feat(tenants): provision the product tenant with the registry UUID on create (#21)

Dockerfile

@@ -3,7 +3,7 @@
 #   /tenant-registry  — long-running API server
 #   /migrate          — one-shot schema migrator (Orca init container in prod)
 
-FROM golang:1.24-alpine AS build
+FROM golang:1.25-alpine AS build
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download

cmd/server/main.go

@@ -13,6 +13,7 @@ import (
 	"gitea.meghsakha.com/platform/tenant-registry/internal/authn"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/config"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/keycloak"
+	"gitea.meghsakha.com/platform/tenant-registry/internal/product"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/server"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
 )
@@ -74,7 +75,19 @@ func main() {
 		slog.Warn("AUTH_ENABLED=false — API is unauthenticated (dev only)")
 	}
 
-	handler := server.NewRouter(&server.Server{Cfg: cfg, Log: logger, Store: s, Keycloak: kc, Auth: av})
+	// Downstream product provisioning. Wired only when PRODUCT_API_URL is set;
+	// otherwise a no-op so an unconfigured deployment still creates tenants.
+	// The product's gate is not yet enforcing, so no token is attached today —
+	// AuthHeaderFunc is the seam for when it is.
+	var pv product.Provisioner = product.NoopProvisioner{}
+	if cfg.ProductAPIURL != "" {
+		pv = product.NewHTTPProvisioner(cfg.ProductAPIURL, cfg.ProductAPIPath, nil, cfg.ProductTimeout)
+		slog.Info("product provisioner configured", "url", cfg.ProductAPIURL, "path", cfg.ProductAPIPath)
+	} else {
+		slog.Warn("PRODUCT_API_URL not set — product tenant provisioning disabled (anchors may diverge)")
+	}
+
+	handler := server.NewRouter(&server.Server{Cfg: cfg, Log: logger, Store: s, Keycloak: kc, Auth: av, Product: pv})
 	srv := &http.Server{
 		Addr:         cfg.Addr,
 		Handler:      handler,

internal/config/config.go

@@ -27,6 +27,13 @@ type Config struct {
 	// contains AuthAudience.
 	AuthEnabled  bool
 	AuthAudience string
+
+	// Downstream product provisioning. When ProductAPIURL is set, tenant
+	// creation also provisions the tenant in the product's own database with
+	// the SAME registry UUID, so both anchors agree. Empty ⇒ no-op adapter.
+	ProductAPIURL  string
+	ProductAPIPath string
+	ProductTimeout time.Duration
 }
 
 func Load() (*Config, error) {
@@ -49,6 +56,10 @@ func Load() (*Config, error) {
 
 		AuthEnabled:  getenv("AUTH_ENABLED", "false") == "true",
 		AuthAudience: getenv("AUTH_EXPECTED_AUDIENCE", "tenant-registry"),
+
+		ProductAPIURL:  os.Getenv("PRODUCT_API_URL"),
+		ProductAPIPath: getenv("PRODUCT_API_TENANTS_PATH", "/sdk/v1/tenants"),
+		ProductTimeout: 10 * time.Second,
 	}, nil
 }
 

internal/keycloak/adapter.go

@@ -75,11 +75,12 @@ type Adapter interface {
 	SyncClaims(ctx context.Context, userID string, c Claims) error
 
 	// Memberships resolves the tenants user userID (the Keycloak user id,
-	// i.e. the JWT `sub`) belongs to, as Keycloak records them. The realm
-	// has no Organizations yet, so this reads the user's attribute
-	// projection — zero or one memberships. When the realm migrates to
-	// Organizations this becomes an org-membership query and callers keep
-	// working unchanged. Returns ErrUserNotFound for an unknown user id.
+	// i.e. the JWT `sub`) belongs to, as Keycloak records them. Since the
+	// realm enabled Organizations (2026-09-01) this is an org-membership
+	// query: one membership per enabled org the user belongs to (alias =
+	// tenant slug, org attribute tenant_id = registry UUID). The legacy
+	// user-attribute projection no longer grants membership on its own.
+	// Returns ErrUserNotFound for an unknown user id.
 	Memberships(ctx context.Context, userID string) ([]Claims, error)
 
