openclaw/docs/concepts/typebox.md

Multi-channel AI gateway with extensible messaging integrations

---
summary: "TypeBox schemas as the single source of truth for the gateway protocol"
read_when:
  - Updating protocol schemas or codegen
title: "TypeBox"
---

TypeBox is a TypeScript-first schema library. OpenClaw uses it to define the **Gateway WebSocket protocol** (handshake, request/response, server events). Those schemas drive **runtime validation** (TypeBox Compile), **JSON Schema export**, and **Swift codegen** for the macOS app. One source of truth; everything else is generated.

For the higher-level protocol context, start with [Gateway architecture](/concepts/architecture).

## Mental model (30 seconds)

Every Gateway WS message is one of three frames:

- **Request**: `{ type: "req", id, method, params }`
- **Response**: `{ type: "res", id, ok, payload | error }`
- **Event**: `{ type: "event", event, payload, seq?, stateVersion? }`

The first frame **must** be a `connect` request. After that, clients call methods (e.g. `health`, `send`, `chat.send`) and subscribe to events (e.g. `presence`, `tick`, `agent`).

Connection flow (minimal):

```text
Client                    Gateway
  |---- req:connect -------->|
  |<---- res:hello-ok --------|
  |<---- event:tick ----------|
  |---- req:health ---------->|
  |<---- res:health ----------|
```

Common methods and events:

| Category   | Examples                                                   | Notes                                        |
| ---------- | ---------------------------------------------------------- | -------------------------------------------- |
| Core       | `connect`, `health`, `status`                              | `connect` must be first                      |
| Messaging  | `send`, `agent`, `agent.wait`, `system-event`, `logs.tail` | side-effecting methods need `idempotencyKey` |
| Chat       | `chat.history`, `chat.send`, `chat.abort`                  | WebChat uses these                           |
| Sessions   | `sessions.list`, `sessions.patch`, `sessions.delete`       | session admin                                |
| Automation | `wake`, `cron.list`, `cron.run`, `cron.runs`               | wake and cron control                        |
| Nodes      | `node.list`, `node.invoke`, `node.pair.*`                  | Gateway WS plus node actions                 |
| Events     | `tick`, `presence`, `agent`, `chat`, `health`, `shutdown`  | server push                                  |

The authoritative advertised **discovery** inventory lives in `src/gateway/server-methods-list.ts` (`listGatewayMethods`, `GATEWAY_EVENTS`).

## Where the schemas live

- Source barrels: `packages/gateway-protocol/src/schema-modules.ts` owns the canonical domain-module list, while the public `schema.ts` wrapper also exposes `ProtocolSchemas`.
- Generator registry: ordered `protocol-schema-fragment-*.ts` files map stable names to the canonical TypeBox objects from their owner modules. `protocol-schemas.ts` composes those fragments in a fixed order and rejects duplicate keys.
- Runtime validators: `packages/gateway-protocol/src/validator-registry.ts`, using the lazy TypeBox Compile owner in `protocol-validator.ts`
- Advertised feature/discovery registry: `src/gateway/server-methods-list.ts`
- Server handshake and method dispatch: `src/gateway/server-core-runtime.ts`
- Node client: `src/gateway/client.ts`
- Generated JSON Schema: `dist/protocol.schema.json` (build output, not committed)
- Generated Swift models: `apps/shared/OpenClawKit/Sources/OpenClawProtocol/GatewayModels.swift`

## Current pipeline

- `pnpm protocol:gen` writes JSON Schema (draft-07) to `dist/protocol.schema.json`.
- `pnpm protocol:gen:swift` generates the Swift gateway models.
- `pnpm protocol:check:swift` verifies the committed Swift models without rewriting them.
- `pnpm protocol:gen:kotlin` generates the Android protocol models and constants.
- `pnpm protocol:check` checks the registry structure, runs all three generators, and verifies the committed Swift and Kotlin output. The JSON Schema output is a gitignored build artifact with no committed baseline to diff against, so `pnpm protocol:gen` instead asserts the published-document contract (required frame definitions, frame ordering, `type` discriminator mapping, non-empty method metadata) and fails the check when the generated schema drifts from it.

