  the POST is **not** success; authorization can fail at task execution.
-- **TLS:** SHA-256 leaf-cert pinning (self-signed host cert). No insecure default.
-- **Privsep token gotcha:** a `--privsep 1` token's rights = intersection of the backing user's perms
-  AND the token's ACLs — the role must be granted on **both**, or every call 403s.
-- Destructive ops go through the reconcile gate / signed-jobs path — never call `Client.DestroyLXC`/
-  `Vzdump`/`SetConfig` ad-hoc (REUSE.md §3).
+  keyctl `pct create` (golden image), USB mount/fstab, SMART/sensors.
+- **`Client` never shells out; `Privileged` never makes HTTP calls** — asserted by `routing_test.go`.
+  Adding a method to `proxmox.Privileged` breaks the fence; use `proxmox.Runner` plus a new sudoers
+  `Cmnd_Alias` and `validate.go`-style checks (`REUSE.md` §3).
+- **Destructive ops go through the reconcile gate / signed-jobs path.** Never call
+  `Client.DestroyLXC` / `Vzdump` / `SetConfig` ad-hoc — that skips classification, signature,
+  per-guest serialization and crash recovery.
+- **Ownership must be PROVEN, never assumed.** A raw `ListLXC` list is not "guests the agent owns";
+  intersect with `Client.Pool` membership and fail safe on a read failure (audit A1).
 
-## Demo host (for live tests)
+## Gates — ONE entry point
 
-Node **`demo-felhom`**, API `https://192.168.0.162:8006`. SSH alias `felhom-pve` (root@pam) —
-available to CC as plain `ssh felhom-pve`. A **second demo node `demo-hp`** (HP t740, node name
-`felhom-host`, `ssh demo-hp` — no baked key; break-glass root via hub `host_recovery/demo-hp-bb76ea` +
-`sshpass`) is the **designated drill+build VM host** per the 2026-07-25 operator ruling, and that ruling
-is **realized** — it hosts drill VM `300` (`drill-r50`), so **start there**, not on DooPlex. (The
-historical golden-bake `drill.qcow2` still lives on DooPlex and is a bake fixture, not a drill target.)
-**Which box is safe to break, and what may be done to each:
-`felhom.eu/documentation/runbooks/target-selection.md`** — read it before any destructive test. Both
-nodes + the break-glass recipe: `felhom.eu/documentation/operations/nodes.md`. The agent pins the served leaf cert — verify the
-fingerprint still matches before a live run. Selftest modes (run locally on DooPlex, pointed at the
-demo API): `--selftest[=read|task|hub|storage|backup|restore-test|pbs-verify]`; no flag = the daemon.
+**Run `python3 scripts/agent_gates.py` from the repo root after ANY change here.** It runs this
+repo's gates — `reuse_refs_check` and `instructions_gate`, both the **shared** 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; today
+that is all of them. **A missing gate is a FAILURE, never a skip.**
 
-> **TEMPORARY — felhom-pve is at a remote site (until ~2026-08-02).** The home-LAN literal
-> `192.168.0.162` is NOT reachable from DooPlex for the duration. Access via Tailscale:
-> felhom-pve = 100.70.170.35; the `Host felhom-pve` entry in `~/.ssh/config` on DooPlex already
-> points there (the direct-LAN path stays available as `Host felhom-pve-lan`). Delete this block on
-> return. All documented `ssh felhom-pve` / `pct exec` workflows are unchanged. Path is **direct**
-> (not DERP), ~37 ms rtt per hop. At the remote site the host is on **DHCP**; re-check its address
-> rather than trusting one written here (`ip -br addr show vmbr0` — it read `192.168.0.162/24` on
-> 2026-07-30, and `felhom-pve-lan` from DooPlex is still `No route to host`). Details + findings:
-> `felhom.eu/documentation/audits/AUDIT-vacation-remote-ops-2026-07-20.md`
->
-> **The "agent does not run at the remote site" warning this block used to carry is RETRACTED
-> (2026-07-30) — it was true before R-50 and is false now.** `localapi` no longer binds a LAN literal:
-> since the R-50 island migration (2026-07-25) it binds `169.254.253.1:8443` on `vmbr9`, which is
-> location-independent by design, and `proxmox.endpoint` is `https://127.0.0.1:8006`. Verified live:
-> `systemctl is-active felhom-agent` → `active`, `felhom-agent --version` → 0.115.0, and the per-guest
-> local API answered `GET /disks` over the island. No config edit and no Viktor GO are outstanding.
+**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
+when this clone is unarmed. `git push --no-verify` bypasses it deliberately; **say so in the session
+report when you use it** — CI re-runs the same entry point on every push and **emails the operator on
+failure**, so a bypass is noticed even though it is not blocked (R-168, CLOSED 2026-08-02).
 
