hub v0.44.0: PBS DR tier SLICE 1 — felhom-tenantsync surface (script+client) + hub provisioning flow (consume-once host secret, pbs_dr desired-state descriptor, fail-closed + idempotent, re-issue)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6
2026-07-10 20:49:48 +02:00
parent 00afadc1fe
commit ce6a56691e
19 changed files with 1743 additions and 0 deletions
@@ -66,6 +66,14 @@
 | `(*Handler).handleArtifactManifest` | hub/internal/api/handler.go (~L1550) | `GET /api/v1/artifacts/{id}` | Serving the vouched set to the bootstrap script | Auth mirrors handleConfigRetrieve exactly. Unset manifest = empty fields, not an error. |
 | `normalizeFloorInput` / `normalizeSHA256` | hub/internal/web/configs.go (~L27 / ~L627) | `(raw string) (string, bool)` | Validating operator-typed versions / shas | Empty string is VALID (means "clear"). Reuse for any new version/sha form field. |

+### PBS DR tier / tenantsync (hub/internal/tenantsync/, web/pbsdr.go, api/pbsdr.go)
+
+| Symbol | File | Short signature | Use for | Gotchas |
+|---|---|---|---|---|
+| `tenantsync.Client` (`Provision`/`Reissue`/`Fingerprint`) | hub/internal/tenantsync/client.go | `(ctx, customerID) (*Result, error)` | ep0 per-customer PBS tenancy over the pinned-SSH forced-command channel (the wgsync twin) | `Result.TokenSecret` is transient custody → `SaveHostPBSSecret` immediately, never log the struct. Error paths NEVER embed stdout (the secret channel) — do not "improve" diagnostics by quoting the response. `ErrTokenExists` is typed: provision refuses an existing token; re-issue is the explicit path. |
+| `(*Store).SaveHostPBSSecret` / `ConsumeHostPBSSecret` | hub/internal/store/pbsdr.go | `(hostID, value)` / `(hostID) (string, error)` | HOST-scoped consume-once secret (the one_time_secrets host twin) | Same-tx mark-consumed; re-save resets consumption (re-issue supersedes). The agent consumes via `POST /api/v1/hosts/{id}/pbs/consume-token` (api/pbsdr.go). |
+| `(*Server).applyPBSDR` + `mergePBSDR`/`readPBSDR` | hub/internal/web/pbsdr.go | `(ctx, r, cfg) error` | The config form's PBS DR section → HOST desired_json `pbs_dr` descriptor + generation bump | Descriptor lives in the host desired_json, NOT ConfigJSON (buildConfigJSON drops foreign keys on re-save). Fail-closed before SaveCustomerConfig; already-provisioned = success-no-op (red-proofed); disable keeps the ep0 tenancy. |
+
 ### Config generation & secrets hygiene (hub/internal/configgen/)

 | Symbol | File | Short signature | Use for | Gotchas |
@@ -129,6 +137,8 @@
 | `api.ConfigTemplateProvider` | hub/internal/api/handler.go (~L24) | `web.TemplateFetcher` (Gitea-pulled controller.yaml template) | stub providers in api tests |
 | `api.LatestVersionProvider` | hub/internal/api/handler.go (~L31) | `web.VersionChecker` (registry poll) | hub/internal/api/config_version_ack_test.go |
 | `mailRateLimiter.now` (func seam) | hub/internal/api/mail.go (~L27) | `time.Now` | hub/internal/api/mail_test.go clock injection |
+| `web.tenancyProvisioner` | hub/internal/web/pbsdr.go | `*tenantsync.Client` (pinned SSH to ep0's felhom-tenantsync) | `fakeTenancy` in hub/internal/web/pbsdr_test.go; in-process SSH server in hub/internal/tenantsync/client_test.go |
+| Cross-repo: ep0 tenancy surface | `scripts/felhom-tenantsync.sh` (JSON stdin/stdout forced command) | installed on ep0 per runbook offsite-endpoint.md §10 | provision/reissue/fingerprint ops; token secret rides stdout ONLY; the peersync script/key are untouched |
 | Cross-repo: controller → hub | `POST /api/v1/report` (frozen) + `POST /api/v1/event` | felhom-controller repo | new event types MUST enter `allowedEventTypes` (hub/internal/api/handler.go ~L1063) or the controller gets 400 |
 | Cross-repo: agent → hub | `POST /api/v1/host-report`, `/host-enroll`, jobs/desired-state/escrow routes (handler.go ~L145–189) | felhom-agent repo | hub/internal/api/host_test.go, desired_test.go, escrow_test.go, dr_test.go |
 | Cross-repo: Day-0 bootstrap → hub | `GET /api/v1/config/{id}` + `/artifacts/{id}` (X-Retrieval-Password) | scripts/felhom-host-install.sh (fetches + sha256-verifies against the hub-vouched manifest) | hub/internal/api/artifact_test.go |
@@ -1,5 +1,45 @@
 # Felhom Hub — Changelog

+## v0.44.0 — PBS DR tier SLICE 1: ep0 tenantsync surface + hub provisioning (2026-07-10)
+
+Builds on SPIKE-pbs-tier-provisioning (00afadc). The operator ticks "PBS DR tier (ep0)" on a
+customer config → the hub verifies the host's WG peer (the agent self-registers it; absence is
+fail-closed) → provisions the per-customer ep0 PBS namespace + privilege-separated token over the
+NEW `felhom-tenantsync` forced-command surface (peersync untouched) → stores the token secret
+CONSUME-ONCE, host-scoped → serves the non-secret descriptor via the host desired-state (generation
+bump). The agent apply-bridge is SLICE 2 — nothing is live-provisioned yet.
+
+- **`scripts/felhom-tenantsync.sh` v1.0.0** (installed on ep0 per runbook §10): JSON-on-stdin/stdout;
+  ops `provision` (existing token = hard error `token_exists` — re-issue is explicit), `reissue`
+  (delete-token purges ACLs → recreate → re-grant), `fingerprint`. Dual-grant per spike §3;
+  own-namespace self-check with one regen retry (the spike's transient-403 note) then rollback.
+  Secret hygiene: the token secret rides stdout ONLY (all tool stdout → stderr; never a file/argv).
+  NO deprovision op — namespace/data deletion stays a deliberate, separate decision.
+- **`internal/tenantsync`**: the wgsync twin — pinned host key (exact-match, constrained
+  HostKeyAlgorithms), per-op JSON exec, typed `ErrTokenExists`. Divergence from wgsync: error
+  messages NEVER embed stdout (the secret channel) — red-proof-style contract test
+  (`TestErrors_NeverEmbedStdout`).
+- **Store**: `host_pbs_secrets` (host-scoped consume-once, the `one_time_secrets` twin) +
+  `SaveHostPBSSecret`/`ConsumeHostPBSSecret` (same-tx mark; re-save resets).
+- **API**: `POST /api/v1/hosts/{id}/pbs/consume-token` — per-host key, self-scoped (global key =
+  operator recovery); 200 exactly once → 404; a foreign key's 403 does NOT burn the secret.
+  (Task spec wrote `/host/{id}/…`; implemented under `/hosts/` for namespace consistency with
+  every other agent-facing route.)
+- **Web**: config-form section "PBS DR tier (ep0)" (enable + storage-id, default `felhom-pbs` —
+  the descriptor carries the id so the slice-2 bridge is name-agnostic and the demo's
+  `felhom-offsite` adoption dissolves the naming collision) + provisioned line + **Re-issue PBS
+  credentials** (the offsite F4 precedent). `applyPBSDR` merges the non-secret `pbs_dr` descriptor
+  into the HOST `desired_json` (admin-set path, `SetHostDesired` bump) — ConfigJSON never carries
+  it. Fail-closed on: no tenantsync key, no enrolled host, no WG peer, no endpoint record,
+  tenantsync error, `token_exists` (message points at Re-issue). Already-provisioned re-save =
+  success-no-op (no re-key, no second secret, no spurious bump). Disable = descriptor
+  `enabled:false`, tenancy kept.
+- **Deploy**: `manifests/hub.yaml` gains `TENANTSYNC_SSH_KEY_FILE` + optional `Secret/tenantsync`
+  mount (same endpoint addr + pinned host key as peersync, its own key).
+- Red-proofs run and recorded (REPORT.md): consume-once mark drop → the secret re-serves (store +
+  API layers); fail-closed guard swallow → 303 half-save; idempotency short-circuit drop →
+  token rotation + fresh secret + spurious bump.
+
 ## v0.43.1 — Git Sync form hint: credentials are optional (2026-07-10)

 Pairs with controller v0.112.0 (anonymous registry self-update). The config editor's Git Sync section
@@ -23,6 +23,7 @@ import (
 	"gitea.dooplex.hu/admin/felhom-hub/internal/notify"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/web"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/tenantsync"
 	"gitea.dooplex.hu/admin/felhom-hub/internal/wgsync"
 	"gopkg.in/yaml.v3"
 )
@@ -366,6 +367,28 @@ func main() {
 		} else {
 			logger.Printf("[INFO] WG peer-sync disabled (endpoint not configured)")
 		}
+
+		// PBS DR tier (SLICE 1): the tenantsync client — same endpoint address + pinned host key
+		// as peersync, its OWN private key (the authorized_keys line selects the forced command).
+		tsKeyFile := os.Getenv("TENANTSYNC_SSH_KEY_FILE")
+		if wgAddr != "" && wgHostKey != "" && tsKeyFile != "" {
+			keyPEM, err := os.ReadFile(tsKeyFile)
+			if os.IsNotExist(err) {
+				// The env names the mount path unconditionally; the optional Secret may not exist yet.
+				logger.Printf("[INFO] PBS DR tenantsync disabled (key %s not present)", tsKeyFile)
+			} else if err != nil {
+				logger.Printf("[ERROR] PBS DR tenantsync disabled: read key file %s: %v", tsKeyFile, err)
+			} else if tsClient, err := tenantsync.New(tenantsync.Config{
+				Addr: wgAddr, User: wgUser, PrivateKey: keyPEM, HostKeyLine: wgHostKey,
+			}, logger); err != nil {
+				logger.Printf("[ERROR] PBS DR tenantsync disabled: %v", err)
+			} else {
+				webServer.SetTenantSync(tsClient)
+				logger.Printf("[INFO] PBS DR tenantsync enabled (endpoint %s, user %s)", wgAddr, wgUser)
+			}
+		} else {
+			logger.Printf("[INFO] PBS DR tenantsync disabled (key or endpoint not configured)")
+		}
 	}

 	// Session cleanup — removes expired sessions every hour
@@ -181,6 +181,10 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	case r.Method == http.MethodPost && strings.HasPrefix(path, "/hosts/") && strings.HasSuffix(path, "/wg"):
 		hostID := strings.TrimSuffix(strings.TrimPrefix(path, "/hosts/"), "/wg")
 		h.handleRegisterHostWG(w, r, hostID)
+	// PBS DR tier (SLICE 1): the agent's consume-once fetch of its PBS token secret (api/pbsdr.go).
+	case r.Method == http.MethodPost && strings.HasPrefix(path, "/hosts/") && strings.HasSuffix(path, "/pbs/consume-token"):
+		hostID := strings.TrimSuffix(strings.TrimPrefix(path, "/hosts/"), "/pbs/consume-token")
+		h.handleConsumePBSToken(w, r, hostID)
 	// Desired-state serving (slice 10A) — per-host-key, self-scoped (a host reads only its own).
 	case r.Method == http.MethodGet && strings.HasPrefix(path, "/hosts/") && strings.HasSuffix(path, "/desired-state"):
 		hostID := strings.TrimSuffix(strings.TrimPrefix(path, "/hosts/"), "/desired-state")
@@ -0,0 +1,47 @@
+package api
+
+// PBS DR tier (SLICE 1): the agent-facing consume-once endpoint for the host's PBS token secret.
