# 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 → Sense (scheduled compute)
                        │
                        └→ Workflow (Sense return with workflow directive) → Log
```

| Concept | Metaphor | Role |
|---------|----------|------|
| **Sense** | 👁️ Perception | A `compute()` function that samples or derives data. Each sense has its own SQLite database. |
| **Reflex** | ⚡ Reaction | Declarative rules that **only schedule Sense computes** (interval and/or `on` signal names). Reflex YAML cannot reference workflows. |
| **Signal** | 📡 Notification | Emitted when a sense returns a non-null value that is routed as a normal signal (see Sense → Workflow below). Other reflexes can listen via `on`. |
| **Workflow** | 🔧 Action | Stateful multi-step execution with Roles and a Moderator. Started from a Sense return value or from CLI/daemon IPC—not from reflex YAML. |
| **Log** | 📝 Record | Immutable audit trail. Queryable by senses, but **cannot** trigger reflexes (prevents feedback loops). |

**Sense → Workflow:** if `compute()` returns a plain object with a string field `workflow` in the form `name|maxRounds|prompt` (only the first two `|` delimit name and rounds; the rest is the prompt), the engine starts that workflow and **does not** emit a Signal for that return. `workflow: null` or `""` means “emit a signal” and strip the key from the payload. Invalid `workflow` strings are treated like a normal signal (directive stripped). See `@uncaged/nerve-core` `routeSenseComputeOutput` / `parseSenseWorkflowDirective`.

Three extension points for **what / when / multi-step action** — reflexes never replace Sense-driven workflow launches.

## Packages

| Package | Description |
|---------|-------------|
| [`@uncaged/nerve-core`](./packages/core) | Shared types, config parser, Sense→workflow routing, daemon IPC protocol |
| [`@uncaged/nerve-store`](./packages/store) | Append-only log SQLite, JSONL archive, CAS blob store, workflow run rows |
| [`@uncaged/nerve-daemon`](./packages/daemon) | Kernel, workers, signal bus, reflex scheduler, workflow manager, file watcher, IPC |
| [`@uncaged/nerve-cli`](./packages/cli) | CLI (`nerve`) — init, validate, daemon, dev, logs, sense, store, workflow |

## 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 (sense-only), optional workflows (concurrency), and optional engine `max_rounds`:

```yaml
max_rounds: 100              # default moderator cap (e.g. CLI workflow trigger)

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
    grace_period: 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

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

YAML must **not** include `workflow:` under `reflexes` — the parser rejects it. Declare workflows under `workflows:` and start them from Sense `compute()` or `nerve workflow trigger`.

**Example — Sense starts a workflow** (`senses/disk-pressure/compute.ts`):

```typescript
export async function compute() {
  const full = await diskNearlyFull();
  if (!full) return null;
  return {
    path: "/data",
    workflow: "cleanup|10|Disk partition nearly full", // name|maxRounds|prompt
  };
}
```

## Architecture

```
┌────────────────────────────────────────────────────────────────────────┐
│  Kernel                                                                 │
│                                                                         │
│  ┌──────────────┐   watches nerve.yaml / senses / workflows            │
│  │ File Watcher ├──────────────────────────────────────────┐           │
│  └──────────────┘                                          │           │
│  ┌──────────────┐   CLI ↔ newline JSON (trigger-workflow, │           │
│  │ Daemon IPC   │   trigger-sense, list-senses)            │           │
│  └──────┬───────┘                                          ▼           │
│         │            ┌──────────┐   ┌──────────┐   ┌──────────┐        │
│         │            │ 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  │──→ @uncaged/nerve-store │
│                              └───────────────────┘    (logs.db, …)   │
└────────────────────────────────────────────────────────────────────────┘
```

- **Worker pool** — one child process per sense group; isolation between groups.
- **Signal Bus** — in-memory pub/sub for signal distribution.
- **Reflex Scheduler** — interval timers + signal subscriptions, with throttle/coalesce.
- **Workflow Manager** — concurrency (drop/queue), per-workflow workers, crash recovery.
- **File watcher** — hot reload for config, sense modules, and workflow modules.
- **Daemon IPC** — Unix domain socket; used by the CLI when the daemon is running.
- **Log / blob storage** — implemented in `@uncaged/nerve-store` (WAL SQLite, JSONL archive, CAS blobs).

## 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