# nerve

**Observation engine for autonomous agents** — sense the world, react to changes, run workflows.

Nerve is a lightweight daemon that continuously observes external state through **Senses**, reacts via declarative **Reflexes**, and orchestrates multi-step **Workflows**. Built for the [Uncaged](https://github.com/uncaged) agent framework.

## Core Concepts

```
External World → Sense → Signal → Reflex → Workflow → Log
                  ↑                                     ↑
              "what to observe"                  "what to do"
```

| Concept | Metaphor | Role |
|---------|----------|------|
| **Sense** | 👁️ Perception | A `compute()` function that samples or derives data. Each sense has its own SQLite database. |
| **Reflex** | ⚡ Reaction | Declarative trigger — interval-based, event-driven, or both. Connects senses to actions. |
| **Signal** | 📡 Notification | Emitted when a sense returns non-null. Other reflexes can listen for signals. |
| **Workflow** | 🔧 Action | Stateful multi-step execution with Roles (actors) and a Moderator (coordinator). |
| **Log** | 📝 Record | Immutable audit trail. Queryable by senses, but **cannot** trigger reflexes (prevents feedback loops). |

Three extension points, fully orthogonal — a Sense doesn't know when it runs, a Reflex doesn't know what it computes, a Workflow doesn't know why it was triggered.

## Packages

| Package | Description |
|---------|-------------|
| [`@uncaged/nerve-core`](./packages/core) | Shared types and config parser |
| [`@uncaged/nerve-daemon`](./packages/daemon) | The observation engine — kernel, sense runtime, reflex scheduler, workflow manager |
| [`@uncaged/nerve-cli`](./packages/cli) | CLI tool (`nerve`) — init, start, stop, logs, query |

## Quick Start

```bash
# Requirements: Node.js ≥ 22.5, pnpm
pnpm add -g @uncaged/nerve-cli

# Initialize a workspace
mkdir my-agent && cd my-agent
nerve init

# Write a sense
cat > senses/cpu-usage/compute.ts << 'EOF'
export async function compute() {
  const [load] = (await import("node:os")).loadavg();
  return load > 2.0 ? { load } : null;  // signal only when load is high
}
EOF

# Configure reflexes in nerve.yaml
cat > nerve.yaml << 'EOF'
senses:
  cpu-usage:
    group: system
    throttle: 10s

reflexes:
  - kind: sense
    sense: cpu-usage
    interval: 30s
EOF

# Run
nerve dev          # foreground (development)
nerve daemon start # background (production)
nerve status       # check health
nerve logs         # view logs
```

## Configuration

`nerve.yaml` declares senses, reflexes, and workflows:

```yaml
senses:
  cpu-usage:
    group: system          # senses in the same group share a worker process
    throttle: 10s          # min interval between computes
    timeout: 30s           # max compute duration
    gracePeriod: 5s        # wait before first compute after startup

reflexes:
  - kind: sense
    sense: cpu-usage
    interval: 30s          # periodic trigger
    on: [disk-pressure]    # also trigger on signals from other senses

  - kind: workflow
    workflow: cleanup
    on: [disk-pressure]    # start a workflow when signal fires

workflows:
  cleanup:
    concurrency: 1
    overflow: drop         # discard if already running
  code-review:
    concurrency: 3
    overflow: queue
    maxQueue: 20
```

## Architecture

```
┌─────────────────────────────────────────────────────────┐
│  Kernel                                                 │
│                                                         │
│  ┌──────────┐   ┌──────────┐   ┌──────────┐           │
│  │ Worker   │   │ Worker   │   │ Worker   │  (1 per   │
│  │ (group A)│   │ (group B)│   │ (group C)│   group)  │
│  │ sense-1  │   │ sense-3  │   │ sense-5  │           │
│  │ sense-2  │   │ sense-4  │   │          │           │
│  └────┬─────┘   └────┬─────┘   └────┬─────┘           │
│       │              │              │                   │
│       └──────────────┼──────────────┘                   │
│                      ▼                                  │
│              ┌──────────────┐                           │
│              │  Signal Bus  │                           │
│              └──────┬───────┘                           │
│                     ▼                                   │
│           ┌──────────────────┐                          │
│           │ Reflex Scheduler │                          │
│           └────────┬─────────┘                          │
│                    ▼                                    │
│          ┌───────────────────┐                          │
│          │ Workflow Manager  │──→ Log Store (SQLite)    │
│          └───────────────────┘                          │
└─────────────────────────────────────────────────────────┘
```

- **Worker processes** — one per sense group, forked by the kernel. Isolated compute execution.
- **Signal Bus** — in-memory pub/sub for signal distribution.
- **Reflex Scheduler** — interval timers + signal subscriptions, with throttle/coalesce.
- **Workflow Manager** — concurrency control (drop/queue), thread lifecycle tracking.
- **Log Store** — WAL-mode SQLite via `node:sqlite`, with archival and retention policies.

## Tech Stack

- **Zero native addons** — uses Node.js built-in `node:sqlite` (DatabaseSync)
- **Drizzle ORM** v1.0 for sense databases
- **rslib** (rspack) for building
- **Biome** for formatting/linting
- **Vitest** for testing
- **pnpm** workspaces for monorepo management

## Development

```bash
git clone https://git.shazhou.work/uncaged/nerve.git
cd nerve
pnpm install
pnpm build
pnpm -r test     # run all tests
```

## Design Documents

- [RFC-001: Observation Engine](./docs/rfc-001-observation-engine.md) — Sense, Signal, Reflex model
- [RFC-002: Workflow Engine](./docs/rfc-002-workflow-engine.md) — Stateful workflow execution
- [Coding Conventions](./docs/coding-conventions.md)

## License

MIT