+// The hub stored the secret at provision time (tenantsync → Store.SaveHostPBSSecret); the agent
+// fetches it EXACTLY ONCE with its per-host key while applying the desired-state pbs_dr block
+// (SLICE 2). The controller-side offsite consume endpoint is the precedent; this is its host-side
+// twin. The secret value is never logged.
+
+import (
+	"database/sql"
+	"encoding/json"
+	"net/http"
+)
+
+// handleConsumePBSToken serves POST /api/v1/hosts/{host_id}/pbs/consume-token. Per-host key,
+// self-scoped (the global key may consume on a host's behalf — the operator recovery path).
+// 200 exactly once per stored secret; 404 when absent or already consumed; 403 on a foreign key.
+func (h *Handler) handleConsumePBSToken(w http.ResponseWriter, r *http.Request, pathHostID string) {
+	authHostID, _, isGlobal, ok := h.checkAuthHost(r)
+	if !ok {
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+	if pathHostID == "" {
+		http.Error(w, "Missing host_id", http.StatusBadRequest)
+		return
+	}
+	if !isGlobal && authHostID != pathHostID {
+		http.Error(w, "Forbidden: host_id mismatch", http.StatusForbidden)
+		return
+	}
+
+	secret, err := h.store.ConsumeHostPBSSecret(pathHostID)
+	if err == sql.ErrNoRows {
+		http.Error(w, "No unconsumed PBS token secret for this host", http.StatusNotFound)
+		return
+	}
+	if err != nil {
+		h.logger.Printf("[ERROR] pbs consume-token %s: %v", pathHostID, err)
+		http.Error(w, "Internal error", http.StatusInternalServerError)
+		return
+	}
+	h.logger.Printf("[INFO] pbs token secret consumed by host %s (single-use; value withheld from logs)", pathHostID)
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]string{"token_secret": secret})
+}
@@ -0,0 +1,80 @@
+package api
+
+// PBS DR SLICE 1 — the agent-facing consume-once endpoint. The contract: 200 with the secret
+// EXACTLY once per stored value, 404 after (and when nothing is stored), 403 on a foreign
+// host's key WITHOUT burning the secret, 401 unauthenticated.
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
+)
+
+func TestConsumePBSToken_OnceThen404(t *testing.T) {
+	h, st, _ := newTestHandler(t)
+	st.UpsertHost(&store.Host{HostID: "h1", CustomerID: "c1", APIKey: "HKEY"})
+	if err := st.SaveHostPBSSecret("h1", "tok-secret-1"); err != nil {
+		t.Fatalf("seed secret: %v", err)
+	}
+
+	rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "HKEY", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("first consume = %d, want 200 (%s)", rr.Code, rr.Body.String())
+	}
+	var resp map[string]string
+	if err := json.Unmarshal(rr.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("response parse: %v", err)
+	}
+	if resp["token_secret"] != "tok-secret-1" {
+		t.Errorf("token_secret = %q, want tok-secret-1", resp["token_secret"])
+	}
+
+	// Consume-once: the second fetch MUST 404. (Red-proof: drop the consumed_at UPDATE in
+	// store.ConsumeHostPBSSecret → this returns 200 with the secret again → FAIL.)
+	rr = do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "HKEY", "")
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("second consume = %d (%s), want 404 — single-use broken", rr.Code, rr.Body.String())
+	}
+}
+
+func TestConsumePBSToken_ForeignKeyForbiddenAndSecretSurvives(t *testing.T) {
+	h, st, _ := newTestHandler(t)
+	st.UpsertHost(&store.Host{HostID: "h1", CustomerID: "c1", APIKey: "HKEY"})
+	st.UpsertHost(&store.Host{HostID: "h2", CustomerID: "c2", APIKey: "HKEY2"})
+	if err := st.SaveHostPBSSecret("h1", "tok-secret-1"); err != nil {
+		t.Fatalf("seed secret: %v", err)
+	}
+
+	// h2's key against h1's path → 403, and the attempt must NOT consume h1's secret.
+	rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "HKEY2", "")
+	if rr.Code != http.StatusForbidden {
+		t.Fatalf("foreign-key consume = %d, want 403", rr.Code)
+	}
+	rr = do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "HKEY", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("own consume after foreign 403 = %d, want 200 — the 403 burned the secret", rr.Code)
+	}
+}
+
+func TestConsumePBSToken_AuthMatrix(t *testing.T) {
+	h, st, _ := newTestHandler(t)
+	st.UpsertHost(&store.Host{HostID: "h1", CustomerID: "c1", APIKey: "HKEY"})
+	st.SaveHostPBSSecret("h1", "tok-secret-1")
+
+	if rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "", ""); rr.Code != http.StatusUnauthorized {
+		t.Errorf("unauthenticated = %d, want 401", rr.Code)
+	}
+	if rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "bogus", ""); rr.Code != http.StatusUnauthorized {
+		t.Errorf("bogus key = %d, want 401", rr.Code)
+	}
+	// The global key may consume on a host's behalf (operator recovery path).
+	if rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", globalKey, ""); rr.Code != http.StatusOK {
+		t.Errorf("global key = %d, want 200", rr.Code)
+	}
+	// Nothing stored (just consumed above) → 404, not an error leak.
+	if rr := do(h, http.MethodPost, "/hosts/h1/pbs/consume-token", "HKEY", ""); rr.Code != http.StatusNotFound {
+		t.Errorf("post-consume = %d, want 404", rr.Code)
+	}
+}
@@ -0,0 +1,40 @@
+package store
+
+// PBS DR tier (SLICE 1): the HOST-scoped one-time PBS token secret — the host/agent twin of the
+// customer-scoped one_time_secrets pair (SaveOneTimeSecret/ConsumeOneTimeSecret). The hub stores
+// the tenantsync-returned token secret here; the agent consumes it EXACTLY ONCE with its per-host
+// key. Transient custody: never logged, never in desired-state or any served config.
+
+// SaveHostPBSSecret stores (last-write-wins) the one-time PBS token secret for a host, resetting
+// the consumed flag (a re-issue supersedes any prior unconsumed value). Never logged.
+func (s *Store) SaveHostPBSSecret(hostID, value string) error {
+	_, err := s.db.Exec(`
+		INSERT INTO host_pbs_secrets (host_id, value, created_at, consumed_at)
+		VALUES (?, ?, datetime('now'), NULL)
+		ON CONFLICT(host_id) DO UPDATE SET value = excluded.value, created_at = datetime('now'), consumed_at = NULL`,
+		hostID, value)
+	return err
+}
+
+// ConsumeHostPBSSecret returns the host's one-time PBS token secret and marks it consumed in the
+// SAME transaction (single use). A second call — or a call when none is stored — returns
+// ("", sql.ErrNoRows). The value is never logged.
+func (s *Store) ConsumeHostPBSSecret(hostID string) (string, error) {
+	tx, err := s.db.Begin()
+	if err != nil {
+		return "", err
+	}
+	defer tx.Rollback()
+	var value string
+	err = tx.QueryRow(`SELECT value FROM host_pbs_secrets WHERE host_id = ? AND consumed_at IS NULL`, hostID).Scan(&value)
+	if err != nil {
+		return "", err // sql.ErrNoRows when absent OR already consumed
+	}
+	if _, err := tx.Exec(`UPDATE host_pbs_secrets SET consumed_at = datetime('now') WHERE host_id = ?`, hostID); err != nil {
+		return "", err
+	}
+	if err := tx.Commit(); err != nil {
+		return "", err
+	}
+	return value, nil
+}
@@ -0,0 +1,43 @@
+package store
+
+import (
+	"database/sql"
+	"testing"
+)
+
+// The host-scoped consume-once contract (PBS DR SLICE 1): exactly one read per stored value,
+// a re-save resets the consumed flag (re-issue supersedes), absence is sql.ErrNoRows.
+func TestHostPBSSecret_ConsumeOnce(t *testing.T) {
+	s := newTestStore(t)
+
+	if _, err := s.ConsumeHostPBSSecret("h1"); err != sql.ErrNoRows {
+		t.Fatalf("consume with nothing stored = %v, want sql.ErrNoRows", err)
+	}
+
+	if err := s.SaveHostPBSSecret("h1", "secret-1"); err != nil {
+		t.Fatalf("save: %v", err)
+	}
+	got, err := s.ConsumeHostPBSSecret("h1")
+	if err != nil || got != "secret-1" {
+		t.Fatalf("first consume = (%q, %v), want (secret-1, nil)", got, err)
+	}
+	// Single use: the second consume MUST be ErrNoRows (red-proof: dropping the consumed_at
+	// UPDATE in ConsumeHostPBSSecret makes this assert fail with the value returned again).
+	if got, err := s.ConsumeHostPBSSecret("h1"); err != sql.ErrNoRows {
+		t.Fatalf("second consume = (%q, %v), want sql.ErrNoRows — consume-once broken", got, err)
+	}
+
+	// Re-issue path: a fresh save resets consumption and serves the NEW value once.
+	if err := s.SaveHostPBSSecret("h1", "secret-2"); err != nil {
+		t.Fatalf("re-save: %v", err)
+	}
+	got, err = s.ConsumeHostPBSSecret("h1")
+	if err != nil || got != "secret-2" {
+		t.Fatalf("post-reissue consume = (%q, %v), want (secret-2, nil)", got, err)
+	}
+
+	// Host isolation: h2 never sees h1's rows.
+	if _, err := s.ConsumeHostPBSSecret("h2"); err != sql.ErrNoRows {
+		t.Fatalf("foreign host consume = %v, want sql.ErrNoRows", err)
+	}
+}
@@ -440,6 +440,23 @@ func (s *Store) migrate() error {
 		return err
 	}

+	// PBS DR tier (SLICE 1, v0.44.0): the one-time PBS token secret, HOST-scoped — the sibling of
+	// one_time_secrets (customer/controller custody) for host/agent custody. The hub receives the
+	// secret over the tenantsync channel, stores it here, and the AGENT consumes it exactly once
+	// (POST /api/v1/hosts/{id}/pbs/consume-token, per-host key). consumed_at marks it spent; a
+	// re-issue supersedes any unconsumed value. Never logged, never in desired-state/ConfigJSON.
+	_, err = s.db.Exec(`
+		CREATE TABLE IF NOT EXISTS host_pbs_secrets (
+			host_id     TEXT PRIMARY KEY,
+			value       TEXT NOT NULL,
+			created_at  DATETIME NOT NULL DEFAULT (datetime('now')),
+			consumed_at DATETIME
+		);
+	`)
+	if err != nil {
+		return err
+	}
+
 	// v0.43.0 — remote app-log diagnostics. Additive columns on app_log_issues:
 	// context = JSON array of ±5 redacted lines around the FIRST occurrence (first capture
 	// wins — stable repro context, no churn); context_customer = whose box it came from
@@ -0,0 +1,219 @@
+// Package tenantsync drives the offsite endpoint's per-customer PBS tenancy surface (PBS DR tier
+// SLICE 1) — the structural twin of internal/wgsync: SSH with a PINNED host key (exact-match or
+// refuse, no fallback) to a forced-command script (`felhom-tenantsync` — its OWN key + sudoers
+// line; the peersync surface is untouched). JSON on stdin, JSON on stdout, one op per session.
+//
+// SECRET HYGIENE (load-bearing divergence from wgsync): the script's stdout carries the one-time
+// PBS token secret. It is parsed into Result and handed to the caller for the consume-once store
+// write — it is NEVER logged, and error messages NEVER embed stdout bytes (stderr only). Do not
+// "improve" the diagnostics by quoting the response.
