implement paywall (#161)

* implement core foundation

* inject deps

* fix incorrect migration

* tail migration

* use transaction for migration

* fix: inject deps for tests

* cleanup billing management for admin

* upgrade stripe sdk to v85

* set price env variables

* cleanup billing management

* allow multiple dev windows

* fix: settings scroll

* feat: show nice video thumbnail in listview

* feat: implement freemium restrictions

* remove unnecessary comments

* refactor

* docs

* format

* tweak network settings better hierarchy

go/cmd/particleprocessorworker/main.go

@@ -6,8 +6,10 @@ import (
 	"log"
 	"log/slog"
 	"os"
+	"strings"
 	"time"
 
+	"github.com/flowy-live/llink/internal/billing"
 	"github.com/flowy-live/llink/internal/db"
 	"github.com/flowy-live/llink/internal/depot"
 	"github.com/flowy-live/llink/internal/particle"
@@ -43,6 +45,7 @@ func main() {
 	db.Init()
 	defer db.Cleanup()
 	processingRepo := particle.NewProcessingRepository(db.Pool())
+	billingSvc := billing.NewServiceForWorker(db.Pool())
 
 	storageClient, err := storage.NewClient(ctx)
 	if err != nil {
@@ -104,6 +107,7 @@ func main() {
 
 			updateParentLastChildCreatedAt(ctx, change.Doc)
 			transcribeMediaParticle(ctx, depotSvc, speechSvc, change.Doc)
+			recordFreemiumUsage(ctx, billingSvc, change.Doc)
 
 			if err := processingRepo.MarkProcessed(ctx, particleID); err != nil {
 				slog.Error("failed to mark particle as processed", "particleID", particleID, "error", err)
@@ -192,6 +196,59 @@ func toFirestoreTranscript(result *speech.TranscriptResult) particle.FirestoreTr
 	}
 }
 
+// recordFreemiumUsage bumps the network's daily message counter for non-container
+// particles. Idempotent via the surrounding processed_particles guard: the worker
+// only reaches this path on first-seen particles, so a crash/restart won't
+// double-count.
+func recordFreemiumUsage(ctx context.Context, billingSvc billing.Service, doc *firestore.DocumentSnapshot) {
+	rawType, err := doc.DataAt("type")
+	if err != nil {
+		slog.Error("failed to read particle type", "error", err, "particleID", doc.Ref.ID)
+		return
+	}
+	typeStr, ok := rawType.(string)
+	if !ok {
+		slog.Error("particle type is not a string", "particleID", doc.Ref.ID, "type", rawType)
+		return
+	}
+	particleType, err := particle.ParseParticleType(typeStr)
+	if err != nil {
+		slog.Error("invalid particle type", "error", err, "particleID", doc.Ref.ID)
+		return
+	}
+	// Containers (stream/folder) don't count as "messages" for the daily cap.
+	if particleType == particle.TypeStream || particleType == particle.TypeFolder {
+		return
+	}
+
+	networkID, err := networkIDFromParticlePath(doc.Ref.Path)
+	if err != nil {
+		slog.Error("failed to derive network id", "error", err, "path", doc.Ref.Path)
+		return
+	}
+
+	if err := billingSvc.IncrementDailyUsage(ctx, networkID, doc.CreateTime); err != nil {
+		slog.Error("failed to increment daily usage", "error", err, "networkID", networkID, "particleID", doc.Ref.ID)
+	}
+}
+
+// networkIDFromParticlePath extracts the network id from a Firestore particle
+// document path. Particles live at `networks/{network_id}/children/.../children/{id}`
+// at arbitrary nesting depth, so the network id is always the second segment
+// of the full doc path (which itself is rooted under the Firestore db path:
+// `projects/.../documents/networks/{network_id}/...`).
+func networkIDFromParticlePath(path string) (string, error) {
+	// doc.Ref.Path is the full resource path; find the "networks" collection
+	// and return the next segment.
+	segments := strings.Split(path, "/")
+	for i, seg := range segments {
+		if seg == "networks" && i+1 < len(segments) {
+			return segments[i+1], nil
+		}
+	}
+	return "", fmt.Errorf("no networks segment in path: %s", path)
+}
+
 // updateParentLastChildCreatedAt updates the parent stream's last_child_created_at
 // to the child's actual created_at timestamp, so it stays directly comparable with
 // playback markers (which also store child created_at values).