 	// Health pings the admin endpoint. Used by readyz and the cluster cold-

internal/keycloak/client_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -24,6 +25,7 @@ type stubKC struct {
 	emailCalls  atomic.Int32
 	healthCalls atomic.Int32
 	syncCalls   atomic.Int32
+	lastOrgBody string
 
 	tokenFails atomic.Bool // when true, /token returns 401 once
 }
@@ -53,6 +55,8 @@ func newStubKC(t *testing.T) *stubKC {
 	mux.HandleFunc("/admin/realms/test-realm/organizations", func(w http.ResponseWriter, r *http.Request) {
 		s.orgCalls.Add(1)
 		if r.Method == http.MethodPost {
+			body, _ := io.ReadAll(r.Body)
+			s.lastOrgBody = string(body)
 			w.Header().Set("Location", s.srv.URL+"/admin/realms/test-realm/organizations/org-xyz")
 			w.WriteHeader(http.StatusCreated)
 			return
@@ -135,6 +139,12 @@ func TestHTTPAdapter_createOrgAndInvite(t *testing.T) {
 		t.Errorf("call counts: org=%d user=%d member=%d email=%d",
 			s.orgCalls.Load(), s.userCalls.Load(), s.memberCalls.Load(), s.emailCalls.Load())
 	}
+	// KC 26 rejects a domainless org; the adapter must send a synthetic
+	// per-slug domain so onboarding actually provisions.
+	if !strings.Contains(s.lastOrgBody, `"domains"`) ||
+		!strings.Contains(s.lastOrgBody, "acme.tenant.breakpilot.com") {
+		t.Errorf("org create body missing synthetic domain: %s", s.lastOrgBody)
+	}
 }
 
 func TestHTTPAdapter_emailMissingAdminEmailRejected(t *testing.T) {

internal/keycloak/orgs.go

@@ -13,6 +13,11 @@ import (
 
 // ─── organizations API ───────────────────────────────────────────────────
 
+// orgDomainSuffix namespaces the synthetic org domain. The slug is unique in
+// the registry, so "<slug>.tenant.breakpilot.com" is unique per organization
+// and never a real deliverable mail domain we might clash with.
+const orgDomainSuffix = ".tenant.breakpilot.com"
+
 type orgCreate struct {
 	Name        string              `json:"name"`
 	Alias       string              `json:"alias"`
@@ -50,6 +55,16 @@ func (a *HTTPAdapter) CreateOrgAndInvite(ctx context.Context, in InviteInput) (*
 		Name:        in.Name,
 		Alias:       in.Slug,
 		Description: fmt.Sprintf("Auto-provisioned from tenant-registry %s", in.TenantID),
+		// Keycloak 26 rejects an organization with no domain ("You must
+		// provide at least one domain"). Membership is registry-authoritative
+		// (model B2), so we do NOT use Keycloak's email-domain auto-join; a
+		// synthetic per-tenant domain derived from the unique slug satisfies
+		// the constraint without depending on the customer's real mail domain
+		// (which may be a shared public domain and would collide across
+		// tenants). Unverified is fine — verification only gates auto-join.
+		Domains: []map[string]any{
+			{"name": in.Slug + orgDomainSuffix, "verified": false},
+		},
 		Attributes: map[string][]string{
 			"tenant_id": {in.TenantID},
 		},

internal/keycloak/users.go

@@ -18,7 +18,33 @@ type userRepresentation struct {
 	Attributes map[string][]string `json:"attributes"`
 }
 