+package tenantsync
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log"
+	"net"
+	"regexp"
+	"strings"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// ErrTokenExists is the typed "provision refused: the token already exists" outcome — the hub
+// treats it as a state mismatch (a descriptor should exist; re-issue is the explicit recovery).
+var ErrTokenExists = errors.New("tenantsync: token already exists on the endpoint (re-issue is the explicit path)")
+
+// customerIDRe mirrors the script's validation — refuse client-side before a wasted SSH round-trip.
+var customerIDRe = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9_.-]{0,30}$`)
+
+// Config configures the SSH client. Addr/User/HostKeyLine are typically the SAME values as the
+// peersync client (same box, same low-priv user, same pinned host key); PrivateKey is tenantsync's
+// OWN key (the authorized_keys line selects the forced command).
+type Config struct {
+	Addr        string        // "host:22"
+	User        string        // "felhom-peersync"
+	PrivateKey  []byte        // PEM private key (from the mounted Secret file)
+	HostKeyLine string        // single authorized_keys-format line of the endpoint's host pubkey
+	Timeout     time.Duration // default 60s (tenancy ops run several PBS commands)
+}
+
+// Result is the script's ok-response: the descriptor fields + the ONE-TIME token secret.
+// TokenSecret is transient custody — store it consume-once immediately, never log the struct.
+type Result struct {
+	TokenID     string `json:"token_id"`
+	TokenSecret string `json:"token_secret"`
+	Fingerprint string `json:"fingerprint"`
+	Datastore   string `json:"datastore"`
+	Namespace   string `json:"namespace"`
+}
+
+// Client is a pinned-host-key SSH per-op executor. Construct with New (parses keys up front).
+type Client struct {
+	addr    string
+	user    string
+	signer  ssh.Signer
+	hostKey ssh.PublicKey
+	timeout time.Duration
+	logger  *log.Logger
+}
+
+// New builds a Client, failing early on an unparsable private key or host-key line.
+func New(cfg Config, logger *log.Logger) (*Client, error) {
+	if cfg.Addr == "" || cfg.User == "" {
+		return nil, fmt.Errorf("tenantsync: Addr and User are required")
+	}
+	signer, err := ssh.ParsePrivateKey(cfg.PrivateKey)
+	if err != nil {
+		return nil, fmt.Errorf("tenantsync: parse private key: %w", err)
+	}
+	hostKey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(cfg.HostKeyLine))
+	if err != nil {
+		return nil, fmt.Errorf("tenantsync: parse host key line: %w", err)
+	}
+	timeout := cfg.Timeout
+	if timeout == 0 {
+		timeout = 60 * time.Second
+	}
+	if logger == nil {
+		logger = log.Default()
+	}
+	return &Client{
+		addr: cfg.Addr, user: cfg.User, signer: signer,
+		hostKey: hostKey, timeout: timeout, logger: logger,
+	}, nil
+}
+
+// Provision creates the customer's namespace + privilege-separated token on the endpoint.
+// An already-existing token is the typed ErrTokenExists (never silently re-keyed).
+func (c *Client) Provision(ctx context.Context, customerID string) (*Result, error) {
+	return c.tenancyOp(ctx, "provision", customerID)
+}
+
+// Reissue explicitly re-keys the customer's token (delete + recreate + re-grant, script-side).
+func (c *Client) Reissue(ctx context.Context, customerID string) (*Result, error) {
+	return c.tenancyOp(ctx, "reissue", customerID)
+}
+
+// Fingerprint returns the endpoint PBS's API cert fingerprint (the descriptor field).
+func (c *Client) Fingerprint(ctx context.Context) (string, error) {
+	stdout, stderr, runErr := c.exec(ctx, []byte(`{"op":"fingerprint"}`))
+	resp, err := parseResponse(stdout, stderr, runErr)
+	if err != nil {
+		return "", err
+	}
+	if resp.Fingerprint == "" {
+		return "", fmt.Errorf("tenantsync: fingerprint op returned an empty fingerprint")
+	}
+	return resp.Fingerprint, nil
+}
+
+func (c *Client) tenancyOp(ctx context.Context, op, customerID string) (*Result, error) {
+	if !customerIDRe.MatchString(customerID) {
+		return nil, fmt.Errorf("tenantsync: invalid customer_id %q", customerID)
+	}
+	payload, err := json.Marshal(map[string]string{"op": op, "customer_id": customerID})
+	if err != nil {
+		return nil, err
+	}
+	stdout, stderr, runErr := c.exec(ctx, payload)
+	resp, err := parseResponse(stdout, stderr, runErr)
+	if err != nil {
+		return nil, err
+	}
+	if resp.TokenSecret == "" || resp.TokenID == "" || resp.Namespace == "" || resp.Fingerprint == "" || resp.Datastore == "" {
+		// Field NAMES only — never values (TokenSecret).
+		return nil, fmt.Errorf("tenantsync: %s response is missing required fields", op)
+	}
+	c.logger.Printf("[INFO] tenantsync: %s ok for %s (ns=%s, token_id=%s; secret withheld from logs)",
+		op, customerID, resp.Namespace, resp.TokenID)
+	return &resp.Result, nil
+}
+
+// response is the script's stdout contract — ok carries the Result fields, error carries code+error.
+type response struct {
+	Status string `json:"status"`
+	Code   string `json:"code"`
+	Error  string `json:"error"`
+	Result
+}
+
+// parseResponse turns (stdout, stderr, runErr) into a typed outcome. The script emits its error
+// JSON on stdout and exits 1, so a run error is parsed for the typed code FIRST; only when stdout
+// carries no usable JSON does the raw failure (with stderr, NEVER stdout) surface.
+func parseResponse(stdout, stderr []byte, runErr error) (*response, error) {
+	var resp response
+	parseOK := json.Unmarshal(bytes.TrimSpace(stdout), &resp) == nil
+	if parseOK && resp.Status == "error" {
+		if resp.Code == "token_exists" {
+			return nil, ErrTokenExists
+		}
+		return nil, fmt.Errorf("tenantsync: endpoint refused: %s (code %s)", resp.Error, resp.Code)
+	}
+	if runErr != nil {
+		return nil, fmt.Errorf("tenantsync: remote op failed: %w (stderr: %s)",
+			runErr, strings.TrimSpace(string(stderr)))
+	}
+	if !parseOK || resp.Status != "ok" {
+		// stdout may carry the secret — report shape only, never bytes.
+		return nil, fmt.Errorf("tenantsync: malformed endpoint response (%d stdout bytes; stderr: %s)",
+			len(bytes.TrimSpace(stdout)), strings.TrimSpace(string(stderr)))
+	}
+	return &resp, nil
+}
+
+// exec runs one forced-command session: payload on stdin, returns stdout/stderr. The connection
+// discipline (pinned key, constrained HostKeyAlgorithms, deadline both sides of the handshake)
+// is wgsync.Push's, verbatim — that shape is live-proven against the real sshd.
+func (c *Client) exec(ctx context.Context, payload []byte) (stdout, stderr []byte, err error) {
+	sshCfg := &ssh.ClientConfig{
+		User:            c.user,
+		Auth:            []ssh.AuthMethod{ssh.PublicKeys(c.signer)},
+		HostKeyCallback: ssh.FixedHostKey(c.hostKey),
+		// Constrain negotiation to the PINNED key's algorithm — a multi-hostkey sshd (stock:
+		// ECDSA + ed25519) otherwise presents a different type and FixedHostKey refuses a
+		// legitimate server (wgsync S1 live finding).
+		HostKeyAlgorithms: []string{c.hostKey.Type()},
+		Timeout:           c.timeout,
+	}
+	dialer := net.Dialer{Timeout: c.timeout}
+	conn, err := dialer.DialContext(ctx, "tcp", c.addr)
+	if err != nil {
+		return nil, nil, fmt.Errorf("tenantsync: dial %s: %w", c.addr, err)
+	}
+	if dl, ok := ctx.Deadline(); ok {
+		conn.SetDeadline(dl)
+	} else {
+		conn.SetDeadline(time.Now().Add(c.timeout))
+	}
+	sconn, chans, reqs, err := ssh.NewClientConn(conn, c.addr, sshCfg)
+	if err != nil {
+		conn.Close()
+		return nil, nil, fmt.Errorf("tenantsync: ssh handshake %s: %w", c.addr, err)
+	}
+	client := ssh.NewClient(sconn, chans, reqs)
+	defer client.Close()
+	conn.SetDeadline(time.Time{})
+	if dl, ok := ctx.Deadline(); ok {
+		conn.SetDeadline(dl)
+	}
+
+	session, err := client.NewSession()
+	if err != nil {
+		return nil, nil, fmt.Errorf("tenantsync: session: %w", err)
+	}
+	defer session.Close()
+
+	var outBuf, errBuf bytes.Buffer
+	session.Stdin = bytes.NewReader(payload)
+	session.Stdout = &outBuf
+	session.Stderr = &errBuf
+
+	// The forced command overrides this string; it documents intent on the wire.
+	runErr := session.Run("felhom-tenantsync")
+	return outBuf.Bytes(), errBuf.Bytes(), runErr
+}
@@ -0,0 +1,300 @@
+package tenantsync
+
+// The tenancy SSH client against an IN-PROCESS x/crypto/ssh server (the wgsync client_test
+// pattern). Beyond the transport round-trip, these pin the package's two load-bearing contracts:
+// the typed token_exists outcome, and the secret-hygiene rule that NO error message ever embeds
+// stdout bytes (stdout is the secret channel).