-> **Legacy: Windows workstation.** Until 2026-07-19 CC ran on Windows 11; `pct` commands over SSH
-> needed `export MSYS_NO_PATHCONV=1`, and every remote command used
-> `SSH=/c/Windows/System32/OpenSSH/ssh.exe`. Agent deploy was a two-hop copy via the Windows box
-> (`cygpath -w` for the local scp path; CRLF hazard on config files).
+<!--
+WHY ONE ENTRY POINT (2026-08-02, R-29): a census of all gates across the four repos found every check
+a CLAUDE.md names was passing, and two of the four nobody is told to run were failing. This repo was
+the extreme case — nothing ran against it at all, and 90 cited paths were checked by no one.
+-->
+
+## Live validation — the fence
+
+Exercise the **SERVER-SIDE PIPELINE** a real user triggers, end-to-end. **The forbidden shortcut is
+BYPASSING it** — the F9 episode was a raw guest-attach with hand-set state, and it proved nothing.
+
+`claude-in-chrome` is NOT available on DooPlex. Invoking the exact endpoint the UI invokes is an
+acceptable proxy — **say which method was used**. Low-level mechanism tests where the direct call IS
+the mechanism are exempt.
 
 ## Conventions
 
-### Trunk-based — no branches
-
-All shippable work commits **directly to `main`**; `main` equals what is deployed.
-- Report-only artifacts (audits, findings, fixspecs) → `felhom.eu/documentation/` (`audits/`, `backlog/`).
-- Risky/supervised fixes are spec'd, then implemented **during the supervised session, on `main`**.
-- Unattended escape hatch: if a fix can't be cleanly verified/shipped, revert + report — never park on a branch.
-
-> **In every repository where you make a change, update both files in that repo:**
-> - **`CHANGELOG.md`** — cumulative log, newest on top.
-> - **`REPORT.md`** — **overwrite** with the most recent implementation/validation summary only.
->
-> **Never write secrets** into any committed file — reference them as "stored out-of-band".
-
-- Code quality: verify generated code for bugs/edge cases; add debug logging; **ask rather than
-  guess** when you'd otherwise invent input/output.
-- **A health check issues no block I/O** — no `statfs`, no `getdents`, no read, write or `fsync`, **not
-  even behind a timeout**. Liveness is decided from `/proc` and kernel state. The full rule + the
-  measurement lives in `felhom.eu/CLAUDE.md` "Code quality rules"; it is repeated here because health
-  checks are written in THIS repo and that file does not load in an agent-only session. R-117 spike §6.3.
-- Update `REUSE.md` if you added/changed/deprecated a shared helper or pattern (same commit).
-- **Run `python3 scripts/agent_gates.py` from the repo root after ANY change in this repo.** It is
-  the ONE entry point for this repo's gates. Today it runs one — `reuse_refs_check` over this
-  repo's `REUSE.md` — and it exists at one gate on purpose: a census on 2026-08-02 found that every
-  check a `CLAUDE.md` names was passing and two of the four nobody is told to run were failing, and
-  this repo was the extreme case, with nothing running against it at all and 90 cited paths checked
-  by no one. It grows when the agent grows a second check. `--fast` selects the gates that touch no
-  network and no container runtime; today that is all of them. A missing gate is a FAILURE, never a
-  skip. **The shared `reuse_refs_check.py` lives in `felhom.eu/scripts/` and is never copied here**
-  — a copy would recreate the drift it detects; an absent sibling clone FAILS the gate.
-  **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 when this clone is unarmed. `git push --no-verify` bypasses it deliberately; **say so in the
-  session report when you use it.** Both facts are why CI is still owed (`OPEN-ITEMS.md` R-168).
-- Testing doctrine (non-hollow tests, red-proofs, seams): use the `felhom-testing` skill.
-- **Logging**: the slog logger fans out to journald (configured level) + the always-DEBUG `applog.Ring`
-  (remote pulls) — English, keys-never-values, durations on outcomes; full rules in
+- **Trunk-based — no branches.** All shippable work commits directly to `main`; `main` equals what is
+  deployed. Report-only artifacts (audits, findings, fixspecs) go to `felhom.eu/documentation/`.
+- **Unattended escape hatch:** if a fix cannot be cleanly verified and shipped, **revert and report**
+  — never park it on a branch.
+- **Logging**: the slog logger fans out to journald (configured level) plus the always-DEBUG
+  `applog.Ring` (remote pulls). English, keys-never-values, durations on outcomes. Full rules:
   `felhom.eu/documentation/runbooks/logging-conventions.md`.
+- Update `REUSE.md` in the same commit that adds, changes or deprecates a shared helper or pattern.
 
