fix: feed repitition

internal/handler/social.go

@@ -259,6 +259,14 @@ func (h *PostHandler) Feed(w http.ResponseWriter, r *http.Request) {
 	response.JSON(w, http.StatusOK, posts)
 }
 
+// FeedReset — POST /feed/reset. Clears the caller's home-feed seen-set so the
+// next page starts fresh. Called on logout and on page unload (the realtime
+// socket dropping) to evict the set promptly rather than waiting for its TTL.
+func (h *PostHandler) FeedReset(w http.ResponseWriter, r *http.Request) {
+	h.svc.ResetFeed(r.Context(), middleware.UserID(r.Context()))
+	response.NoContent(w)
+}
+
 // FeedNewUsers — GET /feed/new-users. Up to 5 accounts that joined in the last
 // 24h, for the feed's "new on the platform" discovery strip. Returns [] when
 // there are none (the client hides the section).

internal/handler/soketi_webhook.go

@@ -0,0 +1,107 @@
+package handler
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/prabhupadasays/spsays-bff/internal/repository"
+	"go.uber.org/zap"
+)
+
+// notifChannelPrefix is the public per-user channel the frontend subscribes to
+// for realtime notifications. Because it's keyed by user, a `channel_vacated`
+// webhook on it means that user's *last* connection dropped — i.e. they went
+// offline (across all their tabs) — so we can evict their feed seen-set.
+const notifChannelPrefix = "notifications."
+
+// SoketiWebhookHandler receives Soketi (Pusher-compatible) webhooks. Soketi
+// signs each delivery with the app secret (X-Pusher-Signature = hex
+// HMAC-SHA256 of the raw body); we verify before acting. On channel_vacated
+// for a per-user notifications channel we clear that user's home-feed seen-set
+// — prompt cleanup of a true offline/disconnect, complementing the page-unload
+// beacon and the set's own TTL.
+type SoketiWebhookHandler struct {
+	appKey    string
+	appSecret string
+	feed      *repository.FeedRepo
+	logger    *zap.Logger
+}
+
+func NewSoketiWebhookHandler(appKey, appSecret string, feed *repository.FeedRepo, logger *zap.Logger) *SoketiWebhookHandler {
+	return &SoketiWebhookHandler{appKey: appKey, appSecret: appSecret, feed: feed, logger: logger}
+}
+
+type soketiWebhookBody struct {
+	Events []struct {
+		Name    string `json:"name"`
+		Channel string `json:"channel"`
+	} `json:"events"`
+}
+
+// Handle — POST /webhooks/soketi. Public route: the HMAC signature is the
+// authentication, not a session cookie. Returns 200 on a valid signature so
+// Soketi doesn't retry; 401 on a bad/absent signature.
+func (h *SoketiWebhookHandler) Handle(w http.ResponseWriter, r *http.Request) {
+	// Without a configured secret there's nothing to verify against — refuse
+	// rather than trust unsigned input.
+	if h.appSecret == "" {
+		w.WriteHeader(http.StatusServiceUnavailable)
+		return
+	}
+	body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20)) // 1 MiB cap
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+	if key := r.Header.Get("X-Pusher-Key"); h.appKey != "" && key != h.appKey {
+		h.logger.Warn("soketi webhook: app key mismatch", zap.String("got", key))
+		w.WriteHeader(http.StatusUnauthorized)
+		return
+	}
+	if !validSoketiSignature(h.appSecret, r.Header.Get("X-Pusher-Signature"), body) {
+		// Almost always a secret mismatch between Soketi and the BFF.
+		h.logger.Warn("soketi webhook: bad signature", zap.Int("body_bytes", len(body)))
+		w.WriteHeader(http.StatusUnauthorized)
+		return
+	}
+
+	var payload soketiWebhookBody
+	if err := json.Unmarshal(body, &payload); err != nil {
+		h.logger.Warn("soketi webhook: bad payload", zap.Error(err))
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+	ctx := r.Context()
+	cleared := 0
+	for _, e := range payload.Events {
+		// A per-user notifications channel emptying = that user is offline.
+		if e.Name != "channel_vacated" {
+			continue
+		}
+		if uid, ok := strings.CutPrefix(e.Channel, notifChannelPrefix); ok && uid != "" {
+			h.feed.Reset(ctx, uid)
+			cleared++
+		}
+	}
+	h.logger.Debug("soketi webhook: verified",
+		zap.Int("events", len(payload.Events)),
+		zap.Int("feed_sets_cleared", cleared))
+	w.WriteHeader(http.StatusOK)
+}
+
+// validSoketiSignature is a constant-time check of the hex HMAC-SHA256 of the
+// raw body keyed by the app secret.
+func validSoketiSignature(secret, provided string, body []byte) bool {
+	if provided == "" {
+		return false
+	}
+	mac := hmac.New(sha256.New, []byte(secret))
+	mac.Write(body)
+	expected := hex.EncodeToString(mac.Sum(nil))
+	return hmac.Equal([]byte(expected), []byte(provided))
+}