+
+import (
+	"bytes"
+	"context"
+	"encoding/pem"
+	"errors"
+	"io"
+	"log"
+	"net"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"crypto/ed25519"
+	"crypto/rand"
+
+	"golang.org/x/crypto/ssh"
+)
+
+func testKeys(t *testing.T) ([]byte, ssh.Signer) {
+	t.Helper()
+	_, priv, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatalf("ed25519: %v", err)
+	}
+	block, err := ssh.MarshalPrivateKey(priv, "")
+	if err != nil {
+		t.Fatalf("MarshalPrivateKey: %v", err)
+	}
+	signer, err := ssh.NewSignerFromKey(priv)
+	if err != nil {
+		t.Fatalf("NewSignerFromKey: %v", err)
+	}
+	return pem.EncodeToMemory(block), signer
+}
+
+type testServer struct {
+	addr     string
+	mu       sync.Mutex
+	captured []byte
+	cmd      string
+}
+
+func startTestServer(t *testing.T, hostSigner, clientSigner ssh.Signer,
+	stdoutResp, stderrResp string, exitStatus uint32) *testServer {
+	t.Helper()
+	cfg := &ssh.ServerConfig{
+		PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
+			if bytes.Equal(key.Marshal(), clientSigner.PublicKey().Marshal()) {
+				return &ssh.Permissions{}, nil
+			}
+			return nil, io.EOF
+		},
+	}
+	cfg.AddHostKey(hostSigner)
+
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	t.Cleanup(func() { ln.Close() })
+	srv := &testServer{addr: ln.Addr().String()}
+
+	go func() {
+		conn, err := ln.Accept()
+		if err != nil {
+			return
+		}
+		sconn, chans, reqs, err := ssh.NewServerConn(conn, cfg)
+		if err != nil {
+			return
+		}
+		defer sconn.Close()
+		go ssh.DiscardRequests(reqs)
+		for newCh := range chans {
+			if newCh.ChannelType() != "session" {
+				newCh.Reject(ssh.UnknownChannelType, "unsupported")
+				continue
+			}
+			ch, chReqs, err := newCh.Accept()
+			if err != nil {
+				continue
+			}
+			go func() {
+				for req := range chReqs {
+					if req.Type == "exec" {
+						var p struct{ Command string }
+						ssh.Unmarshal(req.Payload, &p)
+						srv.mu.Lock()
+						srv.cmd = p.Command
+						srv.mu.Unlock()
+						req.Reply(true, nil)
+						data, _ := io.ReadAll(ch)
+						srv.mu.Lock()
+						srv.captured = data
+						srv.mu.Unlock()
+						if stderrResp != "" {
+							ch.Stderr().Write([]byte(stderrResp))
+						}
+						if stdoutResp != "" {
+							ch.Write([]byte(stdoutResp))
+						}
+						ch.SendRequest("exit-status", false, ssh.Marshal(struct{ Status uint32 }{exitStatus}))
+						ch.Close()
+						return
+					}
+					req.Reply(false, nil)
+				}
+			}()
+		}
+	}()
+	return srv
+}
+
+func hostKeyLine(t *testing.T, s ssh.Signer) string {
+	t.Helper()
+	return strings.TrimSpace(string(ssh.MarshalAuthorizedKey(s.PublicKey())))
+}
+
+func newTestClient(t *testing.T, addr, hostKey string, clientPEM []byte) *Client {
+	t.Helper()
+	c, err := New(Config{
+		Addr: addr, User: "felhom-peersync", PrivateKey: clientPEM,
+		HostKeyLine: hostKey, Timeout: 5 * time.Second,
+	}, log.New(io.Discard, "", 0))
+	if err != nil {
+		t.Fatalf("tenantsync.New: %v", err)
+	}
+	return c
+}
+
+const okResp = `{"status":"ok","token_id":"felhom@pbs!peti","token_secret":"s3cr3t-uuid-value",` +
+	`"fingerprint":"aa:bb","datastore":"felhom-offsite","namespace":"peti"}`
+
+func TestProvision_RoundTripParsesResult(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	srv := startTestServer(t, hostSigner, clientSigner, okResp, "", 0)
+	c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+	res, err := c.Provision(context.Background(), "peti")
+	if err != nil {
+		t.Fatalf("Provision: %v", err)
+	}
+	if res.TokenID != "felhom@pbs!peti" || res.TokenSecret != "s3cr3t-uuid-value" ||
+		res.Fingerprint != "aa:bb" || res.Datastore != "felhom-offsite" || res.Namespace != "peti" {
+		t.Errorf("Result mis-parsed: %+v", res)
+	}
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	if want := `{"customer_id":"peti","op":"provision"}`; string(srv.captured) != want {
+		t.Errorf("server received %q, want %q", srv.captured, want)
+	}
+	if srv.cmd != "felhom-tenantsync" {
+		t.Errorf("exec command = %q, want felhom-tenantsync", srv.cmd)
+	}
+}
+
+func TestProvision_TokenExistsIsTypedError(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	// The script emits the error JSON on stdout AND exits 1 — both must map to ErrTokenExists.
+	srv := startTestServer(t, hostSigner, clientSigner,
+		`{"status":"error","code":"token_exists","error":"token felhom@pbs!peti already exists"}`, "", 1)
+	c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+	_, err := c.Provision(context.Background(), "peti")
+	if !errors.Is(err, ErrTokenExists) {
+		t.Fatalf("err = %v, want ErrTokenExists", err)
+	}
+}
+
+func TestReissue_SendsReissueOp(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	srv := startTestServer(t, hostSigner, clientSigner, okResp, "", 0)
+	c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+	if _, err := c.Reissue(context.Background(), "peti"); err != nil {
+		t.Fatalf("Reissue: %v", err)
+	}
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	if want := `{"customer_id":"peti","op":"reissue"}`; string(srv.captured) != want {
+		t.Errorf("server received %q, want %q", srv.captured, want)
+	}
+}
+
+func TestFingerprint_Op(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	srv := startTestServer(t, hostSigner, clientSigner, `{"status":"ok","fingerprint":"cc:dd"}`, "", 0)
+	c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+	fp, err := c.Fingerprint(context.Background())
+	if err != nil {
+		t.Fatalf("Fingerprint: %v", err)
+	}
+	if fp != "cc:dd" {
+		t.Errorf("fingerprint = %q, want cc:dd", fp)
+	}
+}
+
+// TestErrors_NeverEmbedStdout is the secret-hygiene contract: stdout may carry the token secret,
+// so NO error path may quote it. A malformed-but-secret-bearing stdout must yield an error that
+// does not contain the marker bytes. (wgsync quotes stdout in its malformed error — this package
+// deliberately must not; that divergence is the point of this test.)
+func TestErrors_NeverEmbedStdout(t *testing.T) {
+	cases := []struct {
+		name       string
+		stdout     string
+		exitStatus uint32
+	}{
+		{"malformed-ok-exit", `garbage SECRET-MARKER garbage`, 0},
+		{"malformed-fail-exit", `partial {"token_secret":"SECRET-MARKER"`, 1},
+		{"wrong-status", `{"status":"weird","token_secret":"SECRET-MARKER"}`, 0},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			clientPEM, clientSigner := testKeys(t)
+			_, hostSigner := testKeys(t)
+			srv := startTestServer(t, hostSigner, clientSigner, tc.stdout, "some stderr", tc.exitStatus)
+			c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+			_, err := c.Provision(context.Background(), "peti")
+			if err == nil {
+				t.Fatal("Provision accepted a malformed response")
+			}
+			if strings.Contains(err.Error(), "SECRET-MARKER") {
+				t.Errorf("error %q embeds stdout bytes — the secret channel leaked into logs", err)
+			}
+		})
+	}
+}
+
+func TestOkResponseMissingFieldsRefused(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	srv := startTestServer(t, hostSigner, clientSigner,
+		`{"status":"ok","token_id":"felhom@pbs!peti"}`, "", 0) // no secret/ns/fp/ds
+	c := newTestClient(t, srv.addr, hostKeyLine(t, hostSigner), clientPEM)
+
+	if _, err := c.Provision(context.Background(), "peti"); err == nil {
+		t.Fatal("Provision accepted an ok-response with missing fields")
+	}
+}
+
+func TestWrongHostKeyRefused(t *testing.T) {
+	clientPEM, clientSigner := testKeys(t)
+	_, hostSigner := testKeys(t)
+	_, otherSigner := testKeys(t)
+	srv := startTestServer(t, hostSigner, clientSigner, okResp, "", 0)
+	c := newTestClient(t, srv.addr, hostKeyLine(t, otherSigner), clientPEM)
+
+	_, err := c.Provision(context.Background(), "peti")
+	if err == nil {
+		t.Fatal("Provision succeeded against a server with the WRONG host key — the pin is dead")
+	}
+	srv.mu.Lock()
+	defer srv.mu.Unlock()
+	if len(srv.captured) != 0 {
+		t.Errorf("payload leaked to a mis-keyed server: %q", srv.captured)
+	}
+}
+
+func TestInvalidCustomerIDRefusedClientSide(t *testing.T) {
+	clientPEM, _ := testKeys(t)
+	_, hostSigner := testKeys(t)
+	// No server needed — the refusal must happen before any dial.
+	c := newTestClient(t, "127.0.0.1:1", hostKeyLine(t, hostSigner), clientPEM)
+	for _, bad := range []string{"", "-leading-dash", ".dot", "has space", strings.Repeat("x", 40)} {
+		if _, err := c.Provision(context.Background(), bad); err == nil {
+			t.Errorf("customer_id %q accepted", bad)
+		}
+	}
+}
+
+func TestNew_BadInputsFailEarly(t *testing.T) {
+	clientPEM, _ := testKeys(t)
+	_, hostSigner := testKeys(t)
+	hk := hostKeyLine(t, hostSigner)
+	logger := log.New(io.Discard, "", 0)
+
+	if _, err := New(Config{Addr: "x:22", User: "u", PrivateKey: []byte("not-a-key"), HostKeyLine: hk}, logger); err == nil {
+		t.Error("bad private key accepted")
+	}
+	if _, err := New(Config{Addr: "x:22", User: "u", PrivateKey: clientPEM, HostKeyLine: "not a key line"}, logger); err == nil {
+		t.Error("bad host key line accepted")
+	}
+	if _, err := New(Config{User: "u", PrivateKey: clientPEM, HostKeyLine: hk}, logger); err == nil {
+		t.Error("missing addr accepted")
+	}
+}
@@ -413,12 +413,14 @@ func (s *Server) handleConfigNewForm(w http.ResponseWriter, r *http.Request) {
 		ActiveNav string
 		Error     string
 		CSRFField template.HTML
+		PBSDR     pbsDRView
 	}{
 		IsNew:     true,
 		Config:    &store.CustomerConfig{},
 		Overrides: make(map[string]interface{}),
 		ActiveNav: "configs",
 		CSRFField: s.csrfField(r),
+		PBSDR:     s.pbsDRViewFor(""),
 	}
 	s.templates.ExecuteTemplate(w, "config_form.html", data)
 }
@@ -484,6 +486,13 @@ func (s *Server) handleConfigCreate(w http.ResponseWriter, r *http.Request) {
 		return
 	}

+	// PBS DR tier (fail-closed, same discipline; the descriptor lives in the HOST desired-state).
+	if err := s.applyPBSDR(r.Context(), r, cfg); err != nil {
+		s.logger.Printf("[ERROR] pbsdr provision for %s: %v", customerID, err)
+		http.Error(w, "PBS DR provisioning failed: "+err.Error(), http.StatusBadGateway)
+		return
+	}
+
 	if err := s.store.SaveCustomerConfig(cfg); err != nil {
 		s.logger.Printf("[ERROR] Failed to save config for %s: %v", customerID, err)
 		http.Error(w, "Internal error", http.StatusInternalServerError)
@@ -512,12 +521,14 @@ func (s *Server) handleConfigEditForm(w http.ResponseWriter, r *http.Request, cu
 		ActiveNav string
 		Error     string
 		CSRFField template.HTML
+		PBSDR     pbsDRView
 	}{
 		IsNew:     false,
 		Config:    cfg,
 		Overrides: overrides,
 		ActiveNav: "configs",
 		CSRFField: s.csrfField(r),
+		PBSDR:     s.pbsDRViewFor(customerID),
 	}
 	s.templates.ExecuteTemplate(w, "config_form.html", data)
 }
@@ -546,6 +557,14 @@ func (s *Server) handleConfigUpdate(w http.ResponseWriter, r *http.Request, cust
 		return
 	}

+	// PBS DR tier (fail-closed; idempotent on an already-provisioned descriptor — no re-key,
+	// no second secret, no spurious generation bump).
+	if err := s.applyPBSDR(r.Context(), r, cfg); err != nil {
+		s.logger.Printf("[ERROR] pbsdr provision for %s: %v", customerID, err)
+		http.Error(w, "PBS DR provisioning failed: "+err.Error(), http.StatusBadGateway)
+		return
+	}
+
 	if err := s.store.SaveCustomerConfig(cfg); err != nil {
 		s.logger.Printf("[ERROR] Failed to update config for %s: %v", customerID, err)
 		http.Error(w, "Internal error", http.StatusInternalServerError)
@@ -897,6 +916,7 @@ func (s *Server) renderConfigForm(w http.ResponseWriter, r *http.Request, isNew
 		ActiveNav string
 		Error     string
 		CSRFField template.HTML
+		PBSDR     pbsDRView
 	}{
 		IsNew:     isNew,
 		Config:    cfg,
@@ -904,6 +924,7 @@ func (s *Server) renderConfigForm(w http.ResponseWriter, r *http.Request, isNew
 		ActiveNav: "configs",
 		Error:     errMsg,
 		CSRFField: s.csrfField(r),
+		PBSDR:     s.pbsDRViewFor(cfg.CustomerID),
 	}
 	s.templates.ExecuteTemplate(w, "config_form.html", data)
 }
@@ -154,6 +154,7 @@ func TestConfigForm_DebugRenderState(t *testing.T) {
 			ActiveNav string
 			Error     string
 			CSRFField string
+			PBSDR     pbsDRView
 		}{
 			Config:    &store.CustomerConfig{CustomerID: "c1"},
 			Overrides: overrides,
@@ -0,0 +1,308 @@
+package web
+
+// PBS DR tier (SLICE 1): the hub-side provisioning flow behind the customer config form's
+// "PBS DR tier (ep0)" section. On enable+save: verify the host's WG peer exists (the agent
+// self-registers its pubkey — absence is fail-closed, nothing to allocate here) → provision the
+// per-customer ep0 tenancy over the tenantsync channel → store the token secret CONSUME-ONCE
+// (host-scoped; the agent fetches it via POST /api/v1/hosts/{id}/pbs/consume-token) → merge the
+// NON-SECRET descriptor into the host's desired_json under "pbs_dr" (the admin-set path;
+// SetHostDesired bumps the generation, which is the agent's change signal).
