diff --git a/go/Dockerfile.memberreconciler b/go/Dockerfile.memberreconciler
new file mode 100644
index 0000000..75afb40
--- /dev/null
+++ b/go/Dockerfile.memberreconciler
@@ -0,0 +1,20 @@
+# golang two stage build
+FROM golang:1.25 AS first-stage
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download && go mod verify
+
+COPY . .
+
+WORKDIR /app/cmd/memberreconciler
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o main
+RUN ls
+
+FROM alpine:latest AS second-stage
+
+WORKDIR /app
+COPY --from=first-stage /app/cmd/memberreconciler .
+RUN echo "copied over binary to production stage"
+CMD ["./main"]
diff --git a/go/cmd/emailnotifierjob/main.go b/go/cmd/emailnotifierjob/main.go
index 84871d9..e115ac2 100644
--- a/go/cmd/emailnotifierjob/main.go
+++ b/go/cmd/emailnotifierjob/main.go
@@ -68,7 +68,7 @@ func main() {
 
 	// Initialize services
 	humanSvc := human.NewService(db.Pool())
-	networkSvc := network.NewService(db.Pool(), aeroSvc, billing.Noop())
+	networkSvc := network.NewService(db.Pool(), aeroSvc, billing.Noop(), nil)
 
 	slog.Info("starting email notification cycle")
 	if err := runNotificationCycle(ctx, firestoreClient, aeroSvc, pusherSvc, humanSvc, networkSvc); err != nil {
diff --git a/go/cmd/memberreconciler/main.go b/go/cmd/memberreconciler/main.go
new file mode 100644
index 0000000..aa66823
--- /dev/null
+++ b/go/cmd/memberreconciler/main.go
@@ -0,0 +1,144 @@
+// memberreconciler is a one-shot job (also safe to run on a cron) that makes
+// the Firestore membership mirror (humans/{humanId}.networks) match the
+// authoritative Postgres network_members table.
+//
+// Run before flipping Stage 1 Firestore rules so existing humans have their
+// mirror docs populated, and on a cron to heal any drift from a dropped mirror
+// write in network.Service.
+//
+// The reconciler reads the current Firestore state and only writes humans
+// whose mirrored networks differ from Postgres. Writes cost ~3x reads, and in
+// steady state drift is rare, so read-first keeps the cron nearly free.
+package main
+
+import (
+	"context"
+	"log/slog"
+	"os"
+	"slices"
+	"time"
+
+	"cloud.google.com/go/firestore"
+	"github.com/flowy-live/llink/internal/billing"
+	"github.com/flowy-live/llink/internal/db"
+	"github.com/flowy-live/llink/internal/human"
+	"github.com/flowy-live/llink/internal/network"
+	"github.com/flowy-live/llink/internal/utils"
+	"google.golang.org/api/iterator"
+)
+
+func main() {
+	ctx := context.Background()
+
+	db.Init()
+	defer db.Cleanup()
+
+	gcpProject := utils.MustGetEnv("GCP_PROJECT")
+	fs, err := firestore.NewClient(ctx, gcpProject)
+	if err != nil {
+		slog.Error("failed to create Firestore client", "error", err)
+		os.Exit(1)
+	}
+	defer fs.Close()
+
+	humanSvc := human.NewService(db.Pool())
+	// billing/aero/fs unused here — we only call ListAllMemberships.
+	networkSvc := network.NewService(db.Pool(), nil, billing.Noop(), nil)
+
+	started := time.Now()
+	written, scanned, err := reconcile(ctx, fs, humanSvc, networkSvc)
+	if err != nil {
+		slog.Error("reconciliation failed", "error", err, "elapsed", time.Since(started))
+		os.Exit(1)
+	}
+	slog.Info("reconciliation complete",
+		"humans_scanned", scanned,
+		"humans_written", written,
+		"elapsed", time.Since(started),
+	)
+}
+
+func reconcile(
+	ctx context.Context,
+	fs *firestore.Client,
+	humanSvc human.Service,
+	networkSvc network.Service,
+) (written, scanned int, err error) {
+	humans, err := humanSvc.ListAll(ctx)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	memberships, err := networkSvc.ListAllMemberships(ctx)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	current, err := snapshotMirror(ctx, fs)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	bulk := fs.BulkWriter(ctx)
+	for _, h := range humans {
+		scanned++
+		desired := memberships[h.ID]
+		if desired == nil {
+			desired = []string{}
+		}
+		if sameSet(current[h.ID], desired) {
+			continue
+		}
+		if _, err := bulk.Set(fs.Collection("humans").Doc(h.ID), map[string]any{
+			"networks":   desired,
+			"updated_at": firestore.ServerTimestamp,
+		}, firestore.MergeAll); err != nil {
+			return written, scanned, err
+		}
+		written++
+	}
+	bulk.End()
+	return written, scanned, nil
+}
+
+// snapshotMirror streams the humans collection once and returns a map of
+// humanId -> current networks array. One iterator, N billed reads.
+func snapshotMirror(ctx context.Context, fs *firestore.Client) (map[string][]string, error) {
+	out := map[string][]string{}
+	iter := fs.Collection("humans").Documents(ctx)
+	defer iter.Stop()
+	for {
+		doc, err := iter.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		var data struct {
+			Networks []string `firestore:"networks"`
+		}
+		if err := doc.DataTo(&data); err != nil {
+			slog.Warn("skipping malformed mirror doc", "id", doc.Ref.ID, "error", err)
+			continue
+		}
+		out[doc.Ref.ID] = data.Networks
+	}
+	return out, nil
+}
+
+// sameSet reports whether a and b contain the same elements, ignoring order
+// and duplicates. Firestore array ops don't preserve order, so set equality is
+// the right comparison for the networks array.
+func sameSet(a, b []string) bool {
+	if len(a) == 0 && len(b) == 0 {
+		return true
+	}
+	ac := slices.Clone(a)
+	bc := slices.Clone(b)
+	slices.Sort(ac)
+	slices.Sort(bc)
+	ac = slices.Compact(ac)
+	bc = slices.Compact(bc)
+	return slices.Equal(ac, bc)
+}
diff --git a/go/cmd/orion/main.go b/go/cmd/orion/main.go
index b45faf0..c6fda4e 100644
--- a/go/cmd/orion/main.go
+++ b/go/cmd/orion/main.go
@@ -9,6 +9,7 @@ import (
 
