dimos/web: LCM<->WebSocket bridge + Babylon operator console

[Nabla7]

Extracts the sim viewer's browser stack into dimos/web so it works with any blueprint:

• dimos/web/lcm_bridge — subscribe-all LCM<->WebSocket bridge; browser code is
  just another bus peer (@dimos/msgs decodes the same bytes). Latest-wins buffering
  • per-channel rate caps, tested both directions over a real socket.
• dimos/web/viewer — the Babylon operator console: scene mesh/splat, robot via
  server-side FK, pointclouds (web worker), nav path, camera, WASD teleop,
  click-to-nav. Renders only, owns no state — the browser-physics/entity-authority
  half stays in the sim tree; entity mirroring is a documented stub in app.js.
• Wired into the G1 sim blueprint. On by default in sim, DIMOS_ENABLE_BABYLON=0 kills it.

Try it:

dimos --transport lcm --simulation mujoco --scene-package dimos_office run unitree-g1-groot-wbc

Console on :8091. Focus Robot, Enable Drive, WASD walks the G1; the Lidar layer streams /global_map.

--transport lcm matters: the bridge doesn't tap zenoh yet (follow-up: a zenoh
subscribe-all tap — same payload bytes, same browser framing, only the tap changes).
Server-level QoS only, LAN trust. Details in the package READMEs.

Diff is +5.2k/-0, but ~3.4k is the console frontend ported from the sim viewer;
new Python is ~1.6k (bridge, module, FK helpers, tests). Only existing file
touched: the G1 blueprint (+60 lines).

Input for #2710 / #2708 / #2502 — the local "bridge as a DimOS module" case,
alongside hosted teleop (#2745) covering the internet case.

[greptile-apps]

Greptile Summary

This PR adds a browser operator console and an LCM WebSocket bridge. The main changes are:

• New subscribe-all LCM to WebSocket bridge with browser client helpers.
• New Babylon viewer server with robot FK, assets, pointclouds, camera, path, and teleop UI.
• G1 MuJoCo blueprint wiring that launches the viewer by default in sim.
• Web extra dependency updates and bridge integration tests.

Confidence Score: 4/5

The bridge publish path needs a fix before merging.

• Browser clients can republish arbitrary LCM channels through /lcm-ws.
• The viewer starts this bridge in the sim path and exposes command publishing.
• The main viewer data contracts look consistent from the changed code.

dimos/web/lcm_bridge/bridge.py

Security Review

The new WebSocket bridge allows unauthenticated clients to republish arbitrary LCM packets to the bus. This exposes command channels such as /cmd_vel to any host that can reach the bridge listener.

Important Files Changed

Filename	Overview
dimos/web/lcm_bridge/bridge.py	Adds the core LCM subscribe-all bridge, with a publish-side channel control gap and a small cross-thread client-state race.
dimos/web/lcm_bridge/module.py	Adds the standalone bridge server and status/static routes.
dimos/web/viewer/module.py	Adds the Babylon viewer server, asset/config routes, embedded bridge, and robot-pose websocket stream.
dimos/web/viewer/static/app.js	Adds the browser console UI, LCM subscriptions, teleop publishing, and rendering paths.
dimos/robot/unitree/g1/blueprints/basic/unitree_g1_groot_wbc.py	Wires the Babylon viewer into the G1 MuJoCo blueprint with environment toggles.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  Browser[Browser console] -->|LC02 packets over /lcm-ws| Bridge[LcmWebSocketBridge]
  Bridge -->|publish_packet| LCM[(LCM bus)]
  LCM -->|subscribe-all| Bridge
  Bridge -->|filtered/rate-capped packets| Browser
  Sim[G1 sim modules] -->|joint_state / odom| Viewer[BabylonViewerModule]
  Viewer -->|robot pose over /ws| Browser

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart LR
  Browser[Browser console] -->|LC02 packets over /lcm-ws| Bridge[LcmWebSocketBridge]
  Bridge -->|publish_packet| LCM[(LCM bus)]
  LCM -->|subscribe-all| Bridge
  Bridge -->|filtered/rate-capped packets| Browser
  Sim[G1 sim modules] -->|joint_state / odom| Viewer[BabylonViewerModule]
  Viewer -->|robot pose over /ws| Browser

Loading

_{Reviews (1): Last reviewed commit: "refactor(web): strip authority/physics f..." | Re-trigger Greptile}

[greptile-apps]

Arbitrary Bus Publish Path

Any client that can reach /lcm-ws can send a valid LC02 frame for any channel, and this line republishes it without a publish allowlist or blocklist. Since the new servers bind on all interfaces and the viewer uses this path for /cmd_vel, a LAN browser can inject actuator or control messages beyond the console topics.

[greptile-apps]

Cross-Thread Client Gate

The LCM reader thread checks _clients while websocket connect and disconnect mutate it on the Starlette loop. A bus message that arrives during the first client accept can see the set as empty and return before scheduling _enqueue, so the newly connected browser can miss its first update even though the loop-side enqueue path would otherwise handle the client safely.