-// Memberships implements Adapter against GET /admin/realms/{realm}/users/{id}.
+// memberOrgRepresentation is the slice of OrganizationRepresentation the
+// membership query needs: the alias IS the tenant slug and the org
+// attribute "tenant_id" carries the registry tenant UUID (both written by
+// CreateOrgAndInvite, or provisioned by the realm admin for pre-existing
+// tenants).
+type memberOrgRepresentation struct {
+	ID         string              `json:"id"`
+	Alias      string              `json:"alias"`
+	Enabled    bool                `json:"enabled"`
+	Attributes map[string][]string `json:"attributes"`
+}
+
+// Memberships implements Adapter with Keycloak Organizations as the
+// authoritative membership source (prod shape, realm orgs enabled
+// 2026-09-01):
+//
+//  1. GET /users/{id} — preserves ErrUserNotFound semantics and supplies
+//     the per-user claim attributes (org_roles / products / plan /
+//     tenant_status) that SyncClaims maintains.
+//  2. GET /organizations/members/{id}/organizations — the memberships.
+//
+// One Claims entry per ENABLED organization: TenantID = org attribute
+// "tenant_id" (registry UUID), TenantSlug = org alias. A disabled org
+// grants no membership. A user in no organization has zero memberships —
+// the legacy user-attribute tenant projection is NO LONGER consulted for
+// membership, so a stale tenant_id/tenant_slug user attribute cannot
+// grant access the org model has revoked.
 func (a *HTTPAdapter) Memberships(ctx context.Context, userID string) ([]Claims, error) {
 	var u userRepresentation
 	resp, err := a.adminCall(ctx, http.MethodGet, "/users/"+userID, nil, &u)
@@ -33,25 +59,34 @@ func (a *HTTPAdapter) Memberships(ctx context.Context, userID string) ([]Claims,
 		_ = resp.Body.Close()
 		return nil, fmt.Errorf("keycloak get user: %d", resp.StatusCode)
 	}
-	return claimsFromAttributes(u.Attributes), nil
+
+	var orgs []memberOrgRepresentation
+	resp, err = a.adminCall(
+		ctx, http.MethodGet, "/organizations/members/"+userID+"/organizations", nil, &orgs,
+	)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode/100 != 2 {
+		_ = resp.Body.Close()
+		return nil, fmt.Errorf("keycloak member organizations: %d", resp.StatusCode)
 	}
 
-// claimsFromAttributes builds the membership list from a user's attribute
-// projection. A user with no tenant_id and no tenant_slug attribute simply
-// has no memberships — that is a valid state, not an error.
-func claimsFromAttributes(attrs map[string][]string) []Claims {
-	c := Claims{
-		TenantID:     attrValue(attrs, "tenant_id"),
-		TenantSlug:   attrValue(attrs, "tenant_slug"),
-		OrgRoles:     attrValues(attrs, "org_roles"),
-		Products:     attrValues(attrs, "products"),
-		Plan:         attrValue(attrs, "plan"),
-		TenantStatus: attrValue(attrs, "tenant_status"),
+	claims := []Claims{}
+	for _, org := range orgs {
+		if !org.Enabled {
+			continue
 		}
-	if c.TenantID == "" && c.TenantSlug == "" {
-		return []Claims{}
+		claims = append(claims, Claims{
+			TenantID:     attrValue(org.Attributes, "tenant_id"),
+			TenantSlug:   org.Alias,
+			OrgRoles:     attrValues(u.Attributes, "org_roles"),
+			Products:     attrValues(u.Attributes, "products"),
+			Plan:         attrValue(u.Attributes, "plan"),
+			TenantStatus: attrValue(u.Attributes, "tenant_status"),
+		})
 	}
-	return []Claims{c}
+	return claims, nil
 }
 
 func attrValue(attrs map[string][]string, key string) string {

internal/keycloak/users_test.go

@@ -9,9 +9,13 @@ import (
 	"testing"
 )
 
-// stubUsersKC is a users-endpoint-only KC look-alike; stubKC (client_test.go)
-// covers the org/invite paths and doesn't register GET /users/{id}.
-func stubUsersKC(t *testing.T, users map[string]userRepresentation) *httptest.Server {
+// stubUsersKC is a users+organizations KC look-alike; stubKC (client_test.go)
+// covers the org-create/invite paths and doesn't register these reads.
+func stubUsersKC(
+	t *testing.T,
+	users map[string]userRepresentation,
+	memberOrgs map[string][]memberOrgRepresentation,
+) *httptest.Server {
 	t.Helper()
 	mux := http.NewServeMux()
 	mux.HandleFunc("/realms/test-realm/protocol/openid-connect/token", func(w http.ResponseWriter, _ *http.Request) {
@@ -28,6 +32,14 @@ func stubUsersKC(t *testing.T, users map[string]userRepresentation) *httptest.Se
 		w.Header().Set("Content-Type", "application/json")
 		_ = json.NewEncoder(w).Encode(u)
 	})
+	mux.HandleFunc("GET /admin/realms/test-realm/organizations/members/{id}/organizations", func(w http.ResponseWriter, r *http.Request) {
+		orgs, ok := memberOrgs[r.PathValue("id")]
+		if !ok {
+			orgs = []memberOrgRepresentation{}
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(orgs)
+	})
 	srv := httptest.NewServer(mux)
 	t.Cleanup(srv.Close)
 	return srv
@@ -40,10 +52,11 @@ func usersAdapter(srv *httptest.Server) *HTTPAdapter {
 }
 
