v0.133.0: a restore-test can never fill a box's disk; leftovers retried on a timer (R-672, R-673)

Space preflight before anything is created (uncompressed size from the vzdump log / PBS
snapshot, x1.2 + 5 GiB, thin metadata, off the tested guest's pool when another storage
is eligible, unknown refuses, reported as a non-pass result). Failed scratch teardown and
the stale-lock sweep retried every 10 min (the sweep under the heavy-op gate). A thin
pool crossing 90% requests an immediate host report. Six red-proofs.

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

REUSE.md

@@ -85,6 +85,8 @@
 | `Client.Pool` | internal/proxmox/query.go | `Pool(ctx, name) (PoolInfo, error)` | felhom-pool membership (the ownership registry, A1) | Needs `Pool.Audit` at `/pool/<name>` (host-install v1.9.0+); `Pool.Allocate` does NOT satisfy the read; members can be storages (type `storage`, vmid 0) — filter them |
 | `Client` mutate wrappers (`RestoreLXC/Vzdump/DestroyLXC/Snapshot/Rollback/SetConfig/ResizeLXC/Start/Stop`) | internal/proxmox/mutate.go | return `(upid, error)` | all API mutations | Async → always pair with WaitTask; route via gate/queue, not ad-hoc |
 | `Client.PoolAddVMID` | internal/proxmox/mutate.go | `PoolAddVMID(ctx, pool, vmid) error` | re-assert pool membership after a restore-over-existing (campaign-2 R2) | SYNC (no UPID, don't WaitTask); PVE `PUT /pools` is additive (merge, not replace) — `delete=1` removes; idempotent (already-member swallowed); needs `Pool.Allocate` at `/pool/<pool>`. `pct restore --pool` sets membership only at CREATE — a restore over an existing vmid drops it, so bring-up re-asserts post-restore |
+| `reconcile.PreflightRestoreSpace` + `restorespace.Provider` (v0.133.0) | internal/reconcile/restoretest_space.go, internal/restorespace/restorespace.go | `PreflightRestoreSpace(ctx, space, policy, archive, rawCfg, configured) SpaceVerdict` | ANY step that restores or copies a guest onto a storage — size it first | The restored size is UNCOMPRESSED (vzdump log "Total bytes written" / PBS snapshot size) — never the archive FILE (6.9 GB file → 22.6 GB restore, R-672); an unknown refuses; eligibility needs Datastore.AllocateSpace on `/storage/<id>` specifically (the `/` grant answers every path) |
+| `Engine.RetryScratchTeardown` + the daemon janitor (v0.133.0) | internal/reconcile/restoretest_retry.go, cmd/felhom-agent/janitor.go | `RetryScratchTeardown(ctx) ScratchRetryResult` | retrying a leftover on a TIMER instead of only at start | Never `Recover` on a timer — it also resolves generic in-flight ops; a periodic sweep that unlocks guests holds the one-heavy-op gate (`InFlight.TryAcquire`) |
 | `TLSConfig.build` / `normalizeFingerprint` | internal/proxmox/tls.go | `build() (*tls.Config, error)` | PVE leaf-cert SHA-256 pinning | No insecure default |
 | `pinnedTLS` | internal/pbs/pin.go | `pinnedTLS(fingerprint) (*tls.Config, error)` | PBS leaf pinning | Same model as PVE; 64-hex fingerprint normalized |
 | `httpx.NewTransport` | internal/httpx/transport.go | `NewTransport(tlsCfg, idleConnTimeout) *http.Transport` | **EVERY** hand-rolled `http.Transport` in this repo — pbs, hub and proxmox all pin TLS, so none can use `http.DefaultTransport` | **R-344: never inline `&http.Transport{TLSClientConfig: ...}` again.** A composite literal takes `IdleConnTimeout` **zero, which means retain idle connections FOREVER** — `http.DefaultTransport` sets 90s and a literal does not inherit it. Combined with a client rebuilt per cycle and dropped (`pbsTargetsFromPVE`), that stranded **388 sockets on ep0 in 46 h**, held open on BOTH sides. `idleConnTimeout <= 0` means **use the default**, never "no timeout". Returns a **FRESH** transport every call — a shared one would pool connections across differently pinned endpoints. Pinned by `internal/pbs/client_leak_test.go` (server-side connection counting) + `internal/httpx/transport_test.go` |

cmd/felhom-agent/janitor.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/backup"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+)
+
+// janitorInterval is how often the leftovers of an interrupted restore-test or backup are retried
+// (R-672 rule 3, R-673). Both used to be resolved ONLY at agent start: on 2026-09-24 a failed scratch
+// teardown kept a full thin pool full for 2.5 h, and a stale `snapshot-delete` lock blocked 9201's
+// whole-box backups for five hours — each cleared within a minute of an agent restart.
+const janitorInterval = 10 * time.Minute
+
+// janitorDeps are the janitor's seams (tests drive one pass with fakes).
+type janitorDeps struct {
+	retryScratch func(ctx context.Context) reconcile.ScratchRetryResult
+	staleLocks   func(ctx context.Context) // localapi Server.RecoverStaleLockedGuests; nil when the local API is off
+	heavy        *backup.InFlight
+	record       func(hub.RestoreTest)
+	now          func() time.Time
+	logger       *slog.Logger
+}
+
+// janitorPass is one pass. The stale-lock sweep runs only while holding the one-heavy-operation gate, so
+// no agent backup can START between its "no vzdump is running" check and its unlock (at start-up the
+// sweep ran before the backup loop existed; on a timer that ordering must be made, not assumed). A busy
+// gate skips the sweep this pass — the next pass retries.
+func janitorPass(ctx context.Context, d janitorDeps) {
+	if d.retryScratch != nil {
+		r := d.retryScratch(ctx)
+		if r.Examined > 0 {
+			d.logger.Info("janitor: restore-test scratch retry pass", "examined", r.Examined,
+				"destroyed", r.Destroyed, "already_gone", r.Clean, "failed", r.Failed)
+		}
+		for _, vmid := range r.GaveUp {
+			// The operator is told through the existing restore-test failure path: the hub raises
+			// restore_test_failed (operator) once per distinct archive — this record's archive names
+			// the stuck scratch guest.
+			if d.record != nil {
+				d.record(hub.RestoreTest{
+					SourceArchive: fmt.Sprintf("scratch-teardown:%d", vmid),
+					ScratchVMID:   vmid,
+					Pass:          false,
+					Error: fmt.Sprintf("restore-test scratch guest %d could not be torn down after %d retries — it holds its disks; remove it by hand (pct destroy %d) after checking what keeps it busy",
+						vmid, reconcile.MaxTeardownTries, vmid),
+					TestedAt: d.now().UTC().Format(time.RFC3339),
+				})
+			}
+		}
+	}
+	if d.staleLocks != nil {
+		release, busy, ok := d.heavy.TryAcquire("stale-lock-sweep")
+		if !ok {
+			d.logger.Info("janitor: stale-lock sweep deferred — a heavy operation is in flight", "busy", busy)
+			return
+		}
+		defer release()
+		d.staleLocks(ctx)
+	}
+}
+
+// runJanitor runs janitorPass every janitorInterval until ctx ends.
+func runJanitor(ctx context.Context, d janitorDeps) {
+	d.logger.Info("janitor: starting (restore-test scratch retry + stale-lock sweep)", "interval", janitorInterval)
+	t := time.NewTicker(janitorInterval)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			janitorPass(ctx, d)
+		}
+	}
+}

cmd/felhom-agent/janitor_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/backup"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+)
+
+// R-672 / R-673 (v0.133.0): one janitor pass, driven with fakes.
+
+func quiet() *slog.Logger { return slog.New(slog.NewTextHandler(io.Discard, nil)) }
+
+// A scratch the engine gave up on reaches the hub as a failed restore-test record naming it — the
+// existing operator path (restore_test_failed). Never a pass.
+func TestJanitor_GaveUpIsReportedAsAFailure(t *testing.T) {
+	var got []hub.RestoreTest
+	janitorPass(context.Background(), janitorDeps{
+		retryScratch: func(context.Context) reconcile.ScratchRetryResult {
+			return reconcile.ScratchRetryResult{Examined: 1, Failed: 1, GaveUp: []int{990000}}
+		},
+		heavy: &backup.InFlight{}, record: func(r hub.RestoreTest) { got = append(got, r) },
+		now: time.Now, logger: quiet(),
+	})
+	if len(got) != 1 || got[0].Pass || got[0].ScratchVMID != 990000 || !strings.Contains(got[0].Error, "990000") {
+		t.Fatalf("records = %+v — want one FAILED record naming scratch 990000", got)
+	}
+}
+
+// R-673: the stale-lock sweep runs only while holding the one-heavy-operation gate, so no agent backup can
+// start between its "no vzdump running" check and its unlock.
+//
+// COMPANION RED-PROOF (REPORT): drop the TryAcquire → "the sweep ran while a backup held the gate".
+func TestJanitor_StaleLockSweepWaitsForTheHeavyGate(t *testing.T) {
+	heavy := &backup.InFlight{}
+	swept := 0
+	d := janitorDeps{staleLocks: func(context.Context) { swept++ }, heavy: heavy, now: time.Now, logger: quiet()}
+	release, _, ok := heavy.TryAcquire("backup")
+	if !ok {
+		t.Fatal("setup")
+	}
+	janitorPass(context.Background(), d)
+	if swept != 0 {
+		t.Fatal("the sweep ran while a backup held the gate")
+	}
+	release()
+	janitorPass(context.Background(), d)
+	if swept != 1 {
+		t.Fatalf("swept %d times with the gate free — want 1", swept)
+	}
+	if _, _, ok := heavy.TryAcquire("after"); !ok {
+		t.Fatal("the sweep did not release the gate")
+	}
+}

