# Streaming a desktop agent to your phone with zero npm dependencies

> Source: <https://dev.to/joey020907/streaming-a-desktop-agent-to-your-phone-with-zero-npm-dependencies-3728>
> Published: 2026-08-16 07:05:08+00:00

One WebSocket, one Node process, one HTML file. Here's the architecture behind DeepSeek Phone Harness, and the three decisions that made it work.

Last weekend I built [DeepSeek Phone Harness](https://github.com/2903077918-lgtm/DeepSeek-phone-harness) — a mobile remote for DeepSeek Harness. The constraint I set myself: **zero npm dependencies**. Not because I'm a purist, but because a tool like this should be "clone and run," not "install 47 packages and hope."

Here's the architecture that made it work.

```
Phone browser (relay.html)
   │  HTTPS / Tailscale
   ▼
Agent (Node, :8788)  ── http server + static page + WS relay
   │ 127.0.0.1:3080
   ▼
DeepSeek Harness gateway (dsh web)
```

The Agent is a translator, not a replacement: it speaks REST to the phone and RPC to DSH.

DSH exposes `events.mux`

— a WebSocket stream carrying approvals, questions, and session events in one pipe. Instead of opening one connection per concern, I keep **one persistent connection** and route frames locally:

| Frame | Goes to |
|---|---|
`approval/requested` |
pending table → phone approval cards |
`question/requested` |
pending table → phone answer cards |
`session/event` |
ring buffer (200/session) → phone stream polling |

The phone polls `/api/events?afterSeq=N`

— each poll returns only new bytes, which keeps 4G streaming smooth.

The single most important bug I fixed: DSH agents call `ask_user_question`

through a **separate channel** from approvals. If you only listen for `approval/requested`

, the moment the agent asks something the task deadlocks *forever* — it's waiting for a human answer that the phone never shows.

The answer protocol had to match the Web GUI exactly:

```
{ "ok": true, "value": { "sessionId": "...", "answer": { "answers": [{ "id": "q1", "selected": ["..."] }] } } }
```

Every `tool/call`

event creates a tool card (name, icon, status, **file path extracted from arguments**). Every `tool/result`

pairs back by `callId`

and flips the card to done/failed. Tapping expands the full arguments and result.

One trap: DSH's `tool/result`

content is **double-nested** (`content[].content[].text`

) — my first version read one level too shallow and results came back empty. Lesson: capture a real payload before trusting any schema.

`relay.html`

)"Phone remote for a desktop agent" sounds like it needs a platform team. It doesn't. The barrier to entry for this whole category just collapsed — **anyone with Node 22+ can build or extend one in a weekend.**

The code is open (MIT):

Questions about the architecture? Happy to go deeper in the comments.