When a gateway schema affects native clients, run `pnpm protocol:gen:swift`, review the generated diff, then run `pnpm protocol:check:swift`. Commit the schema and `GatewayModels.swift` update together. Stable decoding behavior belongs in the focused `GatewayModelsCompatibilityTests.swift` regressions rather than in handwritten model copies.

## How the schemas are used at runtime

- **Server side**: every inbound frame is validated with TypeBox Compile. The handshake only accepts a `connect` request whose params match `ConnectParams`.
- **Client side**: the JS client validates event and response frames before using them.
- **Feature discovery**: the Gateway sends a conservative `features.methods` and `features.events` list in `hello-ok`, from `listGatewayMethods()` and `GATEWAY_EVENTS`.
- That discovery list is not a generated dump of every callable helper in `coreGatewayHandlers`; some helper RPCs are implemented in `src/gateway/server-methods/*.ts` without being enumerated in the advertised feature list.

## Example frames

Connect (first message):

```json
{
  "type": "req",
  "id": "c1",
  "method": "connect",
  "params": {
    "minProtocol": 3,
    "maxProtocol": 4,
    "client": {
      "id": "openclaw-macos",
      "displayName": "macos",
      "version": "1.0.0",
      "platform": "macos 15.1",
      "mode": "ui",
      "instanceId": "A1B2"
    }
  }
}
```

Hello-ok response:

```json
{
  "type": "res",
  "id": "c1",
  "ok": true,
  "payload": {
    "type": "hello-ok",
    "protocol": 4,
    "server": { "version": "dev", "connId": "ws-1" },
    "features": { "methods": ["health"], "events": ["tick"] },
    "snapshot": {
      "presence": [],
      "health": {},
      "stateVersion": { "presence": 0, "health": 0 },
      "uptimeMs": 0
    },
    "auth": { "role": "operator", "scopes": ["operator.read"] },
    "policy": { "maxPayload": 1048576, "maxBufferedBytes": 1048576, "tickIntervalMs": 30000 }
  }
}
```

Request and response:

```json
{ "type": "req", "id": "r1", "method": "health" }
```

```json
{ "type": "res", "id": "r1", "ok": true, "payload": { "ok": true } }
```

Event:

```json
{ "type": "event", "event": "tick", "payload": { "ts": 1730000000 }, "seq": 12 }
```

## Minimal client (Node.js)

Smallest useful flow: connect + health.

```ts
import { WebSocket } from "ws";

const ws = new WebSocket("ws://127.0.0.1:18789");

ws.on("open", () => {
  ws.send(
    JSON.stringify({
      type: "req",
      id: "c1",
      method: "connect",
      params: {
        minProtocol: 4,
        maxProtocol: 4,
        client: {
          id: "cli",
          displayName: "example",
          version: "dev",
          platform: "node",
          mode: "cli",
        },
      },
    }),
  );
});

ws.on("message", (data) => {
  const msg = JSON.parse(String(data));
  if (msg.type === "res" && msg.id === "c1" && msg.ok) {
    ws.send(JSON.stringify({ type: "req", id: "h1", method: "health" }));
  }
  if (msg.type === "res" && msg.id === "h1") {
    console.log("health:", msg.payload);
    ws.close();
  }
});
```

## Worked example: add a method end-to-end

Example: add a new `system.echo` request that returns `{ ok: true, text }`.