 func TestHTTPAdapter_Memberships(t *testing.T) {
-	srv := stubUsersKC(t, map[string]userRepresentation{
+	users := map[string]userRepresentation{
 		"u-1": {ID: "u-1", Username: "test@breakpilot.com", Enabled: true, Attributes: map[string][]string{
-			"tenant_id":     {"acme-001"},
-			"tenant_slug":   {"acme"},
+			// legacy projection attrs — MUST NOT grant membership on their own
+			"tenant_id":     {"stale-legacy-001"},
+			"tenant_slug":   {"stale"},
 			"tenant_status": {"active"},
 			"plan":          {"Scale"},
 			"org_roles":     {"IT_ADMIN", "FINANCE"},
@@ -51,10 +64,30 @@ func TestHTTPAdapter_Memberships(t *testing.T) {
 			"products": {"compliance##certifai"},
 		}},
 		"u-2": {ID: "u-2", Username: "bare@breakpilot.com", Enabled: true},
-	})
+		"u-3": {ID: "u-3", Username: "multi@breakpilot.com", Enabled: true},
+		"u-4": {ID: "u-4", Username: "attrs-only@breakpilot.com", Enabled: true, Attributes: map[string][]string{
+			"tenant_id":   {"acme-001"},
+			"tenant_slug": {"acme"},
+		}},
+	}
+	memberOrgs := map[string][]memberOrgRepresentation{
+		"u-1": {{
+			ID: "org-1", Alias: "acme", Enabled: true,
+			Attributes: map[string][]string{"tenant_id": {"2f875d6a-1d94-433a-b2ec-8529451a2d89"}},
+		}},
+		"u-3": {
+			{ID: "org-1", Alias: "acme", Enabled: true,
+				Attributes: map[string][]string{"tenant_id": {"2f875d6a-1d94-433a-b2ec-8529451a2d89"}}},
+			{ID: "org-2", Alias: "globex", Enabled: true,
+				Attributes: map[string][]string{"tenant_id": {"7c3f2b10-0000-4000-8000-000000000042"}}},
+			{ID: "org-3", Alias: "disabled-co", Enabled: false,
+				Attributes: map[string][]string{"tenant_id": {"9e9e9e9e-0000-4000-8000-000000000099"}}},
+		},
+	}
+	srv := stubUsersKC(t, users, memberOrgs)
 	a := usersAdapter(srv)
 
-	t.Run("attribute projection becomes one membership", func(t *testing.T) {
+	t.Run("org membership becomes the claim, org attrs are authoritative", func(t *testing.T) {
 		got, err := a.Memberships(context.Background(), "u-1")
 		if err != nil {
 			t.Fatalf("memberships: %v", err)
@@ -63,8 +96,14 @@ func TestHTTPAdapter_Memberships(t *testing.T) {
 			t.Fatalf("want 1 membership, got %d", len(got))
 		}
 		c := got[0]
-		if c.TenantID != "acme-001" || c.TenantSlug != "acme" || c.Plan != "Scale" || c.TenantStatus != "active" {
-			t.Errorf("scalar claims wrong: %+v", c)
+		// tenant identity comes from the ORG (alias + tenant_id attribute),
+		// never from the user's legacy projection attributes
+		if c.TenantID != "2f875d6a-1d94-433a-b2ec-8529451a2d89" || c.TenantSlug != "acme" {
+			t.Errorf("org identity wrong: %+v", c)
+		}
+		// per-user claim attrs still ride along
+		if c.Plan != "Scale" || c.TenantStatus != "active" {
+			t.Errorf("user claim attrs wrong: %+v", c)
 		}
 		if len(c.OrgRoles) != 2 || c.OrgRoles[0] != "IT_ADMIN" || c.OrgRoles[1] != "FINANCE" {
 			t.Errorf("org_roles wrong: %v", c.OrgRoles)
@@ -74,7 +113,7 @@ func TestHTTPAdapter_Memberships(t *testing.T) {
 		}
 	})
 
