Architecture

Makechain uses a layered architecture with single-chain Simplex BFT consensus and serial per-project execution.

System overview

Layers

Message Layer

Every message is a self-authenticating envelope containing a BLAKE3 hash, Ed25519 signature, and the signer's public key. Messages are structurally validated before entering the mempool.

Consensus Layer

A single Simplex BFT consensus chain orders all messages. The leader proposes blocks by draining the mempool, and the execution engine processes them in two phases.

The two phases are:

1. Account pre-pass — SIGNER_ADD, SIGNER_REMOVE, ACCOUNT_DATA, VERIFICATION_ADD / VERIFICATION_REMOVE, LINK_ADD / LINK_REMOVE, REACTION_ADD / REACTION_REMOVE, PROJECT_CREATE, PROJECT_REMOVE, STORAGE_CLAIM, and FORK are applied serially because they touch shared owner_address-scoped account state
2. Serial project execution — Remaining project-scoped messages are grouped by project_id and executed serially per group against a shared BatchStore overlay on QMDB

This single-chain model achieves high throughput through consensus pipelining (multiple blocks in flight) without the complexity of cross-shard coordination. Non-proposer validators can optionally broadcast subblock payloads — signed mempool snapshots — to help the proposer build fuller blocks (see Consensus).

State Layer

State is stored in a prefix-namespaced key-value store with lexicographic ordering for range scans:

QMDB is the single source of truth. During block execution, a BatchStore creates a local mutations overlay on QMDB, then merkleizes and applies the changeset atomically on commit. API queries use a QmdbReadStore for lock-free reads. The StateStore trait keeps the storage backend pluggable.

Content Storage

The consensus layer stores only message metadata (~100-500 bytes). File content (blobs, trees) lives in external storage, referenced by optional content_digest (integrity hash) and url (locator) in commit bundles. These fields are self-attested — validators do not fetch or verify content.

Commonware Primitives

Makechain builds on the Commonware Library:

Indexer and event processor

The indexer (cargo build --bin indexer --features indexer) streams finalized blocks from a node via gRPC, decodes messages, and writes them into Postgres. It publishes events to Redis streams for downstream consumers.

The event processor (cargo build --bin event-processor --features event-processor) consumes Redis streams published by the indexer and maintains denormalized query tables in Postgres — projects, accounts, collaborators, links, and reactions. Processors are idempotent and checkpoint-based, allowing safe restarts without data loss.

Both binaries are feature-gated and require external Postgres and Redis instances.

gRPC API

The node exposes a gRPC service on port 50051 (configurable) with:

• grpc-web support — browser clients via HTTP/1.1 (tonic-web)
• CORS — configured for cross-origin grpc-web requests
• Server reflection — runtime service discovery (grpc reflection v1)
• Message streaming — SubscribeMessages with type and project_id filters