Memby v0.1.53: Android TV client plus gateway

Android TV client for Emby (Kotlin, Compose for TV) and the Memby gateway
(Go, Postgres, Redis) that fronts it.

Client:
- Setup, profiles, home rows, Media3 playback, system screensaver (Dream)
- Backend chosen at build time: gateway when memby.gatewayUrl is set,
  otherwise direct to Emby. Both paths stay working.
- Server-composed home rows, rendered verbatim so new row types ship
  without an app release
- Full-screen animated maintenance state, row engagement telemetry

Gateway:
- One request per TV screen; auth, caching, search and row shaping
- Library import from Emby into Postgres (manual, then hourly incremental)
- Recommendations from viewing history (recency-weighted genre affinity)
- Admin page for imports, an offline switch, and per-row analytics
- Video always direct-plays from Emby; only metadata passes through

Identity is com.ponzischeme89.memby throughout, replacing
com.mattcohen.embyclientsname. A changed applicationId installs as a new
app: TVs need a fresh sign-in and the old package uninstalled.

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

server/internal/api/auth.go

@@ -0,0 +1,101 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"github.com/ponzischeme89/memby/server/internal/cache"
+	"github.com/ponzischeme89/memby/server/internal/store"
+)
+
+type loginRequest struct {
+	Username string `json:"username"`
+	Password string `json:"password"`
+	DeviceID string `json:"deviceId"`
+}
+
+type loginResponse struct {
+	Token    string `json:"token"`
+	UserID   string `json:"userId"`
+	Username string `json:"username"`
+	ServerID string `json:"serverId"`
+}
+
+// handleLogin exchanges Emby credentials for a gateway token.
+//
+// The Emby access token stays here: the TV only ever holds the gateway token, so
+// revoking a device is a DELETE in Postgres rather than an Emby-side cleanup.
+func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
+	var req loginRequest
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 8<<10)).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "malformed request body")
+		return
+	}
+	req.Username = strings.TrimSpace(req.Username)
+	if req.Username == "" {
+		writeError(w, http.StatusBadRequest, "username is required")
+		return
+	}
+	if req.DeviceID == "" {
+		req.DeviceID = "memby-tv"
+	}
+
+	auth, err := s.emby.Authenticate(r.Context(), req.Username, req.Password, req.DeviceID)
+	if err != nil {
+		// Never echo Emby's body here: a failed sign-in is the one place a wrong
+		// password could be reflected back.
+		s.log.Warn("emby authentication failed", "username", req.Username)
+		writeError(w, http.StatusUnauthorized, "sign-in failed")
+		return
+	}
+
+	token, err := newToken()
+	if err != nil {
+		s.log.Error("token generation failed", "error", err)
+		writeError(w, http.StatusInternalServerError, "could not issue a token")
+		return
+	}
+
+	sess := store.Session{
+		TokenHash:  hashToken(token),
+		EmbyUserID: auth.User.ID,
+		EmbyToken:  auth.AccessToken,
+		Username:   auth.User.Name,
+		ServerID:   auth.ServerID,
+		DeviceID:   req.DeviceID,
+	}
+	if sess.Username == "" {
+		sess.Username = req.Username
+	}
+	if err := s.store.CreateSession(r.Context(), sess); err != nil {
+		s.log.Error("session persist failed", "error", err)
+		writeError(w, http.StatusInternalServerError, "could not start a session")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, loginResponse{
+		Token:    token,
+		UserID:   sess.EmbyUserID,
+		Username: sess.Username,
+		ServerID: sess.ServerID,
+	})
+}
+
+func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request, sess store.Session) {
+	if err := s.store.DeleteSession(r.Context(), sess.TokenHash); err != nil {
+		s.log.Error("session delete failed", "error", err)
+	}
+	_ = s.cache.Delete(r.Context(), cache.SessionKey(hexHash(sess.TokenHash)))
+	_ = s.cache.InvalidateUser(r.Context(), sess.EmbyUserID)
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// handleSession lets the TV confirm a stored token is still good before rendering.
+func (s *Server) handleSession(w http.ResponseWriter, _ *http.Request, sess store.Session) {
+	writeJSON(w, http.StatusOK, loginResponse{
+		UserID:   sess.EmbyUserID,
+		Username: sess.Username,
+		ServerID: sess.ServerID,
+	})
+}