+//
+// Fail-closed like applyOffsite: any error means NO descriptor write, NO bump, NO half-enabled
+// state. Idempotent: an already-provisioned descriptor short-circuits — no tenantsync call, no
+// second secret, no spurious bump. Disable rewrites the descriptor with enabled=false (bump) —
+// the ep0 namespace/token are NOT deprovisioned (the offsite-disable precedent: data deletion is
+// a deliberate, separate decision).
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/tenantsync"
+)
+
+// tenancyProvisioner is the tenantsync seam — satisfied by *tenantsync.Client; tests inject a fake.
+type tenancyProvisioner interface {
+	Provision(ctx context.Context, customerID string) (*tenantsync.Result, error)
+	Reissue(ctx context.Context, customerID string) (*tenantsync.Result, error)
+}
+
+// SetTenantSync enables PBS DR tier provisioning (optional). Without it, saving a config with the
+// tier enabled returns an error (not configured on this hub); the form section still renders.
+func (s *Server) SetTenantSync(p tenancyProvisioner) { s.tenantsync = p }
+
+// pbsDRDescriptor is the NON-SECRET pbs_dr block in a host's desired_json. It NEVER carries the
+// token secret (that is host_pbs_secrets custody, consume-once).
+type pbsDRDescriptor struct {
+	Enabled     bool   `json:"enabled"`
+	StorageID   string `json:"storage_id,omitempty"`
+	PBSTunnelIP string `json:"pbs_tunnel_ip,omitempty"`
+	Datastore   string `json:"datastore,omitempty"`
+	Namespace   string `json:"namespace,omitempty"`
+	TokenID     string `json:"token_id,omitempty"`
+	Fingerprint string `json:"fingerprint,omitempty"`
+}
+
+// defaultPBSStorageID is the storage-entry id the agent bridge creates on a customer box. The DEMO
+// host's adopted manual entry is `felhom-offsite` — the descriptor carries the id so the bridge is
+// name-agnostic and the felhom-pbs collision on the demo dissolves (spike naming note).
+const defaultPBSStorageID = "felhom-pbs"
+
+// pveStorageIDRe validates the operator-typed storage id (PVE storage-id grammar, conservative).
+var pveStorageIDRe = regexp.MustCompile(`^[A-Za-z][A-Za-z0-9_.-]{0,27}$`)
+
+// readPBSDR extracts the pbs_dr descriptor from a host's desired_json ("" / absent → nil).
+func readPBSDR(desiredJSON string) *pbsDRDescriptor {
+	var doc struct {
+		PBSDR *pbsDRDescriptor `json:"pbs_dr"`
+	}
+	if err := json.Unmarshal([]byte(desiredJSON), &doc); err != nil {
+		return nil
+	}
+	return doc.PBSDR
+}
+
+// mergePBSDR merges the descriptor under the "pbs_dr" key of a desired_json object, preserving
+// every other key (the operator blob, dr blocks…). Same shape as offsite.MergeDescriptor.
+func mergePBSDR(desiredJSON string, d *pbsDRDescriptor) (string, error) {
+	obj := map[string]json.RawMessage{}
+	if strings.TrimSpace(desiredJSON) != "" && desiredJSON != "{}" {
+		if err := json.Unmarshal([]byte(desiredJSON), &obj); err != nil {
+			return "", fmt.Errorf("pbsdr: parse desired_json: %w", err)
+		}
+	}
+	db, err := json.Marshal(d)
+	if err != nil {
+		return "", err
+	}
+	obj["pbs_dr"] = db
+	out, err := json.Marshal(obj)
+	if err != nil {
+		return "", err
+	}
+	return string(out), nil
+}
+
+// applyPBSDR handles the config form's PBS DR section on create/update. Called BEFORE
+// SaveCustomerConfig (fail-closed: an error must abort the whole save). The descriptor lives in
+// the HOST's desired_json — ConfigJSON never carries pbs_dr (single source of truth).
+func (s *Server) applyPBSDR(ctx context.Context, r *http.Request, cfg *store.CustomerConfig) error {
+	enabled := r.FormValue("pbsdr_enabled") == "on" || r.FormValue("pbsdr_enabled") == "true"
+	storageID := strings.TrimSpace(r.FormValue("pbsdr_storage_id"))
+	if storageID == "" {
+		storageID = defaultPBSStorageID
+	}
+
+	host, err := s.store.GetHostByCustomer(cfg.CustomerID)
+	if err != nil {
+		return fmt.Errorf("pbsdr: host lookup: %w", err)
+	}
+	if host == nil {
+		if !enabled {
+			return nil // nothing enrolled, nothing enabled — nothing to do
+		}
+		return fmt.Errorf("no host enrolled for customer %s yet — the PBS DR tier needs the enrolled host", cfg.CustomerID)
+	}
+	cur := readPBSDR(host.DesiredJSON)
+
+	if !enabled {
+		// Disable = descriptor enabled:false (coords kept; NO ep0 deprovision). Only when there is
+		// something to disable — otherwise a pure no-op (no spurious bump).
+		if cur == nil || !cur.Enabled {
+			return nil
+		}
+		cur.Enabled = false
+		merged, err := mergePBSDR(host.DesiredJSON, cur)
+		if err != nil {
+			return err
+		}
+		gen, err := s.store.SetHostDesired(host.HostID, []byte(merged))
+		if err != nil {
+			return fmt.Errorf("pbsdr: desired-state write: %w", err)
+		}
+		s.logger.Printf("[INFO] pbsdr disabled for %s (host %s, gen %d; ep0 tenancy kept)", cfg.CustomerID, host.HostID, gen)
+		return nil
+	}
+
+	if !pveStorageIDRe.MatchString(storageID) {
+		return fmt.Errorf("invalid PBS storage id %q", storageID)
+	}
+
+	// Already provisioned → success-no-op (descriptor re-served unchanged; NO new secret, no
+	// tenantsync call). Only an actual change (re-enable, storage id edit) rewrites + bumps.
+	if cur != nil && cur.Namespace != "" {
+		if cur.Enabled && cur.StorageID == storageID {
+			return nil
+		}
+		cur.Enabled = true
+		cur.StorageID = storageID
+		merged, err := mergePBSDR(host.DesiredJSON, cur)
+		if err != nil {
+			return err
+		}
+		gen, err := s.store.SetHostDesired(host.HostID, []byte(merged))
+		if err != nil {
+			return fmt.Errorf("pbsdr: desired-state write: %w", err)
+		}
+		s.logger.Printf("[INFO] pbsdr descriptor updated for %s (host %s, gen %d; tenancy unchanged)", cfg.CustomerID, host.HostID, gen)
+		return nil
+	}
+
+	// Fresh provision. Fail-closed preconditions first.
+	if s.tenantsync == nil {
+		return fmt.Errorf("PBS DR provisioning is not configured on this hub (no tenantsync key)")
+	}
+	if _, err := s.store.GetWGPeerForHost(host.HostID); err == sql.ErrNoRows {
+		return fmt.Errorf("host %s has not reported a WG key yet — the tunnel peer must exist before the PBS DR tier", host.HostID)
+	} else if err != nil {
+		return fmt.Errorf("pbsdr: wg peer lookup: %w", err)
+	}
+	ep, err := s.store.GetWGEndpoint()
+	if err == sql.ErrNoRows {
+		return fmt.Errorf("wg endpoint not configured — register ep0 before the PBS DR tier")
+	} else if err != nil {
+		return fmt.Errorf("pbsdr: wg endpoint read: %w", err)
+	}
+
+	// Detach from the request context (the applyOffsite F1 precedent): once provisioning starts,
+	// provision→store-secret→descriptor must complete; an impatient re-click must not cancel
+	// between the ep0 mutation and the consume-once store write (a stranded token would need a
+	// manual re-issue). The absolute timeout still bounds a hung SSH exec.
+	ctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 2*time.Minute)
+	defer cancel()
+	res, err := s.tenantsync.Provision(ctx, cfg.CustomerID)
+	if errors.Is(err, tenantsync.ErrTokenExists) {
+		// ep0 has a token but the hub has no descriptor — state mismatch (lost hub state or a
+		// half-torn earlier attempt). Never silently re-key: the operator decides via Re-issue.
+		return fmt.Errorf("the endpoint already holds a PBS token for %s but the hub has no descriptor — use the explicit \"Re-issue PBS credentials\" action", cfg.CustomerID)
+	}
+	if err != nil {
+		return err
+	}
+
+	// The atom: secret first (consume-once custody), then descriptor+bump (the agent's signal).
+	if err := s.store.SaveHostPBSSecret(host.HostID, res.TokenSecret); err != nil {
+		return fmt.Errorf("pbsdr: store one-time token secret: %w", err)
+	}
+	desc := &pbsDRDescriptor{
+		Enabled:     true,
+		StorageID:   storageID,
+		PBSTunnelIP: ep.PBSTunnelIP,
+		Datastore:   res.Datastore,
+		Namespace:   res.Namespace,
+		TokenID:     res.TokenID,
+		Fingerprint: res.Fingerprint,
+	}
+	merged, err := mergePBSDR(host.DesiredJSON, desc)
+	if err != nil {
+		return err
+	}
+	gen, err := s.store.SetHostDesired(host.HostID, []byte(merged))
+	if err != nil {
+		return fmt.Errorf("pbsdr: desired-state write: %w", err)
+	}
+	s.logger.Printf("[INFO] pbsdr provisioned for %s (host %s, ns %s, token_id %s, gen %d; secret stored consume-once, withheld from logs)",
+		cfg.CustomerID, host.HostID, res.Namespace, res.TokenID, gen)
+	return nil
+}
+
+// handlePBSDRReissue explicitly re-keys the customer's ep0 PBS token (the offsite F4 precedent):
+// tenantsync reissue → fresh consume-once secret → descriptor refresh + generation bump so the
+// agent re-runs its bridge and consumes the fresh secret. The secret value is never logged.
+func (s *Server) handlePBSDRReissue(w http.ResponseWriter, r *http.Request, customerID string) {
+	if s.tenantsync == nil {
+		http.Error(w, "PBS DR provisioning is not configured on this hub", http.StatusBadGateway)
+		return
+	}
+	cfg, err := s.store.GetCustomerConfig(customerID)
+	if err != nil || cfg == nil {
+		http.NotFound(w, r)
+		return
+	}
+	host, err := s.store.GetHostByCustomer(customerID)
+	if err != nil || host == nil {
+		http.Error(w, "No host enrolled for this customer", http.StatusBadRequest)
+		return
+	}
+	cur := readPBSDR(host.DesiredJSON)
+	if cur == nil || cur.Namespace == "" {
+		http.Error(w, "No provisioned PBS DR tier for this customer", http.StatusBadRequest)
+		return
+	}
+
+	// Same detached-ctx discipline as applyPBSDR: reissue→store→bump is the atom.