cmd/felhom-agent/main.go

@@ -50,6 +50,7 @@ import (
 	"gitea.dooplex.hu/admin/felhom-agent/internal/provision"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/restorespace"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/selfheal"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/selfupdate"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/signedjobs"
@@ -897,6 +898,13 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 	// it finds nothing to flag. The re-mount dispatch is off the poll path (a goroutine).
 	storageTrigger := make(chan struct{}, 1)
 	loop.SetTrigger(storageTrigger)
+	// R-672: a thin pool crossing 90 % requests a report at once (the hub's storage-fill alarm).
+	observer.SetThinHighTrigger(func() {
+		select {
+		case storageTrigger <- struct{}{}:
+		default:
+		}
+	})
 	remounter := &gateRemounter{gate: gate, ops: hostOps, hostID: cfg.Hub.HostID, logger: logger}
 	// Drive intent store (slice 10 P3 self-heal): persisted, durable-id-keyed enroll/eject/decommission
 	// state. Gates the watchdog's self-heal re-mount to ENROLLED drives, and the local API records
@@ -963,6 +971,7 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		Logger:   logger,
 	})
 
+	rtSpace, rtPolicy := restoreSpaceFor(cfg, px, hostOps)
 	engine := reconcile.NewEngine(reconcile.EngineOptions{
 		API:      px,
 		Queue:    queue,
@@ -971,6 +980,9 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		Gate:     gate,
 		HostID:   cfg.Hub.HostID,
 		Logger:   logger,
+		// R-672: the restore-test's space preflight (nil would refuse every test — fail-closed).
+		RestoreSpace: rtSpace,
+		SpacePolicy:  rtPolicy,
 	})
 
 	// Crash recovery (doc 03 §10): resolve any op that was in flight when the agent
@@ -1407,6 +1419,16 @@ func runDaemon(cfg config.Config, logger *slog.Logger, logRing *applog.Ring) int
 		go localSrv.WatchControllers(ctx)
 		go func() { errc <- localSrv.Run(ctx) }()
 	}
+	// R-672 / R-673: retry a failed restore-test teardown and sweep stale backup locks on a timer, not
+	// only at start-up (janitor.go).
+	{
+		jd := janitorDeps{retryScratch: engine.RetryScratchTeardown, heavy: heavyOps,
+			record: backupStore.RecordRestoreTest, now: time.Now, logger: logger}
+		if localSrv != nil {
+			jd.staleLocks = localSrv.RecoverStaleLockedGuests
+		}
+		go runJanitor(ctx, jd)
+	}
 	if lanLoop != nil {
 		lanServers = 1
 		go func() { errc <- lanLoop.Run(ctx) }()
@@ -2209,6 +2231,17 @@ func formatOrDash(t time.Time) string {
 	return t.UTC().Format(time.RFC3339)
 }
 
+// restoreSpaceFor builds the restore-test's space preflight (R-672): the production provider over the
+// Proxmox API + the privileged `lvs` metadata read, and the configured margin.
+func restoreSpaceFor(cfg config.Config, px *proxmox.Client, ops *storage.SudoHostOps) (reconcile.RestoreSpace, reconcile.SpacePolicy) {
+	factor, reserve := cfg.Backup.RestoreTestSpace()
+	p := &restorespace.Provider{API: px}
+	if ops != nil {
+		p.ThinMeta = ops.ThinPoolMetadata
+	}
+	return p, reconcile.SpacePolicy{Factor: factor, ReserveBytes: reserve}
+}
+
 func runSelftestRestoreTest(ctx context.Context, cfg config.Config, logger *slog.Logger, archive string) int {
 	if err := cfg.Validate(); err != nil {
 		fmt.Fprintln(os.Stderr, "selftest: proxmox not configured:", err)
@@ -2239,8 +2272,10 @@ func runSelftestRestoreTest(ctx context.Context, cfg config.Config, logger *slog
 		}
 	}
 	gate := reconcile.NewGate(nil, cfg.Hub.HostID, reconcile.SlogAudit{Logger: logger}, logger)
+	rtSpace, rtPolicy := restoreSpaceFor(cfg, px, newHostOps(cfg, logger))
 	engine := reconcile.NewEngine(reconcile.EngineOptions{
 		API: px, Queue: queue, Journal: journal, Gate: gate, HostID: cfg.Hub.HostID, Logger: logger,
+		RestoreSpace: rtSpace, SpacePolicy: rtPolicy,
 	})
 
 	fmt.Printf("=== felhom-agent %s selftest=restore-test ===\n", version)
@@ -2270,10 +2305,16 @@ func runSelftestRestoreTest(ctx context.Context, cfg config.Config, logger *slog
 		RestoreTaskTimeout: restoreTaskTimeout(cfg, rtTier),
 	})
 	printJSON("restore-test record", backup.ToHubRestoreTest(res, time.Now().UTC()))
+	if res.Skipped && res.SkipReason != "" {
+		fmt.Printf("  space preflight: storage=%s required=%d avail=%d\n", res.TargetStorage, res.RequiredBytes, res.AvailBytes)
+		fmt.Printf("=== selftest=restore-test SKIPPED — %s ===\n", res.SkipReason)
+		return 4
+	}
 	if res.Skipped {
 		fmt.Println("=== selftest=restore-test SKIPPED (no free scratch VMID in band) ===")
 		return 0
 	}
+	fmt.Printf("  space preflight passed: storage=%s required=%d avail=%d\n", res.TargetStorage, res.RequiredBytes, res.AvailBytes)
 	if res.Err != nil || !res.Pass {
 		fmt.Fprintf(os.Stderr, "  [FAIL] restore-test (scratch %d): %v\n", res.ScratchVMID, res.Err)
 		return 1

internal/backup/r672_skip_test.go

@@ -0,0 +1,36 @@
+package backup
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+)
+
+// R-672 (v0.133.0): a restore-test the SPACE preflight refused is the test's RESULT — recorded for the
+// hub as pass=false with the reason, never dropped (a band skip still is) and never a pass.
+//
+// COMPANION RED-PROOF (REPORT): the scheduler's pre-v0.133.0 `if res.Skipped { return }` → "a space
+// refusal never reached the host report".
+func TestR672_SpaceSkipIsReportedNotDropped(t *testing.T) {
+	store := NewStore()
+	rt := &fakeRTRunner{res: reconcile.RestoreTestResult{Archive: "vol", Skipped: true,
+		SkipReason: "skipped: not enough space on local-lvm: restoring 21.1 GiB (vzdump log) needs 30.3 GiB free, has 21.6 GiB"}}
+	s := NewScheduler(SchedulerOptions{
+		Runner: rt, Pick: func(context.Context) (string, error) { return "vol", nil }, Store: store,
+		Spec: func(context.Context, string) reconcile.RestoreTestSpec {
+			return reconcile.RestoreTestSpec{RestoreStorage: "local-lvm", ScratchMin: 990000, ScratchMax: 990009}
+		},
+		Cadence: time.Hour, Logger: quiet(),
+	})
+	s.tick(context.Background())
+	got := store.RestoreTests(context.Background())
+	if len(got) != 1 {
+		t.Fatalf("a space refusal never reached the host report: %+v", got)
+	}
+	if got[0].Pass || !got[0].Skipped || !strings.HasPrefix(got[0].Error, "skipped: not enough space") {
+		t.Fatalf("record = %+v — want pass=false, skipped, the reason as the error", got[0])
+	}
+}

internal/backup/runner.go

@@ -520,5 +520,10 @@ func ToHubRestoreTest(res reconcile.RestoreTestResult, testedAt time.Time) hub.R
 	if res.Err != nil {
 		rt.Error = res.Err.Error()
 	}
+	if res.SkipReason != "" { // R-672: the space preflight refused — reported, never a pass
+		rt.Pass = false
+		rt.Skipped = true
+		rt.Error = res.SkipReason
+	}
 	return rt
 }

internal/backup/schedule.go

@@ -208,9 +208,11 @@ func (s *Scheduler) tick(ctx context.Context) {
 	spec := s.spec(ctx, archive)
 	spec.Archive = archive
 	res := s.runner.RunRestoreTest(ctx, spec)
-	if res.Skipped {
+	if res.Skipped && res.SkipReason == "" {
 		return // already logged by the engine (no free scratch VMID)
 	}
+	// R-672: a SPACE refusal is the test's result — reported (pass=false, the reason as the error),
+	// never dropped and never a pass. It earns no rotation credit, so the tier stays due.
 	rt := ToHubRestoreTest(res, s.now())
 	s.store.RecordRestoreTest(rt)
 	// Rotation credit is given ONLY on success. A failing tier must keep sorting first, or a tier

internal/config/config.go

@@ -345,6 +345,12 @@ type BackupConfig struct {
 	// between an archive settling and its proof, and the retry rate of a tier whose restore-test
 	// keeps failing. See defaultRestoreTestEvalInterval for the measurement it was chosen from.
 	RestoreTestEvalIntervalSeconds int `json:"restore_test_eval_interval_seconds"`
+	// RestoreTestSpaceFactor / RestoreTestSpaceReserveGiB are the restore-test's space margin (R-672,
+	// v0.133.0): a test starts only when the target storage has free ≥ restored × factor + reserve,
+	// `restored` being the UNCOMPRESSED size. 0/unset → 1.2 and 5 GiB. A test config may raise them to
+	// watch the refusal (the brief's live case a).
+	RestoreTestSpaceFactor     float64 `json:"restore_test_space_factor,omitempty"`
+	RestoreTestSpaceReserveGiB float64 `json:"restore_test_space_reserve_gib,omitempty"`
 	// RestoreTestSettleSeconds is how long an archive must have sat on its tier before it is a
 	// restore-test candidate (R-86); 0 → default (24h), negative → 0 (no settle requirement).
 	// Restore-testing an archive a backup is still writing proves nothing about the backup that
@@ -615,6 +621,20 @@ func (b BackupConfig) RestoreTestEvalInterval() time.Duration {
 	}
 }
 
