feat(seo): add sitemap generator

internal/config/config.go

@@ -66,6 +66,10 @@ type Config struct {
 	// Frontend
 	FrontendURL string // for CORS + reset/verify links in emails
 
+	// RevalidateSecret authenticates BFF→frontend on-demand cache
+	// revalidation pings (POST /api/revalidate). Empty disables the pings.
+	RevalidateSecret string
+
 	// BFF public URL — the externally-reachable origin of this server. Used
 	// to build the OAuth redirect_uri the provider sees (must match the
 	// allow-list configured in the provider's console). In dev this is
@@ -147,7 +151,8 @@ func Load() (*Config, error) {
 		CookieDomain:  getEnv("COOKIE_DOMAIN", ""),
 		CookieSecure:  getEnvBool("COOKIE_SECURE", false),
 
-		FrontendURL: getEnv("FRONTEND_URL", "http://localhost:3000"),
+		FrontendURL:      getEnv("FRONTEND_URL", "http://localhost:3000"),
+		RevalidateSecret: getEnv("REVALIDATE_SECRET", ""),
 
 		BFFPublicURL: getEnv("BFF_PUBLIC_URL", "http://localhost:8080"),
 

internal/server/server.go

@@ -20,6 +20,7 @@ import (
 	"github.com/prabhupadasays/spsays-bff/pkg/oauth"
 	"github.com/prabhupadasays/spsays-bff/pkg/realtime"
 	"github.com/prabhupadasays/spsays-bff/pkg/response"
+	"github.com/prabhupadasays/spsays-bff/pkg/revalidate"
 	"github.com/prabhupadasays/spsays-bff/pkg/shorturl"
 	"go.uber.org/zap"
 )
@@ -163,6 +164,7 @@ func (s *Server) initAuth(cfg *config.Config, logger *zap.Logger) {
 	}, logger)
 
 	authSvc := service.NewAuthService(userRepo, tokenRepo, oauthRepo, issuer, mail, logger, cfg.FrontendURL)
+	authSvc.SetRevalidator(revalidate.New(cfg.FrontendURL, cfg.RevalidateSecret, logger))
 	userSvc := service.NewUserService(userRepo, r2)
 
 	// Social repositories + services share the same Postgres pool and R2 client.

internal/service/auth_service.go

@@ -21,6 +21,7 @@ import (
 	"github.com/prabhupadasays/spsays-bff/internal/repository"
 	"github.com/prabhupadasays/spsays-bff/pkg/auth"
 	"github.com/prabhupadasays/spsays-bff/pkg/mailer"
+	"github.com/prabhupadasays/spsays-bff/pkg/revalidate"
 	"go.uber.org/zap"
 	"golang.org/x/crypto/bcrypt"
 )
@@ -45,12 +46,17 @@ type AuthService struct {
 	mail     mailer.Mailer
 	logger   *zap.Logger
 	frontend string // FrontendURL — used to build reset / verify links
+	reval    *revalidate.Client // optional — pings sitemap revalidation on new signups
 
 	// TTLs — surfaced as fields so tests can shrink them.
 	PasswordResetTTL time.Duration
 	EmailVerifyTTL   time.Duration
 }
 
+// SetRevalidator wires the frontend cache-revalidation client. Optional —
+// when unset, new-signup sitemap pings are simply skipped.
+func (s *AuthService) SetRevalidator(r *revalidate.Client) { s.reval = r }
+
 // NewAuthService wires the dependencies. `oauthRepo` may be nil — pass nil if
 // the OAuth flows aren't wired (handler then returns 503).
 func NewAuthService(
@@ -140,6 +146,9 @@ func (s *AuthService) SignUp(ctx context.Context, email, password, name string)
 		s.logger.Warn("verification email failed", zap.String("user", u.ID), zap.Error(err))
 	}
 
+	// New public profile → refresh the sitemap so it's crawlable promptly.
+	s.reval.Trigger("sitemap")
+
 	return s.issueSession(u)
 }
 
@@ -445,6 +454,8 @@ func (s *AuthService) SignInWithOAuth(ctx context.Context, prof OAuthProfile) (*
 		optStr(prof.Email), optStr(prof.Name), optStr(prof.AvatarURL)); err != nil {
 		return nil, err
 	}
+	// New public profile → refresh the sitemap so it's crawlable promptly.
+	s.reval.Trigger("sitemap")
 	return s.issueSession(u)
 }