feat: show when there is an active huddle

This introduces a webhook which listens to events from livekit and
updates our firestore stream particle. It keeps the client simple,
reacting to changes to firestore docs.

go/internal/handler/handler.go

@@ -4,10 +4,13 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"log/slog"
 	"net/http"
+	"strings"
 	"time"
 
+	"cloud.google.com/go/firestore"
 	"github.com/flowy-live/llink/internal/auth"
 	"github.com/flowy-live/llink/internal/depot"
 	"github.com/flowy-live/llink/internal/human"
@@ -17,27 +20,30 @@ import (
 	"github.com/flowy-live/llink/internal/particle"
 	"github.com/flowy-live/llink/internal/utils"
 	"github.com/flowy-live/llink/internal/waitlist"
+	"github.com/livekit/protocol/webhook"
 )
 
 type Handler struct {
-	authSvc       auth.AuthService
-	humanSvc      human.Service
-	networkSvc    network.Service
-	particleSvc   particle.Service
-	depotSvc      depot.Service
-	waitlistSvc   waitlist.Service
-	livekitClient livekit.Client
+	authSvc         auth.AuthService
+	humanSvc        human.Service
+	networkSvc      network.Service
+	particleSvc     particle.Service
+	depotSvc        depot.Service
+	waitlistSvc     waitlist.Service
+	livekitClient   livekit.Client
+	firestoreClient *firestore.Client
 }
 
-func NewHandler(authSvc auth.AuthService, humanSvc human.Service, networkSvc network.Service, particleSvc particle.Service, depotSvc depot.Service, waitlistSvc waitlist.Service, livekitClient livekit.Client) *Handler {
+func NewHandler(authSvc auth.AuthService, humanSvc human.Service, networkSvc network.Service, particleSvc particle.Service, depotSvc depot.Service, waitlistSvc waitlist.Service, livekitClient livekit.Client, firestoreClient *firestore.Client) *Handler {
 	return &Handler{
-		authSvc:       authSvc,
-		humanSvc:      humanSvc,
-		networkSvc:    networkSvc,
-		particleSvc:   particleSvc,
-		depotSvc:      depotSvc,
-		waitlistSvc:   waitlistSvc,
-		livekitClient: livekitClient,
+		authSvc:         authSvc,
+		humanSvc:        humanSvc,
+		networkSvc:      networkSvc,
+		particleSvc:     particleSvc,
+		depotSvc:        depotSvc,
+		waitlistSvc:     waitlistSvc,
+		livekitClient:   livekitClient,
+		firestoreClient: firestoreClient,
 	}
 }
 
@@ -115,7 +121,8 @@ type RevokeInvitationRequest struct {
 // LiveKit DTOs
 
 type GetLivekitTokenRequest struct {
-	RoomId string `json:"room_id"`
+	NetworkId string `json:"network_id"`
+	StreamId  string `json:"stream_id"`
 }
 
 type GetLivekitTokenResponse struct {
@@ -1076,14 +1083,21 @@ func (h *Handler) GetLivekitToken(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if req.RoomId == "" {
-		http.Error(w, "room_id is required", http.StatusBadRequest)
+	if req.NetworkId == "" {
+		http.Error(w, "network_id is required", http.StatusBadRequest)
+		return
+	}
+	if req.StreamId == "" {
+		http.Error(w, "stream_id is required", http.StatusBadRequest)
 		return
 	}
 
-	token, err := h.livekitClient.GetJoinToken(req.RoomId, humanId, humanEmail)
+	// Compose room name encoding both network and stream IDs for webhook resolution
+	roomName := req.NetworkId + "/" + req.StreamId
+
+	token, err := h.livekitClient.GetJoinToken(roomName, humanId, humanEmail)
 	if err != nil {
-		slog.Error("failed to generate livekit token", "error", err, "humanId", humanId, "roomId", req.RoomId)
+		slog.Error("failed to generate livekit token", "error", err, "humanId", humanId, "roomName", roomName)
 		http.Error(w, "failed to generate token", http.StatusInternalServerError)
 		return
 	}
@@ -1092,6 +1106,72 @@ func (h *Handler) GetLivekitToken(w http.ResponseWriter, r *http.Request) {
 	json.NewEncoder(w).Encode(GetLivekitTokenResponse{Token: token, ServerUrl: h.livekitClient.ServerUrl()})
 }
 
+// HandleLivekitWebhook processes LiveKit webhook events for huddle presence.
+// It verifies the webhook signature (not user auth), then updates the stream
+// particle's huddle_active_participants field in Firestore.
+func (h *Handler) HandleLivekitWebhook(w http.ResponseWriter, r *http.Request) {
+	event, err := webhook.ReceiveWebhookEvent(r, h.livekitClient.KeyProvider())
+	if err != nil {
+		slog.Error("failed to verify livekit webhook", "error", err)
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	eventType := event.GetEvent()
+	slog.Info("received livekit webhook", "event", eventType, "room", event.GetRoom().GetName())
+
+	switch eventType {
+	case "participant_joined", "participant_left", "room_finished":
+		// Handle these events
+	default:
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	// Parse room name to extract networkId and streamId
+	roomName := event.GetRoom().GetName()
+	parts := strings.SplitN(roomName, "/", 2)
+	if len(parts) != 2 {
+		slog.Error("invalid room name format", "room", roomName)
+		http.Error(w, "invalid room name", http.StatusBadRequest)
+		return
+	}
+	networkId, streamId := parts[0], parts[1]
+	docPath := fmt.Sprintf("networks/%s/children/%s", networkId, streamId)
+	docRef := h.firestoreClient.Doc(docPath)
+	ctx := r.Context()
+
+	var participantIds []string
+
+	if eventType == "room_finished" {
+		// Room is done — clear the participants
+		participantIds = []string{}
+	} else {
+		// Use ListParticipants for authoritative state (avoids drift from missed webhooks)
+		participants, err := h.livekitClient.ListParticipants(ctx, roomName)
+		if err != nil {
+			slog.Error("failed to list participants", "error", err, "room", roomName)
+			// Return 200 so LiveKit doesn't retry
+			w.WriteHeader(http.StatusOK)
+			return
+		}
+
+		participantIds = make([]string, 0, len(participants))
+		for _, p := range participants {
+			participantIds = append(participantIds, p.Identity)
+		}
+	}
+
+	_, err = docRef.Update(ctx, []firestore.Update{
+		{Path: "huddle_active_participants", Value: participantIds},
+	})
+	if err != nil {
+		slog.Error("failed to update huddle participants in firestore", "error", err, "path", docPath)
+	}
+
+	w.WriteHeader(http.StatusOK)
+}
+
 func extractBearerToken(r *http.Request) string {
 	authHeader := r.Header.Get("Authorization")
 	if authHeader == "" {