212 lines
12 KiB
Markdown
212 lines
12 KiB
Markdown
# REPORT — v0.97.0: R-82 Slice A — per-target backup tiers (2026-07-26)
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Slice A of R-82 (the backup target split). **Mechanism only — no box's behaviour changes until a
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`backup_targets` entry is added to its config, which is Slice D.** An untouched config resolves to
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exactly one tier and behaves byte-identically to v0.96.0.
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Phase-0 gates: `felhom.eu/documentation/audits/SPIKE-r82-phase0-2026-07-26.md`.
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Operator ruling 2026-07-26: datastore growth deferred, proceed. Capacity state recorded in
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`felhom.eu/documentation/architecture/07-backup-architecture.md` §9.1.
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**STOPPED at the Slice A boundary as specified.** Slices B/C/D/E not started.
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---
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## 1. What was wrong
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`BackupTarget()` returned ONE string and `BackupCadence()` ONE 24 h window. "Local daily **and** PBS
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weekly" was not expressible at all — which is why the DR promise is unbacked today: demo-felhom holds
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a single PBS snapshot from 2026-07-18 (a healing artifact, not a job) and demo-hp has **zero, ever**,
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despite `pbs_dr` reporting `applied` since 07-21.
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## 2. Files modified
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| File | Change |
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|---|---|
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| `internal/config/config.go` | `BackupTargetConfig`, `BackupConfig.ExtraTargets` (`backup_targets`), `BackupTier`, `BackupTiers()` |
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| `internal/localapi/server.go` | per-target due/status/POST, `?target=` resolution, `/backup/tiers`, jobs keyed by (vmid,target), per-tier job ids |
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| `internal/localapi/backup_tiers.go` | **NEW** — `normalizeBackupTiers` (the compatibility core) |
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| `cmd/felhom-agent/main.go` | one runner per tier; tier-rejection warnings logged at **ERROR** |
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| `internal/config/backup_tiers_test.go` | **NEW** — 7 tests |
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| `internal/localapi/backup_tiers_test.go` | **NEW** — 13 tests |
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| `CHANGELOG.md`, `REUSE.md` | v0.97.0 entry; new canonical-helper row |
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Commit: **`739b3c3`** on `main`, pushed.
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## 3. The compatibility rule — how it is enforced
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The agent and controller deploy independently, so the untargeted contract is **frozen**:
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- `BackupDueResponse.Target` / `BackupResponse.Target` / `BackupStatusResponse.Target` are all
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`omitempty` and left **EMPTY** for an untargeted request → the response marshals to the pre-R-82
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**bytes**, not merely a compatible shape. Verified live:
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`{"ok":true,"data":{"vmid":8200,"due":false,"reason":"within cadence window","age_seconds":7200}}`
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- The untargeted verdict comes from the **primary tier only** — a fresh backup on another tier must
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not satisfy it (own test).
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- The **primary tier's job-id format is unchanged**; only additive tiers carry a target segment.
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- An unknown `?target=` is a **400, never a silent fallback**. A controller asking about a tier this
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agent does not serve must find out, not act on a different tier's freshness.
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- `GET /backup/tiers` 404s on a pre-R-82 agent — that 404 is Slice B's designed capability probe.
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## 4. Design decisions, and why
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**One runner per tier** (not a target-parameterised runner). The runner holds target, mode, notes and
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retention as immutable construction state, and `localPruneSpec` reads that retention — parameterising
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a single runner by target would make it possible to pair tier A's target with tier B's retention. One
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runner per tier makes each tier's policy structurally inseparable from its target.
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**A missing cadence is REJECTED, not defaulted.** Defaulting an extra tier to the 24 h local default
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would quietly turn a weekly DR tier into a daily one and fill the 37.2 GB datastore. A tier whose
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cadence you did not state is not a tier. `main.go` logs every rejection at **ERROR** — a silently
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dropped backup tier is the "applied and empty" fault R-82 exists to fix.
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**`keep_last` unset = never prune.** The fail-safe: a DR tier must not start pruning itself because
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someone forgot a field. Negative values clamp to the same.
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**Jobs keyed by (vmid, target).** This is what lets the weekly night run both backups inside ONE
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quiesce window (Slice B). It also fixed a real defect — see §6.
