TypeScript SDK¶

@tuvl/client is the official TypeScript SDK for the tuvl workflow engine. It gives frontend and Node.js applications a type-safe, zero-config way to invoke workflows across three transports — plain REST, Server-Sent Events, and gRPC-Web — from a single unified API.

How it fits in the stack¶

Your app (React / Vue / Node.js)
        │
        │  import { TuvlClient } from "@tuvl/client"
        ▼
┌──────────────────────────┐
│        TuvlClient        │  auto-selects transport
├──────────────────────────┤
│   REST  │  SSE  │  gRPC  │
└────┬────┴───┬───┴────┬───┘
     │        │        │
     ▼        ▼        ▼
     POST   stream   stream
         tuvl server :8000
              │
         WorkflowEngine

The client uses the /api/_system/workflows/{name} manifest endpoint to discover each workflow's trigger path and streaming hints at runtime, so you never hardcode API paths in the frontend.

Transports¶

REST (default)¶

Used when no onProgress callback is provided, or when mode: "rest" is forced. The server runs the full workflow synchronously and returns a single JSON response.

Best for: fast workflows (functional, router, model-op steps only), simple CRUD-like calls, server-side Node.js where streaming UI is not needed.

SSE (Server-Sent Events)¶

Activated automatically when onProgress is provided and the workflow manifest reports has_slow_steps: true (meaning it contains agent, mcp, or api_call steps). Can also be forced with mode: "sse".

The server streams one event per step as it completes, then a final done event with the result. Uses standard fetch + ReadableStream — works in browsers (Chrome 78+, Firefox 100+, Safari 15+) and Node.js 18+.

Best for: LLM agent workflows, MCP calls, long-running API chains where showing progress matters.

gRPC-Web¶

Force with mode: "grpc". Uses binary protobuf framing over HTTP/1.1 (the gRPC-Web spec) via sonora on the server. Requires optional peer dependencies:

npm install @protobuf-ts/grpcweb-transport @protobuf-ts/runtime-rpc

The gRPC module is dynamically imported — zero bundle cost if never used.

Server-side sonora patches

tuvl ships vendored patches for sonora 0.2.3 (patches/sonora-asgi-fixes.patch) that fix two wire-protocol bugs: incorrect trailer byte encoding and a Content-Type header echo that caused @protobuf-ts to reject responses. These are applied automatically by make setup. Client code requires no changes — the fixes are transparent.

Best for: high-throughput environments, teams already using protobuf tooling, future server-defined UI plugins.

Manifest caching¶

On the first execute() call for a workflow, the client fetches the manifest and caches it for 60 seconds (configurable via manifestCacheTtl). Subsequent calls reuse the cache, avoiding an extra round-trip. The cache can be cleared manually:

client.invalidateManifest("screen-candidate"); // one workflow
client.invalidateManifest();                   // all workflows

Authentication¶

The SDK injects a Authorization: Bearer <token> header on every request. The token is set at construction time and can be updated at any time:

const client = new TuvlClient({ baseUrl, token: initialToken });

// After token refresh:
client.setToken(newToken);

Per-call overrides are also supported:

await client.execute("admin-workflow", {
  payload: {},
  token: elevatedToken,
});

Error handling¶

execute() throws on:

Network errors (fetch failure)
HTTP 4xx / 5xx from the server
A workflow error event (SSE or gRPC stream)
An SSE stream that closes without a done event

try {
  const result = await client.execute("screen-candidate", { payload });
} catch (err) {
  // err.message contains the server error detail
}

Next steps¶

Quickstart — install and make your first call in 5 minutes
API Reference — complete method and type reference