-	t.Run("user without tenant attributes has zero memberships", func(t *testing.T) {
+	t.Run("user in no org has zero memberships", func(t *testing.T) {
 		got, err := a.Memberships(context.Background(), "u-2")
 		if err != nil {
 			t.Fatalf("memberships: %v", err)
@@ -84,6 +123,29 @@ func TestHTTPAdapter_Memberships(t *testing.T) {
 		}
 	})
 
+	t.Run("legacy tenant attributes alone grant NO membership", func(t *testing.T) {
+		got, err := a.Memberships(context.Background(), "u-4")
+		if err != nil {
+			t.Fatalf("memberships: %v", err)
+		}
+		if len(got) != 0 {
+			t.Fatalf("attribute projection must not grant membership, got %+v", got)
+		}
+	})
+
+	t.Run("multiple orgs give multiple memberships, disabled org skipped", func(t *testing.T) {
+		got, err := a.Memberships(context.Background(), "u-3")
+		if err != nil {
+			t.Fatalf("memberships: %v", err)
+		}
+		if len(got) != 2 {
+			t.Fatalf("want 2 memberships (disabled org skipped), got %d", len(got))
+		}
+		if got[0].TenantSlug != "acme" || got[1].TenantSlug != "globex" {
+			t.Errorf("slugs wrong: %+v", got)
+		}
+	})
+
 	t.Run("unknown user is ErrUserNotFound", func(t *testing.T) {
 		_, err := a.Memberships(context.Background(), "nope")
 		if !errors.Is(err, ErrUserNotFound) {
@@ -92,15 +154,24 @@ func TestHTTPAdapter_Memberships(t *testing.T) {
 	})
 }
 
-func TestMock_Memberships(t *testing.T) {
-	m := NewMock()
-	if _, err := m.Memberships(context.Background(), "ghost"); !errors.Is(err, ErrUserNotFound) {
-		t.Fatalf("want ErrUserNotFound, got %v", err)
-	}
-	want := Claims{TenantSlug: "acme", OrgRoles: []string{"IT_ADMIN"}}
-	m.Claims["u-1"] = want
-	got, err := m.Memberships(context.Background(), "u-1")
-	if err != nil || len(got) != 1 || got[0].TenantSlug != "acme" {
-		t.Fatalf("got %+v err %v", got, err)
+func TestHTTPAdapter_Memberships_OrgQueryFailure(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/realms/test-realm/protocol/openid-connect/token", func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{"access_token": "t", "expires_in": 60})
+	})
+	mux.HandleFunc("GET /admin/realms/test-realm/users/{id}", func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(userRepresentation{ID: "u-1", Enabled: true})
+	})
+	mux.HandleFunc("GET /admin/realms/test-realm/organizations/members/{id}/organizations", func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	})
+	srv := httptest.NewServer(mux)
+	t.Cleanup(srv.Close)
+
+	_, err := usersAdapter(srv).Memberships(context.Background(), "u-1")
+	if err == nil {
+		t.Fatal("want error when the org query fails, got nil")
 	}
 }