+	ctx, cancel := context.WithTimeout(context.WithoutCancel(r.Context()), 2*time.Minute)
+	defer cancel()
+	res, err := s.tenantsync.Reissue(ctx, customerID)
+	if err != nil {
+		s.logger.Printf("[ERROR] pbsdr reissue for %s: %v", customerID, err)
+		http.Error(w, "PBS credential re-issue failed: "+err.Error(), http.StatusBadGateway)
+		return
+	}
+	if err := s.store.SaveHostPBSSecret(host.HostID, res.TokenSecret); err != nil {
+		s.logger.Printf("[ERROR] pbsdr reissue for %s: secret store: %v", customerID, err)
+		http.Error(w, "Re-issued on the endpoint but storing the secret failed — re-issue again", http.StatusInternalServerError)
+		return
+	}
+	cur.TokenID = res.TokenID
+	cur.Fingerprint = res.Fingerprint
+	cur.Datastore = res.Datastore
+	cur.Namespace = res.Namespace
+	merged, err := mergePBSDR(host.DesiredJSON, cur)
+	if err == nil {
+		_, err = s.store.SetHostDesired(host.HostID, []byte(merged))
+	}
+	if err != nil {
+		s.logger.Printf("[ERROR] pbsdr reissue for %s: descriptor bump: %v", customerID, err)
+		http.Error(w, "Credential re-issued but the descriptor bump failed — save the config once to trigger the pickup", http.StatusInternalServerError)
+		return
+	}
+	s.logger.Printf("[INFO] pbsdr credentials re-issued for %s (host %s; fresh consume-once secret stored)", customerID, host.HostID)
+	http.Redirect(w, r, "/customers/"+customerID+"?flash=pbsdr_reissued", http.StatusSeeOther)
+}
+
+// pbsDRView is the config form's render model for the PBS DR section.
+type pbsDRView struct {
+	Supported   bool   // tenantsync configured on this hub
+	NoHost      bool   // no enrolled host for the customer (enable would fail-closed)
+	HostID      string
+	Enabled     bool
+	StorageID   string // current or the default
+	Provisioned bool
+	Namespace   string
+	TokenID     string
+}
+
+// pbsDRViewFor loads the section state for the form. Read-only; every error degrades to a
+// zero-ish view (the section still renders).
+func (s *Server) pbsDRViewFor(customerID string) pbsDRView {
+	v := pbsDRView{Supported: s.tenantsync != nil, StorageID: defaultPBSStorageID}
+	if customerID == "" {
+		v.NoHost = true
+		return v
+	}
+	host, err := s.store.GetHostByCustomer(customerID)
+	if err != nil || host == nil {
+		v.NoHost = true
+		return v
+	}
+	v.HostID = host.HostID
+	if d := readPBSDR(host.DesiredJSON); d != nil {
+		v.Enabled = d.Enabled
+		if d.StorageID != "" {
+			v.StorageID = d.StorageID
+		}
+		v.Provisioned = d.Namespace != ""
+		v.Namespace = d.Namespace
+		v.TokenID = d.TokenID
+	}
+	return v
+}
@@ -0,0 +1,373 @@
+package web
+
+// PBS DR SLICE 1 — the provisioning flow behind the config form, against a FAKE tenancy
+// provisioner (no SSH in CI). The load-bearing contracts: descriptor lands in the HOST
+// desired_json + generation bump; the secret is stored consume-once and appears NOWHERE else
+// (ConfigJSON, desired-state, logs); every failure is fail-closed (no descriptor, no bump, no
+// secret); an already-provisioned re-save is a pure no-op (no re-key, no second secret, no
+// spurious bump); re-issue rotates the secret + bumps.
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"errors"
+	"log"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/tenantsync"
+)
+
+type fakeTenancy struct {
+	provisionCalls int
+	reissueCalls   int
+	err            error
+	secret         string
+}
+
+func (f *fakeTenancy) result(customerID string) *tenantsync.Result {
+	return &tenantsync.Result{
+		TokenID:     "felhom@pbs!" + customerID,
+		TokenSecret: f.secret,
+		Fingerprint: "aa:bb:cc",
+		Datastore:   "felhom-offsite",
+		Namespace:   customerID,
+	}
+}
+
+func (f *fakeTenancy) Provision(ctx context.Context, customerID string) (*tenantsync.Result, error) {
+	f.provisionCalls++
+	if f.err != nil {
+		return nil, f.err
+	}
+	return f.result(customerID), nil
+}
+
+func (f *fakeTenancy) Reissue(ctx context.Context, customerID string) (*tenantsync.Result, error) {
+	f.reissueCalls++
+	if f.err != nil {
+		return nil, f.err
+	}
+	return f.result(customerID), nil
+}
+
+// newPBSDRServer builds a server + store with the full provisioning preconditions satisfied:
+// customer config, enrolled host, WG endpoint record, bound WG peer. The logger is captured so
+// tests can grep-assert the secret never reaches it.
+func newPBSDRServer(t *testing.T, fake *fakeTenancy) (*Server, *store.Store, *bytes.Buffer) {
+	t.Helper()
+	s, st := newTestServer(t)
+	logBuf := &bytes.Buffer{}
+	s.logger = log.New(logBuf, "", 0)
+	if fake != nil {
+		s.SetTenantSync(fake)
+	}
+	if err := st.SaveCustomerConfig(&store.CustomerConfig{
+		CustomerID: "peti", APIKey: "capi", RetrievalPassword: "pw",
+	}); err != nil {
+		t.Fatalf("seed config: %v", err)
+	}
+	if err := st.UpsertHost(&store.Host{HostID: "peti-01", CustomerID: "peti", APIKey: "hapi"}); err != nil {
+		t.Fatalf("seed host: %v", err)
+	}
+	if err := st.SetWGEndpoint(&store.WGEndpoint{
+		EndpointID: "ep0", DNSName: "ep0.felhom.eu", WGPort: 443,
+		ServerPubkey: "SPK", TunnelSubnet: "10.77.0.0/24", PBSTunnelIP: "10.77.0.1",
+	}); err != nil {
+		t.Fatalf("seed endpoint: %v", err)
+	}
+	if _, _, err := st.RegisterWGPeerForHost("peti-01", "PETIPUBKEY"); err != nil {
+		t.Fatalf("seed wg peer: %v", err)
+	}
+	return s, st, logBuf
+}
+
+// postUpdate drives the REAL handler pipeline (handleConfigUpdate → applyPBSDR → save).
+func postUpdate(t *testing.T, s *Server, form url.Values) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest("POST", "/configs/peti", strings.NewReader(form.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	rr := httptest.NewRecorder()
+	s.handleConfigUpdate(rr, req, "peti")
+	return rr
+}
+
+func hostState(t *testing.T, st *store.Store) (desc *pbsDRDescriptor, desiredJSON string, gen int64) {
+	t.Helper()
+	h, err := st.GetHost("peti-01")
+	if err != nil || h == nil {
+		t.Fatalf("host read: %v", err)
+	}
+	return readPBSDR(h.DesiredJSON), h.DesiredJSON, h.DesiredGeneration
+}
+
+func TestPBSDR_ProvisionHappyPath(t *testing.T) {
+	fake := &fakeTenancy{secret: "SUPER-SECRET-TOKEN"}
+	s, st, logBuf := newPBSDRServer(t, fake)
+
+	rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}, "pbsdr_storage_id": {"felhom-pbs"}})
+	if rr.Code != 303 {
+		t.Fatalf("save = %d (%s), want 303", rr.Code, rr.Body.String())
+	}
+	if fake.provisionCalls != 1 {
+		t.Errorf("provision calls = %d, want 1", fake.provisionCalls)
+	}
+
+	desc, desiredJSON, gen := hostState(t, st)
+	if desc == nil {
+		t.Fatalf("no pbs_dr descriptor in desired_json: %s", desiredJSON)
+	}
+	if !desc.Enabled || desc.StorageID != "felhom-pbs" || desc.PBSTunnelIP != "10.77.0.1" ||
+		desc.Datastore != "felhom-offsite" || desc.Namespace != "peti" ||
+		desc.TokenID != "felhom@pbs!peti" || desc.Fingerprint != "aa:bb:cc" {
+		t.Errorf("descriptor wrong: %+v", desc)
+	}
+	if gen != 1 {
+		t.Errorf("desired_generation = %d, want 1 (exactly one bump)", gen)
+	}
+
+	// The secret: stored consume-once for the HOST…
+	got, err := st.ConsumeHostPBSSecret("peti-01")
+	if err != nil || got != "SUPER-SECRET-TOKEN" {
+		t.Fatalf("consume = (%q, %v), want the stored secret", got, err)
+	}
+	// …and NOWHERE else: not in the desired-state, not in ConfigJSON, not in any log line.
+	if strings.Contains(desiredJSON, "SUPER-SECRET-TOKEN") {
+		t.Error("secret leaked into desired_json")
+	}
+	cfg, _ := st.GetCustomerConfig("peti")
+	if strings.Contains(cfg.ConfigJSON, "SUPER-SECRET-TOKEN") || strings.Contains(cfg.ConfigJSON, "pbs_dr") {
+		t.Errorf("ConfigJSON must carry neither the secret nor the descriptor: %s", cfg.ConfigJSON)
+	}
+	if strings.Contains(logBuf.String(), "SUPER-SECRET-TOKEN") {
+		t.Error("secret leaked into the hub log")
+	}
+}
+
+func TestPBSDR_ResaveIsNoOp(t *testing.T) {
+	fake := &fakeTenancy{secret: "SUPER-SECRET-TOKEN"}
+	s, st, _ := newPBSDRServer(t, fake)
+
+	postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+	if _, err := st.ConsumeHostPBSSecret("peti-01"); err != nil {
+		t.Fatalf("first secret consume: %v", err)
+	}
+
+	// Idempotent re-save: NO re-key, NO second secret row, NO spurious generation bump.
+	// (Red-proof: dropping the already-provisioned short-circuit in applyPBSDR re-runs
+	// Provision → calls=2 + a fresh consumable secret → FAIL.)
+	rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+	if rr.Code != 303 {
+		t.Fatalf("re-save = %d, want 303 (already-provisioned is success-no-op)", rr.Code)
+	}
+	if fake.provisionCalls != 1 {
+		t.Errorf("provision calls after re-save = %d, want 1 (token must not rotate)", fake.provisionCalls)
+	}
+	if _, err := st.ConsumeHostPBSSecret("peti-01"); err != sql.ErrNoRows {
+		t.Errorf("re-save created a fresh secret (consume err %v, want ErrNoRows)", err)
+	}
+	if _, _, gen := hostState(t, st); gen != 1 {
+		t.Errorf("generation after re-save = %d, want 1 (no spurious bump)", gen)
+	}
+}
+
+func TestPBSDR_FailClosed(t *testing.T) {
+	t.Run("no WG peer", func(t *testing.T) {
+		fake := &fakeTenancy{secret: "S"}
+		s, st, _ := newPBSDRServer(t, fake)
+		// Kill the precondition: the host has never registered a WG key.
+		if err := st.RemoveWGPeer("PETIPUBKEY"); err != nil {
+			t.Fatalf("remove seed peer: %v", err)
+		}
+		rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+		if rr.Code != 502 {
+			t.Fatalf("save without WG peer = %d, want 502", rr.Code)
+		}
+		if fake.provisionCalls != 0 {
+			t.Errorf("provision reached despite missing peer (%d calls)", fake.provisionCalls)
+		}
+		h, _ := st.GetHost("peti-01")
+		if readPBSDR(h.DesiredJSON) != nil || h.DesiredGeneration != 0 {
+			t.Errorf("fail-closed violated: desc=%v gen=%d", readPBSDR(h.DesiredJSON), h.DesiredGeneration)
+		}
+	})
+
+	t.Run("tenantsync error", func(t *testing.T) {
+		fake := &fakeTenancy{err: errors.New("ssh boom")}
+		s, st, _ := newPBSDRServer(t, fake)
+		rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+		if rr.Code != 502 {
+			t.Fatalf("save with tenantsync error = %d, want 502", rr.Code)
+		}
+		desc, _, gen := hostState(t, st)
+		if desc != nil || gen != 0 {
+			t.Errorf("fail-closed violated: desc=%+v gen=%d", desc, gen)
+		}
+		if _, err := st.ConsumeHostPBSSecret("peti-01"); err != sql.ErrNoRows {
+			t.Errorf("a secret exists after a failed provision (err %v)", err)
+		}
+		// Fail-closed also means the config save itself was aborted.
