v0.54.0: Phase 2b — restore-from-recovery-unit + fail-closed data-key gate

Restore recreates an app from its on-drive unit + the guest's own secrets,
regenerating nothing. reconcileRestoreSecrets (pure, unit-tested) merges the unit's
non-secret env with secrets recovered from the live app.yaml and FAILS CLOSED if a
data-encrypting key is unrecoverable (refuse — a PBS whole-guest restore is needed —
rather than regenerate and corrupt). Resettable secrets missing → warn + proceed.

- backup: RestoreFromRecoveryUnit (manifest -> recover secrets -> gate -> restore
  volumes -> recreate definition + redeploy w/ re-pull); falls back to volume-only.
- seams: RecoverStackSecrets/RecreateStackFromUnit (adapter +encKey),
  stacks.RedeployFromEnv. Wired into /backup/restore.
- tests: gate (refuse/proceed/verbatim) + data_key parsing.

Gate + reconcile + data_key parsing unit-tested; capture live-validated (v0.53.1).
Full readable-data e2e vs AdventureLog needs the auth-gated dashboard restore — pending.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

controller/internal/stacks/deploy.go

@@ -431,6 +431,48 @@ func (m *Manager) UpdateStackConfig(name string, values map[string]string) error
 	return m.RefreshStatus()
 }
 
+// RedeployFromEnv writes app.yaml from the given FULL env (encrypting secret fields) and (re-)deploys
+// the stack with `docker compose up -d`, which re-pulls the pinned image. Used by the restore-from-unit
+// flow (Phase 2b): unlike UpdateStackConfig it sets the full env INCLUDING locked secrets — which were
+// recovered from the guest's own app.yaml, never regenerated. Caller is responsible for the gate.
+func (m *Manager) RedeployFromEnv(name string, env map[string]string) error {
+	stack, ok := m.GetStack(name)
+	if !ok {
+		return fmt.Errorf("stack %q not found", name)
+	}
+	stackDir := filepath.Dir(stack.ComposePath)
+	meta := LoadMetadata(stackDir)
+
+	cfg := &AppConfig{
+		Deployed:   true,
+		DeployedAt: time.Now().UTC().Format(time.RFC3339),
+		Env:        env,
+	}
+	for _, f := range meta.DeployFields {
+		if f.LockedAfterDeploy {
+			cfg.LockedFields = append(cfg.LockedFields, f.EnvVar)
+		}
+	}
+	if err := SaveAppConfig(stackDir, cfg, m.encKey, SensitiveEnvVars(&meta)); err != nil {
+		return fmt.Errorf("saving app config: %w", err)
+	}
+
+	m.mu.Lock()
+	if s, ok := m.stacks[name]; ok {
+		s.Deployed = true
+		s.AppConfig = cfg
+	}
+	m.mu.Unlock()
+
+	m.logger.Printf("[INFO] [stacks] Redeploying %s from recovery unit with %d env vars", name, len(env))
+	deployEnv := m.stackEnv(stackDir) // decrypts secrets back for compose
+	if _, err := m.composeExecCustomEnv(stackDir, deployEnv, "up", "-d"); err != nil {
+		return fmt.Errorf("compose up: %w", err)
+	}
+	m.logPostStartStatus(name, stackDir, deployEnv)
+	return m.RefreshStatus()
+}
+
 // composeExecWithEnv runs a compose command with custom env vars injected.
 func (m *Manager) composeExecWithEnv(dir string, env map[string]string, args ...string) (string, error) {
 	cmdEnv := os.Environ()