Most “AI phones” still mean a voice assistant bolted onto a conventional app grid. STEPX Neo, from 阶跃终端 / STEPX under model lab 阶跃星辰 (StepFun), is framed differently. Chairman 印奇 (Yin Qi) and Chinese launch coverage describe it as a large-model-native agent phone (先行版): the primary surface after unlock is the agent, and apps are the fallback. That architectural bet — agent UI first, MCP as the main tool contract, tokens bundled into the sticker price — is what makes the device interesting to overseas engineers and PMs, even if you cannot buy one outside China today.
What ¥3999 actually buys
Coverage is consistent that ¥3999 is not a hardware-only SKU. The stack includes the phone, Step AOS 1.0, Step Studio (a natural-language IDE for AI apps, games, agents, and skills), and access to Step series models, plus a continuous 12-month STEPX Token Plan at 10 billion tokens per month (每月百亿). Pre-sale opened Oct 13 at 21:00; general sale on JD, Tmall, and Douyin started Oct 16 at 10:13. Colors reported: 碳黑 (carbon black) and 硅银 (silicon silver).
Hardware roundups put a Snapdragon 8 Gen 5 behind 16GB+256GB, a 6.36" OLED around 2670×1200 at 120Hz, ultrasonic fingerprint, and an independent AI side button. Camera kit: 32MP front; rear 50MP main with OIS plus 8MP ultrawide. Chinese hardware pieces also list a 6260mAh battery with 80W wired charging — attribute those figures to the roundups, not an independent tear-down.
No confirmed global SKU. Retail is China channels (JD / Tmall / Douyin) at ¥3999 ≈ $560. Agent services, Alipay-linked partners, and the token plan assume a China account stack. Treat overseas use as speculative gray-import territory, not a supported product.
What the ¥3999 stack claims to include. Asterisked items (battery, always-on listen draw, dual-domain recall latency, partner counts) are vendor or press claims.
Agent-native OS, not an AI skin
Step AOS 1.0 is described as agent-native. An English AsiaICT writeup soft-attributes a rework across Android / Linux / RTOS layers; Chinese coverage focuses on the dual entry model: unlock lands in the 阶跃 Amoo agent UI, while a swipe returns you to a classic app home. That split is the product thesis — the phone can still behave like a phone, but the default contract is “talk to an agent that holds tools,” not “open an app that maybe embeds a model.”
Amoo’s tool path is reported as MCP first, with GUI automation as fallback, plus A2A and atomic system capabilities (camera, payments hooks, etc.). Launch coverage claims on the order of ~100 partners and Alipay 300+ services — press numbers, not audited catalogs. Memory is dual-domain (user vs agent) with fast-recall claims around ~15 ms in 钛媒体 reporting; again, vendor/press, not independent measurement.
The rear of the phone carries a MiniLED dot-matrix window used as Amoo’s status / expression surface — a second screen that makes the agent’s state visible without waking the main OLED. Audio is a 6-mic array plus a low-power audio chip and Whisper 1.0 pick-up; StepFun claims the always-on listen path draws about 1.2% battery over 24 hours — a vendor claim.
Why MCP on a phone matters
For people already wiring agents with the Model Context Protocol, a handset that treats MCP as the primary app contract is a different product category from “Gemini in the assistant” or “Copilot key.” Skills and services become portable tool definitions rather than deep links into proprietary assistant plugins. Step Studio pushes the same idea upward: natural-language authoring of AI apps/games/agents/skills with MCP/A2A outward. Whether the China partner graph is useful to a foreign developer is a separate question — the interesting signal is the pricing shape: tokens are not an afterthought subscription; they are baked into the device economics for a year at a stated 10B/month ceiling.
Growth offer and honest caveats
Marketing also floats a “星辰船票” program: the first 10,000 qualifying users get a 5-year 0-yuan swap to future STEPX devices. Read the fine print before treating that as a guaranteed upgrade path.
- China-only retail — no confirmed international SKU or global Play/App distribution story.
- Vendor / press claims — battery capacity and charge rate, always-on listen draw, dual-domain ~15 ms recall, partner and Alipay service counts come from Chinese coverage and vendor framing; not third-party audited here.
- OS internals — “Android/Linux/RTOS rework” is soft-attributed via English AsiaICT context; treat as directional, not a verified kernel tree.
- Token plan terms — 12 months continuous at 10B/month for buyers; overage, transferability, and renewal after year one are not independently confirmed in the sources below.
- MCP ecosystem lock-in — primary tools will skew toward China partners and Alipay-linked services; overseas engineers should assume limited cross-border usefulness until proven otherwise.
Bottom line: STEPX Neo is one of the clearest China-market attempts to sell a phone as an agent runtime with a token meter, not as a flagship that happens to ship an assistant. If you care about MCP-first device contracts and bundled inference economics, the product shape is worth watching — even while availability stays China retail and several headline numbers remain press claims.