R-331 (controller half): forward stats_known so the hub can tell empty from unmeasured (v0.225.0)

The hub's operator Backup card read `Snapshots 0 / Repo Size 0 MB / Integrity
Unknown` for EVERY customer, because it rendered the report's `backup` object --
whose snapshot/size/integrity fields have had NO producer since disk-tier restic
moved to the host agent (slice 8C). buildBackupReport leaves them zero
deliberately and says so. Measured on demo-hp 2026-08-30 while that night's log
said `[offbox] backup OK: 8 app(s) backed up, 67 snapshot(s), 2m14s`.

The live numbers were always in the report's `offsite` object, which the hub
already reads for its Offsite page and its fill/staleness alarms. The hub fix is
to render that -- and that made exactly ONE field mandatory that was not being
forwarded.

snapshot_count:0 means two opposite things: "holds nothing" and "never
measured". R-225 measured that confusion inside this repo (a rebuilt box
rendered 0 pillanatkep over a store really holding snapshot f3d9cd67), and
settings.OffboxTarget.StatsKnown fixed it for the controller's own UI. It was
never put on the wire, so the hub was free to make the identical mistake one
layer up -- and did. OffboxReportStatus.StatsKnown now carries it, omitempty, so
an older controller sends no key and a reader degrades to UNKNOWN, never to
EMPTY. Absence is ignorance, not emptiness.

The four dead BackupReport fields stay on the wire (historical reports in the
hub store must keep parsing) but now carry a warning naming R-331 and pointing
at Offsite. TestBackupReport_DeadFieldsStayZero fails the moment a producer
appears for one -- the prompt to update the hub card in the SAME change rather
than ship a field nothing renders.

RED-PROOF: drop `StatsKnown: t.StatsKnown` -> "a MEASURED empty repository
reported stats_known=<nil>". Tests assert the JSON the hub sees, not the Go
struct: measured-empty and never-measured must differ ON THE WIRE, which is the
entire point of the field.

Green gate clean: 28 packages, rc 0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LB8FmJaGd2cyjvy6dbEjpM

REUSE.md

@@ -61,6 +61,7 @@
 
 | Symbol | File | Short signature | Use for | Gotchas |
 |---|---|---|---|---|
+| `Manager.OffboxReportStatus` + `OffboxReportStatus.StatsKnown` (R-331, v0.225.0) | controller/internal/backup/offbox.go (~L1627) | `() *OffboxReportStatus` | THE off-site summary the hub reports on — snapshots, repo size, quota, last SUCCESSFUL run, declared state | **This object, not `report.BackupReport`, is where the hub gets live backup numbers.** `BackupReport`'s `SnapshotCount`/`RepoSizeMB`/`IntegrityOK` have had no producer since slice 8C; the hub rendered them anyway and told every operator every customer had `Snapshots 0` (R-331, measured on demo-hp over a repository holding 67). **`StatsKnown` must ride with the counts or they are unreadable**: zero is what an unread repository and a genuinely empty one both look like, and they are opposite news (R-225 measured that live). It is `omitempty`, so an older controller sends no key and a reader MUST degrade to "unknown", never to "empty". nil = nothing to say, EXCEPT the declared `needs_credential`/`awaiting_recovery_key` states, which report an object while disabled |
 | `backup.ErrOffboxSealedPackageHeld` + `IsOffboxSealedPackageHeld` + `sealedPackageHeld` + `OffboxAwaitingRecoveryKey` (R-241, v0.206.0) | controller/internal/backup/offbox.go | sentinel; `(error) bool`; `() bool`; `() bool` | **THE MINT GUARD** — a box never creates a repository key while the hub holds a sealed package for it | **The guard is a CONJUNCTION** (package held AND no key present). Widening it to "never mint" leaves a first-time box unable to start, waiting for a package that will never exist — pinned by `TestR241_ScenarioB_FirstTimeBoxStillMints`. **The refusal is a HOLDING state, not a failure:** `ApplyOffsiteTarget` catches the sentinel and still writes the transport, so `/recovery`'s synchronous tier-up (R-219) can bring the tier up the instant the key arrives; returning the error instead leaves `needsOffsiteCredential` true and the hub re-staging a consumed credential for ever. `OffboxAwaitingRecoveryKey` is **DERIVED, never stored** — and **`t.Enabled` is load-bearing in it**: a customer who switched off-site OFF is not awaiting anything (the Scenario-E carve-out `needsOffsiteCredential` makes two functions above; the first draft omitted it and an existing test caught it). A nil settings store reads as "no package held" — a transient read failure must never become a permanently-held tier |
 | `settings.HubEscrowKeySHA256` + `SetHubEscrowKeySHA256` / `GetHubEscrowKeySHA256`, and `OffsiteRecoveryOffer` **shape (c)** (R-241, v0.206.0) | controller/internal/settings/settings.go, controller/internal/backup/offbox.go | `(sha, checkedAt string) error` / `() (string, string)` | **THE DISCRIMINATOR the recovery screen asks** — does the hub hold a package for a key other than the one we use? | **The comparison was ALREADY computed on every ACK since SLICE 3 and persisted nowhere** — that is R-241's second half. Wire the recorder in `main.go`'s `EscrowAutoConfirmer` literal or shape (c) reads an empty hash for ever and the fix ships INERT (pinned by `TestMainWiresRecordEscrowKeyHash`). **§7.2 staleness, decided:** a KNOWN DIFFERENCE offers **however old the reading** — age is deliberately NOT gated on, because gating makes a box offline from the hub silently stop offering; an **ABSENT hash falls back to (a)/(b)** and does NOT offer, because `""` is the hub positively saying its package seals no key (legacy hash-less escrow), not an unknown. `CheckedAt` is for diagnosis, never a gate |
 | `backup.AbandonStatus` / `AbandonSweep` / `CancelAbandon` / `ClearAbandonPurgeIfConfirmed` / `ExtendAbandon` / `StopAbandon` + `AbandonGraceDays` (R-241, v0.206.0) | controller/internal/backup/offbox_abandon.go | see file | **The 14-day abandonment countdown** — the ONLY thing in the product that deletes a customer's off-site history | **BOTH HALVES OR NEITHER.** The set-aside store and the sealed package that protects it are two halves of one thing; removing only one leaves a package that opens nothing, or ciphertext nobody can decrypt. Not atomic across two machines, so it is a **two-phase commit**: delete the store, set `AbandonPurgeRequested`, and keep declaring it until the hub's ACK stops reporting a superseded package — the confirmation rides the SAME ACK as the request. **The countdown starts in `ResetOrphanedRepo`, NOT in the shared `resetOrphanedRepo`** — the helper is also the UNCLAIMED auto-reset, where nobody decided anything. **The recovery offer stays reachable for the whole grace** (a grace in which recovery is impossible is decorative). **Drive it with `SetOffboxClock`, never a shortened live timer** (§7.4). A transport failure leaves the countdown DUE so tomorrow retries; the operator levers REFUSE rather than no-op when nothing is running or the store is already gone |