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

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 }