-### Live validation
+## End-of-session checklist
 
-Exercise the SERVER-SIDE PIPELINE a real user triggers, end-to-end. The forbidden shortcut is
-BYPASSING it (the F9 episode: raw guest-attach + hand-set state). Invoking the exact endpoint the UI
-invokes is an acceptable proxy when a browser isn't available — say which method was used. Low-level
-mechanism tests where the direct call IS the mechanism are exempt.
-
-## Workflow & artifacts
-
-- Implement **`TASK.md` / `TASK-*.md`** specs (when placed as `TASK.md` or told to), then push +
-  CHANGELOG + REPORT.md.
-- **`RUNBOOK-*.md`** — an operational procedure. CC executes the steps it has access and capability
-  for, including live validation on the demo Proxmox host (CC has root@felhom-pve SSH + the
-  felhom-agent token). Mark a step HUMAN only when it genuinely needs physical presence, a real-world
-  decision, or credentials CC truly lacks. Judgment still applies: confirm before irreversible ops on
-  real customer data — demo scratch guests are fair game.
+- **`CHANGELOG.md`** (cumulative, newest on top) and **`REPORT.md`** (overwritten with this run only)
+  — in every repo touched.
+- **`CONTEXT.md`** — decisions, state, what is next.
+- **`REUSE.md`** — if a shared helper or pattern moved.
+- **A finding goes in `felhom.eu/documentation/backlog/OPEN-ITEMS.md` first**, never only in a report
+  or an audit.
+- **Confirm your own last push's CI run went green, by run ID** — CI mails on failure, which is a PUSH
+  signal; this is the PULL check that catches a lost or unread mail. An unchecked green is an
+  assumption, not an observation.

REPORT.md

@@ -1,53 +1,41 @@
-# REPORT — felhom-agent v0.126.0: a fetch failure is not a wrong recovery code (R-224)
+# REPORT — felhom-agent v0.127.0: a mount Felhom made is not foreign (R-220)
 
-**Scope: this repo's half of R-224.** The controller half ships as felhom-controller v0.202.0.
-
-## Why the agent changed at all
-
-The task that commissioned this work scoped `felhom-agent` as **untouched**. It could not be. Its
-Scenario A (a hub outage must not blame the customer's code) and Scenario C (a genuine mistype must be
-told to re-check the ten words) are **mutually unsatisfiable** while this agent answers both with one
-HTTP 400 and one sentence. No value available to the controller separates them. The task's own §5
-anticipates this — *"if the step is not recoverable from the value, make it so, and say what that
-cost"* — and §4.3 says the source outranks the register's recorded shape. **The cost is this version,
-a publish, and a `MinAgent` coupling on the controller side.**
+**Scope: the host half of R-220.** The customer-facing refusal message is the controller's half and
+ships as felhom-controller v0.203.0.
 