 	"cloud.google.com/go/firestore"
 	"cloud.google.com/go/storage"
+	firebase "firebase.google.com/go/v4"
 	pbaero "github.com/flowy-live/llink/genproto/aero"
 	"github.com/flowy-live/llink/internal"
 	"github.com/flowy-live/llink/internal/auth"
@@ -62,7 +63,19 @@ func main() {
 	defer aeroServer.Close()
 	aeroSvc := pbaero.NewPrimaryClient(aeroServer)
 
-	authSvc := auth.NewAuthService(redisClient, aeroSvc)
+	gcpProject := utils.MustGetEnv("GCP_PROJECT")
+	fbApp, err := firebase.NewApp(ctx, &firebase.Config{ProjectID: gcpProject})
+	if err != nil {
+		slog.Error("failed to init Firebase Admin app", "error", err)
+		os.Exit(1)
+	}
+	fbAuth, err := fbApp.Auth(ctx)
+	if err != nil {
+		slog.Error("failed to create Firebase auth client", "error", err)
+		os.Exit(1)
+	}
+
+	authSvc := auth.NewAuthService(redisClient, aeroSvc, fbAuth)
 	humanSvc := human.NewService(db.Pool())
 
 	billingSvc, err := billing.NewService(ctx, db.Pool(), billing.Config{
@@ -78,7 +91,14 @@ func main() {
 		os.Exit(1)
 	}
 
-	networkSvc := network.NewService(db.Pool(), aeroSvc, billingSvc)
+	firestoreClient, err := firestore.NewClient(ctx, gcpProject)
+	if err != nil {
+		slog.Error("failed to create Firestore client", "error", err)
+		os.Exit(1)
+	}
+	defer firestoreClient.Close()
+
+	networkSvc := network.NewService(db.Pool(), aeroSvc, billingSvc, firestoreClient)
 	particleSvc := particle.NewService(db.Pool(), networkSvc)
 	depotSvc := depot.NewService(db.Pool(), storageClient, depot.Config{
 		GoogleServiceAccountEmail: utils.MustGetEnv("GOOGLE_SERVICE_ACCOUNT_EMAIL"),
@@ -87,14 +107,6 @@ func main() {
 	waitlistSvc := waitlist.NewService(db.Pool(), aeroSvc)
 	livekitClient := livekit.NewClient()
 
-	gcpProject := utils.MustGetEnv("GCP_PROJECT")
-	firestoreClient, err := firestore.NewClient(ctx, gcpProject)
-	if err != nil {
-		slog.Error("failed to create Firestore client", "error", err)
-		os.Exit(1)
-	}
-	defer firestoreClient.Close()
-
 	h := handler.NewHandler(authSvc, humanSvc, networkSvc, particleSvc, depotSvc, waitlistSvc, billingSvc, livekitClient, firestoreClient)
 
 	withAuth := func(hf http.HandlerFunc) http.Handler {
@@ -125,6 +137,7 @@ func main() {
 	// Auth
 	mux.Handle("POST /auth/sign-out", withAuth(h.SignOut))
 	mux.Handle("GET /auth/me", withAuth(h.GetCurrentHuman))
+	mux.Handle("POST /auth/firebase-token", withAuth(h.FirebaseToken))
 
 	// Settings
 	mux.Handle("PATCH /humans/me/settings", withAuth(h.UpdateSettings))
diff --git a/go/cmd/pusherservice/main.go b/go/cmd/pusherservice/main.go
index 0dab5cb..21fd9b7 100644
--- a/go/cmd/pusherservice/main.go
+++ b/go/cmd/pusherservice/main.go
@@ -37,8 +37,8 @@ func main() {
 	pusherRedis := internal.ConnectAndTestRedis(db.RedisDBPusher)
 
