REPORT + CLAUDE: slice 8B.2 agent half (snapshotted phase, v0.13.0)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -15,7 +15,7 @@
 - Module `gitea.dooplex.hu/admin/felhom-agent`; binary `felhom-agent` (`cmd/felhom-agent/`).
 - **Pure Go stdlib + `golang.org/x/crypto` only** — no web frameworks.
 - `go.mod` directive **go 1.25.0**; dep `golang.org/x/crypto v0.52.0` (declares go 1.25, will NOT build on Go 1.24). The **build server (192.168.0.180) runs go1.26.0** (upstream Go on PATH, backward-compatible). Build/run the agent there for live tests (same LAN as the demo host).
-- Version: `version` var in `cmd/felhom-agent/main.go`, overridable via `-ldflags "-X main.version=<v>"`; `--version` flag. **Current: v0.12.0** (slice 8C Phase A: the `/disks` endpoints — `internal/localapi/disks.go` + `internal/storage` `mkfs` executor + `InspectDevice`/`DeviceProbe` data-bearing detection. **Security centerpiece**: `POST /disks/format` inspects the device itself; data-bearing → `ClassStorageWipe` → gate → `pending_signature` refused (caller's claim ignored); blank → benign `mkfs`. `FELHOM_FORMAT` sudoers. Controller de-privileging is `felhom-controller` v0.37.0. Plus slice 8B: `internal/localapi` `/backup/due` real **cadence** policy + `/backup/status` **phases** (idle|running|done|failed) + `POST /backup` single-flight job id — the app-consistent backup the controller's quiesce loop drives; `backup.backup_cadence_seconds`. Plus slice 8A: the per-guest **local-API server** `internal/localapi` — the doc 03 §6 authorization gate, 7 self-scoped endpoints, hashed per-guest token store, persisted self-signed leaf w/ stable pin; the **provisioning back-half** `internal/provision` — mint token → render `bootstrap.json` → write 0600 → `chown 100000:100000` → `pct set` bind mount, host-side/F3, no registry cred in guest; `--selftest=provision`; `build-golden.sh` now bakes the controller. Plus v0.9.0's PBS escrow. Runtime dep: `proxmox-backup-client`). Bump on meaningful changes + add a CHANGELOG entry.
+- Version: `version` var in `cmd/felhom-agent/main.go`, overridable via `-ldflags "-X main.version=<v>"`; `--version` flag. **Current: v0.13.0** (slice 8B.2: `/backup/status` gains a **`snapshotted`** phase — `BackupRunner.BackupWithSnapshotHook` tails the vzdump task log for the `create storage snapshot` marker (snapshot mode only) and fires a hook so the controller resumes its app at snapshot-taken, not backup-done. Plus slice 8C Phase A: the `/disks` endpoints — `internal/localapi/disks.go` + `internal/storage` `mkfs` executor + `InspectDevice`/`DeviceProbe` data-bearing detection. **Security centerpiece**: `POST /disks/format` inspects the device itself; data-bearing → `ClassStorageWipe` → gate → `pending_signature` refused (caller's claim ignored); blank → benign `mkfs`. `FELHOM_FORMAT` sudoers. Controller de-privileging is `felhom-controller` v0.37.0. Plus slice 8B: `internal/localapi` `/backup/due` real **cadence** policy + `/backup/status` **phases** (idle|running|done|failed) + `POST /backup` single-flight job id — the app-consistent backup the controller's quiesce loop drives; `backup.backup_cadence_seconds`. Plus slice 8A: the per-guest **local-API server** `internal/localapi` — the doc 03 §6 authorization gate, 7 self-scoped endpoints, hashed per-guest token store, persisted self-signed leaf w/ stable pin; the **provisioning back-half** `internal/provision` — mint token → render `bootstrap.json` → write 0600 → `chown 100000:100000` → `pct set` bind mount, host-side/F3, no registry cred in guest; `--selftest=provision`; `build-golden.sh` now bakes the controller. Plus v0.9.0's PBS escrow. Runtime dep: `proxmox-backup-client`). Bump on meaningful changes + add a CHANGELOG entry.
 
 ## Layout
 

REPORT.md

@@ -1,49 +1,53 @@
-# REPORT — slice 8C Phase A (agent half): disk endpoints + data-bearing classifier gate (v0.12.0) (2026-06-10)
+# REPORT — slice 8B.2 (agent half): quiesce downtime optimization — `snapshotted` phase (v0.13.0) (2026-06-10)
 
-> Overwrite-latest report. Cumulative history: [CHANGELOG.md](CHANGELOG.md). Implements the
-> host-agent half of `TASK — Slice 8C`. The controller de-privileging + disk-subsystem retirement is
-> the `felhom-controller` half (v0.37.0). No hub change.
+> Overwrite-latest report. Cumulative history: [CHANGELOG.md](CHANGELOG.md). Implements the agent
+> half of `TASK — Slice 8B.2`. The controller early-resume is `felhom-controller` v0.38.0. No hub change.
 
