Stage 10: admin console & dictionary ops (complaint review, hot-reload, broadcasts)

Server-rendered admin console in the backend at /_gm (internal/adminconsole),
fronted on the gateway's public listener by Basic-Auth + a verbatim reverse proxy
(mounted on the edge mux below the h2c wrap). A same-origin check guards its POSTs;
no operator identity is tracked. This supersedes the Stage 6 gateway-fronts-
/api/v1/admin model: GATEWAY_ADMIN_ADDR and the backend /api/v1/admin ping are
dropped and gateway/internal/admin is repurposed to the verbatim proxy.

- Complaints: migration 00008 (+ jetgen) adds disposition/resolution_note/
  resolved_at/applied_in_version + the deferred status CHECK; resolution feeds a
  query-derived pending dictionary-change pipeline (marked applied after a reload).
- Dictionary hot-reload: per-version subdir BACKEND_DICT_DIR/<version>/ via the new
  Registry.LoadAvailable; engine.OpenWithVersions restores resident versions on
  restart. Partially addresses TODO-2.
- Broadcasts: a backend Telegram-connector client (internal/connector,
  BACKEND_CONNECTOR_ADDR) for SendToUser / SendToGameChannel (discharges the Stage 9
  forward-note).
- Admin reads: account.ListAccounts/CountAccounts/Identities and
  game.ListGames/CountGames/GameByID/ListComplaints/GetComplaint/CountComplaints/
  ResolveComplaint/DictionaryChanges/MarkChangesApplied.
- Tests: adminconsole render, engine reload, same-origin guard, gateway verbatim
  proxy + h2c console mount, inttest complaint pipeline + list/count + /_gm console.
- Docs: PLAN (Stage 10 done + refinements + TODO-2), ARCHITECTURE §1/§5/§6/§12/§13,
  FUNCTIONAL (+_ru), TESTING, backend/gateway READMEs.

gateway/internal/admin/admin.go

@@ -1,8 +1,11 @@
-// Package admin is the gateway's admin surface: HTTP Basic-Auth in front of a
-// reverse proxy to the backend admin API (docs/ARCHITECTURE.md §12). The gateway
-// validates the operator credential and forwards authenticated requests to
-// backend /api/v1/admin/*; the backend trusts the gateway on this segment. The
-// admin API itself is filled in Stage 10.
+// Package admin is the gateway's admin edge: HTTP Basic-Auth in front of a reverse
+// proxy that forwards the operator's browser to the backend's server-rendered admin
+// console under /_gm. The proxy is mounted at /_gm/ on the gateway's public listener
+// (below the h2c wrap, see internal/connectsrv) and forwards verbatim — an inbound
+// /_gm/<rest> reaches <backendURL>/_gm/<rest>, preserving the inbound Host so the
+// backend's same-origin check sees the public origin. The backend trusts the gateway
+// on this segment and adds the console's same-origin CSRF guard
+// (docs/ARCHITECTURE.md §12).
 package admin
 
 import (
@@ -11,17 +14,14 @@ import (
 	"net/http"
 	"net/http/httputil"
 	"net/url"
-	"strings"
 
 	"go.uber.org/zap"
 )
 
-// backendAdminPrefix is where the backend mounts its admin API.
-const backendAdminPrefix = "/api/v1/admin"
-
 // NewProxy returns a handler that checks Basic-Auth against user/password and
-// reverse-proxies the request to the backend admin API, mapping an inbound
-// /admin/<rest> path to <backendURL>/api/v1/admin/<rest>.
+// reverse-proxies the request verbatim to the backend: the inbound path is
+// preserved, so /_gm/<rest> reaches <backendURL>/_gm/<rest>. It is mounted at /_gm/
+// on the gateway's public listener.
 func NewProxy(backendURL, user, password string, log *zap.Logger) (http.Handler, error) {
 	target, err := url.Parse(backendURL)
 	if err != nil {
@@ -32,10 +32,8 @@ func NewProxy(backendURL, user, password string, log *zap.Logger) (http.Handler,
 	}
 	proxy := &httputil.ReverseProxy{
 		Rewrite: func(pr *httputil.ProxyRequest) {
-			pr.SetURL(target)
-			rel := strings.TrimPrefix(pr.In.URL.Path, "/admin")
-			pr.Out.URL.Path = backendAdminPrefix + rel
-			pr.Out.Host = pr.In.Host
+			pr.SetURL(target)        // backend scheme+host; the inbound /_gm path is preserved
+			pr.Out.Host = pr.In.Host // keep the public Host for the backend same-origin check
 		},
 		ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
 			log.Warn("admin proxy upstream error", zap.String("path", r.URL.Path), zap.Error(err))

gateway/internal/admin/admin_test.go

@@ -9,27 +9,28 @@ import (
 	"scrabble/gateway/internal/admin"
 )
 