 	// Services
-	authSvc := auth.NewAuthService(authRedis, nil)                   // nil aeroSvc — pusher only calls GetSession
-	networkSvc := network.NewService(db.Pool(), nil, billing.Noop()) // nil aeroSvc / noop billing — pusher never mutates membership
+	authSvc := auth.NewAuthService(authRedis, nil, nil)                    // nil aeroSvc / fbAuth — pusher only calls GetSession
+	networkSvc := network.NewService(db.Pool(), nil, billing.Noop(), nil)  // nil aeroSvc / noop billing / nil firestore — pusher never mutates membership
 
 	// Pod identity (use hostname in k8s, which is the pod name)
 	podID, err := os.Hostname()
diff --git a/go/go.mod b/go/go.mod
index e9326e0..d9b8116 100644
--- a/go/go.mod
+++ b/go/go.mod
@@ -37,10 +37,12 @@ require (
 	cloud.google.com/go/longrunning v0.7.0 // indirect
 	cloud.google.com/go/monitoring v1.24.2 // indirect
 	dario.cat/mergo v1.0.2 // indirect
+	firebase.google.com/go/v4 v4.19.0 // indirect
 	github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c // indirect
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.30.0 // indirect
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.54.0 // indirect
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.54.0 // indirect
+	github.com/MicahParks/keyfunc v1.9.0 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/antlr4-go/antlr/v4 v4.13.1 // indirect
 	github.com/benbjohnson/clock v1.3.5 // indirect
@@ -77,6 +79,8 @@ require (
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-ole/go-ole v1.2.6 // indirect
 	github.com/gofrs/uuid/v5 v5.2.0 // indirect
+	github.com/golang-jwt/jwt/v4 v4.5.2 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/cel-go v0.27.0 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.7 // indirect
@@ -173,6 +177,7 @@ require (
 	golang.org/x/text v0.34.0 // indirect
 	golang.org/x/time v0.14.0 // indirect
 	google.golang.org/api v0.256.0 // indirect
+	google.golang.org/appengine/v2 v2.0.6 // indirect
 	google.golang.org/genproto v0.0.0-20250922171735-9219d122eba9 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20260209200024-4cfbd4190f57 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57 // indirect
diff --git a/go/go.sum b/go/go.sum
index db9694f..39a66c2 100644
--- a/go/go.sum
+++ b/go/go.sum
@@ -30,6 +30,8 @@ cloud.google.com/go/trace v1.11.6 h1:2O2zjPzqPYAHrn3OKl029qlqG6W8ZdYaOWRyr8NgMT4
 cloud.google.com/go/trace v1.11.6/go.mod h1:GA855OeDEBiBMzcckLPE2kDunIpC72N+Pq8WFieFjnI=
 dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
 dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
+firebase.google.com/go/v4 v4.19.0 h1:f5NMlC2YHFsncz00c2+ecBr+ZYlRMhKIhj1z8Iz0lD8=
+firebase.google.com/go/v4 v4.19.0/go.mod h1:P7UfBpzc8+Z3MckX79+zsWzKVfpGryr6HLbAe7gCWfs=
 github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6 h1:He8afgbRMd7mFxO99hRNu+6tazq8nFF9lIwo9JFroBk=
 github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6/go.mod h1:8o94RPi1/7XTJvwPpRSzSUedZrtlirdB3r9Z20bi2f8=
 github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c h1:udKWzYgxTojEKWjV8V+WSxDXJ4NFATAsZjh8iIbsQIg=
@@ -42,6 +44,8 @@ github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/cloudmock v0
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/cloudmock v0.54.0/go.mod h1:vB2GH9GAYYJTO3mEn8oYwzEdhlayZIdQz6zdzgUIRvA=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.54.0 h1:s0WlVbf9qpvkh1c/uDAPElam0WrL7fHRIidgZJ7UqZI=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.54.0/go.mod h1:Mf6O40IAyB9zR/1J8nGDDPirZQQPbYJni8Yisy7NTMc=
