dsh-lanmode

Open the DeepSeek Harness Web UI from another device — a phone, a tablet, the laptop on the other side of the room — and have all of it work, including the parts the UI switches off when the page is not localhost.

Works whether you put a reverse proxy in front of the harness or let this plugin serve the network itself. Pick a mode, restart, done.

What breaks without it

Reach the UI at a LAN address and you get some mix of:

• Settings → Models: settings are unavailable in this browser
• Settings → Plugins → Plugin configuration: empty, no cards at all
• every plugin's settings card: blank, and saving silently does nothing
• on plain HTTP, nothing loads at all: sessions and models never render

None of that is the server refusing. The server serves settings over the network perfectly well.

Why it happens

Two independent things.

The settings service turns itself off. The UI decides from the page's hostname:

isLoopback: pageLocation === undefined || isLoopbackHostname(hostname)

isLoopbackHostname accepts localhost, [::1] and 127.0.0.0/8, nothing else. Anything else puts the settings service into a process-local mode where the shared mirror of the settings document is never read, every namespace reports status: "unavailable" for the life of the page, and writes are dropped before they reach the wire.

Some Web APIs only exist on a secure context. crypto.randomUUID is called on boot-critical paths, and navigator.clipboard behind the copy buttons. Over plain HTTP from a LAN address the browser withholds both.

What the plugin does

Everything happens through the web server's official index tap: one script is injected into index.html ahead of the boot manifest. No product source is modified, and removing the plugin restores the page exactly.

Piece	Setting	What it does
Settings	settings	Hands every package a connection whose isLoopback reads true. The shared mirror, every namespace scope, the core's own pages and every plugin's settings section then behave as they do on localhost.
crypto.randomUUID	randomUuid	Provides an RFC 4122 v4 implementation over crypto.getRandomValues, which insecure origins do have. A no-op where the real one exists.
navigator.clipboard	clipboard	Provides a writeText fallback so the copy buttons keep working. A no-op where the real one exists.

One package is excluded on purpose: deliverables, where the flag decides whether a produced file may be opened locally. Forcing it there would ask the Host to open paths on the server's desktop. Nothing else in the web UI reads the flag.

The exclusion list replaced an allow list, and the reason is worth writing down. A namespace scope is bound like this:

bind(spec) {
  const ctx = this.ctx                      // the caller's context
  const connection = ctx.get('connection')
  ... connection.isLoopback ? 'host' : 'memory'
}

this.ctx belongs to whichever plugin calls bind, not to the settings package. Handing the substitute to the settings packages alone therefore fixed the shared mirror and the core's own pages, while every plugin's own settings section still went to memory mode and reported that the harness had not announced its settings.

Two modes

- id: dsh-lanmode
  config:
    mode: proxy        # proxy | direct | auto

proxy (default) — something already listens on the network in front of the harness: nginx, Caddy, Tailscale serve, an SSH tunnel. The plugin only repairs the page and touches nothing else. This is the safe default: it cannot collide with whatever you already run.

direct — no proxy anywhere. The plugin opens a listener of its own and forwards to the harness, rewriting Host and Origin to the loopback authority so the harness's same-origin fence is satisfied:

- id: dsh-lanmode
  config:
    mode: direct
    directHost: '0.0.0.0'   # every interface
    directPort: 3088

Then open http://<the machine's IP>:3088 from any device on the network.

A listener rather than rebinding the harness itself, for two reasons: a bind host lives in the config tree and cannot be a switch inside the plugin, and rebinding to 0.0.0.0 collides with a reverse proxy already holding that port.

auto — work it out. The plugin knocks on this machine's own network addresses at the harness port: the harness itself listens on loopback only, so anything answering there is a proxy, and the mode is proxy. When nothing answers and the direct port is free, it is direct. When it cannot tell — no addresses, no known port, a probe that errored — it picks proxy and opens nothing: an unnecessary listener on a network address is an open door, and one is not opened on a guess.