+		cfg, _ := st.GetCustomerConfig("peti")
+		if cfg.CustomerName == "half-saved" {
+			t.Error("config row saved despite provisioning failure")
+		}
+	})
+
+	t.Run("token_exists points at re-issue", func(t *testing.T) {
+		fake := &fakeTenancy{err: tenantsync.ErrTokenExists}
+		s, st, _ := newPBSDRServer(t, fake)
+		rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+		if rr.Code != 502 || !strings.Contains(rr.Body.String(), "Re-issue") {
+			t.Fatalf("token_exists = %d (%s), want 502 mentioning Re-issue", rr.Code, rr.Body.String())
+		}
+		if desc, _, gen := hostState(t, st); desc != nil || gen != 0 {
+			t.Errorf("state written on token_exists: desc=%+v gen=%d", desc, gen)
+		}
+		_ = st
+	})
+
+	t.Run("not configured", func(t *testing.T) {
+		s, st, _ := newPBSDRServer(t, nil) // no tenantsync
+		rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+		if rr.Code != 502 {
+			t.Fatalf("save without tenantsync = %d, want 502", rr.Code)
+		}
+		if desc, _, gen := hostState(t, st); desc != nil || gen != 0 {
+			t.Errorf("state written without a provisioner: desc=%+v gen=%d", desc, gen)
+		}
+	})
+}
+
+func TestPBSDR_DisableKeepsTenancy(t *testing.T) {
+	fake := &fakeTenancy{secret: "S"}
+	s, st, _ := newPBSDRServer(t, fake)
+	postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+
+	// Unchecked box → descriptor enabled:false, coords kept, ONE bump; no endpoint mutation.
+	rr := postUpdate(t, s, url.Values{})
+	if rr.Code != 303 {
+		t.Fatalf("disable save = %d, want 303", rr.Code)
+	}
+	desc, _, gen := hostState(t, st)
+	if desc == nil || desc.Enabled || desc.Namespace != "peti" || desc.TokenID == "" {
+		t.Fatalf("disable must keep coords with enabled=false: %+v", desc)
+	}
+	if gen != 2 {
+		t.Errorf("generation = %d, want 2 (enable + disable)", gen)
+	}
+	// A second disabled save is a pure no-op.
+	postUpdate(t, s, url.Values{})
+	if _, _, gen := hostState(t, st); gen != 2 {
+		t.Errorf("second disabled save bumped generation to %d", gen)
+	}
+	if fake.provisionCalls != 1 || fake.reissueCalls != 0 {
+		t.Errorf("endpoint touched on disable: provision=%d reissue=%d", fake.provisionCalls, fake.reissueCalls)
+	}
+}
+
+func TestPBSDR_StorageIDChangeUpdatesDescriptorOnly(t *testing.T) {
+	fake := &fakeTenancy{secret: "S"}
+	s, st, _ := newPBSDRServer(t, fake)
+	postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+	st.ConsumeHostPBSSecret("peti-01") // spend the provision secret
+
+	rr := postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}, "pbsdr_storage_id": {"felhom-offsite"}})
+	if rr.Code != 303 {
+		t.Fatalf("storage-id change = %d, want 303", rr.Code)
+	}
+	desc, _, gen := hostState(t, st)
+	if desc.StorageID != "felhom-offsite" || !desc.Enabled {
+		t.Errorf("descriptor not updated: %+v", desc)
+	}
+	if gen != 2 {
+		t.Errorf("generation = %d, want 2", gen)
+	}
+	if fake.provisionCalls != 1 {
+		t.Errorf("a descriptor edit re-provisioned the tenancy (%d calls)", fake.provisionCalls)
+	}
+	if _, err := st.ConsumeHostPBSSecret("peti-01"); err != sql.ErrNoRows {
+		t.Errorf("a descriptor edit staged a new secret (err %v)", err)
+	}
+}
+
+func TestPBSDR_Reissue(t *testing.T) {
+	fake := &fakeTenancy{secret: "OLD-SECRET"}
+	s, st, logBuf := newPBSDRServer(t, fake)
+	postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+	st.ConsumeHostPBSSecret("peti-01") // agent already consumed; the dead-end scenario
+
+	fake.secret = "FRESH-SECRET"
+	req := httptest.NewRequest("POST", "/configs/peti/pbsdr-reissue", nil)
+	rr := httptest.NewRecorder()
+	s.handlePBSDRReissue(rr, req, "peti")
+	if rr.Code != 303 {
+		t.Fatalf("reissue = %d (%s), want 303", rr.Code, rr.Body.String())
+	}
+	if fake.reissueCalls != 1 {
+		t.Errorf("reissue calls = %d, want 1", fake.reissueCalls)
+	}
+	got, err := st.ConsumeHostPBSSecret("peti-01")
+	if err != nil || got != "FRESH-SECRET" {
+		t.Fatalf("fresh secret consume = (%q, %v)", got, err)
+	}
+	if _, err := st.ConsumeHostPBSSecret("peti-01"); err != sql.ErrNoRows {
+		t.Error("the old secret path survived the re-issue")
+	}
+	if _, _, gen := hostState(t, st); gen != 2 {
+		t.Errorf("generation = %d, want 2 (provision + reissue)", gen)
+	}
+	if strings.Contains(logBuf.String(), "FRESH-SECRET") || strings.Contains(logBuf.String(), "OLD-SECRET") {
+		t.Error("secret leaked into the hub log")
+	}
+}
+
+func TestPBSDR_ReissueRequiresProvisionedState(t *testing.T) {
+	fake := &fakeTenancy{secret: "S"}
+	s, _, _ := newPBSDRServer(t, fake)
+	req := httptest.NewRequest("POST", "/configs/peti/pbsdr-reissue", nil)
+	rr := httptest.NewRecorder()
+	s.handlePBSDRReissue(rr, req, "peti")
+	if rr.Code != 400 {
+		t.Fatalf("reissue without a provisioned tier = %d, want 400", rr.Code)
+	}
+	if fake.reissueCalls != 0 {
+		t.Errorf("endpoint touched without a descriptor (%d calls)", fake.reissueCalls)
+	}
+}
+
+// The form render leg: the section reflects the provisioned descriptor (checkbox + namespace line)
+// and the fresh-form default storage id.
+func TestPBSDR_FormRendersState(t *testing.T) {
+	fake := &fakeTenancy{secret: "S"}
+	s, _, _ := newPBSDRServer(t, fake)
+	postUpdate(t, s, url.Values{"pbsdr_enabled": {"on"}})
+
+	req := httptest.NewRequest("GET", "/configs/peti/edit", nil)
+	rr := httptest.NewRecorder()
+	s.handleConfigEditForm(rr, req, "peti")
+	out := rr.Body.String()
+	if !strings.Contains(out, `name="pbsdr_enabled" checked`) {
+		t.Error("enabled checkbox not checked after provisioning")
+	}
+	if !strings.Contains(out, "Provisioned: namespace peti, token felhom@pbs!peti") {
+		t.Error("provisioned-state line missing")
+	}
+	if !strings.Contains(out, "pbsdr-reissue") {
+		t.Error("re-issue button missing")
+	}
+	if strings.Contains(out, "S\"") && strings.Contains(out, "token_secret") {
+		t.Error("secret-ish content rendered")
+	}
+
+	// Deadline check on the detached-ctx behavior is out of scope here; the view path must
+	// stay read-only — a render must not have touched provisioning.
+	if fake.provisionCalls != 1 {
+		t.Errorf("rendering the form called provision (%d calls)", fake.provisionCalls)
+	}
+	_ = time.Second
+}
@@ -59,6 +59,7 @@ type Server struct {
 	assetsMgr       *assets.Manager
 	gitea           *gitea.Client       // optional; enables the Day-0 artifact version dropdowns
 	offsite         *offsite.Provisioner // optional; enables Hetzner offsite provisioning (SLICE 1)
+	tenantsync      tenancyProvisioner   // optional; enables PBS DR tier provisioning (web/pbsdr.go)

 	sessions   map[string]*hubSession
 	sessionsMu sync.RWMutex
@@ -367,6 +368,14 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		} else {
 			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
 		}
+	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/pbsdr-reissue"):
+		customerID := strings.TrimPrefix(path, "/configs/")
+		customerID = strings.TrimSuffix(customerID, "/pbsdr-reissue")
+		if r.Method == http.MethodPost {
+			s.handlePBSDRReissue(w, r, customerID)
+		} else {
+			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		}
 	case strings.HasPrefix(path, "/configs/") && strings.HasSuffix(path, "/offsite-freeze"):
 		customerID := strings.TrimPrefix(path, "/configs/")
 		customerID = strings.TrimSuffix(customerID, "/offsite-freeze")
@@ -169,6 +169,36 @@
                {{end}}{{end}}{{end}}
            </details>

+            <details class="card" {{if .PBSDR.Enabled}}open{{end}}>
+                <summary><h2 style="display:inline">PBS DR tier (ep0)</h2></summary>
+                <div class="form-grid" style="margin-top: 1rem;">
+                    <div class="form-group">
+                        <label><input type="checkbox" name="pbsdr_enabled" {{if .PBSDR.Enabled}}checked{{end}}>
+                            Enable PBS DR (provisions the ep0 namespace + token on save; the host agent applies the storage entry)</label>
+                        {{if not .PBSDR.Supported}}
+                        <small class="form-hint">Not configured on this hub (no tenantsync key) — enabling will fail until it is.</small>
+                        {{else if .PBSDR.NoHost}}
+                        <small class="form-hint">No host enrolled for this customer yet — enabling fails until the agent enrolls and reports its WG key.</small>
+                        {{end}}
+                    </div>
+                    <div class="form-group">
+                        <label for="pbsdr_storage_id">PVE storage id</label>
+                        <input type="text" id="pbsdr_storage_id" name="pbsdr_storage_id"
+                            value="{{.PBSDR.StorageID}}" placeholder="felhom-pbs">
+                        <small class="form-hint">The storage-entry id the agent creates on the box. Default felhom-pbs; the demo host's adopted manual entry is felhom-offsite.</small>
+                    </div>
+                </div>
+                {{if .PBSDR.Provisioned}}
+                <p class="form-hint" style="margin-top:.5rem">Provisioned: namespace {{.PBSDR.Namespace}}, token {{.PBSDR.TokenID}} (host {{.PBSDR.HostID}}) — the token secret is delivered to the host agent once (never shown here).</p>
+                <!-- The offsite F4 precedent: explicit operator re-key for a consumed-secret dead-end.