+// RestoreTestSpace returns the restore-test's space margin (R-672): factor (≥ 1) and reserve bytes.
+// Unset or out-of-range → 1.2 and 5 GiB.
+func (b BackupConfig) RestoreTestSpace() (factor float64, reserveBytes int64) {
+	factor = b.RestoreTestSpaceFactor
+	if factor < 1 {
+		factor = 1.2
+	}
+	reserveBytes = int64(b.RestoreTestSpaceReserveGiB * float64(1<<30))
+	if reserveBytes <= 0 {
+		reserveBytes = 5 << 30
+	}
+	return factor, reserveBytes
+}
+
 // RestoreTestSettle returns how long an archive must have sat before it is a restore-test
 // candidate (R-86): a positive value as-is, negative → 0 (no settle requirement), 0 → the default.
 //

internal/hub/report.go

@@ -470,6 +470,10 @@ type RestoreTest struct {
 	// mount layout, not just booted. Additive — a hub that predates them ignores the unknown keys.
 	MountParity    string   `json:"mount_parity,omitempty"`
 	MountInventory []string `json:"mount_inventory,omitempty"`
+	// Skipped (R-672, v0.133.0): the test did NOT run — the space preflight refused, and Error says
+	// why ("skipped: not enough space on …"). Pass is false. A hub that predates the key reads a
+	// failed test with that error, which is the honest reading.
+	Skipped bool `json:"skipped,omitempty"`
 }
 
 // PBSSnapshot is one PBS (offsite) snapshot's inventory + integrity state (doc 03 §8, slice

internal/reconcile/bringup_test.go

@@ -52,7 +52,7 @@ func newDREngine(t *testing.T, api GuestAPI) (*Engine, *fakeRunner, string, *Que
 	t.Cleanup(q.Close)
 	fr := &fakeRunner{}
 	sd := t.TempDir()
-	e := NewEngine(EngineOptions{API: api, Queue: q, Journal: j, Provider: EmptyProvider{}, HostRunner: fr, StateDir: sd})
+	e := NewEngine(EngineOptions{API: api, Queue: q, Journal: j, Provider: EmptyProvider{}, HostRunner: fr, StateDir: sd, RestoreSpace: roomySpace{}})
 	return e, fr, sd, q
 }
 

internal/reconcile/engine.go

@@ -44,6 +44,17 @@ type Engine struct {
 
 	opSeq uint64 // atomic; makes each op id unique per attempt
 
+	// restoreSpace + spacePolicy are the restore-test's space preflight (R-672). nil space REFUSES
+	// every restore-test (fail-closed) — see restoretest_space.go.
+	restoreSpace RestoreSpace
+	spacePolicy  SpacePolicy
+
+	// scratchMu guards activeScratch (the vmids a running restore-test owns — the retry timer never
+	// touches those) and teardownTries (failed timer retries per journal op, R-672 rule 3).
+	scratchMu     sync.Mutex
+	activeScratch map[int]bool
+	teardownTries map[string]int
+
 	// lastRes records the most recent successful Reconcile Result (v0.90.0, R-28 fast-tick source).
 	// The fast-tick reads it to decide convergence: actionable drift is Planned − Pending > 0 (a
 	// destructive pending_signature refusal is EXPECTED state, not drift to hammer on). lastOK is
@@ -86,6 +97,10 @@ type EngineOptions struct {
 	HostRunner proxmox.Runner
 	// StateDir is the agent state dir ("" → /var/lib/felhom-agent); only the 4d swap reads it.
 	StateDir string
+	// RestoreSpace is the restore-test's space preflight (R-672). nil → every restore-test is REFUSED
+	// with its reason (fail-closed). SpacePolicy zero → DefaultSpacePolicy.
+	RestoreSpace RestoreSpace
+	SpacePolicy  SpacePolicy
 }
 
 // NewEngine builds an Engine. The Queue is shared (the single §10 choke point); the
@@ -124,9 +139,24 @@ func NewEngine(opts EngineOptions) *Engine {
 		logger:   logger,
 		hostRun:  opts.HostRunner,
 		stateDir: stateDir,
+
+		restoreSpace:  opts.RestoreSpace,
+		spacePolicy:   policyOrDefault(opts.SpacePolicy),
+		activeScratch: map[int]bool{},
+		teardownTries: map[string]int{},
 	}
 }
 
+func policyOrDefault(p SpacePolicy) SpacePolicy {
+	if p.Factor < 1 {
+		p.Factor = DefaultSpacePolicy.Factor
+	}
+	if p.ReserveBytes <= 0 {
+		p.ReserveBytes = DefaultSpacePolicy.ReserveBytes
+	}
+	return p
+}
+
 // Result summarizes one Reconcile pass.
 type Result struct {
 	Planned  int

internal/reconcile/engine_test.go

@@ -213,7 +213,7 @@ func newEngine(t *testing.T, api GuestAPI, provider DesiredProvider) (*Engine, *
 	t.Cleanup(func() { j.Close() })
 	q := NewQueue()
 	t.Cleanup(q.Close)
-	e := NewEngine(EngineOptions{API: api, Queue: q, Journal: j, Provider: provider})
+	e := NewEngine(EngineOptions{API: api, Queue: q, Journal: j, Provider: provider, RestoreSpace: roomySpace{}})
 	return e, j, q
 }
 

internal/reconcile/restoretest.go

@@ -50,10 +50,18 @@ type RestoreTestResult struct {
 	ScratchVMID int
 	Pass        bool
 	Verified    string // "boot+running" this slice
-	Skipped     bool   // no free scratch VMID in band → test not run
-	Err         error
-	StartedAt   time.Time
-	Duration    time.Duration
+	Skipped     bool   // test not run: no free scratch VMID in band, or the space preflight refused (R-672)
+	// SkipReason is set when the SPACE PREFLIGHT refused (R-672): the test did not run, and this is
+	// reported to the hub as the test's result (pass=false), never as a pass. Empty for a band skip.
+	SkipReason string
+	// TargetStorage is where the restore went (rule 2 may move it off the tested guest's pool);
+	// RequiredBytes/AvailBytes are rule 1's figures.
+	TargetStorage string
+	RequiredBytes int64
+	AvailBytes    int64
+	Err           error
+	StartedAt     time.Time
+	Duration      time.Duration
 	// StartWarnings holds the warning line(s) the guest-start task emitted (e.g. the
 	// systemd-nesting advisory). Populated only when the start exited "WARNINGS: N";
 	// always surfaced, NEVER used to decide pass/fail (the verdict is liveness — waitRunning).
@@ -136,6 +144,29 @@ func (e *Engine) RunRestoreTest(ctx context.Context, spec RestoreTestSpec) Resto
 		return res
 	}
 
+	// R-672: the space preflight, BEFORE anything is journaled or created.
+	rawCfg, err := e.api.ExtractArchiveConfig(ctx, spec.Archive)
+	if err != nil {
+		res.Err = fmt.Errorf("reconcile: restore-test extract archive config: %w", err)
+		return res
+	}
+	v := PreflightRestoreSpace(ctx, e.restoreSpace, e.spacePolicy, spec.Archive, rawCfg, spec.RestoreStorage)
+	res.TargetStorage, res.RequiredBytes, res.AvailBytes = v.Storage, v.Required, v.Avail
+	if !v.OK {
+		res.Skipped = true
+		res.SkipReason = "skipped: " + v.Reason
+		e.logger.Warn("restore-test SKIPPED by the space preflight (R-672) — nothing was created",
+			"archive", spec.Archive, "storage", v.Storage, "required_bytes", v.Required, "avail_bytes", v.Avail, "reason", v.Reason)
+		res.Duration = time.Since(now)
+		return res
+	}
+	if v.Storage != spec.RestoreStorage {
+		e.logger.Info("restore-test: restoring OFF the tested guest's own pool (R-672 rule 2)",
+			"configured", spec.RestoreStorage, "avoided", v.Avoided, "target", v.Storage)
+	}
+	e.logger.Info("restore-test: space preflight passed", "storage", v.Storage, "required_bytes", v.Required, "avail_bytes", v.Avail)
+	spec.RestoreStorage = v.Storage
+
 	lxc, err := e.api.ListLXC(ctx)
 	if err != nil {
 		res.Err = fmt.Errorf("reconcile: restore-test list guests: %w", err)
@@ -164,7 +195,9 @@ func (e *Engine) RunRestoreTest(ctx context.Context, spec RestoreTestSpec) Resto
 		// Serialize on the scratch VMID's lane (inherits §10), and capture the result.
 		var vmidOccupied bool
 		ch := e.queue.Submit(vmid, func() error {
-			vmidOccupied = e.runScratchTest(ctx, vmid, spec, &res)
+			e.markScratch(vmid, true)
+			defer e.markScratch(vmid, false)
+			vmidOccupied = e.runScratchTest(ctx, vmid, spec, rawCfg, &res)
 			return res.Err
 		})
 		<-ch
@@ -182,7 +215,7 @@ func (e *Engine) RunRestoreTest(ctx context.Context, spec RestoreTestSpec) Resto
 // runScratchTest is the journaled body (runs on vmid's queue lane). The occupied return is true
 // ONLY when PVE synchronously refused the restore because the vmid already holds a guest (one
 // the pool-blind band scan couldn't see) — the caller then advances to the next band vmid (F2).
-func (e *Engine) runScratchTest(ctx context.Context, vmid int, spec RestoreTestSpec, res *RestoreTestResult) (occupied bool) {
+func (e *Engine) runScratchTest(ctx context.Context, vmid int, spec RestoreTestSpec, rawCfg string, res *RestoreTestResult) (occupied bool) {
 	base := JournalEntry{OpID: e.scratchOpID(vmid), VMID: vmid, Kind: scratchKind, Scratch: true}
 