 ## What changed
 
 | File | Change |
 |---|---|
-| `internal/escrow/recover.go` | new `ErrBundleFetch` sentinel; the fetch leg joins it with `%w: %w` so the cause survives for the operator log |
-| `internal/localapi/escrow_recover.go` | new `case errors.Is(err, escrow.ErrBundleFetch)` → **502** with its own words; the `default` now carries only the wrong-code case and drops the "or" |
-| `internal/escrow/recover_test.go` | three new tests; the pre-existing `FetchErrorIsDistinct` re-pointed from a string to the sentinel, with the reason it failed to protect |
-| `internal/localapi/escrow_recover_class_test.go` | new — the consequence-level test: four situations, four statuses |
+| `internal/storage/claim.go` | `claimFacts.felhomOwnedMounts`; `classifyClaim` forgives a non-managed mountpoint **only when corroborated**; `felhomOwnedMounts()` + `procMounts()` |
+| `internal/storage/hostops.go` | `mountTable` seam (nil ⇒ real `/proc/mounts`) |
+| `internal/storage/claim_r220_test.go` | new — the own-drive case, the fence, and the corroboration's four edges |
 
-**Four statuses:** `502` fetch failed (the code was **not used**) · `400` fetched and refused ·
-`404` no bundle · `409` bundle predates the field.
+## The shape chosen, and why (§7.3)
 
-## The finding this turned up
+**Candidate (b): the claimed check distinguishes a mount Felhom made from a foreign one** — the task
+called it "nearer the truth" and it is, because the host and its knowledge survive the rebuild while
+the guest's registry does not. Candidate (a) — having the rebuild path clear the raw mounts — would
+have made correctness depend on a cleanup step running, and a cleanup that does not run leaves exactly
+today's defect.
 
-**A green test named the defect and did not prevent it.** `TestRecoverOffsiteRepoPassword_FetchErrorIsDistinct`
-has asserted since v0.125.0 that *"the operator must not be sent to re-read their recovery code because
-the hub was unreachable"*. It passed throughout, because it checked this package's error **string** one
-layer below the local-api `default` that did the merging — and a string is not something a caller can
-branch on. **Mechanism asserted, consequence unpinned**; the project's own rule names this exact case.
-It is also a comment-vs-code entry: `recover.go`'s header said the errors were *"DISTINCT on purpose"*
-and named **three** situations while a fourth was silently folded into one of them.
+**The discriminator is corroboration, not a path prefix**: the same device must ALSO be mounted under
+`/mnt/felhom-drives`. Only enrolment produces that pairing.
+
+**`/proc/mounts` rather than `lsblk MOUNTPOINTS`**, because the lsblk invocation is pinned verbatim in
+the sudoers file; changing it would have coupled this fix to a config rollout. `/proc/mounts` is
+world-readable and needs neither.
 
 ## Green gate
 
-`go build ./...` clean · `go vet ./...` clean · `go test ./...` → **29 packages ok** ·
-`python3 scripts/agent_gates.py --fast` → all gates OK.
+`go build` · `go vet` clean · `go test ./...` → **29 packages ok** · `agent_gates.py --fast` → all OK.
 
-**Red-proofs, each demonstrated failing then restored:**
-
-| Mutation | Result |
+| Red-proof | Result |
 |---|---|
-| remove the `%w: %w` join (pre-R-224 wrap) | `FetchFailureIsClassifiedAsFetch` **FAILS** |
-| delete the `ErrBundleFetch` handler case | fetch answers `400 "the recovery code did not open the sealed bundle"` — **the exact defect**, and both status tests **FAIL** |
+| remove the `felhomOwnedMounts` exemption | **FAILS** — "device is mounted at /mnt/adatok (sdb)", the pre-fix refusal |
+| over-widen the exemption to any `/mnt/*` | **FAILS** — "/mnt/someone-elses-disk was offered for formatting" |
 
 ## Not changed
 
-No Proxmox surface, no privileged path, no report/hub contract, no config schema. The route's
-success path, its scoping and its R-handling discipline (`R = ""` on both paths, never logged, never
-persisted) are untouched.
+No sudoers, no allowlisted command, no PVE surface, no format path. Every other claim signal
+(system disk, read-only, LVM PV, ZFS member, member FSTYPEs, empty-topology backstop) is untouched.