internal/product/product.go

@@ -0,0 +1,106 @@
+// Package product provisions a tenant into the downstream product database.
+//
+// The registry is the authority for tenant identity (ratified model B2), so a
+// product must anchor its own tenant row to the SAME canonical UUID. Without
+// this the anchors diverge: the registry knows "acme", the product database
+// does not, and the product's gate rejects every request from that tenant
+// because it cannot resolve the org slug.
+//
+// The Provisioner is a port, mirroring keycloak.Adapter: handlers depend on the
+// interface, main wires the HTTP implementation when PRODUCT_API_URL is set and
+// a no-op otherwise (dev convenience, and so an unconfigured deployment does
+// not fail tenant creation).
+package product
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+// ErrUnavailable means the product API could not be reached or refused us.
+var ErrUnavailable = errors.New("product: provisioning API unavailable")
+
+// Tenant is the minimal identity a product needs to create its own row.
+type Tenant struct {
+	ID   string `json:"id"` // the registry UUID — the whole point
+	Name string `json:"name"`
+	Slug string `json:"slug"`
+}
+
+// Provisioner creates the tenant in a product's own datastore.
+type Provisioner interface {
+	ProvisionTenant(ctx context.Context, t Tenant) error
+}
+
+// NoopProvisioner is wired when PRODUCT_API_URL is unset.
+type NoopProvisioner struct{}
+
+func (NoopProvisioner) ProvisionTenant(context.Context, Tenant) error { return nil }
+
+// AuthHeaderFunc supplies an Authorization header per call, so a token is
+// fetched lazily and refreshed rather than captured at construction. Nil means
+// no header, which is the correct behaviour against a product whose gate is
+// not yet enforcing.
+type AuthHeaderFunc func(context.Context) (string, error)
+
+// HTTPProvisioner calls the product's tenant-create endpoint.
+type HTTPProvisioner struct {
+	BaseURL string
+	Path    string // e.g. /sdk/v1/tenants
+	Auth    AuthHeaderFunc
+	Client  *http.Client
+}
+
+func NewHTTPProvisioner(baseURL, path string, auth AuthHeaderFunc, timeout time.Duration) *HTTPProvisioner {
+	if path == "" {
+		path = "/sdk/v1/tenants"
+	}
+	return &HTTPProvisioner{
+		BaseURL: baseURL, Path: path, Auth: auth,
+		Client: &http.Client{Timeout: timeout},
+	}
+}
+
+func (p *HTTPProvisioner) ProvisionTenant(ctx context.Context, t Tenant) error {
+	body, err := json.Marshal(t)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, p.BaseURL+p.Path, bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	if p.Auth != nil {
+		h, aerr := p.Auth(ctx)
+		if aerr != nil {
+			return fmt.Errorf("%w: %v", ErrUnavailable, aerr)
+		}
+		if h != "" {
+			req.Header.Set("Authorization", h)
+		}
+	}
+	resp, err := p.Client.Do(req)
+	if err != nil {
+		return fmt.Errorf("%w: %v", ErrUnavailable, err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	switch {
+	case resp.StatusCode == http.StatusConflict:
+		// Already provisioned. The product's insert is idempotent on the
+		// primary key, so this is success from our point of view.
+		return nil
+	case resp.StatusCode/100 == 2:
+		return nil
+	default:
+		b, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
+		return fmt.Errorf("%w: %d %s", ErrUnavailable, resp.StatusCode, b)
+	}
+}