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## 5. The Slice A.4 finding (Slice C depends on this)
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**A PBS-targeted vzdump will appear in BOTH arrays**, and this is expected, not a bug:
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- in `backups[]` as `Backup{TargetID:"felhom-pbs", Archive:"felhom-pbs:backup/ct/9201/…"}` — written
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by the runner, recorded in the agent's in-memory store;
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- in `pbs_snapshots[]` — enumerated **independently** from the PBS API by the agent's verify loop.
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**Double-counting is harmless for freshness** (the hub takes a max, which is idempotent).
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**Mis-attribution is not.** If Slice C treats `backups[]` as "the local tier" and `pbs_snapshots[]`
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as "the PBS tier", a PBS-target `Backup` record would be attributed to the local tier and make a
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**stale local tier look fresh**.
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**The rule Slice C must implement:** classify a `backups[]` entry by joining its `target_id` to
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`storage_targets[].name` and reading `.type == "pbs"` — **by target type, never by array membership.**
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Verified live that the discriminator is present in production reports:
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```
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demo-felhom name=felhom-pbs type=pbs content=backup reachable=true
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demo-felhom name=local type=local content=…,backup reachable=true
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demo-hp name=felhom-pbs type=pbs content=backup reachable=true
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drill-r50 name=local type=local content=backup,… reachable=true (no PBS storage yet)
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```
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This is preferable to keying off `pbs_dr.storage_id`, which is `null` on drill-r50.
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## 6. Tests — 748 → 768 (+20)
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Full gate green, **`go vet` run unpiped** (rc printed separately; R-81 recorded that piping it into
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`head` reports rc=0 while failing):
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```
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go build ./... rc=0
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go vet ./... rc=0
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go test ./... rc=0 (every package ok)
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```
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### Red-proof #1 — old controller ↔ new agent (mandatory) — OBSERVED
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Removed the untargeted compat branch in `tierFromRequest` so it echoes the primary's id like any
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other tier:
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```
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--- FAIL: TestBackupDue_Untargeted_ResponseBytesUnchanged (0.00s)
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backup_tiers_test.go:105: UNTARGETED response MUST NOT carry a target key — an old controller
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sees a changed contract; body: {"ok":true,"data":{"vmid":8200,"due":false,
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"reason":"within cadence window","age_seconds":7200,"target":"local"}}
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```
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Restored; suite green.
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### A defect the tests caught (worth recording)
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`TestBackupPost_SingleFlightIsPerTierNotPerGuest` **failed on first run**:
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```
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backup_tiers_test.go:320: PER-TIER single-flight violated: the PBS request was handed the LOCAL
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job id "backup-8200-1781092800000000000" — the controller would believe the PBS backup ran
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```
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Job ids were `backup-<vmid>-<unixnano>` — unique only by clock luck, and identical under an injected
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clock or two tiers starting in the same nanosecond. Fixed so ids are unique **per tier by
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construction**, with the primary's format left unchanged. This is precisely the failure mode Slice B
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would have hit on the weekly both-due night.
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## 7. Live validation performed
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**No live deploy — see §8.** The strongest zero-risk check available was run instead: an end-to-end
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wire test composing the REAL path `agent.json bytes → config.BackupConfig → BackupTiers() →
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localapi.BackupTier → a real TLS listener`, driven by a real HTTP client (`httptest`'s own trusting
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client — TLS verification was **not** disabled). Unit tests cover each half; this proves the join,
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which is where a per-tier mis-wire would actually live.
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```
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tier armed: target=local cadence=24h0m0s keep_last=3 primary=true
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tier armed: target=felhom-pbs cadence=168h0m0s keep_last=2 primary=false
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GET /backup/tiers -> 200 {"tiers":[{"target":"local","cadence_seconds":86400,"primary":true},
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{"target":"felhom-pbs","cadence_seconds":604800,"primary":false}]}
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GET /backup/due (UNTARGETED) -> 200 {"vmid":8200,"due":false,"reason":"within cadence window","age_seconds":7200}
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GET /backup/due?target=local -> 200 {…,"due":false,"target":"local"}
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GET /backup/due?target=felhom-pbs -> 200 {…,"due":true,"reason":"older than cadence","age_seconds":691200,"target":"felhom-pbs"}
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GET /backup/due?target=bogus -> 400 {"ok":false,"error":"unknown backup target: bogus"}
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```
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The fixture is the exact `agent.json` shape Slice D will write: fresh daily local (2 h) + a PBS
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snapshot at 8 days. The DR tier correctly reports **due** while the local tier does not — the
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behaviour whose absence is the entire bug. Harness deleted; tree clean.