+github.com/MicahParks/keyfunc v1.9.0 h1:lhKd5xrFHLNOWrDc4Tyb/Q1AJ4LCzQ48GVJyVIID3+o=
+github.com/MicahParks/keyfunc v1.9.0/go.mod h1:IdnCilugA0O/99dW+/MkvlyrsX8+L8+x95xuVNtM5jw=
 github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
 github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5 h1:TngWCqHvy9oXAN6lEVMRuU21PR1EtLVZJmdB18Gu3Rw=
@@ -142,12 +146,17 @@ github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9L
 github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/gofrs/uuid/v5 v5.2.0 h1:qw1GMx6/y8vhVsx626ImfKMuS5CvJmhIKKtuyvfajMM=
 github.com/gofrs/uuid/v5 v5.2.0/go.mod h1:CDOjlDMVAtN56jqyRUZh58JT31Tiw7/oQyEXZV+9bD8=
+github.com/golang-jwt/jwt/v4 v4.4.2/go.mod h1:m21LjoU+eqJr34lmDMbreY2eSTRJ1cv77w39/MY0Ch0=
+github.com/golang-jwt/jwt/v4 v4.5.2 h1:YtQM7lnr8iZ+j5q71MGKkNw9Mn7AjHM68uc9g5fXeUI=
+github.com/golang-jwt/jwt/v4 v4.5.2/go.mod h1:m21LjoU+eqJr34lmDMbreY2eSTRJ1cv77w39/MY0Ch0=
 github.com/golang-migrate/migrate/v4 v4.19.1 h1:OCyb44lFuQfYXYLx1SCxPZQGU7mcaZ7gH9yH4jSFbBA=
 github.com/golang-migrate/migrate/v4 v4.19.1/go.mod h1:CTcgfjxhaUtsLipnLoQRWCrjYXycRz/g5+RWDuYgPrE=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
 github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/cel-go v0.27.0 h1:e7ih85+4qVrBuqQWTW4FKSqZYokVuc3HnhH5keboFTo=
 github.com/google/cel-go v0.27.0/go.mod h1:tTJ11FWqnhw5KKpnWpvW9CJC3Y9GK4EIS0WXnBbebzw=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
@@ -456,6 +465,7 @@ golang.org/x/term v0.40.0/go.mod h1:w2P8uVp06p2iyKKuvXIm7N/y0UCRt3UfJTfZ7oOpglM=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
@@ -473,6 +483,9 @@ gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
 google.golang.org/api v0.256.0 h1:u6Khm8+F9sxbCTYNoBHg6/Hwv0N/i+V94MvkOSor6oI=
 google.golang.org/api v0.256.0/go.mod h1:KIgPhksXADEKJlnEoRa9qAII4rXcy40vfI8HRqcU964=
+google.golang.org/appengine v1.6.8 h1:IhEN5q69dyKagZPYMSdIjS2HqprW324FRQZJcGqPAsM=
+google.golang.org/appengine/v2 v2.0.6 h1:LvPZLGuchSBslPBp+LAhihBeGSiRh1myRoYK4NtuBIw=
+google.golang.org/appengine/v2 v2.0.6/go.mod h1:WoEXGoXNfa0mLvaH5sV3ZSGXwVmy8yf7Z1JKf3J3wLI=
 google.golang.org/genproto v0.0.0-20250922171735-9219d122eba9 h1:LvZVVaPE0JSqL+ZWb6ErZfnEOKIqqFWUJE2D0fObSmc=
 google.golang.org/genproto v0.0.0-20250922171735-9219d122eba9/go.mod h1:QFOrLhdAe2PsTp3vQY4quuLKTi9j3XG3r6JPPaw7MSc=
 google.golang.org/genproto/googleapis/api v0.0.0-20260209200024-4cfbd4190f57 h1:JLQynH/LBHfCTSbDWl+py8C+Rg/k1OVH3xfcaiANuF0=
@@ -481,6 +494,8 @@ google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57 h1:
 google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
 google.golang.org/grpc v1.79.1 h1:zGhSi45ODB9/p3VAawt9a+O/MULLl9dpizzNNpq7flY=
 google.golang.org/grpc v1.79.1/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
 google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
diff --git a/go/internal/auth/service.go b/go/internal/auth/service.go
index 0d6a85b..24222b9 100644
--- a/go/internal/auth/service.go
+++ b/go/internal/auth/service.go
@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	firebaseauth "firebase.google.com/go/v4/auth"
 	"github.com/flowy-live/llink/genproto/aero"
 	"github.com/flowy-live/llink/internal/utils"
 	"github.com/redis/go-redis/v9"
@@ -56,16 +57,30 @@ type AuthService interface {
 	ExtendSession(ctx context.Context, sessionToken string) error
 	SignOut(ctx context.Context, sessionToken string) error
 