-func newAdmin(t *testing.T) (*httptest.Server, func()) {
+// newAdmin fronts a fake backend with the admin proxy. The fake backend records the
+// path it receives so a test can assert the proxy forwards /_gm verbatim.
+func newAdmin(t *testing.T) (front *httptest.Server, gotPath *string, cleanup func()) {
 	t.Helper()
+	var path string
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.URL.Path != "/api/v1/admin/ping" {
-			t.Errorf("backend path = %q, want /api/v1/admin/ping", r.URL.Path)
-		}
-		_, _ = w.Write([]byte("pong"))
+		path = r.URL.Path
+		_, _ = w.Write([]byte("console"))
 	}))
 	proxy, err := admin.NewProxy(backend.URL, "ops", "secret", nil)
 	if err != nil {
 		t.Fatalf("new proxy: %v", err)
 	}
-	front := httptest.NewServer(proxy)
-	return front, func() { front.Close(); backend.Close() }
+	front = httptest.NewServer(proxy)
+	return front, &path, func() { front.Close(); backend.Close() }
 }
 
 func TestAdminRejectsMissingCredentials(t *testing.T) {
-	front, cleanup := newAdmin(t)
+	front, _, cleanup := newAdmin(t)
 	defer cleanup()
 
-	resp, err := http.Get(front.URL + "/admin/ping")
+	resp, err := http.Get(front.URL + "/_gm/")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -37,13 +38,16 @@ func TestAdminRejectsMissingCredentials(t *testing.T) {
 	if resp.StatusCode != http.StatusUnauthorized {
 		t.Fatalf("status = %d, want 401", resp.StatusCode)
 	}
+	if resp.Header.Get("WWW-Authenticate") == "" {
+		t.Error("missing WWW-Authenticate challenge")
+	}
 }
 
-func TestAdminProxiesWithCredentials(t *testing.T) {
-	front, cleanup := newAdmin(t)
+func TestAdminProxiesVerbatimWithCredentials(t *testing.T) {
+	front, gotPath, cleanup := newAdmin(t)
 	defer cleanup()
 
-	req, _ := http.NewRequest(http.MethodGet, front.URL+"/admin/ping", nil)
+	req, _ := http.NewRequest(http.MethodGet, front.URL+"/_gm/complaints", nil)
 	req.SetBasicAuth("ops", "secret")
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
@@ -51,16 +55,19 @@ func TestAdminProxiesWithCredentials(t *testing.T) {
 	}
 	defer func() { _ = resp.Body.Close() }()
 	body, _ := io.ReadAll(resp.Body)
-	if resp.StatusCode != http.StatusOK || string(body) != "pong" {
-		t.Fatalf("status = %d body = %q, want 200 pong", resp.StatusCode, body)
+	if resp.StatusCode != http.StatusOK || string(body) != "console" {
+		t.Fatalf("status = %d body = %q, want 200 console", resp.StatusCode, body)
+	}
+	if *gotPath != "/_gm/complaints" {
+		t.Errorf("backend path = %q, want /_gm/complaints (verbatim)", *gotPath)
 	}
 }
 
 func TestAdminRejectsWrongPassword(t *testing.T) {
-	front, cleanup := newAdmin(t)
+	front, _, cleanup := newAdmin(t)
 	defer cleanup()
 
-	req, _ := http.NewRequest(http.MethodGet, front.URL+"/admin/ping", nil)
+	req, _ := http.NewRequest(http.MethodGet, front.URL+"/_gm/", nil)
 	req.SetBasicAuth("ops", "wrong")
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {

gateway/internal/config/config.go

@@ -11,11 +11,9 @@ import (
 
 // Config holds the gateway's runtime configuration.
 type Config struct {
-	// HTTPAddr is the public Connect/h2c listener address (host:port).
+	// HTTPAddr is the public Connect/h2c listener address (host:port). It also
+	// serves the admin console at /_gm when admin credentials are configured.
 	HTTPAddr string
-	// AdminAddr is the admin reverse-proxy listener address. Admin is enabled only
-	// when AdminUser and AdminPassword are also set.
-	AdminAddr string
 	// LogLevel is the zap log level: "debug", "info", "warn" or "error".
 	LogLevel string
 	// BackendHTTPURL is the base URL of the backend REST API (gateway -> backend).
@@ -59,7 +57,6 @@ type RateLimitConfig struct {
 // Defaults applied when the corresponding environment variable is unset.
 const (
 	defaultHTTPAddr              = ":8081"
-	defaultAdminAddr             = ":8082"
 	defaultLogLevel              = "info"
 	defaultBackendHTTPURL        = "http://localhost:8080"
 	defaultBackendGRPCAddr       = "localhost:9090"
@@ -85,7 +82,6 @@ func Load() (Config, error) {
 	var err error
 	c := Config{
 		HTTPAddr:        envOr("GATEWAY_HTTP_ADDR", defaultHTTPAddr),
-		AdminAddr:       envOr("GATEWAY_ADMIN_ADDR", defaultAdminAddr),
 		LogLevel:        envOr("GATEWAY_LOG_LEVEL", defaultLogLevel),
 		BackendHTTPURL:  envOr("GATEWAY_BACKEND_HTTP_URL", defaultBackendHTTPURL),
 		BackendGRPCAddr: envOr("GATEWAY_BACKEND_GRPC_ADDR", defaultBackendGRPCAddr),
@@ -113,10 +109,10 @@ func Load() (Config, error) {
 	return c, nil
 }
 