 	// OWN the scratch guest's cleanup BEFORE any mutation. From here, a crash is recoverable.
@@ -215,11 +248,7 @@ func (e *Engine) runScratchTest(ctx context.Context, vmid int, spec RestoreTestS
 	//    genuinely EXTRACTED — full fidelity; the added runtime IS the verification), the two
 	//    structural binds → throwaway stand-ins. An unreadable archive config or an unknown
 	//    topology REFUSES up front — never restore a partial guest to "verify" it.
-	rawCfg, err := e.api.ExtractArchiveConfig(ctx, spec.Archive)
-	if err != nil {
-		res.Err = fmt.Errorf("reconcile: restore-test extract archive config: %w", err)
-		return false
-	}
+	// The archive's config was read ONCE, by the space preflight (R-672), and is passed in.
 	mountOverrides, err := drRestoreOverrides(rawCfg, spec.RestoreStorage)
 	if err != nil {
 		res.Err = fmt.Errorf("reconcile: restore-test: %w", err)

internal/reconcile/restoretest_retry.go

@@ -0,0 +1,94 @@
+package reconcile
+
+import "context"
+
+// ── A failed scratch teardown is retried on a TIMER, not only at agent start (R-672 rule 3) ────────
+//
+// MEASURED 2026-09-24 on demo-hp: the scheduled restore-test's teardown failed (`lvremove … contains a
+// filesystem in use`, a transient hold) and logged "left for Recover" — and Recover runs ONLY at agent
+// start, so the 22 GiB scratch guest sat in the full pool for 2.5 hours until an agent restart. The
+// timer calls RetryScratchTeardown every 10 minutes: the SAME resolution as Recover (recoverScratch —
+// the gate's benign scratch destroy, idempotent when the guest is already gone), restricted to Scratch
+// entries that carry a launch-proof UPID and that no running restore-test owns. After
+// MaxTeardownTries failed attempts for one entry the operator is told (the caller reports it); the
+// timer keeps trying.
+
+// MaxTeardownTries is how many failed timer retries of one scratch entry happen before the operator
+// is told.
+const MaxTeardownTries = 3
+
+// ScratchRetryResult summarizes one timer pass.
+type ScratchRetryResult struct {
+	Examined  int
+	Destroyed int
+	Clean     int // already gone
+	Failed    int
+	// GaveUp lists the scratch vmids whose failed tries reached MaxTeardownTries IN THIS PASS — each
+	// is reported exactly once (the caller tells the operator).
+	GaveUp []int
+}
+
+func (e *Engine) markScratch(vmid int, active bool) {
+	e.scratchMu.Lock()
+	defer e.scratchMu.Unlock()
+	if active {
+		e.activeScratch[vmid] = true
+	} else {
+		delete(e.activeScratch, vmid)
+	}
+}
+
+func (e *Engine) scratchActive(vmid int) bool {
+	e.scratchMu.Lock()
+	defer e.scratchMu.Unlock()
+	return e.activeScratch[vmid]
+}
+
+// RetryScratchTeardown is the timer's pass. It never touches a non-Scratch entry (unlike Recover,
+// which also resolves generic in-flight operations and must therefore run only at start), never an
+// entry without a launch-proof UPID (nothing was created), and never a vmid a running test owns.
+func (e *Engine) RetryScratchTeardown(ctx context.Context) ScratchRetryResult {
+	var out ScratchRetryResult
+	if e.journal == nil {
+		return out
+	}
+	for _, entry := range e.journal.InFlight() {
+		if !entry.Scratch || entry.UPID == "" || e.scratchActive(entry.VMID) {
+			continue
+		}
+		out.Examined++
+		var r RecoverResult
+		e.recoverScratch(ctx, entry, &r)
+		switch {
+		case r.ScratchDestroyed > 0:
+			out.Destroyed++
+			e.forgetTries(entry.OpID)
+		case r.ScratchClean > 0:
+			out.Clean++
+			e.forgetTries(entry.OpID)
+		default:
+			out.Failed++
+			n := e.addTry(entry.OpID)
+			e.logger.Warn("restore-test: scratch teardown retry failed (timer)", "vmid", entry.VMID, "op_id", entry.OpID, "try", n)
+			if n == MaxTeardownTries {
+				out.GaveUp = append(out.GaveUp, entry.VMID)
+				e.logger.Error("restore-test: scratch guest still NOT torn down after repeated retries — telling the operator",
+					"vmid", entry.VMID, "tries", n)
+			}
+		}
+	}
+	return out
+}
+
+func (e *Engine) addTry(op string) int {
+	e.scratchMu.Lock()
+	defer e.scratchMu.Unlock()
+	e.teardownTries[op]++
+	return e.teardownTries[op]
+}
+
+func (e *Engine) forgetTries(op string) {
+	e.scratchMu.Lock()
+	defer e.scratchMu.Unlock()
+	delete(e.teardownTries, op)
+}

internal/reconcile/restoretest_retry_test.go

@@ -0,0 +1,73 @@
+package reconcile
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// R-672 rule 3 (v0.133.0): a failed scratch teardown is retried on a TIMER. The consequence asserted:
+// the leaked scratch guest is destroyed by a timer pass (not only by a restart's Recover), the operator
+// is told exactly once after MaxTeardownTries failures, and a vmid a running test owns is never touched.
+
+// leakScratch runs a restore-test whose teardown fails, leaving scratch 990000 in-flight — the
+// 2026-09-24 shape ("lvremove … contains a filesystem in use").
+func leakScratch(t *testing.T) (*Engine, *fakeAPI, *Journal) {
+	t.Helper()
+	api := &fakeAPI{cfg: map[int]proxmox.GuestConfig{990000: scratchCfg()}, restoreUPID: "UPID:r", destroyErr: errors.New("lvremove: contains a filesystem in use")}
+	e, j := spaceEngine(t, api, roomySpace{})
+	e.RunRestoreTest(context.Background(), RestoreTestSpec{Archive: "local:backup/x.tar.zst", RestoreStorage: "local-lvm", ScratchMin: 990000, ScratchMax: 990009})
+	if len(j.InFlight()) != 1 {
+		t.Fatalf("setup: want the scratch left in-flight after a failed teardown, got %+v", j.InFlight())
+	}
+	api.lxc = []proxmox.Guest{{VMID: 990000}}
+	return e, api, j
+}
+
+// COMPANION RED-PROOF (REPORT): make RetryScratchTeardown return without touching the journal (the
+// v0.132.0 shape — only Recover at start resolved a leak) → "the leaked scratch was not destroyed by
+// the timer".
+func TestRetry_TheTimerDestroysALeakedScratch(t *testing.T) {
+	e, api, j := leakScratch(t)
+	api.destroyErr = nil // the transient hold is gone
+	before := len(api.destroys)
+	r := e.RetryScratchTeardown(context.Background())
+	if r.Destroyed != 1 || len(api.destroys) != before+1 || api.destroys[len(api.destroys)-1] != 990000 {
+		t.Fatalf("the leaked scratch was not destroyed by the timer: result=%+v destroys=%v", r, api.destroys)
+	}
+	if len(j.InFlight()) != 0 {
+		t.Fatalf("the entry is still in flight after a successful retry: %+v", j.InFlight())
+	}
+	if r2 := e.RetryScratchTeardown(context.Background()); r2.Examined != 0 {
+		t.Fatalf("a resolved entry was examined again: %+v", r2)
+	}
+}
+
+func TestRetry_OperatorToldOnceAfterThreeFailures(t *testing.T) {
+	e, _, _ := leakScratch(t)
+	var gave [][]int
+	for i := 0; i < MaxTeardownTries+2; i++ {
+		gave = append(gave, e.RetryScratchTeardown(context.Background()).GaveUp)
+	}
+	for i, g := range gave {
+		want := 0
+		if i == MaxTeardownTries-1 {
+			want = 1
+		}
+		if len(g) != want {
+			t.Fatalf("pass %d gave up on %v — want the operator told exactly once, on pass %d", i+1, g, MaxTeardownTries)
+		}
+	}
+}
+
+func TestRetry_NeverTouchesARunningTest(t *testing.T) {
+	e, api, _ := leakScratch(t)
+	api.destroyErr = nil
+	e.markScratch(990000, true) // a restore-test is (again) working on this vmid
+	before := len(api.destroys)
+	if r := e.RetryScratchTeardown(context.Background()); r.Examined != 0 || len(api.destroys) != before {
+		t.Fatalf("the timer touched a scratch a running test owns: %+v destroys=%v", r, api.destroys)
+	}
+}

