felhom-agent/REPORT.md

# REPORT — R-82: per-target backup tiers, agent v0.97.0 → v0.102.0 (2026-07-26)

**Overwritten** per the standing rule. Live on **demo-felhom** and **demo-hp**.
Full cross-repo arc + the Phase-0 gates: `felhom.eu/REPORT.md`.

## Versions in this arc

| | |
|---|---|
| **v0.97.0** | Slice A — per-target cadence/retention, `/backup/tiers`, per-tier due + runner + job keys |
| **v0.98.0** | the 30-minute false failure — per-tier vzdump wait bound |
| **v0.99.0** | operator rulings — 2-week offsite retention (scoped PBS prune opt-in) + one backup at a time per guest |
| **v0.100.0** | the restore tier comes from the ARCHIVE, not the configured target |
| **v0.101.0** | a leaked restore-test scratch can no longer auto-start (`onboot=0` at restore time) |
| **v0.102.0** | an unprovisioned tier DEFERS instead of firing at a missing storage |
| **v0.103.0** | **R-84** — an agent restart no longer triggers a redundant backup |

## Four defects found by RUNNING it, not reviewing it

1. **v0.98.0** — a 41-minute PBS backup was recorded `success:false` at 30 minutes **while it was
   still running**, and it later completed `TASK OK`. Worse than "the backup didn't happen": the
   tier stays permanently due and the retry collides with the guest lock.
2. **v0.100.0** — a `felhom-pbs:` archive was classified `local` and got the 10-minute bound against
   a 14.46 GB WAN restore, failing at 600 s. **A silent regression of the S4.1 fix** — the mechanism
   was never removed; its *input* changed when `local_backup_target` was retargeted to `local`. A fix
   keyed on *"the configured target"* stops holding the moment more than one target exists.
3. **v0.101.0** — a leaked scratch guest kept `onboot: 1`, so a host reboot would have started a
   clone of the live guest. `onboot=0` is now set **at restore time**, because "after" is the path
   that leaks.
4. **v0.102.0** — a tier fires at a storage that does not exist yet (a fresh box before DR
   provisioning). Now deferred, going live with no restart once the storage appears.
5. **v0.103.0 (R-84)** — three redundant local backups ran on demo-felhom in one afternoon of
   deploys, because the in-memory `Store` is empty after a restart and the due-check read that as
   "no backup ever". On the offsite tier that is a wasted multi-hour WAN upload after every agent
   deploy. The due-check now consults the STORAGE (ground truth: a pruned archive correctly stops
   counting, where a persisted record would keep claiming a backup that no longer exists).

## The frozen contract

Untargeted `/backup/due`, `POST /backup` and `/backup/status` keep the **primary tier and the
pre-R-82 response bytes** (`Target` is `omitempty` and stays empty); the primary's job-id format is
unchanged. Verified live on demo-felhom:

```
/backup/due (untargeted)      {"vmid":9201,"due":true,"reason":"no successful backup recorded yet"}
/backup/due?target=felhom-pbs {...,"target":"felhom-pbs"}
/backup/due?target=bogus      400 "unknown backup target: bogus"
```

An unknown `?target=` is a **400, never a silent fallback** — a caller asking about a tier this agent
does not serve must find out, not act on another tier's freshness.

## Fail-safe directions, stated once

- Unparseable timestamp → **due** (a spurious backup is cheap; a skipped one is not).
- Storage-view error → **present** (`"I could not check"` is not `"not there"` — reading it that way
  would silently suppress backups, the rule this project has relearned three times).
- Missing tier cadence → **rejected, logged at ERROR** (never defaulted: a weekly DR tier silently
  running daily would fill the datastore).
- Unset `keep_last` → **never prune** (a DR tier must not start pruning itself because someone forgot
  a field). The primary tier keeps the **absolute** PBS-prune refusal, because its target *and*
  retention both default and could prune the DR by accident.

## Live validation (demo-felhom)

Both tiers armed: `local 24h keep_last=3 wait 30m` + `felhom-pbs 168h keep_last=2 wait 12h
prune_pbs_allowed=true`. First real PBS-targeted backup: **`TASK OK`, 41 minutes, 14.46 GB
snapshot**, and it **restored cleanly** (`vzrestore: stopped OK`). Measured incremental cost:
**+2.7 GB on disk** for a 14.46 GB logical snapshot (~81 % dedup).

**demo-hp — the box that had ZERO offsite snapshots, ever:** deployed via the documented break-glass
path (binary + config backed up first), tier armed, and its **first ever** PBS backup **landed** —
`felhom-pbs:backup/ct/9201/2026-07-26T15:42:42Z`, **4.25 GB**, into a namespace that was verifiably
empty beforehand. That is the R-82 finding closed on the box where it was worst.

**R-84 proven live on both boxes** — immediately after a restart, with the in-memory store cold, the
due-check reports real ages read from the storage instead of "no successful backup recorded yet":

```
demo-felhom  local age=5298s   felhom-pbs age=14373s   both due:false
demo-hp      local age=498s    felhom-pbs age=2346s    both due:false
```

Before v0.103.0 every one of those would have said "no successful backup recorded yet" and triggered
a redundant backup — on the offsite tier, a multi-hour upload.

## The restore round-trip — PASSED (demo-hp, 2026-07-26)

```
source_archive : felhom-pbs:backup/ct/9201/2026-07-26T15:42:42Z
source_tier    : pbs        <- the v0.100.0 fix; the earlier attempt said "local" and died at 600s
pass           : true
verified       : boot+running
mount_parity   : ok         <- mp0=/var/lib/docker 50G, mp1=/mnt/sys_drive 20G, mp8/mp9 stand-ins
duration       : 4m5s       (restore + boot + verify + teardown)
```

`mount_parity` is the non-hollow half — a boot-only verify cannot see a missing data volume. The
scratch tore down **cleanly** (no 403, no leak), confirming that the teardown 403 was a **phantom**
(a short-timeout consequence, as `06-offsite-connectivity.md` already recorded) and correcting my
earlier framing of it as a standing privilege gap.

## Tests

`go build ./... && go vet ./... && go test ./...` — **rc=0, 29 packages**, vet run unpiped.

Red-proofs observed and restored: old-controller compat (`"target":"local"` leaking into the
untargeted body), the per-tier wait bound, and the `onboot` override. A per-tier single-flight defect
was caught **by its own test** before it ever shipped — job ids were unique only by clock luck, so
the PBS request was handed the local job's id.

**Process failure recorded:** I ran the suite and committed in the same command, read
`packages ok: 28` and pushed without checking `rc=1`; five of my own tests were failing (a harness
artifact, fixed in the follow-up). That is the exact exit-code trap recorded twice earlier in this
arc.

## NOT done

1. The **scheduled** restore-test still only ever selects the **primary** tier, so the offsite tier
   is never automatically restore-tested — arguably the more important half of "is the DR tier real?".
2. The agent does not report per-tier **cadences**, so the hub must infer "PBS ⇒ weekly" from storage
   type.
3. The **unattended** offsite restore-test — the scheduled path still only selects the primary tier.
   (The manual/selftest round-trip is now PROVEN: `pass:true`, `verified:"boot+running"`,
   `mount_parity:"ok"`, `source_tier:"pbs"`, 4m5s, clean teardown on demo-hp.)