Backup classification: schema + parser + pure classifier (INERT, v0.132.0)

Task 2 of the backup-classification-redesign arc. Ships the referential-
coupling classification as DATA + PARSER + PURE CLASSIFIER, deliberately
inert — no backup tier changes behavior. Task 3 (tier policy engine) and
Task 4 (manual .fab UI) consume it.

- appbackup/classify.go: BackupSpec/BindSpec/ComposeBind/ClassifiedBind;
  ClassifyBinds (SQ5 two-level default — explicit beats :ro; unlisted
  writable→mandatory, unlisted :ro→excluded; nil spec→legacy/false);
  ValidateBackupSpec (whole-block-reject on any defect, first defect named).
- stacks/classify_binds.go: ParseComposeClassifiableBinds — ${VAR}-relative
  binds + :ro flag (NOT ParseComposeHDDMounts/ExportDataMounts, the traps).
- Metadata.Backup + LoadMetadata as the single validation choke point (bad
  catalog block → nil + one ERROR → legacy, within one sync cycle).
- Manager.ClassifiedBinds + StackDataProvider.GetStackClassifiedBinds seam
  (delegated by stackAdapter, nil-stubbed in every fake) — wired + tested
  now so Task 3 consumes a tested seam.

INERT: full pre-existing suite green with zero test-logic edits. +14 tests;
red-proofs RP-1..RP-4 confirmed. The 13 catalog backup: blocks ship in the
same app-catalog change (this controller deploys first).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A45Qop8YY8tS94bz63LFne

REUSE.md

@@ -69,6 +69,9 @@
 | `resolveContainerState` / `aggregateState` | controller/internal/stacks/manager.go | `(dockerState, dockerStatus)` / `([]ContainerInfo)` | State classification | `.State` says "running" even when unhealthy — `.Status` parse is the fix |
 | `Manager.logPostStartStatus` | controller/internal/stacks/manager.go | `(name, stackDir, env)` | Async post-start verification | compose up exits 0 on crash-loops; this is the detection. Goroutine + 3s, never blocks |
 | `Manager.EnsureBaseStack` | controller/internal/stacks/infra.go | `() error` | Traefik/cloudflared/FileBrowser infra convergence | Renders from `internal/infra` templates |
+| `appbackup.ClassifyBinds` / `ValidateBackupSpec` | controller/internal/appbackup/classify.go | `(spec, binds) ([]ClassifiedBind, bool)` / `(spec, binds) error` | Backup-classification (Task 2, referential coupling) — pure | Two-level default: explicit wins over `:ro`; unlisted writable→mandatory, unlisted `:ro`→excluded; nil spec→legacy/false. Validate REJECTS the WHOLE block on any defect (whole-block semantics). INERT — no tier consumes it yet |
+| `ParseComposeClassifiableBinds` | controller/internal/stacks/classify_binds.go | `(composePath) []appbackup.ComposeBind` | `${VAR}`-relative binds + `:ro` for classification | Do NOT use `ParseComposeHDDMounts`/`ExportDataMounts` as classifier input (§traps) — they resolve absolutes, drop `:ro`, or union the userdata ROOT. Short-syntax only |
+| `Manager.ClassifiedBinds` + `StackDataProvider.GetStackClassifiedBinds` | controller/internal/stacks/metadata.go, appbackup/appdata.go | `(name) ([]appbackup.ClassifiedBind, bool)` | Per-stack classification through the REAL LoadMetadata validate path | The wired seam Task 3 consumes; LoadMetadata is the SINGLE validation choke point (bad block → nil + one ERROR → legacy) |
 | `backup.Manager.DumpAppVolumesSafe` | controller/internal/backup/backup.go | `(stackName) error` | Volume tar of a live app | Stops → dumps → restarts; surfaces BOTH errors (app may be left stopped). Check `GetDockerVolumes()!=0` + `IsProtectedStack` BEFORE calling — it stops the stack before its own volume check (see `runVolumeDumps`) |
 | `backup.Manager.ListRestorePoints` | controller/internal/backup/restore_points.go | `(stackName) ([]RestorePoint, bool)` | Restorable keep-side backups (the /api/backup/snapshots payload) | ONE point per app (the current unit); tier always 1 — never list Tier-2 (not restorable via /backup/restore) |
 | `backup.Manager.RestoreTier2Files` | controller/internal/backup/tier2_restore.go | `(stackName) (filesRestored int, err error)` | In-place ADDITIVE-ONLY class-C file restore from the recorded Tier-2 copy (`POST /backup/tier2/restore`) | Never overwrites/deletes live files; refusals (Hungarian) before any stop; source = recorded `DestinationPath`, never re-selected |
@@ -173,6 +176,7 @@
 | `backup.Manager.DumpAppVolumes` on a running DB app | Inconsistent tar of live DB volume | `DumpAppVolumesSafe` (stop → dump → restart, both errors surfaced) |
 | `stacks.Manager.execCommand` / `composeExecCustomEnv` for NEW long-running calls | No context/timeout — a hung docker CLI blocks forever | `exec.CommandContext` + explicit timeout (copy `rsyncCopy` or appexport `composeExecEnv`) |
 | `config.LoadPermissive` | Skips validation — setup-mode only (customer.id/domain may be unset) | `config.Load` everywhere else |
+| `ExportDataMounts` / `ParseComposeHDDMounts` as **backup-classification** input | `ExportDataMounts` unions the `${USERDATA_PATH}` ROOT (export-capture logic, not per-bind); `ParseComposeHDDMounts` resolves absolutes AND drops the `:ro` flag — classification needs `${VAR}`-relative paths + read-only awareness | `ParseComposeClassifiableBinds` (controller/internal/stacks/classify_binds.go) |
 | `docker compose restart` (any wrapper) | Does not pick up new images or env | `RedeployFromEnv` / composeExec `up -d` |
 
 ## 4. Seams & interfaces (testing + cross-repo)