1. **Schema (source of truth)**

Add to `packages/gateway-protocol/src/schema/system-info.ts` (or the closest matching feature module):

```ts
export const SystemEchoParamsSchema = Type.Object(
  { text: NonEmptyString },
  { additionalProperties: false },
);

export const SystemEchoResultSchema = Type.Object(
  { ok: Type.Boolean(), text: NonEmptyString },
  { additionalProperties: false },
);
```

Add both entries to the closest semantic `packages/gateway-protocol/src/schema/protocol-schema-fragment-*.ts` file. Import the owner module as a namespace when that fragment does not already use it, then map the stable registry names to the canonical schema objects:

```ts
import * as system from "./system.js";

export const OperationsProtocolSchemas = {
  // Existing entries stay in their current order.
  // ...
  SystemEchoParams: system.SystemEchoParamsSchema,
  SystemEchoResult: system.SystemEchoResultSchema,
} as const;
```

Do not sort fragment keys or move existing entries: native code generation follows registry insertion order. `protocol-schemas.ts` owns the deliberate fragment order and should change only when introducing a new semantic fragment.

```ts
export type SystemEchoParams = Static<typeof SystemEchoParamsSchema>;
export type SystemEchoResult = Static<typeof SystemEchoResultSchema>;
```

2. **Validation**

In `packages/gateway-protocol/src/validator-registry.ts`, export a validator using its existing lazy compiler:

```ts
export const validateSystemEchoParams = compile(S.SystemEchoParamsSchema);
```

3. **Server behavior**

Add a handler in `src/gateway/server-methods/system.ts`:

```ts
export const systemHandlers: GatewayRequestHandlers = {
  "system.echo": ({ params, respond }) => {
    const text = String(params.text ?? "");
    respond(true, { ok: true, text });
  },
};
```

Register it in `src/gateway/server-methods.ts` (already merges `systemHandlers`), then add `"system.echo"` to the `listGatewayMethods` input in `src/gateway/server-methods-list.ts`.

If the method is callable by operator or node clients, also classify it in `src/gateway/method-scopes.ts` so scope enforcement and `hello-ok` feature advertising stay aligned.

4. **Regenerate**

```bash
pnpm protocol:check
```

5. **Tests and docs**

Add a server test in `src/gateway/server.*.test.ts` and note the method in docs.

## Swift codegen behavior

The Swift generator emits:

- a `GatewayFrame` enum with `req`, `res`, `event`, and `unknown` cases
- strongly typed payload structs/enums
- `ErrorCode` values, `GATEWAY_PROTOCOL_VERSION`, and `GATEWAY_MIN_PROTOCOL_VERSION`

Unknown frame types are preserved as raw payloads for forward compatibility.

## Versioning and compatibility

- `PROTOCOL_VERSION` lives in `packages/gateway-protocol/src/version.ts` (current value: `4`).
- Clients send `minProtocol` and `maxProtocol`; the server rejects ranges that do not include its current protocol.
- The Swift models keep unknown frame types to avoid breaking older clients.

## Schema patterns and conventions

- Most objects use `additionalProperties: false` for strict payloads.
- `NonEmptyString` (`Type.String({ minLength: 1 })`) is the default for IDs and method/event names.
- The top-level `GatewayFrame` uses a **discriminator** on `type`.
- Methods with side effects usually require an `idempotencyKey` in params (example: `send`, `poll`, `agent`, `chat.send`).
- `agent` accepts optional `internalEvents` for runtime-generated orchestration context (for example subagent/cron task completion handoff); treat this as internal API surface.

## Live schema JSON

Generated JSON Schema is a build artifact, not committed to the repo. During the package rollout, the current beta schema is available at:

- [`protocol.schema.json`](https://unpkg.com/@openclaw/gateway-protocol@beta/protocol.schema.json)

## When you change schemas

1. Update the TypeBox schemas in the owning `packages/gateway-protocol/src/schema/*.ts` module and register them in the closest `protocol-schema-fragment-*.ts` file without reordering existing keys.
2. Register the method/event in `src/gateway/server-methods-list.ts`.
3. Update `src/gateway/method-scopes.ts` when the new RPC needs operator or node scope classification.
4. Run `pnpm protocol:check`.
5. Commit the regenerated Swift models.

## Related

- [Rich output protocol](/reference/rich-output-protocol)
- [RPC adapters](/reference/rpc)