+	// MintFirebaseCustomToken returns a Firebase custom token with uid=humanId
+	// and no custom claims. Network membership is enforced via a Firestore
+	// mirror (humans/{humanId}.networks) read at rule eval time, so the token
+	// only needs to carry identity.
+	MintFirebaseCustomToken(ctx context.Context, humanId string) (string, error)
+
 	IsSystemAdmin(ctx context.Context, email string) bool
 }
 
 type authServiceImpl struct {
 	redisClient *redis.Client
 	aeroSvc     pbaero.PrimaryClient
+	fbAuth      *firebaseauth.Client
 }
 
-func NewAuthService(redisClient *redis.Client, aeroSvc pbaero.PrimaryClient) AuthService {
-	return &authServiceImpl{redisClient: redisClient, aeroSvc: aeroSvc}
+func NewAuthService(redisClient *redis.Client, aeroSvc pbaero.PrimaryClient, fbAuth *firebaseauth.Client) AuthService {
+	return &authServiceImpl{redisClient: redisClient, aeroSvc: aeroSvc, fbAuth: fbAuth}
+}
+
+func (a *authServiceImpl) MintFirebaseCustomToken(ctx context.Context, humanId string) (string, error) {
+	if humanId == "" {
+		return "", errors.New("humanId is required")
+	}
+	return a.fbAuth.CustomToken(ctx, humanId)
 }
 
 func (a *authServiceImpl) IsSystemAdmin(ctx context.Context, email string) bool {
diff --git a/go/internal/handler/handler.go b/go/internal/handler/handler.go
index 85feeec..7989edc 100644
--- a/go/internal/handler/handler.go
+++ b/go/internal/handler/handler.go
@@ -94,6 +94,10 @@ type SignInResponse struct {
 	Token string `json:"token"`
 }
 
+type FirebaseTokenResponse struct {
+	Token string `json:"token"`
+}
+
 // Network Request DTOs
 
 type CreateNetworkRequest struct {
@@ -240,6 +244,27 @@ func (h *Handler) SignIn(w http.ResponseWriter, r *http.Request) {
 	json.NewEncoder(w).Encode(resp)
 }
 
+// FirebaseToken mints a Firebase custom token for the authenticated human so
+// the client can signInWithCustomToken and have request.auth.uid populated in
+// Firestore security rules.
+func (h *Handler) FirebaseToken(w http.ResponseWriter, r *http.Request) {
+	humanId, ok := middleware.HumanIdFromContext(r.Context())
+	if !ok {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	token, err := h.authSvc.MintFirebaseCustomToken(r.Context(), humanId)
+	if err != nil {
+		slog.Error("failed to mint Firebase custom token", "error", err, "humanId", humanId)
+		http.Error(w, "internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(FirebaseTokenResponse{Token: token})
+}
+
 // SignOut deletes the session from the token in headers
 func (h *Handler) SignOut(w http.ResponseWriter, r *http.Request) {
 	token := extractBearerToken(r)
diff --git a/go/internal/network/repository.go b/go/internal/network/repository.go
index 523a89b..d755ce5 100644
--- a/go/internal/network/repository.go
+++ b/go/internal/network/repository.go
@@ -47,6 +47,7 @@ type repository interface {
 	getNetworksForHuman(ctx context.Context, humanId string) ([]*Network, error)
 	isMember(ctx context.Context, networkID, humanId string) (bool, error)
 	listAll(ctx context.Context) ([]*Network, error)
+	listAllMemberships(ctx context.Context) (map[string][]string, error)
 
 	// Invitations
 	createInvitation(ctx context.Context, networkID, email string) error
@@ -232,6 +233,27 @@ func (r *repositoryImpl) isMember(ctx context.Context, networkID, humanId string
 	return isMember, err
 }
 
+// listAllMemberships returns humanId -> networkIds for every human with at
+// least one membership. Humans with zero memberships are absent from the map;
+// callers layer them in separately.
+func (r *repositoryImpl) listAllMemberships(ctx context.Context) (map[string][]string, error) {
+	rows, err := r.pool.Query(ctx, `SELECT human_id, network_id FROM network_members`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	out := map[string][]string{}
+	for rows.Next() {
+		var humanId, networkId string
+		if err := rows.Scan(&humanId, &networkId); err != nil {
+			return nil, err
+		}
+		out[humanId] = append(out[humanId], networkId)
+	}
+	return out, rows.Err()
+}
+
 func (r *repositoryImpl) listAll(ctx context.Context) ([]*Network, error) {
 	rows, err := r.pool.Query(ctx,
 		`SELECT `+networkColumns+` FROM networks`,
diff --git a/go/internal/network/service.go b/go/internal/network/service.go
index c06392a..1db969a 100644
--- a/go/internal/network/service.go
+++ b/go/internal/network/service.go
@@ -8,6 +8,7 @@ import (
 	"log/slog"
 	"strings"
 
+	"cloud.google.com/go/firestore"
 	pbaero "github.com/flowy-live/llink/genproto/aero"
 	"github.com/flowy-live/llink/internal/billing"
 	"github.com/flowy-live/llink/internal/utils"
@@ -37,6 +38,10 @@ type Service interface {
 	IsMember(ctx context.Context, networkID, humanId string) (bool, error)
 	// ListAll returns all networks with their members
 	ListAll(ctx context.Context) ([]*Network, error)
+	// ListAllMemberships returns humanId -> networkIds for every human with at
+	// least one membership. Humans with zero memberships are absent from the map.
+	// Used by the membership reconciler to diff the Firestore mirror.
+	ListAllMemberships(ctx context.Context) (map[string][]string, error)
 
 	// Invitations (email-based, for users who haven't registered yet)
 	InviteByEmail(ctx context.Context, networkID string, emails []string) error
@@ -51,14 +56,19 @@ type serviceImpl struct {
 	repo       repository
 	aeroSvc    pbaero.PrimaryClient
 	billingSvc billing.Service
+	// fs mirrors network membership into humans/{humanId}.networks so
+	// Firestore security rules can check membership at rule-eval time.
+	// May be nil in services that never mutate membership (pusher).
+	fs *firestore.Client
 }
 
