Chinese AI startup StepFun has started selling a smartphone with a radical premise: the AI agent is the product, and the apps are just tools it borrows.
The STEPX Neo, launched October 13 according to Decrypt, runs Step AOS 1.0 — an operating system built from scratch around an AI agent called Amoo, which sits in the core software layer rather than in an app icon. Pre-orders opened the same evening at 3,999 yuan, roughly $560, with the first sales event following on October 16.
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An Operating System Built for an Agent
Most AI assistants on phones today, like Siri and Google's Gemini, live inside iOS or Android and reach the rest of the system through narrow, carefully gated interfaces. StepFun's argument, first laid out when it previewed the STEPX brand and operating system in Shanghai in July, is that conventional smartphone software was never designed for autonomous task execution — so the company rebuilt the foundation.
Step AOS 1.0 is described as a hybrid of Android, Linux, and real-time operating system components. It breaks phone functions — messaging, apps, files, settings — into small blocks the agent can call directly, using the Model Context Protocol (MCP), the industry standard for connecting AI programs to external software. Users get two entrances: the familiar app grid, and a separate space where Amoo takes requests.
The base layer carries the features agents need to be trusted with real tasks: long-term memory, task scheduling, and security controls.
Amoo: One Agent, Two Memories
The agent itself is designed around a split-memory architecture. One memory stores what it knows about the user — facts, habits, preferences. A second stores what it has learned about carrying out tasks, like how a particular booking flow works.
Computing is split by difficulty. Simple commands, such as setting an alarm, run on a small model inside the phone — some of them entirely offline. Harder requests that span several apps are handed to a larger model in the cloud. A second MiniLED screen on the back of the phone shows what Amoo is doing, a transparency feature aimed squarely at the trust problem that has dogged agent products.
Instead of opening a ride-hailing app, typing an address, and picking a car class, the owner tells the phone where to go and Amoo handles the remaining steps.
Nearly 100 Partners — Where ByteDance Got Blocked
The partner list is where StepFun's approach faces its real test, and so far it is holding. Nearly 100 companies and services have signed on to Amoo, including Alipay, Tencent, Ctrip, Didi, and Meituan — with payments, travel bookings, and content creation still completed through those platforms' own systems.
That cooperation matters because a rival approach fared far worse. ByteDance's Doubao phone agent, which relied on screen-reading and simulated clicks to operate apps it had no official access to, drew blocks from major Chinese apps in December. StepFun's integration-first model is the direct answer: give the agent sanctioned hooks into services instead of letting it impersonate a user's finger.
The Economics: $560 Up Front, Tokens by the Month
The 3,999-yuan price includes 12 months of the STEPX Token Plan, which provides 100 billion tokens a month of agent usage. StepFun has not said what the AI service will cost after the first year — a detail that will determine whether the device is a loss leader for a subscription, like subsidized consoles, or a one-time purchase that keeps working.
The company behind it is one of China's most closely watched AI startups. StepFun was founded in 2023 by former Microsoft vice president Jiang Daxin and is backed by Tencent. Its flagship Step 5 Preview model, launched in September, is a 600-billion-parameter mixture-of-experts system with 27 billion active parameters and a 1 million-token context window — and the company released its open weights this week, according to MarkTechPost. The smaller Step 3.5 Flash is already open-source under the Apache 2.0 license.
Why It Matters Beyond China
Every major phone maker has spent the past two years bolting AI assistants onto traditional operating systems. The STEPX Neo is the first mainstream-priced device to flip that hierarchy and ship at scale with the agent as the primary interface and the app grid as the fallback.
If Amoo's integration model keeps its partners on board where screen-scraping agents got blocked, expect the pattern to travel: Western platform holders are watching the same dynamics, and the first vendor to offer an agent with sanctioned, protocol-level access to the services users actually pay for will have a genuinely new selling point. StepFun's bet is that the post-app phone is not a concept demo — it is a 3,999-yuan product you can order today.
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