What auto cannot see is a proxy sitting on a different port. From outside that is indistinguishable from nobody being there, and the plugin would open its own listener beside it. Set the mode by hand in that case.

The decision is logged with its reason and shown on the diagnostics page.

Changing the mode takes effect on restart.

HTTPS, and the microphone

This is the one thing no substitution can repair. A browser hands out navigator.mediaDevices only over a secure connection, and behind it is a real device — there is nothing to fake. Over plain HTTP on a network address, voice input is impossible in principle.

So the direct-mode listener can speak HTTPS:

- id: dsh-lanmode
  config:
    mode: direct
    tls: self-signed     # off | self-signed | files

self-signed — the plugin issues a certificate itself and keeps it in tlsDir (by default a folder next to the harness data). It goes into the certificate with every address this machine answers on, plus anything in tlsHosts: a certificate issued for one name is refused for every other, even after it has been accepted once. It is reissued when it is about to expire or when a new address appears. The fingerprint is printed to the log at startup — compare it in the browser instead of accepting blindly.

Issuing needs openssl on the machine. Without it the plugin says so plainly and falls back to plain HTTP rather than pretending everything is fine.

files — your own certificate:

    tls: files
    tlsCert: /path/to/cert.pem
    tlsKey: /path/to/key.pem

A self-signed certificate is a compromise, not a solution: the browser will still ask. But it turns "impossible" into "confirm once", and that is the whole difference between voice input working over the network and not.

Replacing a reverse proxy

Direct mode is meant to be the whole answer: install the plugin, set two fields, switch the proxy off. What a reverse proxy in front of the harness has to do, the bridge does — rewrite Host and Origin so the same-origin fence passes, carry WebSockets, keep long-lived streams alive, terminate TLS.

Moving over without anyone noticing. Keep the address, the port and the certificate the browsers have already accepted:

- id: dsh-lanmode
  config:
    mode: direct
    directPort: 3080          # the port the proxy served on
    tls: files
    tlsCert: /path/to/your/existing/fullchain.pem
    tlsKey: /path/to/your/existing/key.pem
    unlockPrivileged: true
    allow:
      - 192.168.0.0/16

Then stop the proxy. Nothing changes for anyone: same URL, same certificate, no second confirmation.

The harness already holds that port on the loopback, so directHost is left alone: the plugin notices the clash and binds this machine's network addresses by name instead of binding everything. It says so in the log.

Starting from nothing. No proxy, no certificate:

- id: dsh-lanmode
  config:
    mode: direct
    directPort: 3088
    tls: self-signed
    unlockPrivileged: true
    allow:
      - 192.168.0.0/16

The browser asks once about the certificate; compare the fingerprint printed in the log and accept it.

What you lose compared with a real proxy. Not much, and it is worth naming: no HTTP/2, no gzip, no request logging beyond refusals, no rate limiting, no virtual hosts. If you need any of those, keep the proxy — the plugin does not mind sitting behind one, and that is exactly what proxy mode is.

What you do not lose. Settings and credentials over the network, WebSockets, streamed replies of any length, TLS, the microphone.

Check after switching, in this order: the conversation opens and a reply streams to the end; settings open and save; a long reply is not cut; the microphone works on /dsh-lanmode/health.

Who may connect

The direct listener has no password and will not get one: the plugin does not intercept anyone else's routes, and inventing its own way into the harness is not its business. But between "no password" and "anyone on the network" there is room:

- id: dsh-lanmode
  config:
    mode: direct
    allow:
      - 192.168.1.0/24
      - 10.0.0.5

Addresses and CIDR ranges, IPv4 and IPv6. An empty list means everyone, which is how the plugin behaves until you fill it in. Refused connections are logged, at a limited rate so a scanner cannot drown the log.

Two honest limits. This is not authentication: whoever is on the list gets in unchecked. And behind a reverse proxy it means nothing — every request arrives from the proxy, so filter there instead.