-// AdminEnabled reports whether the admin proxy should be served (an address and
-// both Basic-Auth credentials are configured).
+// AdminEnabled reports whether the admin console proxy should be mounted (both
+// Basic-Auth credentials are configured).
 func (c Config) AdminEnabled() bool {
-	return c.AdminAddr != "" && c.AdminUser != "" && c.AdminPassword != ""
+	return c.AdminUser != "" && c.AdminPassword != ""
 }
 
 // validate reports whether the configuration values are acceptable.

gateway/internal/connectsrv/console_mount_test.go

@@ -0,0 +1,45 @@
+package connectsrv_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"scrabble/gateway/internal/connectsrv"
+)
+
+// TestHTTPHandlerMountsAdminConsole verifies the admin proxy is reachable at /_gm/
+// through the h2c-wrapped edge mux when configured.
+func TestHTTPHandlerMountsAdminConsole(t *testing.T) {
+	stub := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusTeapot)
+	})
+	srv := connectsrv.NewServer(connectsrv.Deps{AdminProxy: stub})
+	front := httptest.NewServer(srv.HTTPHandler())
+	defer front.Close()
+
+	resp, err := http.Get(front.URL + "/_gm/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode != http.StatusTeapot {
+		t.Fatalf("/_gm status = %d, want 418 (routed to the admin proxy)", resp.StatusCode)
+	}
+}
+
+// TestHTTPHandlerNoAdminConsole verifies /_gm is not served when no proxy is set.
+func TestHTTPHandlerNoAdminConsole(t *testing.T) {
+	srv := connectsrv.NewServer(connectsrv.Deps{})
+	front := httptest.NewServer(srv.HTTPHandler())
+	defer front.Close()
+
+	resp, err := http.Get(front.URL + "/_gm/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode != http.StatusNotFound {
+		t.Fatalf("/_gm status = %d, want 404 (no admin proxy)", resp.StatusCode)
+	}
+}

gateway/internal/connectsrv/server.go

@@ -32,12 +32,13 @@ const heartbeatKind = "heartbeat"
 
 // Server implements edgev1connect.GatewayHandler.
 type Server struct {
-	registry  *transcode.Registry
-	sessions  *session.Cache
-	limiter   *ratelimit.Limiter
-	hub       *push.Hub
-	heartbeat time.Duration
-	log       *zap.Logger
+	registry   *transcode.Registry
+	sessions   *session.Cache
+	limiter    *ratelimit.Limiter
+	hub        *push.Hub
+	heartbeat  time.Duration
+	log        *zap.Logger
+	adminProxy http.Handler
 
 	publicPolicy ratelimit.Policy
 	userPolicy   ratelimit.Policy
@@ -46,13 +47,14 @@ type Server struct {
 
 // Deps carries the Server's dependencies.
 type Deps struct {
-	Registry  *transcode.Registry
-	Sessions  *session.Cache
-	Limiter   *ratelimit.Limiter
-	Hub       *push.Hub
-	RateLimit config.RateLimitConfig
-	Heartbeat time.Duration
-	Logger    *zap.Logger
+	Registry   *transcode.Registry
+	Sessions   *session.Cache
+	Limiter    *ratelimit.Limiter
+	Hub        *push.Hub
+	RateLimit  config.RateLimitConfig
+	Heartbeat  time.Duration
+	Logger     *zap.Logger
+	AdminProxy http.Handler
 }
 
 // NewServer constructs the edge service.
@@ -68,6 +70,7 @@ func NewServer(d Deps) *Server {
 		hub:          d.Hub,
 		heartbeat:    d.Heartbeat,
 		log:          log,
+		adminProxy:   d.AdminProxy,
 		publicPolicy: ratelimit.PerMinute(d.RateLimit.PublicPerMinute, d.RateLimit.PublicBurst),
 		userPolicy:   ratelimit.PerMinute(d.RateLimit.UserPerMinute, d.RateLimit.UserBurst),
 		emailPolicy:  ratelimit.Per(d.RateLimit.EmailPer10Min, 10*time.Minute, d.RateLimit.EmailBurst),
@@ -79,6 +82,12 @@ func (s *Server) HTTPHandler() http.Handler {
 	mux := http.NewServeMux()
 	path, h := edgev1connect.NewGatewayHandler(s)
 	mux.Handle(path, h)
+	if s.adminProxy != nil {
+		// The admin console (backend /_gm) is served on the public listener behind
+		// the proxy's Basic-Auth, mounted below the h2c wrap so the Connect edge keeps
+		// working over h2c (docs/ARCHITECTURE.md §12).
+		mux.Handle("/_gm/", s.adminProxy)
+	}
 	return h2c.NewHandler(mux, &http2.Server{})
 }