-func NewService(pool *pgxpool.Pool, aeroSvc pbaero.PrimaryClient, billingSvc billing.Service) Service {
+func NewService(pool *pgxpool.Pool, aeroSvc pbaero.PrimaryClient, billingSvc billing.Service, fs *firestore.Client) Service {
 	return &serviceImpl{
 		pool:       pool,
 		repo:       newRepository(pool),
 		aeroSvc:    aeroSvc,
 		billingSvc: billingSvc,
+		fs:         fs,
 	}
 }
 
@@ -105,23 +115,66 @@ func (s *serviceImpl) AddMembers(ctx context.Context, networkID string, humanIds
 	if slices.Contains(humanIds, "") {
 		return fmt.Errorf("invalid humanId")
 	}
-	return s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
+	if err := s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
 		for _, humanId := range humanIds {
 			if err := s.repo.addMember(ctx, tx, networkID, humanId); err != nil {
 				return err
 			}
 		}
 		return nil
-	})
+	}); err != nil {
+		return err
+	}
+
+	for _, humanId := range humanIds {
+		s.mirrorAddMembership(ctx, humanId, networkID)
+	}
+	return nil
 }
 
 func (s *serviceImpl) RemoveMember(ctx context.Context, networkID, humanId string) error {
 	if humanId == "" {
 		return fmt.Errorf("invalid humanId")
 	}
-	return s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
+	if err := s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
 		return s.repo.removeMember(ctx, tx, networkID, humanId)
-	})
+	}); err != nil {
+		return err
+	}
+
+	s.mirrorRemoveMembership(ctx, humanId, networkID)
+	return nil
+}
+
+// mirrorAddMembership / mirrorRemoveMembership keep the Firestore membership
+// mirror (humans/{humanId}.networks) in sync with Postgres. Called after the
+// Postgres transaction commits. Failures are logged but not returned: Postgres
+// is the source of truth and the reconciler will heal drift. A missing fs
+// client (pusher) no-ops.
+func (s *serviceImpl) mirrorAddMembership(ctx context.Context, humanId, networkID string) {
+	if s.fs == nil {
+		return
+	}
+	_, err := s.fs.Collection("humans").Doc(humanId).Set(ctx, map[string]any{
+		"networks":   firestore.ArrayUnion(networkID),
+		"updated_at": firestore.ServerTimestamp,
+	}, firestore.MergeAll)
+	if err != nil {
+		slog.Error("firestore mirror add failed", "error", err, "humanId", humanId, "networkID", networkID)
+	}
+}
+
+func (s *serviceImpl) mirrorRemoveMembership(ctx context.Context, humanId, networkID string) {
+	if s.fs == nil {
+		return
+	}
+	_, err := s.fs.Collection("humans").Doc(humanId).Set(ctx, map[string]any{
+		"networks":   firestore.ArrayRemove(networkID),
+		"updated_at": firestore.ServerTimestamp,
+	}, firestore.MergeAll)
+	if err != nil {
+		slog.Error("firestore mirror remove failed", "error", err, "humanId", humanId, "networkID", networkID)
+	}
 }
 
 // mutateMembers runs fn in a tx, recounts seats, calls billing.SyncSeats,
@@ -174,6 +227,10 @@ func (s *serviceImpl) ListAll(ctx context.Context) ([]*Network, error) {
 	return s.repo.listAll(ctx)
 }
 
+func (s *serviceImpl) ListAllMemberships(ctx context.Context) (map[string][]string, error) {
+	return s.repo.listAllMemberships(ctx)
+}
+
 func (s *serviceImpl) InviteByEmail(ctx context.Context, networkID string, emails []string) error {
 	network, err := s.repo.getByID(ctx, networkID)
 	if err != nil {
@@ -226,13 +283,18 @@ func (s *serviceImpl) AcceptInvitation(ctx context.Context, networkID, email, hu
 		return fmt.Errorf("invalid humanId")
 	}
 
-	return s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
+	if err := s.mutateMembers(ctx, networkID, func(tx pgx.Tx) error {
 		err := s.repo.deleteInvitation(ctx, tx, networkID, normalized)
 		if err != nil {
 			return err
 		}
 		return s.repo.addMember(ctx, tx, networkID, humanId)
-	})
+	}); err != nil {
+		return err
+	}
+
+	s.mirrorAddMembership(ctx, humanId, networkID)
+	return nil
 }
 
 func (s *serviceImpl) RevokeInvitation(ctx context.Context, networkID, email string) error {
diff --git a/go/internal/network/service_test.go b/go/internal/network/service_test.go
index c14e4fa..5901267 100644
--- a/go/internal/network/service_test.go
+++ b/go/internal/network/service_test.go
@@ -32,7 +32,7 @@ func newTestService(t *testing.T) network.Service {
 		ShootEmail(gomock.Any(), gomock.Any()).
 		Return(&pbaero.ShootEmailResponse{}, nil).
 		AnyTimes()
-	return network.NewService(dbPool, mockAero, billing.Noop())
+	return network.NewService(dbPool, mockAero, billing.Noop(), nil)
 }
 