internal/reconcile/restoretest_space.go

@@ -0,0 +1,176 @@
+package reconcile
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// ── The restore-test's space preflight (R-672, agent v0.133.0) ─────────────────────────────────────
+//
+// MEASURED 2026-09-24 on demo-hp: the scheduled restore-test restored 9201's archive into `local-lvm`
+// — the SAME thin pool that holds 9201 — with no free-space check. The pool reached 100 %
+// (`out_of_data_space`, `error_if_no_space`), and 9201's rootfs and data volume remounted READ-ONLY.
+// Evidence: felhom.eu `documentation/audits/night-2026-09-24/C-02…C-07`, `audits/r672-2026-09-24/`.
+//
+// THE THREE RULES, all decided here before ANY mutation (before the scratch entry is even journaled):
+//  1. SPACE FIRST. The target storage must have free data ≥ restored × factor + reserve (defaults 1.2 and
+//     5 GiB, `backup.restore_test_space_factor` / `backup.restore_test_space_reserve_gib`), and a thin
+//     pool's metadata must have room for the same share. `restored` is the UNCOMPRESSED size — the
+//     archive FILE is the wrong number: 9201's archive was 6.9 GB and its restore wrote 22.6 GB, so
+//     "file × 1.2 + 5 GiB" (14.3 GB) would have let the 2026-09-24 test run into a pool with 23 GB free.
+//  2. KEEP OFF THE TESTED GUEST'S POOL when another eligible storage (active, takes `rootdir`, and the
+//     agent holds Datastore.AllocateSpace on it) passes rule 1. With only one, rule 1 decides.
+//  3. UNKNOWN REFUSES. An unreadable size, an unreadable storage or an unknown thin-pool metadata fill is
+//     a skip with its reason, never a guess — the fail-safe direction of every guard in this project.
+// A refusal is reported to the hub as the test's RESULT ("skipped: …", pass=false), never as a pass.
+// Pinned by restoretest_space_test.go.
+
+// RestoreSpace is the preflight's seam onto the host. Production: internal/restorespace.
+type RestoreSpace interface {
+	// RestoredBytes is how many bytes restoring `archive` will write (uncompressed), and where that
+	// figure came from (for the log and the refusal).
+	RestoredBytes(ctx context.Context, archive string) (bytes int64, source string, err error)
+	// Free reports the storage's free data bytes and, for a thin pool, its metadata-used fraction.
+	Free(ctx context.Context, storage string) (StorageFree, error)
+	// Eligible lists the storages a restore-test may target: active, content `rootdir`, and the agent
+	// holds Datastore.AllocateSpace there.
+	Eligible(ctx context.Context) ([]string, error)
+}
+
+// StorageFree is one storage's free space as the preflight judges it.
+type StorageFree struct {
+	AvailBytes int64
+	UsedBytes  int64
+	Thin       bool
+	// MetaUsedFraction is the thin pool's metadata use (0..1); MetaKnown false = could not be read.
+	MetaUsedFraction float64
+	MetaKnown        bool
+}
+
+// SpacePolicy is rule 1's margin.
+type SpacePolicy struct {
+	Factor       float64 // ≥ 1
+	ReserveBytes int64
+}
+
+// DefaultSpacePolicy is 1.2 × restored + 5 GiB.
+var DefaultSpacePolicy = SpacePolicy{Factor: 1.2, ReserveBytes: 5 << 30}
+
+// SpaceVerdict is the preflight's answer.
+type SpaceVerdict struct {
+	OK       bool
+	Storage  string // the storage the restore goes to (when OK) or was judged (when not)
+	Required int64
+	Avail    int64
+	Reason   string // empty when OK
+	// Avoided is the tested guest's own storage, when rule 2 moved the restore off it.
+	Avoided string
+}
+
+// requiredBytes is rule 1's figure.
+func (p SpacePolicy) requiredBytes(restored int64) int64 {
+	f := p.Factor
+	if f < 1 {
+		f = DefaultSpacePolicy.Factor
+	}
+	return int64(float64(restored)*f) + p.ReserveBytes
+}
+
+// fits judges one storage against rule 1 (data AND thin metadata). An unknown metadata fill on a thin
+// pool refuses (rule 3).
+func fits(fr StorageFree, required int64) (bool, string) {
+	if fr.AvailBytes < required {
+		return false, fmt.Sprintf("needs %s free, has %s", gib(required), gib(fr.AvailBytes))
+	}
+	if fr.Thin {
+		if !fr.MetaKnown {
+			return false, "thin-pool metadata fill unknown"
+		}
+		// The metadata a restore of `required` bytes needs, in the pool's own proportion of metadata to
+		// data. A pool with no data yet has no proportion to read → only the absolute ceiling applies.
+		need := 0.0
+		if fr.UsedBytes > 0 {
+			need = fr.MetaUsedFraction * float64(required) / float64(fr.UsedBytes)
+		}
+		if fr.MetaUsedFraction+need > 0.9 {
+			return false, fmt.Sprintf("thin-pool metadata would reach %.0f%% (now %.0f%%)", 100*(fr.MetaUsedFraction+need), 100*fr.MetaUsedFraction)
+		}
+	}
+	return true, ""
+}
+
+func gib(b int64) string { return fmt.Sprintf("%.1f GiB", float64(b)/(1<<30)) }
+
+// sourceStorages returns the storage ids that hold the ARCHIVED guest's volumes (rootfs and every mpN
+// that names a `storage:volume`), read from the archive's own embedded config — the guest under test.
+// Bind mounts (a leading "/") carry no storage.
+func sourceStorages(rawCfg string) map[string]bool {
+	out := map[string]bool{}
+	for k, v := range archiveCurrentConfig(rawCfg) {
+		if k != "rootfs" && !(strings.HasPrefix(k, "mp") && len(k) > 2 && k[2] >= '0' && k[2] <= '9') {
+			continue
+		}
+		vol := strings.TrimSpace(strings.SplitN(strings.TrimSpace(v), ",", 2)[0])
+		if vol == "" || strings.HasPrefix(vol, "/") {
+			continue
+		}
+		if st, _, ok := strings.Cut(vol, ":"); ok && st != "" {
+			out[st] = true
+		}
+	}
+	return out
+}
+
+// PreflightRestoreSpace applies the three rules. `configured` is `backup.restore_storage`.
+func PreflightRestoreSpace(ctx context.Context, space RestoreSpace, policy SpacePolicy, archive, rawCfg, configured string) SpaceVerdict {
+	if space == nil {
+		return SpaceVerdict{Storage: configured, Reason: "no space check is wired — refusing (fail-closed)"}
+	}
+	restored, src, err := space.RestoredBytes(ctx, archive)
+	if err != nil || restored <= 0 {
+		return SpaceVerdict{Storage: configured, Reason: fmt.Sprintf("cannot tell how much the restore writes (%v)", err)}
+	}
+	required := policy.requiredBytes(restored)
+	own := sourceStorages(rawCfg)
+
+	// Rule 2: the configured storage holds the guest under test → try the others first.
+	var order []string
+	avoided := ""
+	if own[configured] {
+		eligible, eerr := space.Eligible(ctx)
+		if eerr == nil {
+			sort.Strings(eligible)
+			for _, s := range eligible {
+				if s != configured && !own[s] {
+					order = append(order, s)
+				}
+			}
+		}
+		if len(order) > 0 {
+			avoided = configured
+		}
+	}
+	order = append(order, configured)
+
+	var last SpaceVerdict
+	for _, s := range order {
+		fr, ferr := space.Free(ctx, s)
+		if ferr != nil {
+			last = SpaceVerdict{Storage: s, Required: required, Reason: fmt.Sprintf("cannot read free space on %s (%v)", s, ferr)}
+			continue
+		}
+		ok, why := fits(fr, required)
+		v := SpaceVerdict{OK: ok, Storage: s, Required: required, Avail: fr.AvailBytes}
+		if ok {
+			if s != configured {
+				v.Avoided = avoided
+			}
+			return v
+		}
+		v.Reason = fmt.Sprintf("not enough space on %s: restoring %s (%s) %s", s, gib(restored), src, why)
+		last = v
+	}
+	return last
+}