internal/product/product_test.go

@@ -0,0 +1,88 @@
+package product
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+// The whole point of this port: the product must be created with the
+// REGISTRY's uuid, so both systems anchor to the same tenant identity.
+func TestProvisionTenant_sendsTheRegistryUUID(t *testing.T) {
+	var got Tenant
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewDecoder(r.Body).Decode(&got)
+		w.WriteHeader(http.StatusCreated)
+	}))
+	defer srv.Close()
+
+	p := NewHTTPProvisioner(srv.URL, "/sdk/v1/tenants", nil, 5*time.Second)
+	err := p.ProvisionTenant(context.Background(), Tenant{
+		ID: "2f875d6a-1d94-433a-b2ec-8529451a2d89", Name: "Acme", Slug: "acme",
+	})
+	if err != nil {
+		t.Fatalf("provision: %v", err)
+	}
+	if got.ID != "2f875d6a-1d94-433a-b2ec-8529451a2d89" {
+		t.Errorf("registry uuid not sent: %+v", got)
+	}
+	if got.Slug != "acme" || got.Name != "Acme" {
+		t.Errorf("payload wrong: %+v", got)
+	}
+}
+
+// Re-provisioning must be safe: onboarding may retry, and the product's
+// insert is idempotent on the primary key.
+func TestProvisionTenant_conflictIsSuccess(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusConflict)
+	}))
+	defer srv.Close()
+
+	p := NewHTTPProvisioner(srv.URL, "", nil, 5*time.Second)
+	if err := p.ProvisionTenant(context.Background(), Tenant{ID: "x"}); err != nil {
+		t.Fatalf("409 should be treated as already-provisioned, got %v", err)
+	}
+}
+
+func TestProvisionTenant_serverErrorIsUnavailable(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer srv.Close()
+
+	p := NewHTTPProvisioner(srv.URL, "", nil, 5*time.Second)
+	err := p.ProvisionTenant(context.Background(), Tenant{ID: "x"})
+	if !errors.Is(err, ErrUnavailable) {
+		t.Fatalf("want ErrUnavailable, got %v", err)
+	}
+}
+
+func TestProvisionTenant_attachesAuthHeaderWhenSupplied(t *testing.T) {
+	var seen string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		seen = r.Header.Get("Authorization")
+		w.WriteHeader(http.StatusCreated)
+	}))
+	defer srv.Close()
+
+	p := NewHTTPProvisioner(srv.URL, "", func(context.Context) (string, error) {
+		return "Bearer tok-123", nil
+	}, 5*time.Second)
+	if err := p.ProvisionTenant(context.Background(), Tenant{ID: "x"}); err != nil {
+		t.Fatal(err)
+	}
+	if seen != "Bearer tok-123" {
+		t.Errorf("auth header = %q", seen)
+	}
+}
+
+func TestNoopProvisioner(t *testing.T) {
+	if err := (NoopProvisioner{}).ProvisionTenant(context.Background(), Tenant{}); err != nil {
+		t.Fatal(err)
+	}
+}

internal/server/server.go

@@ -12,6 +12,7 @@ import (
 	"gitea.meghsakha.com/platform/tenant-registry/internal/authn"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/config"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/keycloak"
+	"gitea.meghsakha.com/platform/tenant-registry/internal/product"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
 )
 
@@ -22,6 +23,17 @@ type Server struct {
 	Store    store.Store
 	Keycloak keycloak.Adapter    // never nil — main wires Mock when KC env is unset
 	Auth     *authn.Verifier     // nil ⇒ AUTH_ENABLED=false, API is open (dev only)
+	Product  product.Provisioner // never nil — main wires Noop when PRODUCT_API_URL is unset
+}
+
+// productProvisioner guarantees the "never nil" invariant the struct documents.
+// Tests construct Server directly and would otherwise panic; an unset provisioner
+// simply means no downstream provisioning, never a crash mid-tenant-creation.
+func (s *Server) productProvisioner() product.Provisioner {
+	if s.Product == nil {
+		return product.NoopProvisioner{}
+	}
+	return s.Product
 }
 
 // NewRouter builds the http.Handler with logging middleware applied.

internal/server/tenants.go

@@ -7,6 +7,7 @@ import (
 	"regexp"
 	"time"
 
+	"gitea.meghsakha.com/platform/tenant-registry/internal/product"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
 )
 
@@ -93,6 +94,27 @@ func (s *Server) createTenant(w http.ResponseWriter, r *http.Request) {
 		})
 	}
 
+	// Best-effort product provisioning, same contract as Keycloak above: the
+	// registry is the authority for tenant identity, so the product gets a row
+	// keyed by OUR uuid. A failure must not roll the tenant back — it is
+	// recorded as an audit event so the divergence is traceable and fixable.
+	// Without this the anchors drift and the product's gate rejects every
+	// request from the tenant because it cannot resolve the org slug.
+	if perr := s.productProvisioner().ProvisionTenant(ctx, product.Tenant{
+		ID: t.ID, Name: t.Name, Slug: t.Slug,
+	}); perr != nil {
+		s.emitAudit(ctx, r, store.AuditEvent{
+			TenantID: t.ID, Action: "product.provision_failed",
+			TargetID: t.ID, TargetType: "tenant",
+			Metadata: map[string]interface{}{"err": perr.Error()},
+		})
+	} else {
+		s.emitAudit(ctx, r, store.AuditEvent{
+			TenantID: t.ID, Action: "product.tenant_provisioned",
+			TargetID: t.ID, TargetType: "tenant",
+		})
+	}
+
 	writeJSON(w, http.StatusCreated, createTenantResp{Tenant: t, InviteURL: inviteURL})
 }