 func TestNetworkService(t *testing.T) {
diff --git a/go/internal/particle/service_test.go b/go/internal/particle/service_test.go
index 61a6946..f128705 100644
--- a/go/internal/particle/service_test.go
+++ b/go/internal/particle/service_test.go
@@ -34,7 +34,7 @@ func getStreamStatus(data json.RawMessage) string {
 
 func TestParticleService_CreateAndGet(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network first
@@ -73,7 +73,7 @@ func TestParticleService_CreateAndGet(t *testing.T) {
 
 func TestParticleService_NestedParticles(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network
@@ -119,7 +119,7 @@ func TestParticleService_NestedParticles(t *testing.T) {
 
 func TestParticleService_CustomVisibility(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network with a member
@@ -161,7 +161,7 @@ func TestParticleService_CustomVisibility(t *testing.T) {
 
 func TestParticleService_UpdateAndDelete(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network
@@ -199,7 +199,7 @@ func TestParticleService_UpdateAndDelete(t *testing.T) {
 
 func TestParticleService_ListRootParticles(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network
@@ -225,7 +225,7 @@ func TestParticleService_ListRootParticles(t *testing.T) {
 
 func TestParticleService_OpenCloseStream(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network
@@ -273,7 +273,7 @@ func TestParticleService_OpenCloseStream(t *testing.T) {
 
 func TestParticleService_NotAStream(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network
@@ -302,7 +302,7 @@ func TestParticleService_NotAStream(t *testing.T) {
 
 func TestParticleService_AccessInheritance(t *testing.T) {
 	ctx := context.Background()
-	networkSvc := network.NewService(dbPool, nil, billing.Noop())
+	networkSvc := network.NewService(dbPool, nil, billing.Noop(), nil)
 	svc := particle.NewService(dbPool, networkSvc)
 
 	// Create a network with members
diff --git a/go/k8s/dev/memberreconciler.yaml b/go/k8s/dev/memberreconciler.yaml
new file mode 100644
index 0000000..b876596
--- /dev/null
+++ b/go/k8s/dev/memberreconciler.yaml
@@ -0,0 +1,38 @@
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: memberreconciler
+spec:
+  schedule: "0 2 * * *"
+  concurrencyPolicy: Forbid
+  successfulJobsHistoryLimit: 3
+  failedJobsHistoryLimit: 3
+  jobTemplate:
+    spec:
+      template:
+        metadata:
+          labels:
+            app: memberreconciler
+        spec:
+          serviceAccountName: default-service-account
+          nodeSelector:
+            cloud.google.com/gke-spot: "true"
+          restartPolicy: Never
+          containers:
+          - name: memberreconciler
+            image: "memberreconciler"
+            resources:
+              requests:
+                memory: "64Mi"
+                cpu: 50m
+              limits:
+                memory: "64Mi"
+                cpu: 50m
+            env:
+            - name: "GCP_PROJECT"
+              value: "flowy-dev-440017"
+            - name: "LLINK_POSTGRES_CONNECTION_URL"
+              valueFrom:
+                secretKeyRef:
+                  name: shared-secrets
+                  key: LLINK_POSTGRES_CONNECTION_URL
diff --git a/go/k8s/prod/memberreconciler.yaml b/go/k8s/prod/memberreconciler.yaml
new file mode 100644
index 0000000..88c7d8e
--- /dev/null
+++ b/go/k8s/prod/memberreconciler.yaml
@@ -0,0 +1,36 @@
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: memberreconciler
+spec:
+  schedule: "0 2 * * *"
+  concurrencyPolicy: Forbid
+  successfulJobsHistoryLimit: 3
+  failedJobsHistoryLimit: 3
+  jobTemplate:
+    spec:
+      template:
+        metadata:
+          labels:
+            app: memberreconciler
+        spec:
+          serviceAccountName: default-service-account
+          restartPolicy: Never
+          containers:
+          - name: memberreconciler
+            image: "memberreconciler"
+            resources:
+              requests:
+                memory: "64Mi"
+                cpu: 50m
+              limits:
+                memory: "64Mi"
+                cpu: 50m
+            env:
+            - name: "GCP_PROJECT"
+              value: "flowy-prod-440017"
+            - name: "LLINK_POSTGRES_CONNECTION_URL"
+              valueFrom:
+                secretKeyRef:
+                  name: shared-secrets
+                  key: LLINK_POSTGRES_CONNECTION_URL
diff --git a/go/skaffold.yaml b/go/skaffold.yaml
index 34bbe9c..1669737 100644
--- a/go/skaffold.yaml
+++ b/go/skaffold.yaml
@@ -128,6 +128,41 @@ profiles:
 ---
 apiVersion: skaffold/v4beta11
 kind: Config
+metadata:
+  name: memberreconciler
+build:
+  local: {}
+  tagPolicy:
+    gitCommit:
+      variant: AbbrevCommitSha
+profiles:
+  - name: dev
+    build:
+      artifacts:
+      - image: memberreconciler
+        context: .
+        docker:
+          dockerfile: Dockerfile.memberreconciler
+    manifests:
+      rawYaml:
+      - k8s/dev/memberreconciler.yaml
+    deploy:
+      kubectl: {}
+  - name: prod
+    build:
+      artifacts:
+      - image: memberreconciler
+        context: .
+        docker:
+          dockerfile: Dockerfile.memberreconciler
+    manifests:
+      rawYaml:
+      - k8s/prod/memberreconciler.yaml
+    deploy:
+      kubectl: {}
+---
+apiVersion: skaffold/v4beta11
+kind: Config
 metadata:
   name: pusher
 build:
diff --git a/js/src/api/client.ts b/js/src/api/client.ts
index d1671e0..bb6699d 100644
--- a/js/src/api/client.ts
+++ b/js/src/api/client.ts
@@ -5,6 +5,7 @@ import {
   BillingStatusSchema,
   CheckoutSessionResponseSchema,
   DepotObjectSchema,
+  FirebaseTokenResponseSchema,
   GetLivekitTokenResponseSchema,
   HumanSchema,
   ListInvitationsResponseSchema,
@@ -121,6 +122,14 @@ class ApiClient {
     await this.requestVoid("POST", "/auth/sign-out");
   }
 