internal/storage/claim.go

@@ -53,7 +53,11 @@ type claimFacts struct {
 	nodes       []claimNode // the whole disk + its children (partitions)
 	lvmPV       bool        // pvs (authoritative): the disk / a partition is an LVM physical volume
 	zfsMember   bool        // zpool (authoritative): the disk / a partition is a ZFS pool member
-	gatherErr   string      // non-empty ⇒ a REQUIRED read failed ⇒ fail-safe CLAIMED
+	// felhomOwnedMounts (R-220) — mountpoints OUTSIDE /mnt/felhom-drives that are nevertheless Felhom's
+	// OWN, corroborated from the host mount table: the same device is also mounted at the managed path.
+	// Empty means "nothing corroborated", which is the fail-safe direction.
+	felhomOwnedMounts map[string]bool
+	gatherErr         string // non-empty ⇒ a REQUIRED read failed ⇒ fail-safe CLAIMED
 }
 
 // classifyClaim is the pure guard verdict. unclaimed=true ONLY when the device is provably free for
@@ -81,7 +85,20 @@ func classifyClaim(f claimFacts) (unclaimed bool, reason string) {
 		if memberFSTypes[n.fstype] {
 			return false, "device holds a " + n.fstype + " (" + n.name + ")"
 		}
-		if n.mountpoint != "" && !underFelhomDrives(n.mountpoint) {
+		// ── R-220 — A MOUNT FELHOM ITSELF MADE IS NOT "SOMETHING ELSE". ───────────────────────
+		//
+		// Enrolment mounts a drive TWICE: at the managed path `/mnt/felhom-drives/<name>` and at the
+		// raw `/mnt/<name>` it creates on the host. The host — and therefore that raw mount — survives
+		// a guest rebuild, while the controller's registry does not. So after a rebuild the customer's
+		// own drives looked foreign, `attach` returned an empty list, and the refusal told them to
+		// choose from it. Measured live three times (CAMPAIGN-11 Phase 1, and the R-201 re-walk twice);
+		// unmounting only the raw mounts flipped `attach: []` to both drives every time.
+		//
+		// The fence this must NOT breach: a disk genuinely in use by something else stays refused. So
+		// the exemption is not "any /mnt/* path" — it is CORROBORATED: the same device must ALSO be
+		// mounted at Felhom's managed path, which is a state only Felhom's own enrolment produces.
+		// A foreign disk at /srv/data or /media/x has no such counterpart and is still refused.
+		if n.mountpoint != "" && !underFelhomDrives(n.mountpoint) && !f.felhomOwnedMounts[n.mountpoint] {
 			return false, "device is mounted at " + n.mountpoint + " (" + n.name + ")"
 		}
 	}
@@ -154,6 +171,8 @@ func (h *SudoHostOps) gatherClaimFacts(ctx context.Context, device string) claim
 		return f
 	}
 	f.nodes = nodes
+	// R-220: corroborate which non-managed mountpoints are nevertheless Felhom's own.
+	f.felhomOwnedMounts = felhomOwnedMounts(device, nodes, h.mountTable)
 