internal/reconcile/restoretest_space_test.go

@@ -0,0 +1,156 @@
+package reconcile
+
+import (
+	"context"
+	"errors"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// R-672 (v0.133.0) — the restore-test's space preflight. Every test asserts the CONSEQUENCE: whether the
+// Proxmox API was asked to restore anything, where to, and what the result says — never only the verdict.
+
+const gb = int64(1000 * 1000 * 1000)
+
+// fakeSpace is a configurable RestoreSpace.
+type fakeSpace struct {
+	restored    int64
+	restoredErr error
+	free        map[string]StorageFree
+	freeErr     map[string]error
+	eligible    []string
+}
+
+func (f fakeSpace) RestoredBytes(context.Context, string) (int64, string, error) {
+	return f.restored, "fake", f.restoredErr
+}
+func (f fakeSpace) Free(_ context.Context, s string) (StorageFree, error) {
+	if err := f.freeErr[s]; err != nil {
+		return StorageFree{}, err
+	}
+	fr, ok := f.free[s]
+	if !ok {
+		return StorageFree{}, errors.New("unknown storage")
+	}
+	return fr, nil
+}
+func (f fakeSpace) Eligible(context.Context) ([]string, error) { return f.eligible, nil }
+
+// thin9201 is demo-hp's local-lvm at 10:29 on 2026-09-24, just before the restore-test that filled it:
+// 23.2 GB free, 33.3 GB used, metadata 2.65 %.
+var thin9201 = StorageFree{AvailBytes: 23210892 * 1024, UsedBytes: 33277043 * 1024, Thin: true, MetaUsedFraction: 0.0265, MetaKnown: true}
+
+// archive9201 is 9201's archive config: both volumes on local-lvm.
+const archive9201 = "hostname: demo-hp\nrootfs: local-lvm:vm-9201-disk-0,size=32G\nmp0: local-lvm:vm-9201-disk-1,mp=/var/lib/felhom,backup=1,size=70G\nmp8: /mnt/felhom-drives,mp=/mnt/felhom-drives\n"
+
+func spaceEngine(t *testing.T, api *fakeAPI, sp RestoreSpace) (*Engine, *Journal) {
+	t.Helper()
+	j, err := OpenJournal(filepath.Join(t.TempDir(), "journal.log"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { j.Close() })
+	q := NewQueue()
+	t.Cleanup(q.Close)
+	return NewEngine(EngineOptions{API: api, Queue: q, Journal: j, RestoreSpace: sp}), j
+}
+
+func run9201(e *Engine) RestoreTestResult {
+	return e.RunRestoreTest(context.Background(), RestoreTestSpec{
+		Archive: "local:backup/vzdump-lxc-9201-2026_09_23-06_55_25.tar.zst", RestoreStorage: "local-lvm",
+		ScratchMin: 990000, ScratchMax: 990009, SourceTier: "local",
+	})
+}
+
+// TestSpace_The2026_09_24TestIsRefused replays R-672: 9201's archive restores 22.6 GB (its vzdump log),
+// the pool has 23.2 GB free. The test must NOT start — no restore call, no journaled scratch — and the
+// result must say why, as a non-pass.
+//
+// COMPANION RED-PROOFS (REPORT): (1) the preflight removed (v0.132.0's shape) → a restore into local-lvm
+// is issued; (2) `restored` taken from the archive FILE (6.9 GB, the brief's "archive × 1.2 + 5 GiB") →
+// 6.9×1.2+5.4 = 13.7 GB < 23.2 GB free, so the test starts — the defect the uncompressed size exists for.
+func TestSpace_The2026_09_24TestIsRefused(t *testing.T) {
+	api := &fakeAPI{extractCfg: archive9201, cfg: map[int]proxmox.GuestConfig{990000: scratchCfg()}}
+	e, j := spaceEngine(t, api, fakeSpace{restored: 22607360000, free: map[string]StorageFree{"local-lvm": thin9201}})
+	res := run9201(e)
+	if len(api.restores) != 0 {
+		t.Fatalf("a restore was issued into a pool that cannot take it: %+v", api.restores)
+	}
+	if len(j.InFlight()) != 0 {
+		t.Fatalf("a scratch entry was journaled for a test that must not start: %+v", j.InFlight())
+	}
+	if res.Pass || !res.Skipped || !strings.Contains(res.SkipReason, "not enough space on local-lvm") {
+		t.Fatalf("result = pass=%v skipped=%v reason=%q — want a non-pass skip naming the storage", res.Pass, res.Skipped, res.SkipReason)
+	}
+	if res.RequiredBytes < 32*gb || res.AvailBytes != thin9201.AvailBytes {
+		t.Fatalf("required=%d avail=%d — want ≥ 32 GB required (22.6 × 1.2 + 5 GiB) against 23.2 GB", res.RequiredBytes, res.AvailBytes)
+	}
+}
+
+// TestSpace_KeepsOffTheTestedGuestsPool — rule 2: another eligible storage that fits takes the restore.
+func TestSpace_KeepsOffTheTestedGuestsPool(t *testing.T) {
+	api := &fakeAPI{extractCfg: archive9201, cfg: map[int]proxmox.GuestConfig{990000: scratchCfg()}}
+	e, _ := spaceEngine(t, api, fakeSpace{restored: 22607360000, eligible: []string{"local-lvm", "big-dir"},
+		free: map[string]StorageFree{"local-lvm": {AvailBytes: 900 * gb, UsedBytes: 10 * gb, Thin: true, MetaKnown: true}, "big-dir": {AvailBytes: 500 * gb}}})
+	res := run9201(e)
+	if len(api.restores) != 1 || api.restores[0].Storage != "big-dir" {
+		t.Fatalf("restores = %+v — want ONE restore onto big-dir, off 9201's own pool", api.restores)
+	}
+	if res.TargetStorage != "big-dir" {
+		t.Fatalf("target=%q", res.TargetStorage)
+	}
+	for k, v := range api.restores[0].MountOverrides {
+		if strings.HasPrefix(v, "local-lvm:") {
+			t.Fatalf("%s still lands on the tested guest's pool: %s", k, v)
+		}
+	}
+}
+
+// TestSpace_OnlyOnePool_RuleOneDecides — no other eligible storage: the tested guest's pool is used when it
+// fits (demo-hp's real shape: nvme-scratch takes rootdir but the agent holds no AllocateSpace there).
+func TestSpace_OnlyOnePool_RuleOneDecides(t *testing.T) {
+	api := &fakeAPI{extractCfg: archive9201, cfg: map[int]proxmox.GuestConfig{990000: scratchCfg()}}
+	e, _ := spaceEngine(t, api, fakeSpace{restored: 2 * gb, eligible: []string{"local-lvm"}, free: map[string]StorageFree{"local-lvm": thin9201}})
+	res := run9201(e)
+	if len(api.restores) != 1 || api.restores[0].Storage != "local-lvm" || res.Skipped || res.TargetStorage != "local-lvm" {
+		t.Fatalf("restores=%+v skipped=%v — a 2 GB restore fits 23 GB free on the only pool", api.restores, res.Skipped)
+	}
+}
+
+// TestSpace_UnknownRefuses — rule 3, one case per unknown. Nothing is restored in any of them.
+func TestSpace_UnknownRefuses(t *testing.T) {
+	cases := map[string]RestoreSpace{
+		"no space check wired":   nil,
+		"restore size unknown":   fakeSpace{restoredErr: errors.New("no vzdump log"), free: map[string]StorageFree{"local-lvm": thin9201}},
+		"free space unreadable":  fakeSpace{restored: gb, freeErr: map[string]error{"local-lvm": errors.New("api down")}},
+		"thin metadata unknown":  fakeSpace{restored: gb, free: map[string]StorageFree{"local-lvm": {AvailBytes: 900 * gb, UsedBytes: gb, Thin: true}}},
+		"metadata would overrun": fakeSpace{restored: 10 * gb, free: map[string]StorageFree{"local-lvm": {AvailBytes: 900 * gb, UsedBytes: 10 * gb, Thin: true, MetaUsedFraction: 0.5, MetaKnown: true}}},
+	}
+	for name, sp := range cases {
+		t.Run(name, func(t *testing.T) {
+			api := &fakeAPI{extractCfg: archive9201, cfg: map[int]proxmox.GuestConfig{990000: scratchCfg()}}
+			var e *Engine
+			if sp == nil {
+				e, _ = spaceEngine(t, api, nil)
+			} else {
+				e, _ = spaceEngine(t, api, sp)
+			}
+			res := run9201(e)
+			if len(api.restores) != 0 || res.Pass || !res.Skipped || res.SkipReason == "" {
+				t.Fatalf("restores=%d pass=%v skipped=%v reason=%q — an unknown must refuse before anything moves",
+					len(api.restores), res.Pass, res.Skipped, res.SkipReason)
+			}
+		})
+	}
+}
+
+// TestSpace_SourceStorages reads the tested guest's pools from the ARCHIVE's config, binds excluded.
+func TestSpace_SourceStorages(t *testing.T) {
+	got := sourceStorages(archive9201 + "mp1: other:vm-9201-disk-2,mp=/x,size=1G\n[snap]\nrootfs: snapstore:x\n")
+	if !got["local-lvm"] || !got["other"] || got["snapstore"] || len(got) != 2 {
+		t.Fatalf("sourceStorages = %v — want local-lvm + other, binds and snapshot sections excluded", got)
+	}
+}

internal/reconcile/space_fake_test.go

@@ -0,0 +1,16 @@
+package reconcile
+
+import "context"
+
+// roomySpace is the permissive RestoreSpace the pre-R-672 restore-test tests run with: 1 GiB restored,
+// 1 TiB free, thin metadata known and low. The space rules themselves are pinned in
+// restoretest_space_test.go.
+type roomySpace struct{}
+
+func (roomySpace) RestoredBytes(context.Context, string) (int64, string, error) {
+	return 1 << 30, "test", nil
+}
+func (roomySpace) Free(context.Context, string) (StorageFree, error) {
+	return StorageFree{AvailBytes: 1 << 40, UsedBytes: 1 << 30, Thin: true, MetaUsedFraction: 0.01, MetaKnown: true}, nil
+}
+func (roomySpace) Eligible(context.Context) ([]string, error) { return nil, nil }

