SDKs and CLIs

Ujex ships first-party clients in Python, TypeScript, Go, plus a standalone CLI and an MCP server so any MCP client (Claude Desktop, Cursor, Cline, Zed) can use the product directly.

The same OpenAPI 3.1 spec lives at /openapi.json — you can generate clients in any language if the ones we ship aren't enough.

---

Python — ujex-postbox

pip install ujex-postbox

from ujex_postbox import PostboxClient, plus_address

client = PostboxClient(device_key="apk_...")

resp = client.send(
    to=["alice@vendor.com"],
    subject="Re: invoice",
    body="On it — sending by Friday.",
)
print(resp.id, resp.status, resp.quota_remaining)

# Plus-address a per-task inbox for free (no new inbox needed)
addr = plus_address("agent-hello@ujex.dev", task_id="proj-42")

# Verify an inbound webhook
from ujex_postbox.webhook import verify_signature, parse_inbound_event
ok = verify_signature(raw_body=req.body, signature=req.headers["x-ujex-signature"], secret=SECRET)

Framework adapters (install one or more extras):

pip install 'ujex-postbox[langchain]'
pip install 'ujex-postbox[llamaindex]'
pip install 'ujex-postbox[crewai]'

from ujex_postbox.integrations.langchain import postbox_tools
tools = postbox_tools(client, agent_id="agent-hello")
# pass tools to any LangChain agent / graph

Async variant: AsyncPostboxClient.

---

TypeScript — @ujex/client

npm install @ujex/client firebase

import {UjexClient} from '@ujex/client';

const ap = new UjexClient({
  firebase: {
    apiKey: 'AIzaSy...',
    authDomain: 'axy-ujex.firebaseapp.com',
    projectId: 'axy-ujex',
    appId: '1:...:web:...',
  },
  agentId: process.env.AP_AGENT_ID!,
  deviceKey: process.env.AP_DEVICE_KEY!,
});

await ap.connect();

// Send with human approval
await ap.postbox.send({
  to: ['alice@vendor.com'],
  subject: 'hi',
  body: '...',
  requireHuman: true,
});

// Ask a human for approval
const {id} = await ap.mobile.ask({prompt: 'Send $800 invoice to Bob?', ttlSec: 300});

// Write and search durable memory
await ap.memory.write({name: 'alice-invoice', content: 'Alice prefers invoice email on Friday.'});
const hits = await ap.memory.search({query: 'alice invoice preference', k: 5});

Covers the core Ujex loop first: Postbox, Approvals, Audit, and Recall/Memory. Secondary namespaces such as Gateway, Scheduler, Tools, Identity, and Observe are available for advanced deployments.

---

Go — github.com/axysar/ujex/sdks/go/postbox

go get github.com/axysar/ujex/sdks/go/postbox

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/axysar/ujex/sdks/go/postbox"
)

func main() {
	client := postbox.NewClient(postbox.Options{
		DeviceKey: os.Getenv("UJEX_DEVICE_KEY"),
	})
	resp, err := client.Send(context.Background(), postbox.SendParams{
		To:           []string{"alice@vendor.com"},
		Subject:      "Re: invoice",
		Body:         "On it.",
		RequireHuman: true,
	})
	if err != nil {
		if postbox.IsQuotaExceeded(err) {
			// budget used up — wait until next month roll
		}
		panic(err)
	}
	fmt.Println(resp.ID, resp.Status)
}

Stdlib-only. Context-aware retries on 429/5xx with Retry-After respect.

---

CLI — ujex

# npm-global until the Homebrew tap lands
npm install -g @ujex/cli

ujex init <agentId> <deviceKey>
ujex send alice@vendor.com 'Re: invoice' 'On it.'
ujex ask 'Can I send the $800 invoice to Bob?'
ujex search 'promised alice invoice'
ujex mesh sync
ujex whoami

---

MCP server — @ujex/postbox-mcp

Give any MCP client (Claude Desktop, Cursor, Cline, Zed) direct control of an agent's inbox.

Claude Desktop — ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "ujex-postbox": {
      "command": "npx",
      "args": ["-y", "@ujex/postbox-mcp"],
      "env": {
        "UJEX_DEVICE_KEY": "apk_...",
        "UJEX_AGENT_ID": "agent-hello"
      }
    }
  }
}

Six tools become available to the LLM:

Tool	Purpose
postbox_send_email	Send an email. require_human=true blocks on mobile approval.
postbox_list_messages	List recent inbound / outbound messages w/ pi_score.
postbox_read_message	Read a single message + body + auth verdict.
postbox_list_inboxes	Enumerate inboxes.
postbox_create_plus_address	Build a per-task plus-address (local, no network).
postbox_verify_inbound	Timing-safe HMAC check (local).

Plus one resource: postbox://inbox/{agent_id} streams live mailbox snapshots into the LLM's context.

---

OpenAPI 3.1 spec

Machine-readable spec at /openapi.json. Covers the Postbox surface with full request/response schemas, security schemes, example payloads, and error response shapes (401 / 402 / 404 / 429). Use any code generator (openapi-generator-cli, speakeasy, kiota) to produce a client in your language of choice.

---

Which should I pick?

You want…	Use
"Just wire this into LangChain / LlamaIndex / CrewAI"	Python SDK + the matching integration extra
Full Ujex surface, not just Postbox, in a web or Node backend	@ujex/client
A small, boring Go service that sends mail on behalf of an agent	Go SDK
Let me talk to Postbox from Claude Desktop / Cursor	MCP server
Scripting / ops one-liner	CLI
Any other language	OpenAPI spec + a generator

All SDKs are Apache-2.0 and ship their source on GitHub.