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roz is a workspace of 12 Rust crates. Each crate has a single responsibility, and the dependency graph is intentionally shallow to keep compile times fast and the safety boundary clear.

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Crate Overview

CrateTypeDescription
roz-coreLibraryDomain types, channel manifests, error types. No IO. Everything else depends on this.
roz-agentLibraryAgent runtime: LLM abstraction, tool dispatch, OODA loop, safety guards, constitution.
roz-copperLibraryCopper-rs runtime integration. On-robot task graph execution at 100Hz.
roz-localLibraryLocal agent loop, WASM compilation, sim container management, MCP client.
roz-cliBinaryInteractive TUI and command-line interface. Entry point for roz commands.
roz-safetyBinarySafety daemon: heartbeat tracker, e-stop monitoring, watchdog process.
roz-natsLibraryNATS client wrappers, subject definitions, cloud messaging.
roz-zenohLibraryZenoh client for local peer-to-peer comms between robot processes.
roz-testLibraryShared test utilities, fixtures, and helpers used across crate tests.
roz-dbLibrarysqlx migrations, queries, row-level security (RLS) on every table.
roz-serverBinaryaxum API server. REST + gRPC multiplexed on a single port.
roz-workerBinaryEdge worker binary. Connects via NATS, runs the OODA loop on-robot.

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Zenoh vs NATS

roz uses two messaging systems for different scopes:
  • Zenoh handles local, peer-to-peer communication between processes on the same robot or local network. It provides low-latency pub/sub for sensor data, control commands, and state synchronization without requiring a broker.
  • NATS handles cloud communication between the API server, edge workers, and the safety daemon. It provides reliable messaging with subject-based routing across network boundaries.
The split keeps latency-sensitive robot control traffic local (Zenoh) while using NATS for coordination that needs to cross network boundaries.

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Data Flow

┌─────────────────────────────────────────────────────────────┐
│                        Cloud                                │
│                                                             │
│  ┌────────────┐    NATS     ┌────────────┐                  │
│  │ roz-server │◄───────────►│ roz-worker │                  │
│  │  (axum +   │             │  (edge)    │                  │
│  │   tonic)   │             └─────┬──────┘                  │
│  └─────┬──────┘                   │                         │
│        │                          │                         │
│        │ REST/gRPC                │ NATS                    │
│        │                          │                         │
│  ┌─────┴──────┐             ┌─────┴──────┐                  │
│  │  roz-db    │             │ roz-safety │                  │
│  │  (sqlx)    │             │ (watchdog) │                  │
│  └────────────┘             └────────────┘                  │
└─────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────┐
│                     Local / Robot                            │
│                                                             │
│  ┌────────────┐             ┌────────────┐                  │
│  │  roz-cli   │────────────►│ roz-local  │                  │
│  │  (TUI)     │             │  (agent +  │                  │
│  └────────────┘             │   WASM)    │                  │
│                             └─────┬──────┘                  │
│                                   │                         │
│                          Zenoh    │    MCP (port 8090)       │
│                        ┌─────────┼─────────┐                │
│                        ▼         ▼         ▼                │
│                  ┌──────────┐ ┌──────┐ ┌──────────┐         │
│                  │roz-copper│ │ WASM │ │ Sim      │         │
│                  │ (100Hz)  │ │Sandbox│ │Container │         │
│                  └──────────┘ └──────┘ └──────────┘         │
└─────────────────────────────────────────────────────────────┘

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Dependency Graph

The crate dependency structure keeps roz-core at the root with no IO dependencies. All other crates depend on roz-core for shared types. 
roz-core  (no IO, domain types only)
  ├── roz-agent     (+ LLM provider SDKs, tokio)
  ├── roz-copper    (+ cu29, zenoh)
  ├── roz-nats      (+ async-nats)
  ├── roz-zenoh     (+ zenoh)
  ├── roz-db        (+ sqlx)
  ├── roz-safety    (+ tokio, nats)
  ├── roz-test      (+ tokio, testcontainers)
  ├── roz-local     (+ wasmtime, roz-agent, roz-zenoh)
  ├── roz-server    (+ axum, tonic, roz-db, roz-agent, roz-nats)
  ├── roz-worker    (+ roz-agent, roz-nats, roz-safety)
  └── roz-cli       (+ roz-local, roz-agent, ratatui)
Key constraints enforced by the dependency graph:
  • roz-core has zero IO dependencies. It defines types only.
  • unsafe is denied workspace-wide. This is a safety-critical robotics platform.
  • roz-local depends on roz-agent and roz-zenoh but not on roz-server or roz-db — it runs entirely on the local machine.
  • roz-server depends on roz-db and roz-agent but not on roz-local — it runs in the cloud.

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Source Code

The full crate structure is at github.com/BedrockDynamics/roz-oss.