 	// LVM PV (authoritative). pvs installed but erroring ⇒ fail-safe claimed; absent ⇒ rely on lsblk's
 	// LVM2_member FSTYPE (already in nodes).
@@ -285,3 +304,71 @@ func (h *SudoHostOps) zfsMembers(ctx context.Context, nodes []claimNode, wholeDi
 	}
 	return false, nil
 }
+
+// mountTableSource yields the host mount table as (device, mountpoint) pairs. A seam so the R-220
+// corroboration is unit-testable without a host. nil ⇒ the real /proc/mounts.
+type mountTableSource func() ([][2]string, error)
+
+// procMounts reads /proc/mounts — WORLD-READABLE, so this needs no sudo and no allowlisted command.
+// That matters: the lsblk invocation is pinned verbatim in the sudoers file
+// (`lsblk -J -o NAME,FSTYPE,PTTYPE,MOUNTPOINT /dev/*`), so switching it to the plural MOUNTPOINTS
+// would have meant shipping a sudoers change with the binary — a far larger blast radius than this
+// finding warrants. Reading the mount table directly sidesteps that entirely.
+func procMounts() ([][2]string, error) {
+	data, err := os.ReadFile("/proc/mounts")
+	if err != nil {
+		return nil, err
+	}
+	var out [][2]string
+	for _, line := range strings.Split(string(data), "\n") {
+		fields := strings.Fields(line)
+		if len(fields) < 2 {
+			continue
+		}
+		// /proc/mounts escapes spaces as \040; unescape so a path with a space still compares.
+		out = append(out, [2]string{fields[0], strings.ReplaceAll(fields[1], `\040`, " ")})
+	}
+	return out, nil
+}
+
+// felhomOwnedMounts returns the mountpoints of `device` (and its children) that sit OUTSIDE
+// /mnt/felhom-drives but are still Felhom's own, corroborated by the same device also being mounted
+// UNDER /mnt/felhom-drives. That pairing is what enrolment produces and nothing else does.
+//
+// ⚠ FAIL-SAFE: an unreadable mount table returns an EMPTY set, never a permissive one. The device then
+// classifies exactly as it did before R-220 — refused — because "we could not corroborate" must never
+// read as "it is ours".
+func felhomOwnedMounts(device string, nodes []claimNode, src mountTableSource) map[string]bool {
+	if src == nil {
+		src = procMounts
+	}
+	table, err := src()
+	if err != nil {
+		return nil // unreadable ⇒ corroborate nothing
+	}
+	// Every device name this disk answers to: the whole disk and each child node.
+	devs := map[string]bool{device: true}
+	if wd, ok := wholeDiskOf(device); ok {
+		devs[wd] = true
+	}
+	for _, n := range nodes {
+		devs["/dev/"+n.name] = true
+	}
+	// A device is Felhom-managed only if it is mounted under the managed prefix.
+	managed := map[string]bool{}
+	for _, row := range table {
+		if devs[row[0]] && underFelhomDrives(row[1]) {
+			managed[row[0]] = true
+		}
+	}
+	if len(managed) == 0 {
+		return nil
+	}
+	owned := map[string]bool{}
+	for _, row := range table {
+		if managed[row[0]] && !underFelhomDrives(row[1]) {
+			owned[path.Clean(row[1])] = true
+		}
+	}
+	return owned
+}

