dsh-web-lan-access

LAN / remote access support for the DeepSeek Harness Web UI.

The problem

The Web UI calls crypto.randomUUID() in boot-critical paths (RPC id minting, message ids, draft attachments). That Web API exists only in secure contexts (HTTPS, or http://localhost / http://127.0.0.1). When the UI is served over plain HTTP from a non-loopback address — a LAN IP, a Tailscale IP, or a hostname — crypto.randomUUID is undefined, every RPC throws, and sessions and models never render.

The fix

A host-side plugin that uses the webserver's official index-tap extension point (webServer.tapIndex) to inject a small polyfill (RFC 4122 v4 built on crypto.getRandomValues, which is available on insecure origins) as the first script in <head>, before the boot manifest and the shell entry. On secure origins the polyfill is a no-op.

No product source modified; fully reversible
Version-independent (it only transforms the served index.html)
Platform-independent (Linux / macOS / Windows / Android)

Install

Bundle install (recommended)

Installed from npm:

dsh plugin --profile web add dsh-web-lan-access

(No npm / local development — point pnpm at the repo instead:

dsh plugin --profile web add github:AcidGr/dsh-web-lan-access

)

Restart dsh web, then hard-refresh the browser.

Manual install (no pnpm / offline)

PROFILE="$DSH_HOME/profiles/web"                 # adjust DSH_HOME and profile name
mkdir -p "$PROFILE/plugins" "$PROFILE/node_modules/@dsh-profile"
cp -r dsh-web-lan-access "$PROFILE/plugins/lan-access"
ln -sfn ../../plugins/lan-access "$PROFILE/node_modules/@dsh-profile/lan-access"
# append to $PROFILE/cordis.patch.yml:
#   - insert:
#       - id: lan-access
#         name: '@dsh-profile/lan-access'

Usage

The plugin is self-contained: its bundle patch sets the webserver bind host to 0.0.0.0 directly (the CLI flag --host 0.0.0.0 is hard-rejected for safety on newer harness versions, but the webserver config still accepts it — so no source changes and no --host flag are needed; the CLI --port flag still works).

Install the plugin, then start normally — without --host:
```
dsh --profile web --port 3080
```
When bound to 0.0.0.0, the harness automatically adds every local non-internal IPv4 to the /api trust fence (resolveLanTrust) — LAN IP access needs no extra config.

If you prefer NOT to let the plugin take over the bind host (e.g. you want loopback + a port forward), keep the webserver row override out of your tree and instead forward a port (socat / rinetd / Tailscale serve) from 127.0.0.1:3080, adding the forwarded address to trustedHosts manually.
Domains / remote (e.g. Tailscale) — add your own authorities to trustedHosts:
```
- id: web-runtime
  config:
    trustedHosts:
      - <short-name>            # e.g. myhost — MUST be listed separately!
      - <name>.tailXXXX.ts.net  # full domain
      - 100.x.x.x               # tailnet IP
```
⚠️ The fence compares the Host header literally: a MagicDNS short name (http://myhost:3080) is not the full domain — list the short name on its own line, or every /api call returns 403 (page shell loads, sessions/models absent).

Known limitation: privileged API methods

On unmodified harness builds, a small set of sensitive API methods (settings.*, credentials.*, llm.discoverModels) is pinned to loopback regardless of trustedHosts (isTrustedApiRequest(request, []) in packages/client/connection/src/index.ts). From a remote origin those calls return 403: chat/sessions/models still work, but the Settings pages (including the plugin-config cards) and credentials UI show empty/errors. The polyfill cannot change that — it is a product-side policy. A one-line upstream change (isTrustedApiRequest(request, trustedHosts)) makes them follow the deployment's trusted hosts; until then, edit that line locally or manage those settings from http://127.0.0.1:3080.

Verify

curl http://127.0.0.1:3080/ | grep lan-access-polyfill   # must match

Then open http://<server-ip>:3080 from another device — sessions and models must load.

Security warning

Binding 0.0.0.0 makes the agent reachable without authentication by anyone on the same network (/api is an origin fence, not a login). On a server with a public IP this means the whole internet. Use only on trusted networks, restrict with a firewall (e.g. ufw allow from 192.168.0.0/16), or expose through Tailscale / an authenticated reverse proxy instead. A TLS reverse proxy also removes the need for this polyfill entirely.

Rollback

Bundle install: dsh plugin --profile web remove dsh-web-lan-access
Manual install: delete the lan-access insert block from cordis.patch.yml; optionally start without --host 0.0.0.0

License

MIT

dsh-web-lan-access

dsh-web-lan-access

The problem

The fix

Install

Bundle install (recommended)

Manual install (no pnpm / offline)

Usage

Known limitation: privileged API methods

Verify

Security warning

Rollback

License

Community comments