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Binary built and verified: `felhom-agent 0.97.0` (13.9 MB, `/tmp/felhom-agent-0.97.0`). **Not
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installed anywhere.**
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## 8. NOT live-validated — and the deploy target problem
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**Slice A's "deploy to the drill VM only" step was NOT performed: no drill target is reachable.**
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| Candidate | Status |
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|---|---|
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| **drill-r50** (`drill-r50-0a4f9a`) — the correct target: a live, hub-enrolled drill host | **UNREACHABLE.** Its operator path is wg-only (`10.77.0.4:8822`, OOB `felhom_sshd_active:true`). DooPlex has **no wg interface** — TCP connect to `10.77.0.4:8822` fails. No SSH alias exists |
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| **`/mnt/5_hdd/felhom.eu/drill/drill.qcow2`** on DooPlex | Present but **not a Felhom host** — a bare PVE install whose only snapshot is `virgin` (2026-07-03), powered off. Using it means a full greenfield run (host-install → guest provision → hub enrol), which is a different task with real half-state risk, not "deploy the agent" |
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| demo-felhom / demo-hp | **Production — explicitly excluded by this slice** |
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Consequently the following are unproven and must be proven at Slice D step 1:
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1. **The tier-arming startup log on a real host** (`backup tier armed` × N, and `backup tier REJECTED`
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at ERROR for a bad config). Proven by unit test + the composed wire test only.
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2. **A real vzdump to `felhom-pbs` via the new per-tier runner** — no PBS-targeted backup has been
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run by this code.
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3. **The A.4 double-appearance in a real host-report.** §5 is derived from source plus the live
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`storage_targets` shape; it has not been observed with an actual PBS-target `Backup` record
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present, because none exists yet.
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4. **Per-tier retention against a real storage** — `localPruneSpec`'s PBS refusal is unchanged, so no
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PBS prune can occur, but that is asserted from source, not exercised.
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5. **The restore round-trip.** Per the task's own bar, a tier is only real once a `pct` restore from
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its snapshot yields a working guest. Nothing here approaches that.
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## 9. Open decisions carried forward
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- **PBS pruning is still OFF.** Per-tier retention is plumbed and each tier carries its own
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`keep_last`, but `localPruneSpec` still refuses to prune a PBS-type target, and an unset
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`keep_last` means never-prune. Turning on automatic pruning of the DR datastore is irreversible and
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needs an operator ruling — P0.3 already flagged retention as one of the levers. **Left OFF
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deliberately; with capacity already tight, the wrong default here is unrecoverable.**
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- **The P0.3 capacity constraint stands.** Growth deferred by operator ruling; the 80 % warn is still
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projected at roughly the second additional customer.
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- **drill-r50 has no Tier-3 offsite** (`offsite: null`), so the P0.1 "weekly is sufficient" verdict
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does **not** hold for it. It is first in the Slice D rollout order — its PBS cadence cannot simply
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inherit the fleet ruling.
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## 10. Observations
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1. `local_backup_target` on both production boxes is `"local"`, so `BackupTarget()`'s
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`defaultBackupTarget = "felhom-pbs"` fallback is never exercised in production. A box with that
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key **absent** would send its primary daily backup to PBS — surprising, and worth checking during
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Slice D before writing any config.
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2. The agent's backup `Store` remains in-memory (R-84). Slice A does not change that: after a restart
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both tiers' records are empty until each next run, so `/backup/due` reports **due** for every tier.
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That is fail-safe (a spurious backup, not a skipped one), but on the weekly tier it means a
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restart can pull a PBS backup forward. Worth naming in Slice B's dedup reasoning.
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3. `RestoreTest.SourceTier` is still typed as `"local"` with a comment saying PBS is "Phase B". With a
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real PBS tier arriving, the restore-test's tier attribution should be revisited — not in scope
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here, recorded.
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