+                     Rides the parent form via formaction; _csrf submits with it. -->
+                <button type="submit" class="btn btn-outline" style="margin-top:.5rem"
+                    formaction="/configs/{{.Config.CustomerID}}/pbsdr-reissue" formmethod="POST"
+                    onclick="return confirm('Re-issue the PBS credentials?\n\nThe endpoint token is re-keyed and a fresh one-time secret is staged for the host agent. A box with a working storage entry re-applies on its next desired-state fetch.')">
+                    Re-issue PBS credentials</button>
+                {{end}}
+            </details>
+
            <div style="margin-top: 1.5rem; display: flex; gap: 1rem; align-items: center;">
                <button type="submit" class="btn">{{if .IsNew}}Create Configuration{{else}}Save Changes{{end}}</button>
                <a href="{{if .IsNew}}/configs{{else}}/customers/{{.Config.CustomerID}}{{end}}" class="btn btn-outline">Cancel</a>
@@ -171,6 +171,11 @@ spec:
                  name: wg-endpoint-ssh
                  key: hostkey
                  optional: true
+            # PBS DR tier (SLICE 1): the tenantsync channel — same endpoint + pinned host key as
+            # peersync (env above), its OWN private key from Secret/tenantsync (out-of-band,
+            # runbook offsite-endpoint.md §10). Optional: absent → the hub logs tenantsync disabled.
+            - name: TENANTSYNC_SSH_KEY_FILE
+              value: "/etc/hub-secrets/tenantsync/key"
            # Offsite provisioning (SLICE 1+2): Hetzner Storage Box API token + the NUMERIC id of the
            # pool box, from the out-of-band Secret/storagebox (NOT committed). The token MUST be scoped
            # to the dedicated storage project — NEVER the shared-project token (it can touch ep0).
@@ -206,6 +211,9 @@ spec:
            - name: wg-endpoint-ssh
              mountPath: /etc/hub-secrets/wg-endpoint-ssh
              readOnly: true
+            - name: tenantsync
+              mountPath: /etc/hub-secrets/tenantsync
+              readOnly: true
          livenessProbe:
            httpGet:
              path: /healthz
@@ -235,6 +243,14 @@ spec:
              - key: key
                path: key
                mode: 0400
+        - name: tenantsync
+          secret:
+            secretName: tenantsync
+            optional: true
+            items:
+              - key: key
+                path: key
+                mode: 0400

 # =============================================================================
 # SERVICE
@@ -0,0 +1,162 @@
+#!/usr/bin/env bash
+# felhom-tenantsync v1.0.0 — the offsite endpoint's per-customer PBS tenancy surface (PBS DR tier
+# SLICE 1; spike SPIKE-pbs-tier-provisioning-2026-07-10 §3).
+#
+# Runs as the SSH forced command for the hub's SECOND `felhom-peersync` key (via sudo — its own
+# single sudoers line; the peersync script/key are untouched: one script, one job). JSON on stdin,
+# JSON on stdout. Ops:
+#
+#   {"op":"provision","customer_id":"<id>"}  → ensure namespace <id> (idempotent) → CREATE token
+#       felhom@pbs!<id> (an EXISTING token is a hard error, code "token_exists" — re-issue is the
+#       explicit path) → dual-grant DatastoreBackup on /datastore/felhom-offsite/<id> to BOTH the
+#       user and the token (PBS privsep = intersection) → self-check: list the namespace AS the
+#       new token (one regen retry per the spike's transient-403 note; still failing → rollback)
+#       → {"status":"ok","token_id","token_secret","fingerprint","datastore","namespace"}
+#   {"op":"reissue","customer_id":"<id>"}    → delete-token (its ACLs purge with it — spike) →
+#       recreate → re-grant BOTH → self-check → same ok-shape with the FRESH secret.
+#   {"op":"fingerprint"}                     → {"status":"ok","fingerprint":"<PBS cert sha256>"}
+#
+# NO deprovision op in slice 1 — namespace/data deletion is a deliberate, separate decision (the
+# offsite-disable precedent: disable never destroys data).
+#
+# Secret hygiene (load-bearing):
+#   - The token secret exists ONLY in memory and in the final stdout JSON — never a file, never
+#     stderr (the hub embeds remote stderr in error logs), never an argument.
+#   - The transient root@pam admin token (namespace ops are client-side) is held in memory and
+#     deleted on EVERY exit path (trap). A leftover from a crashed run is deleted at entry.
+#   - All tool stdout is redirected to stderr — the response JSON is the ONLY stdout bytes.
+#
+# Ordering facts this script encodes (all live-proven in the spike — do not "simplify"):
+#   - the token must exist BEFORE its ACL grant (PBS validates the auth-id);
+#   - user delete-token PURGES the token's ACLs → re-issue must re-grant;
+#   - `user generate-token` has no --output-format → the "value" line is sed-parsed;
+#   - proxmox-backup-client needs PBS_FINGERPRINT even against localhost.
+set -euo pipefail
+
+DS=felhom-offsite
+PBS_USER=felhom@pbs
+ADMIN_TOKEN_NAME=tenantsync-admin
+REPO_HOST=localhost
+
+err_json() { # code, message → error JSON on stdout, exit 1
+  printf '{"status":"error","code":"%s","error":"%s"}\n' "$1" "$2"
+  exit 1
+}
+
+command -v jq >/dev/null || err_json internal "jq is required"
+command -v proxmox-backup-manager >/dev/null || err_json internal "proxmox-backup-manager is required"
+command -v proxmox-backup-client >/dev/null || err_json internal "proxmox-backup-client is required"
+
+# 1. Read stdin capped at 64 KiB; validate the envelope BEFORE touching anything.
+payload=$(head -c 65536)
+[ -n "$payload" ] || err_json bad_request "empty payload"
+jq -e 'type == "object" and (.op | type) == "string"' >/dev/null 2>&1 <<<"$payload" \
+  || err_json bad_request "payload must be a JSON object with a string op"
+OP=$(jq -r '.op' <<<"$payload")
+
+export PBS_FINGERPRINT
+PBS_FINGERPRINT=$(proxmox-backup-manager cert info | awk '/Fingerprint/{print $3}' | head -1)
+[ -n "$PBS_FINGERPRINT" ] || err_json internal "could not read the PBS cert fingerprint"
+
+if [ "$OP" = "fingerprint" ]; then
+  printf '{"status":"ok","fingerprint":"%s"}\n' "$PBS_FINGERPRINT"
+  exit 0
+fi
+
+case "$OP" in provision|reissue) ;; *) err_json bad_request "unknown op" ;; esac
+
+# customer_id → the namespace AND the token name. Conservative charset (PBS ns + token grammar,
+# no leading dash/dot so it can never parse as an option).
+CID=$(jq -r '.customer_id // ""' <<<"$payload")
+[[ "$CID" =~ ^[A-Za-z0-9][A-Za-z0-9_.-]{0,30}$ ]] \
+  || err_json bad_request "customer_id must match ^[A-Za-z0-9][A-Za-z0-9_.-]{0,30}\$"
+TOKEN_ID="$PBS_USER!$CID"
+
+log() { echo "felhom-tenantsync: $*" >&2; }
+
+# 2. Transient admin token for the client-side namespace ops. Deleted on every exit; a leftover
+#    from a crashed run is cleared first (generate-token fails on an existing name).
+proxmox-backup-manager user delete-token root@pam "$ADMIN_TOKEN_NAME" >&2 2>/dev/null || true
+ADM=$(proxmox-backup-manager user generate-token root@pam "$ADMIN_TOKEN_NAME" \
+  | sed -n 's/.*"value": "\([^"]*\)".*/\1/p')
+[ -n "$ADM" ] || err_json internal "admin token generation failed"
+cleanup_admin() {
+  proxmox-backup-manager user delete-token root@pam "$ADMIN_TOKEN_NAME" >&2 2>/dev/null || true
+  proxmox-backup-manager acl update "/datastore/$DS" DatastoreAdmin \
+    --auth-id "root@pam!$ADMIN_TOKEN_NAME" --delete >&2 2>/dev/null || true
+}
+trap cleanup_admin EXIT
+proxmox-backup-manager acl update "/datastore/$DS" DatastoreAdmin \
+  --auth-id "root@pam!$ADMIN_TOKEN_NAME" >&2
+
+ADMIN_REPO="root@pam!$ADMIN_TOKEN_NAME@$REPO_HOST:$DS"
+
+# 3. Ensure the shared user + the namespace (both idempotent).
+if ! proxmox-backup-manager user list --output-format json | jq -e --arg u "$PBS_USER" \
+    'any(.[]; .userid == $u)' >/dev/null; then
+  proxmox-backup-manager user create "$PBS_USER" --comment 'offsite tenancy' >&2
+  log "created user $PBS_USER"
+fi
+if ! PBS_PASSWORD="$ADM" proxmox-backup-client namespace list --repository "$ADMIN_REPO" \
+    --output-format json | jq -e --arg ns "$CID" 'any(.[]; .ns == $ns)' >/dev/null; then
+  PBS_PASSWORD="$ADM" proxmox-backup-client namespace create "$CID" --repository "$ADMIN_REPO" >&2
+  log "created namespace $CID"
+fi
+
+token_exists() {
+  proxmox-backup-manager user list-tokens "$PBS_USER" --output-format json \
+    | jq -e --arg t "$TOKEN_ID" 'any(.[]; .tokenid == $t)' >/dev/null
+}
+
+# gen_token → SECRET on stdout of this function only (command substitution), nothing persisted.
+gen_token() {
+  proxmox-backup-manager user generate-token "$PBS_USER" "$CID" \
+    | sed -n 's/.*"value": "\([^"]*\)".*/\1/p'
+}
+
+grant_both() { # dual-grant on the NAMESPACE ACL path (never /ns/<ns> — §4a gotcha)
+  proxmox-backup-manager acl update "/datastore/$DS/$CID" DatastoreBackup --auth-id "$PBS_USER" >&2
+  proxmox-backup-manager acl update "/datastore/$DS/$CID" DatastoreBackup --auth-id "$TOKEN_ID" >&2
+}
+
+self_check() { # own-namespace list AS the new token; secret via env, never argv/stderr
+  PBS_PASSWORD="$1" proxmox-backup-client snapshot list --ns "$CID" \
+    --repository "$TOKEN_ID@$REPO_HOST:$DS" >/dev/null
+}
+
+rollback_token() {
+  proxmox-backup-manager user delete-token "$PBS_USER" "$CID" >&2 2>/dev/null || true
+  proxmox-backup-manager acl update "/datastore/$DS/$CID" DatastoreBackup \
+    --auth-id "$PBS_USER" --delete >&2 2>/dev/null || true
+}
+
+if [ "$OP" = "provision" ]; then
+  if token_exists; then
+    err_json token_exists "token $TOKEN_ID already exists — use the reissue op (explicit re-key)"
+  fi
+else # reissue: delete-token purges its ACLs; recreate + re-grant below
+  proxmox-backup-manager user delete-token "$PBS_USER" "$CID" >&2 2>/dev/null || true
+  log "reissue: old token deleted (ACLs purged with it)"
+fi
+
+SECRET=$(gen_token)
+[ -n "$SECRET" ] || err_json internal "token generation returned no value"
+grant_both
+
+if ! self_check "$SECRET"; then
+  # The spike's transient-403 note: one delete+regen+re-grant retry, then rollback + fail.
+  log "self-check failed — regenerating once (spike transient-403 note)"
+  proxmox-backup-manager user delete-token "$PBS_USER" "$CID" >&2 2>/dev/null || true
+  SECRET=$(gen_token)
+  [ -n "$SECRET" ] || { rollback_token; err_json internal "token regeneration returned no value"; }
+  grant_both
+  if ! self_check "$SECRET"; then
+    rollback_token
+    err_json self_check_failed "own-namespace list as $TOKEN_ID failed twice — rolled back"
+  fi
+fi
+
+log "$OP ok: ns=$CID token=$TOKEN_ID (secret rides stdout only)"
+jq -cn --arg tid "$TOKEN_ID" --arg sec "$SECRET" --arg fp "$PBS_FINGERPRINT" \
+  --arg ds "$DS" --arg ns "$CID" \
+  '{"status":"ok","token_id":$tid,"token_secret":$sec,"fingerprint":$fp,"datastore":$ds,"namespace":$ns}'