internal/restorespace/restorespace.go

@@ -0,0 +1,176 @@
+// Package restorespace is the production seam behind reconcile.RestoreSpace (R-672, agent v0.133.0):
+// how much a restore of an archive writes, how much a storage has free, and which storages a
+// restore-test may target. Every read that cannot answer returns an error — the preflight then
+// REFUSES (reconcile/restoretest_space.go rule 3); nothing here guesses.
+package restorespace
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/reconcile"
+)
+
+// API is the Proxmox subset the provider reads.
+type API interface {
+	ListStorage(ctx context.Context) ([]proxmox.Storage, error)
+	NodeStorage(ctx context.Context) ([]proxmox.Storage, error)
+	StorageContent(ctx context.Context, store string) ([]proxmox.StorageContent, error)
+	Permissions(ctx context.Context, aclPath string) (map[string]int, error)
+}
+
+// Provider implements reconcile.RestoreSpace.
+type Provider struct {
+	API API
+	// ThinMeta reads a thin pool's metadata-used fraction (storage.HostOps.ThinPoolMetadata).
+	ThinMeta func(ctx context.Context, vg, pool string) (float64, bool)
+	// ReadFile reads a vzdump log; nil → os.ReadFile.
+	ReadFile func(name string) ([]byte, error)
+}
+
+var _ reconcile.RestoreSpace = (*Provider)(nil)
+
+// totalWrittenRe is vzdump's own count of the bytes tar wrote into the archive — the UNCOMPRESSED size,
+// i.e. what a restore writes back ("INFO: Total bytes written: 22607360000 (22GiB, 49MiB/s)").
+var totalWrittenRe = regexp.MustCompile(`Total bytes written:\s*(\d+)`)
+
+// archiveExts are the vzdump archive suffixes; the log is the archive name without it + ".log".
+var archiveExts = []string{".tar.zst", ".tar.gz", ".tar.lzo", ".tgz", ".tar"}
+
+func (p *Provider) readFile(name string) ([]byte, error) {
+	if p.ReadFile != nil {
+		return p.ReadFile(name)
+	}
+	return os.ReadFile(name)
+}
+
+// RestoredBytes: a file-backed archive → its vzdump log's "Total bytes written"; a PBS archive → the
+// size Proxmox reports for the snapshot (its logical, uncompressed size). The archive FILE size is never
+// used: it is compressed (6.9 GB for a 22.6 GB restore, measured 2026-09-24).
+func (p *Provider) RestoredBytes(ctx context.Context, archive string) (int64, string, error) {
+	id, vol, ok := strings.Cut(archive, ":")
+	if !ok || id == "" || vol == "" {
+		return 0, "", fmt.Errorf("not a storage volid: %q", archive)
+	}
+	st, err := p.storageConfig(ctx, id)
+	if err != nil {
+		return 0, "", err
+	}
+	switch st.Type {
+	case "pbs":
+		items, err := p.API.StorageContent(ctx, id)
+		if err != nil {
+			return 0, "", fmt.Errorf("list %s: %w", id, err)
+		}
+		for _, it := range items {
+			if it.VolID == archive && it.Size > 0 {
+				return it.Size, "pbs snapshot size", nil
+			}
+		}
+		return 0, "", fmt.Errorf("archive %s not listed on %s with a size", archive, id)
+	default:
+		if st.Path == "" {
+			return 0, "", fmt.Errorf("storage %s (%s) has no path to read a vzdump log from", id, st.Type)
+		}
+		base := path.Base(vol) // "backup/vzdump-lxc-…tar.zst" → "vzdump-lxc-…tar.zst"
+		stem := ""
+		for _, ext := range archiveExts {
+			if strings.HasSuffix(base, ext) {
+				stem = strings.TrimSuffix(base, ext)
+				break
+			}
+		}
+		if stem == "" {
+			return 0, "", fmt.Errorf("unknown archive suffix: %s", base)
+		}
+		logPath := path.Join(st.Path, "dump", stem+".log")
+		b, err := p.readFile(logPath)
+		if err != nil {
+			return 0, "", fmt.Errorf("read vzdump log %s: %w", logPath, err)
+		}
+		m := totalWrittenRe.FindSubmatch(b)
+		if m == nil {
+			return 0, "", fmt.Errorf("vzdump log %s carries no \"Total bytes written\"", logPath)
+		}
+		n, err := strconv.ParseInt(string(m[1]), 10, 64)
+		if err != nil || n <= 0 {
+			return 0, "", fmt.Errorf("vzdump log %s: bad byte count %q", logPath, m[1])
+		}
+		return n, "vzdump log: total bytes written", nil
+	}
+}
+
+func (p *Provider) storageConfig(ctx context.Context, id string) (proxmox.Storage, error) {
+	all, err := p.API.ListStorage(ctx)
+	if err != nil {
+		return proxmox.Storage{}, fmt.Errorf("list storage config: %w", err)
+	}
+	for _, s := range all {
+		if s.Storage == id {
+			return s, nil
+		}
+	}
+	return proxmox.Storage{}, fmt.Errorf("storage %s not configured", id)
+}
+
+// Free reads the node's live usage for `storage`; a thin pool adds its metadata fill.
+func (p *Provider) Free(ctx context.Context, storage string) (reconcile.StorageFree, error) {
+	live, err := p.API.NodeStorage(ctx)
+	if err != nil {
+		return reconcile.StorageFree{}, fmt.Errorf("node storage: %w", err)
+	}
+	for _, s := range live {
+		if s.Storage != storage {
+			continue
+		}
+		if s.Active != 1 {
+			return reconcile.StorageFree{}, fmt.Errorf("storage %s is not active", storage)
+		}
+		fr := reconcile.StorageFree{AvailBytes: s.Avail, UsedBytes: s.Used, Thin: s.Type == "lvmthin"}
+		if fr.Thin {
+			cfg, cerr := p.storageConfig(ctx, storage)
+			if cerr == nil && p.ThinMeta != nil && cfg.VGName != "" && cfg.ThinPool != "" {
+				fr.MetaUsedFraction, fr.MetaKnown = p.ThinMeta(ctx, cfg.VGName, cfg.ThinPool)
+			}
+		}
+		return fr, nil
+	}
+	return reconcile.StorageFree{}, fmt.Errorf("storage %s not reported by the node", storage)
+}
+
+// Eligible: active, content includes `rootdir`, and the agent holds Datastore.AllocateSpace on
+// /storage/<id>. The permission is read for the SPECIFIC privilege — the box-wide grant answers every
+// path with inherited privileges (proxmox.Client.Permissions).
+func (p *Provider) Eligible(ctx context.Context) ([]string, error) {
+	live, err := p.API.NodeStorage(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("node storage: %w", err)
+	}
+	var out []string
+	for _, s := range live {
+		if s.Active != 1 || !hasContent(s.Content, "rootdir") {
+			continue
+		}
+		privs, perr := p.API.Permissions(ctx, "/storage/"+s.Storage)
+		if perr != nil || privs["Datastore.AllocateSpace"] != 1 {
+			continue
+		}
+		out = append(out, s.Storage)
+	}
+	return out, nil
+}
+
+func hasContent(list, want string) bool {
+	for _, c := range strings.Split(list, ",") {
+		if strings.TrimSpace(c) == want {
+			return true
+		}
+	}
+	return false
+}