The price of it working

The harness pins its privileged calls — settings, credentials, agent presets, opening paths on the machine, model discovery — to the loopback on purpose, and no trusted-host list opens them. The bridge presents itself as a loopback client, so those calls go through. That is not a side effect: without it a page on the network shows the settings and can neither read nor write them, which is the whole reason this plugin exists.

The price, stated plainly: any device that reaches this port can read and change your API keys, with no authentication at all. Nothing here asks who you are.

It is a setting, not a secret:

    unlockPrivileged: false   # settings over the network stop working

Off, the privileged calls are refused by the bridge with a message saying why, and everything else keeps working. On — which is the default, because otherwise the plugin does not do its job — the log says at startup exactly what is open, and the diagnostics page shows it as a separate line.

Fill in allow either way. It is not authentication, but it narrows the circle from «the whole network» to «these addresses».

Diagnostics

GET /dsh-lanmode/health — one page answering the questions that otherwise take half an hour: which mode is on and why, what is patched, whether the browser considers the connection secure, and why the microphone is silent. Add ?format=json for the same data in a form you can paste into a bug report.

Half the answers can only come from the browser — a secure connection and a microphone exist nowhere else — so the page checks those in the browser that opened it.

Nothing secret is on that page: it is open to anyone who reached the harness. Turn it off with diagnostics: false.

When the harness changes underneath

The plugin holds on to the harness's internals: the index tap, the name of the package the substitution must leave alone, the shape of the connection object. An upgrade can move any of them, and a plugin that repairs someone else's behaviour must not fail quietly — that already happened once, and it took days of confusing symptoms to notice.

So at startup it checks its own assumptions and says what it found: one line when everything is in place, a loud complaint naming what moved when it is not. The same list is on the diagnostics page.

Settings

All of it can be edited as the dsh-lanmode namespace — in $DSH_HOME/settings.yaml, or from the UI once the settings pages work.

Setting	Default	Meaning
mode	proxy	proxy, direct or auto
directHost	0.0.0.0	direct: which address to listen on
directPort	3088	direct: which port to listen on
tls	off	direct: off, self-signed or files — what the microphone hangs on
tlsDir	—	self-signed: where the issued certificate is kept
tlsHosts	[]	self-signed: extra names and addresses for the certificate
tlsCert	—	files: path to the certificate in PEM
tlsKey	—	files: path to the private key in PEM
allow	[]	direct: addresses and CIDR ranges allowed in. Empty means everyone
unlockPrivileged	true	direct: let the settings and credentials calls through. What makes the plugin work, and what opens your keys to the network
privilegedExtra	[]	direct: extra path patterns to treat as privileged
streamTimeoutMs	0	direct: limit on one request. Zero means none, and that is what long replies need
diagnostics	true	serve GET /dsh-lanmode/health
settings	true	return the settings service
randomUuid	true	provide crypto.randomUUID on plain HTTP
clipboard	true	provide a clipboard fallback on plain HTTP

Checking it

• ?lanmode=invert — report the loopback flag as false even on localhost. The harness then fails exactly the way it does over the LAN; this is how the plugin is verified.
• ?lanmode=off — stand the plugin down entirely, to see the page as it would be without it.

On a loopback page the plugin substitutes true where the real value is already true, so it cannot change behaviour there.

What it is not

Not authentication. It adds no password and does not widen what the server accepts — the harness answers those same calls with or without it. direct mode does make the harness reachable by anyone who can reach that port, exactly as a reverse proxy would. If other people share your network, put a real gate in front of the harness. A plugin cannot do that job: the web server hands plugins their own routes and no way to intercept anyone else's.

No microphone over plain HTTP. Browsers withhold navigator.mediaDevices outside a secure context, so voice input plugins stop working on a plain-HTTP LAN address. Nothing can polyfill that. If you need the microphone, keep HTTPS in front and use proxy mode.

Install

dsh plugin --profile web add @goodandready/dsh-lanmode

Restart the harness, then reload the browser.

License

MIT