v0.5.0: slice 5 Phase B — the host-root surface (mounts + SMART + grow + destructive gate)

The privileged write surface, isolated behind a narrow, arg-validated, adversarially-
tested seam (HostOps), the same discipline as the slice-4 gate. Completes slice 5.

- internal/storage: HostOps seam + SudoHostOps (systemd .mount units by fs-UUID, detach,
  SMART, lvs) via sudoers allowlist + fixed arg vectors, no shell; NoopHostOps fallback.
- validate.go: strict UUID/mount-path/device/LVM validators + in-process systemd-escape.
  Headline test: adversarial matrix (metacharacters/traversal/malformed) refused with
  zero exec.
- smart.go: smartctl SATA + NVMe parse, UNKNOWN-degrade; lvs thin-pool metadata fill.
- observer enrichment (Observe only): fills smart + thin-pool metadata.
- watchdog: benign re-mount response off the poll path (DevicePresent probe, rate-limited).
- reconcile: ActionResize (benign, grow-only) + proxmox.ResizeLXC; destructive storage ops
  (ClassStorageWipe/Decommission) through the slice-4 gate, target-scoped; built+tested,
  inert live.
- --selftest=storage [-watch] live harness; configs/felhom-agent.sudoers; privileged.* knobs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -15,7 +15,7 @@
 - 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**; dep `golang.org/x/crypto v0.52.0` (declares go 1.25, will NOT build on Go 1.24). The **build server (192.168.0.180) runs go1.26.0** (upstream Go on PATH, backward-compatible). Build/run the agent there for live tests (same LAN as the demo host).
-- Version: `version` var in `cmd/felhom-agent/main.go`, overridable via `-ldflags "-X main.version=<v>"`; `--version` flag. **Current: v0.5.0-rc1** (slice 5 Phase A: storage observe/report + watchdog, read-only; Phase B = the host-root surface, pending). Bump on meaningful changes + add a CHANGELOG entry.
+- Version: `version` var in `cmd/felhom-agent/main.go`, overridable via `-ldflags "-X main.version=<v>"`; `--version` flag. **Current: v0.5.0** (slice 5 complete: storage observe/report + watchdog + the host-root surface — mounts/SMART/grow/destructive gate). Bump on meaningful changes + add a CHANGELOG entry.
 
 ## Layout
 
@@ -52,8 +52,9 @@ Built in slices, all on `main`:
 - **v0.3.2** — slice-4 pre-check: reversible `SetConfig` step added to `--selftest=task`; passed live on guest 9999. Findings: LXC `description` write is **synchronous** (empty UPID — dual-mode modeling confirmed); PVE appends a trailing `\n` to `description` on read (reconcile must normalize). First live `VM.Config.*` exercise.
 - **v0.4.0-rc1** — slice-4 **Phase A** (structural): `internal/reconcile` — engine, per-guest serializer (§10), desired-state model + `DesiredProvider` seam, normalization layer (`NormDescription` promoted out of main.go), plan/diff engine (benign Start/Stop/SetConfig set), durable op journal + idempotency store. Wired into `runDaemon` sharing the queue. Runs **live but unfed** (EmptyProvider → zero mutations until slice 10).
 - **v0.4.0** — slice-4 **Phase B** (security core): the benign/destructive **classifier** (provenance + data-bearing, not by verb; scratch/same-txn provenance is agent-internal, never hub-sourced), the **reversibility gate** (destructive → `pending_signature` unless a verified, role-scoped, action-bound operator signature), the **signed-op consuming layer** over `internal/authz` (role-scoping per doc 04 §4, op-to-action binding, idempotency-by-nonce, audit), and the **crash-recovery consumer** (`Recover` over `InFlight()`, resume-or-rollback). The gate fronts the queue's executor (every mutation passes it). **Inert this slice** — no destructive deltas served until slice 10; the destructive path is classified, gated, and adversarially tested but not wired to live execution. `authz` surface untouched.
-- **v0.5.0-rc1** — slice-5 **Phase A** (read-only, live): `internal/storage` — the `StorageTarget` wire contract (filled the slice-3 stub), `durable_id` derivation per type, the `Observer` (builds `storage_targets` from `ListStorage`/`NodeStorage` + non-privileged host reads), and the **storage watchdog** (third daemon goroutine; fast-poll → debounced out-of-band report on a known target's attach/disconnect). No host-root writes. Hub ingest extended to accept/persist `storage_targets`; cross-repo golden kept byte-identical. **Phase B (pending)** = the host-root surface: systemd `.mount` units + sudoers allowlist, benign re-mount, SMART, disk-grow executor, destructive-storage gating.
-- **Next: slice 5 Phase B (host-root surface), then slice 6 (backup/restore)** — the destructive executors the gate already guards.
+- **v0.5.0-rc1** — slice-5 **Phase A** (read-only, live): `internal/storage` — the `StorageTarget` wire contract (filled the slice-3 stub), `durable_id` derivation per type, the `Observer`, and the **storage watchdog** (third daemon goroutine; fast-poll → debounced out-of-band report on a known target's attach/disconnect). Hub ingest accepts/persists `storage_targets`; cross-repo golden byte-identical.
+- **v0.5.0** — slice-5 **Phase B** (the host-root surface): the `HostOps` seam + `SudoHostOps` (systemd `.mount` units by fs-UUID, detach, SMART, lvs) behind a **strict argument validator** (the adversarial matrix is the headline security test — hostile UUID/path/device refused with zero exec); SMART (SATA+NVMe) + thin-pool metadata enrichment; the watchdog's benign **re-mount response** (off the poll path); the **disk-grow executor** (`pct resize`, grow-only, benign) and **destructive storage ops** through the slice-4 gate (target-scoped; built + tested, inert live); `--selftest=storage [-watch]`; `configs/felhom-agent.sudoers`.
+- **Next: slice 6 (backup/restore orchestration)** — vzdump/PBS + the self-restore-test; the restore-overwrite executor the gate already guards.
 
 ## Demo host (for live tests)