+  async getFirebaseToken() {
+    return this.request(
+      FirebaseTokenResponseSchema,
+      "POST",
+      "/auth/firebase-token",
+    );
+  }
+
   // TODO: security: require passing in the particle id once api deprecates this
   async getParticleDownloadUrl(objectId: string): Promise<string> {
     const response = await this.fetch(
diff --git a/js/src/api/types.ts b/js/src/api/types.ts
index d1b1a60..42e014a 100644
--- a/js/src/api/types.ts
+++ b/js/src/api/types.ts
@@ -263,6 +263,11 @@ export const SignInResponseSchema = z.object({
 });
 export type SignInResponse = z.infer<typeof SignInResponseSchema>;
 
+export const FirebaseTokenResponseSchema = z.object({
+  token: z.string(),
+});
+export type FirebaseTokenResponse = z.infer<typeof FirebaseTokenResponseSchema>;
+
 // --- Billing types ---
 
 export const BillingCadenceSchema = z.enum(["monthly", "annual"]);
diff --git a/js/src/firebase.ts b/js/src/firebase.ts
index 8825944..a8e931f 100644
--- a/js/src/firebase.ts
+++ b/js/src/firebase.ts
@@ -1,9 +1,12 @@
 import { initializeApp } from 'firebase/app';
+import { getAuth } from "firebase/auth";
 import { getFirestore } from "firebase/firestore";
 import { appConfig } from "@/config/env";
 
 export const firebaseApp = initializeApp(appConfig.firebase);
 
+export const firebaseAuth = getAuth(firebaseApp);
+
 export const firestoreDb = getFirestore(firebaseApp);
 // simplifying setup to debug production issues
 // export const firestoreDb = initializeFirestore(firebaseApp,
diff --git a/js/src/stores/auth-store.ts b/js/src/stores/auth-store.ts
index 252b5bd..426cb20 100644
--- a/js/src/stores/auth-store.ts
+++ b/js/src/stores/auth-store.ts
@@ -1,8 +1,19 @@
 import { create } from "zustand";
+import { signInWithCustomToken, signOut as firebaseSignOut } from "firebase/auth";
 import { apiClient, ApiError } from "@/api/client";
 import type { Human } from "@/api/types";
+import { firebaseAuth } from "@/firebase";
 import { useSessionStore } from "./session-store";
 
+async function signInToFirebase() {
+  try {
+    const { token } = await apiClient.getFirebaseToken();
+    await signInWithCustomToken(firebaseAuth, token);
+  } catch (e) {
+    console.error("Failed to sign in to Firebase", e);
+  }
+}
+
 type AuthStatus = "idle" | "restoring" | "unauthenticated" | "authenticated";
 
 interface AuthState {
@@ -37,6 +48,7 @@ export const useAuthStore = create<AuthState>((set) => ({
     set({ status: "restoring" });
     try {
       const user = await apiClient.me();
+      await signInToFirebase();
       set({ status: "authenticated", user });
     } catch {
       useSessionStore.getState().clearToken();
@@ -63,6 +75,7 @@ export const useAuthStore = create<AuthState>((set) => ({
     try {
       const { human, token } = await apiClient.signIn({ email, code });
       useSessionStore.getState().setToken(token);
+      await signInToFirebase();
       set({ status: "authenticated", user: human });
     } catch (e) {
       const message =
@@ -81,6 +94,9 @@ export const useAuthStore = create<AuthState>((set) => ({
     } catch {
       // Best-effort — sign out locally regardless
     } finally {
+      await firebaseSignOut(firebaseAuth).catch((e) =>
+        console.error("Firebase sign-out failed", e),
+      );
       useSessionStore.getState().clearToken();
       set({
         status: "unauthenticated",