internal/restorespace/restorespace_test.go

@@ -0,0 +1,133 @@
+package restorespace
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// R-672 (v0.133.0). The provider behind the restore-test's space preflight. No test reaches a real
+// Proxmox or a real file: the API and ReadFile are fakes.
+
+type fakeAPI struct {
+	cfg     []proxmox.Storage
+	live    []proxmox.Storage
+	content map[string][]proxmox.StorageContent
+	perms   map[string]map[string]int
+}
+
+func (f fakeAPI) ListStorage(context.Context) ([]proxmox.Storage, error) { return f.cfg, nil }
+func (f fakeAPI) NodeStorage(context.Context) ([]proxmox.Storage, error) { return f.live, nil }
+func (f fakeAPI) StorageContent(_ context.Context, s string) ([]proxmox.StorageContent, error) {
+	return f.content[s], nil
+}
+func (f fakeAPI) Permissions(_ context.Context, p string) (map[string]int, error) {
+	if m, ok := f.perms[p]; ok {
+		return m, nil
+	}
+	return map[string]int{}, nil
+}
+
+const archive = "local:backup/vzdump-lxc-9201-2026_09_23-06_55_25.tar.zst"
+
+// The real log's tail (demo-hp, 2026-09-23): 22.6 GB written, a 6.91 GB archive file.
+const vzdumpLog = "2026-09-23 07:02:47 INFO: Total bytes written: 22607360000 (22GiB, 49MiB/s)\n2026-09-23 07:02:47 INFO: archive file size: 6.91GB\n"
+
+// demoHP is demo-hp's storage layout: `local` (dir, backups), `local-lvm` (thin), `nvme-scratch` (dir,
+// rootdir — but the agent holds NO grant there), a pbs.
+func demoHP() fakeAPI {
+	return fakeAPI{
+		cfg: []proxmox.Storage{
+			{Storage: "local", Type: "dir", Path: "/var/lib/vz"},
+			{Storage: "local-lvm", Type: "lvmthin", VGName: "pve", ThinPool: "data"},
+			{Storage: "nvme-scratch", Type: "dir", Path: "/mnt/hdd_1"},
+			{Storage: "felhom-pbs", Type: "pbs"},
+		},
+		live: []proxmox.Storage{
+			{Storage: "local", Type: "dir", Content: "vztmpl,backup,iso,import", Active: 1, Avail: 4 << 30, Used: 34 << 30},
+			{Storage: "local-lvm", Type: "lvmthin", Content: "images,rootdir", Active: 1, Avail: 23210892 * 1024, Used: 33277043 * 1024},
+			{Storage: "nvme-scratch", Type: "dir", Content: "images,rootdir", Active: 1, Avail: 800 << 30},
+			{Storage: "felhom-pbs", Type: "pbs", Content: "backup", Active: 0},
+		},
+		content: map[string][]proxmox.StorageContent{
+			"local":      {{VolID: archive, Size: 7417540996}},
+			"felhom-pbs": {{VolID: "felhom-pbs:backup/ct/9201/2026-09-23T02:00:00Z", Size: 21 << 30}},
+		},
+		perms: map[string]map[string]int{
+			"/storage/local":     {"Datastore.Audit": 1, "Datastore.AllocateSpace": 1},
+			"/storage/local-lvm": {"Datastore.Audit": 1, "Datastore.AllocateSpace": 1},
+			// nvme-scratch: only the inherited box-wide Datastore.Audit — the trap proxmox.Permissions names.
+			"/storage/nvme-scratch": {"Datastore.Audit": 1},
+		},
+	}
+}
+
+// TestRestoredBytes_ReadsTheUncompressedSize — the vzdump log's "Total bytes written", never the archive
+// FILE size (6.9 GB for a 22.6 GB restore).
+//
+// COMPANION RED-PROOF (REPORT): return the storage content's Size for a dir storage → 7417540996, and
+// this test fails at "the compressed file size was used".
+func TestRestoredBytes_ReadsTheUncompressedSize(t *testing.T) {
+	var asked string
+	p := &Provider{API: demoHP(), ReadFile: func(n string) ([]byte, error) { asked = n; return []byte(vzdumpLog), nil }}
+	n, src, err := p.RestoredBytes(context.Background(), archive)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n == 7417540996 {
+		t.Fatal("the compressed file size was used — the restore writes 3× that")
+	}
+	if n != 22607360000 || asked != "/var/lib/vz/dump/vzdump-lxc-9201-2026_09_23-06_55_25.log" {
+		t.Fatalf("n=%d from %q (log %q)", n, src, asked)
+	}
+}
+
+func TestRestoredBytes_UnknownIsAnError(t *testing.T) {
+	cases := map[string]*Provider{
+		"no log":           {API: demoHP(), ReadFile: func(string) ([]byte, error) { return nil, errors.New("ENOENT") }},
+		"log without size": {API: demoHP(), ReadFile: func(string) ([]byte, error) { return []byte("ERROR: failed\n"), nil }},
+	}
+	for name, p := range cases {
+		if n, _, err := p.RestoredBytes(context.Background(), archive); err == nil {
+			t.Fatalf("%s: got %d, want an error (the preflight then refuses)", name, n)
+		}
+	}
+	if _, _, err := (&Provider{API: demoHP()}).RestoredBytes(context.Background(), "local:backup/weird.vma"); err == nil {
+		t.Fatal("an unknown archive suffix must be an error")
+	}
+}
+
+func TestRestoredBytes_PBS(t *testing.T) {
+	p := &Provider{API: demoHP()}
+	n, _, err := p.RestoredBytes(context.Background(), "felhom-pbs:backup/ct/9201/2026-09-23T02:00:00Z")
+	if err != nil || n != 21<<30 {
+		t.Fatalf("n=%d err=%v", n, err)
+	}
+}
+
+// TestEligible_NeedsTheSpecificGrant — nvme-scratch takes rootdir but the agent holds only the inherited
+// Datastore.Audit there, so it is NOT eligible; `local` holds no rootdir.
+func TestEligible_NeedsTheSpecificGrant(t *testing.T) {
+	got, err := (&Provider{API: demoHP()}).Eligible(context.Background())
+	if err != nil || len(got) != 1 || got[0] != "local-lvm" {
+		t.Fatalf("eligible = %v (%v) — want only local-lvm on demo-hp", got, err)
+	}
+}
+
+func TestFree_ThinCarriesMetadata(t *testing.T) {
+	p := &Provider{API: demoHP(), ThinMeta: func(_ context.Context, vg, pool string) (float64, bool) {
+		if vg != "pve" || pool != "data" {
+			t.Fatalf("metadata read for %s/%s", vg, pool)
+		}
+		return 0.0265, true
+	}}
+	fr, err := p.Free(context.Background(), "local-lvm")
+	if err != nil || !fr.Thin || !fr.MetaKnown || fr.MetaUsedFraction != 0.0265 || fr.AvailBytes != 23210892*1024 {
+		t.Fatalf("free = %+v err=%v", fr, err)
+	}
+	if _, err := p.Free(context.Background(), "felhom-pbs"); err == nil {
+		t.Fatal("an inactive storage must be an error")
+	}
+}

internal/storage/observe.go

@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"regexp"
 	"strings"
+	"sync"
 
 	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
@@ -35,6 +36,45 @@ type Observer struct {
 	host   HostReader
 	ops    HostOps
 	logger *slog.Logger
+
+	// R-672 (v0.133.0): a thin pool crossing thinPoolAlarmFraction (data OR metadata) requests an
+	// out-of-band host report at once, so the hub's storage-fill alarm sees it in seconds instead of at
+	// the next 15-minute report. Rising edge per pool; re-armed below thinPoolRearmFraction.
+	highMu     sync.Mutex
+	high       map[string]bool
+	onThinHigh func()
+}
+
+const (
+	thinPoolAlarmFraction = 0.90
+	thinPoolRearmFraction = 0.85
+)
+
+// SetThinHighTrigger wires the out-of-band report request (main: the storage trigger channel).
+func (o *Observer) SetThinHighTrigger(f func()) { o.onThinHigh = f }
+
+// noteThinFill is the edge detector. key separates data from metadata so each has its own edge.
+func (o *Observer) noteThinFill(key string, frac float64) {
+	o.highMu.Lock()
+	if o.high == nil {
+		o.high = map[string]bool{}
+	}
+	fire := false
+	switch {
+	case frac >= thinPoolAlarmFraction && !o.high[key]:
+		o.high[key] = true
+		fire = true
+	case frac < thinPoolRearmFraction && o.high[key]:
+		o.high[key] = false
+	}
+	o.highMu.Unlock()
+	if fire {
+		o.logger.Error("storage: thin pool crossed 90% — requesting an immediate host report (the hub alarms)",
+			"pool", key, "fraction", frac)
+		if o.onThinHigh != nil {
+			o.onThinHigh()
+		}
+	}
 }
 
 // NewObserver builds an Observer. host defaults to a ProcHostReader; logger to the
@@ -260,6 +300,7 @@ func (o *Observer) build(s proxmox.Storage, mounts []Mount) observed {
 			o.logger.Warn("storage: lvmthin pool data fill is high (a full pool corrupts every guest on it)",
 				"storage", s.Storage, "data_used_fraction", frac)
 		}
+		o.noteThinFill(s.Storage+"/data", frac)
 	}
 
 	// SMART-only device hint (v0.95.0): a dir-storage that lives INSIDE a shared filesystem (the

internal/storage/observe_thinhigh_test.go

@@ -0,0 +1,34 @@
+package storage
+
+import (
+	"context"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
+)
+
+// R-672 (v0.133.0): a thin pool crossing 90 % requests an out-of-band host report ONCE, through the
+// watchdog's own read path (Known — every few seconds), so the hub's storage-fill alarm sees the pool in
+// seconds, not at the next 15-minute report. Re-armed below 85 %.
+//
+// COMPANION RED-PROOF (REPORT): remove the noteThinFill call from the data path → "no report was
+// requested when the pool crossed 90 %".
+func TestThinHigh_RequestsOneReportPerCrossing(t *testing.T) {
+	pool := proxmox.Storage{Storage: "local-lvm", Type: "lvmthin", Content: "rootdir,images", Total: 1000, Active: 1}
+	api := &fakeStorageAPI{node: "n", cluster: []proxmox.Storage{pool}}
+	o := NewObserver(api, &fakeHostReader{}, nil, quietLogger())
+	asked := 0
+	o.SetThinHighTrigger(func() { asked++ })
+	for i, used := range []int64{800, 910, 950, 1000, 840, 920} {
+		p := pool
+		p.Used, p.Avail, p.UsedFraction = used, 1000-used, float64(used)/1000
+		api.nodeSt = []proxmox.Storage{p}
+		if _, err := o.Known(context.Background()); err != nil {
+			t.Fatal(err)
+		}
+		want := map[int]int{0: 0, 1: 1, 2: 1, 3: 1, 4: 1, 5: 2}[i]
+		if asked != want {
+			t.Fatalf("after %d/1000 used: %d report requests, want %d", used, asked, want)
+		}
+	}
+}