FLEX-WP-0008 T03-T04: tenant-engine live-lookup context adapter, close

internal/adapters/tenantengine: HTTPClient.LiveRoles() calls tenant-engine's
GET /tenants/{id}/roles/live. LiveRolesResult.Available is the load-bearing
field -- false on any transport error, non-200, or malformed body, never
inferred as zero roles. AttachToContext() writes both tenant_roles and
tenant_roles_available into a CheckRequest.Context map; a consuming Rego
policy must check tenant_roles_available before trusting tenant_roles.

Architectural finding recorded in the workplan: engine.go's Check() has no
context-adapter hook, and none of the existing topaz/relationship/rule
adapters are wired into cmd/flex-auth either -- they're standalone packages
for downstream composition. This adapter is a request-preparation helper a
protected system's own request-building code calls before POST /v1/check,
not an engine-internal hook, matching that precedent exactly.

9 Go tests; gofmt/vet/build clean; go test ./... green repo-wide.

Verified as a real three-service chain: live flex-auth serve + live
tenant-engine, created a tenant and granted it a CUS role through the real
flex-auth-gated write path, then read it back through this adapter (via a
throwaway harness, not committed) -- known tenant: roles=[CUS]
available=true; unknown tenant: roles=[] available=false err="status 404".

FLEX-WP-0008 closed: T01-T04 all done. tenant-engine's write path is now
real end-to-end; any other protected system can pull live tenant capability
role context, fail-closed. Remaining open item unchanged from TEN-WP-0003:
KEY-WP-0005 (key-cape's IAM Profile core-claims gap).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/adapters/tenantengine/http_client_test.go

@@ -0,0 +1,117 @@
+package tenantengine_test
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/netkingdom/flex-auth/internal/adapters/tenantengine"
+)
+
+func TestLiveRolesReturnsRolesOnSuccess(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/tenants/t-1/roles/live" {
+			t.Fatalf("unexpected path %s", r.URL.Path)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`{"tenant_id":"t-1","roles":["CUS","VEN"]}`))
+	}))
+	defer server.Close()
+
+	client, err := tenantengine.NewHTTPClient(server.URL)
+	if err != nil {
+		t.Fatalf("NewHTTPClient: %v", err)
+	}
+
+	result, err := client.LiveRoles(context.Background(), "t-1")
+	if err != nil {
+		t.Fatalf("LiveRoles: %v", err)
+	}
+	if !result.Available {
+		t.Fatal("expected Available = true")
+	}
+	if len(result.Roles) != 2 || result.Roles[0] != "CUS" || result.Roles[1] != "VEN" {
+		t.Fatalf("unexpected roles: %v", result.Roles)
+	}
+}
+
+func TestLiveRolesReturnsUnavailableOnNon200(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusServiceUnavailable)
+	}))
+	defer server.Close()
+
+	client, _ := tenantengine.NewHTTPClient(server.URL)
+	result, err := client.LiveRoles(context.Background(), "t-1")
+
+	if err == nil {
+		t.Fatal("expected an error")
+	}
+	if result.Available {
+		t.Fatal("expected Available = false on a 503, not indistinguishable from zero roles")
+	}
+	if result.Roles != nil {
+		t.Fatalf("expected nil roles on failure, got %v", result.Roles)
+	}
+}
+
+func TestLiveRolesReturnsUnavailableOnMalformedBody(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("not json"))
+	}))
+	defer server.Close()
+
+	client, _ := tenantengine.NewHTTPClient(server.URL)
+	result, err := client.LiveRoles(context.Background(), "t-1")
+
+	if err == nil {
+		t.Fatal("expected an error")
+	}
+	if result.Available {
+		t.Fatal("expected Available = false on malformed body")
+	}
+}
+
+func TestLiveRolesReturnsUnavailableOnConnectionFailure(t *testing.T) {
+	client, _ := tenantengine.NewHTTPClient("http://127.0.0.1:1")
+
+	result, err := client.LiveRoles(context.Background(), "t-1")
+
+	if err == nil {
+		t.Fatal("expected an error")
+	}
+	if result.Available {
+		t.Fatal("expected Available = false on connection failure")
+	}
+}
+
+func TestLiveRolesRespectsContextTimeout(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(200 * time.Millisecond)
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"tenant_id":"t-1","roles":[]}`))
+	}))
+	defer server.Close()
+
+	client, _ := tenantengine.NewHTTPClient(server.URL)
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
+	defer cancel()
+
+	result, err := client.LiveRoles(ctx, "t-1")
+
+	if err == nil {
+		t.Fatal("expected a timeout error")
+	}
+	if result.Available {
+		t.Fatal("expected Available = false on timeout")
+	}
+}
+
+func TestNewHTTPClientRequiresBaseURL(t *testing.T) {
+	if _, err := tenantengine.NewHTTPClient(""); err == nil {
+		t.Fatal("expected an error for empty base URL")
+	}
+}