internal/storage/claim_r220_test.go

@@ -0,0 +1,102 @@
+package storage
+
+import "testing"
+
+// ── R-220 — A MOUNT FELHOM ITSELF MADE IS NOT "SOMETHING ELSE" ──────────────────────────────────
+//
+// Enrolment mounts a drive twice: at `/mnt/felhom-drives/<name>` and at the raw `/mnt/<name>` it
+// creates on the host. The host survives a guest rebuild; the controller's registry does not. So after
+// a rebuild the customer's own drives read as claimed-by-something-else, `attach` came back empty, and
+// the refusal told them to pick from the empty list. Measured three times live.
+//
+// The fence: a disk genuinely in use elsewhere must STILL be refused. These assert both directions.
+
+// ── SCENARIO E — the customer's own drive is offered again after a rebuild ───────────────────────
+//
+// RED-PROOF: drop `&& !f.felhomOwnedMounts[n.mountpoint]` from classifyClaim — the pre-R-220 check —
+// and this FAILS with the drive refused and the list empty again.
+func TestClassifyClaim_R220_FelhomsOwnRawMountIsNotForeign(t *testing.T) {
+	f := claimFacts{
+		device: "/dev/sdb", wholeDisk: "/dev/sdb", wholeDiskOK: true,
+		nodes: []claimNode{{name: "sdb", fstype: "ext4", mountpoint: "/mnt/adatok"}},
+		// corroborated: the SAME device is also mounted at the managed path
+		felhomOwnedMounts: map[string]bool{"/mnt/adatok": true},
+	}
+	unclaimed, reason := classifyClaim(f)
+	if !unclaimed {
+		t.Fatalf("R-220 RETURNED: the customer's own drive is refused after a rebuild — %q", reason)
+	}
+}
+
+// ── SCENARIO F — a genuinely foreign mount is STILL refused ──────────────────────────────────────
+//
+// RED-PROOF: over-widen the fix to exempt any /mnt/* path (or to skip the mountpoint check entirely)
+// and this FAILS — a disk another system is using would be offered for formatting.
+func TestClassifyClaim_R220_ForeignMountIsStillRefused(t *testing.T) {
+	for _, mp := range []string{"/srv/data", "/media/photos", "/mnt/someone-elses-disk", "/var/lib/other"} {
+		f := claimFacts{
+			device: "/dev/sdb", wholeDisk: "/dev/sdb", wholeDiskOK: true,
+			nodes:             []claimNode{{name: "sdb", fstype: "ext4", mountpoint: mp}},
+			felhomOwnedMounts: nil, // nothing corroborated it as ours
+		}
+		unclaimed, reason := classifyClaim(f)
+		if unclaimed {
+			t.Fatalf("THE FENCE BROKE: a disk mounted at %s was offered for formatting", mp)
+		}
+		if reason == "" {
+			t.Fatalf("a refusal must carry a reason (%s)", mp)
+		}
+	}
+}
+
+// The corroboration itself: it must require BOTH mounts of the SAME device, and fail safe.
+func TestFelhomOwnedMounts_RequiresTheManagedCounterpart(t *testing.T) {
+	nodes := []claimNode{{name: "sdb"}}
+
+	t.Run("both mounts present -> the raw one is ours", func(t *testing.T) {
+		src := func() ([][2]string, error) {
+			return [][2]string{
+				{"/dev/sdb", "/mnt/adatok"},
+				{"/dev/sdb", "/mnt/felhom-drives/adatok"},
+			}, nil
+		}
+		got := felhomOwnedMounts("/dev/sdb", nodes, src)
+		if !got["/mnt/adatok"] {
+			t.Fatal("the raw enrolment mount was not recognised as Felhom's own")
+		}
+	})
+
+	t.Run("only the raw mount -> corroborates NOTHING", func(t *testing.T) {
+		src := func() ([][2]string, error) {
+			return [][2]string{{"/dev/sdb", "/mnt/adatok"}}, nil
+		}
+		if got := felhomOwnedMounts("/dev/sdb", nodes, src); len(got) != 0 {
+			t.Fatalf("a lone /mnt/<name> mount must corroborate nothing, got %v", got)
+		}
+	})
+
+	t.Run("a DIFFERENT device under the managed path does not vouch for this one", func(t *testing.T) {
+		src := func() ([][2]string, error) {
+			return [][2]string{
+				{"/dev/sdb", "/srv/data"},
+				{"/dev/sdc", "/mnt/felhom-drives/mentes"}, // someone else's, not sdb's
+			}, nil
+		}
+		if got := felhomOwnedMounts("/dev/sdb", nodes, src); got["/srv/data"] {
+			t.Fatal("another device's managed mount vouched for a foreign one")
+		}
+	})
+
+	t.Run("an unreadable mount table corroborates NOTHING (fail-safe)", func(t *testing.T) {
+		src := func() ([][2]string, error) { return nil, errRead }
+		if got := felhomOwnedMounts("/dev/sdb", nodes, src); len(got) != 0 {
+			t.Fatalf("an unreadable mount table must corroborate nothing, got %v", got)
+		}
+	})
+}
+
+var errRead = errNoMountTable{}
+
+type errNoMountTable struct{}
+
+func (errNoMountTable) Error() string { return "mount table unreadable" }

internal/storage/hostops.go

@@ -164,6 +164,9 @@ type SudoHostOps struct {
 	// UNPRIVILEGED read (`systemctl is-failed`) — seam-injected so the reassert's F10 reset-failed path
 	// is unit-testable without a real systemd. Default set in NewSudoHostOps.
 	unitFailed func(ctx context.Context, unit string) bool
+	// mountTable (R-220) yields the host mount table for the "is this mount Felhom's own?"
+	// corroboration. nil ⇒ the real /proc/mounts; tests inject.
+	mountTable mountTableSource
 }
 
 // SudoHostOpsConfig configures a SudoHostOps.

scripts/agent_gates.py

@@ -41,10 +41,13 @@ import sys
 
 ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 SHARED_REUSE = os.path.join(os.path.dirname(ROOT), "felhom.eu", "scripts", "reuse_refs_check.py")
+SHARED_INSTRUCTIONS = os.path.join(
+    os.path.dirname(ROOT), "felhom.eu", "scripts", "instructions_gate.py")
 
 # (label, absolute script path, args, fast)
 GATES = [
     ("reuse-refs", SHARED_REUSE, [ROOT], True),
+    ("instructions", SHARED_INSTRUCTIONS, [ROOT], True),
     ("published", os.path.join(ROOT, "scripts", "check-published-versions.py"), [], False),
 ]