 ## Outcome
 
-The agent now owns disk execution. It serves the §6 disk-management endpoints the controller's UI
-drives, with the **8C security invariant**: the agent decides data-bearing-ness by **inspecting the
-actual device** (agent-internal evidence), NEVER from the caller's claim. A compromised controller
-asserting "this drive is blank" cannot wipe a data-bearing drive — **proven live** (a data-bearing
-device → refused `pending_signature`, `mkfs` never called, the device untouched).
+In snapshot mode an LXC vzdump only needs the app-stopped state captured at the **storage-snapshot
+moment**; after that it reads from the snapshot and the app can safely resume. The agent now emits a
+**`snapshotted`** phase on `GET /backup/status` when the snapshot is taken, so the controller resumes
+its app early — app downtime drops from *whole-backup* to *until-snapshot* with no loss of
+app-consistency.
+
+## Phase 0 (validated first, on the demo — PVE 9.2.2)
+
+- **Snapshot mode is in effect** on local-lvm (lvmthin) — `vzdump --mode snapshot` logs `backup mode:
+  snapshot`, not downgraded to stop.
+- **Marker:** `INFO: create storage snapshot 'vzdump'` — the vzdump-level step after which the backup
+  reads from the snapshot (generic across snapshot-capable storage; only appears in snapshot mode).
+- **Downtime delta:** snapshot created in the first ~1s; archive runs ~23s after. So 8B (resume at
+  `done`) = ~24s app-down; 8B.2 (resume at `snapshotted`) = ~1s — **~95% cut** for a 934 MB guest;
+  the delta grows with guest size.
 
 ## What landed
 
-- **`internal/storage`** — `SudoHostOps.Format(device, fstype)` (device-pinned `mkfs.ext4 -F` /
-  `mkfs.xfs -f`, `ValidateBlockDevice`+`ValidateFSType`, narrow `FELHOM_FORMAT` sudoers).
-  `SudoHostOps.InspectDevice(device)` → `DeviceProbe` (`blkid -p` signatures + `lsblk -J`
-  partitions/mount). **`DeviceProbe.DataBearing()` is conservative**: any filesystem / partition
-  table / partition / mount — OR a probe that did not read cleanly — is data-bearing (fail-safe).
-- **`internal/localapi` — the §6 disk endpoints**, self-scoped (token→guest; cross-guest 403):
-  `GET /disks` (drives + data-bearing flag), `POST /disks/assign` (benign `EnsureMount`),
-  `POST /disks/eject` (benign `Unmount` + dependent guests), `POST /disks/format`.
-  **`/disks/format` is the centerpiece**: the agent inspects the device; blank → benign → `mkfs`;
-  **data-bearing → `ClassStorageWipe` → the slice-4 gate → `pending_signature` (refused)**. The
-  signed completion is slice 10. `storageGateAdapter` bridges to the gate (no new gate/crypto).
+- **`BackupRunner.BackupWithSnapshotHook(ctx, vmid, onSnapshot)`** — while the vzdump runs, a watcher
+  tails the task log (`TaskLogTail`) for the `create storage snapshot` marker and fires `onSnapshot`
+  **once**. It bails on `backup mode: stop` and the marker never appears in stop mode, so it **never
+  fires in stop/downgraded mode**. `Backup` keeps its signature (scheduler/selftest); both share one
+  body. `snapshotWatchInterval` is a package var (prod 1s; tests shrink it).
+- **`/backup/status` phase `snapshotted`** (between `running` and `done`): `handleBackup` passes the
+  hook → `markSnapshotted` flips the running job. `done`/`failed` unchanged; `snapshotted` is additive.
 
 ## Tests
 
-`go test ./...` green; `-race` green (build server). localapi security matrix: blank → mkfs called,
-gate not consulted; **data-bearing → 403, mkfs NEVER called**, gate consulted; ambiguous/unprobed →
-fail-safe destructive; gate-allows still refuses in 8C; assign/eject; cross-guest 403; bad
-device/fstype 400; unconfigured 503. storage: validators (whitelist + injection rejection),
-`InspectDevice` (blank/fs/parttable/mounted/failed-probe-fail-safe), `Format` invokes the right mkfs.
+`go test ./...` green; `-race` green (build server). localapi: snapshot mode → `snapshotted` before
+`done`; stop mode → `snapshotted` never emitted. runner: the watcher fires on the marker; stop-mode
+log never fires.
 
 ## Live validation (demo-felhom)
 
-A provisioned de-privileged controller (v0.37.0) drove the agent: `GET /disks` flagged the mounted
-`felhom-usb` (`/dev/sdb1`) **`data_bearing: true`** and the LVM/PBS/dir storages false. `POST
-/disks/format` on the mounted-vfat `/dev/sda2` → **403** `"device is data-bearing — format requires
-operator authorization (pending_signature)"`; agent log `refusing format of a data-bearing device …
-gate=pending_signature`; **`/dev/sda2` untouched**. Deployed to the standing demo service as v0.12.0.
+End-to-end on a provisioned guest (controller v0.38.0 + a postgres stack): the agent logged `backup
+reached snapshotted (app may resume)` mid-backup, the controller resumed the app at that point, and
+the backup proceeded to `done`. **App downtime ~3s** (quiesce→snapshotted) vs **~23s** if it had
+waited for `done` (~87% cut). The snapshot backup restored **clean** (`database system was shut down`,
+no WAL replay) — the early resume did not compromise app-consistency. Deployed to the demo service as
+v0.13.0.
 
-## Deferred (stated, not built)
+## Deferred / dependency
 
-The operator-**signed completion** of a data-bearing wipe/format → **slice 10**. No spare blank
-`/dev/sd*` on the demo to live-exercise an actual `mkfs` (won't format real disks — covered by unit
-tests). No secrets committed.
+Snapshot-capable storage (lvm-thin/ZFS) is required for the win; on stop/downgraded storage the
+controller falls back to resume-at-`done` (8B). No consistency-contract or crash-safety change. No
+secrets committed.