Connect sign-up to Sendico Facts intake (#46)

backend/shared/database/source/majority.go

@@ -0,0 +1,25 @@
+package source
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/v2/mongo"
+	"go.mongodb.org/mongo-driver/v2/mongo/options"
+	"go.mongodb.org/mongo-driver/v2/mongo/readconcern"
+	"go.mongodb.org/mongo-driver/v2/mongo/readpref"
+	"go.mongodb.org/mongo-driver/v2/mongo/writeconcern"
+)
+
+type majority struct{ Source }
+
+// Majority retains the source's lease and transaction lifecycle while requiring
+// durable writes and primary majority reads for externally visible handoffs.
+func Majority(database Source) Source { return &majority{Source: database} }
+
+func (s *majority) Acquire(ctx context.Context) (*mongo.Database, context.Context, func(), error) {
+	database, scoped, release, err := s.Source.Acquire(ctx)
+	if err != nil {
+		return nil, scoped, release, err
+	}
+	return database.Client().Database(database.Name(), options.Database().SetWriteConcern(writeconcern.Majority()).SetReadConcern(readconcern.Majority()).SetReadPreference(readpref.Primary())), scoped, release, nil
+}