feat(sim): dimsim as connection

[paul-nechifor]

Problem

We need a light-er weight simulator.

Closes DIM-xxx

Solution

• Add the DimSim simulator.
• Add tests which use it.

Breaking Changes

The --simulation flag now takes a parameter: either mujoco or dimsim.

How to Test

Run the apt scene:

uv run dimos --simulation=dimsim run unitree-go2-agentic

Run the empty scene:

uv run dimos --dimsim-scene=empty --simulation=dimsim run unitree-go2-agentic

Run the dimsim tests:

uv run pytest -m dimsim

Contributor License Agreement

• I have read and approved the CLA.

[greptile-apps]

Greptile Summary

This PR introduces DimSim as a new lightweight simulator backend for the Unitree Go2 robot, alongside the MuJoCo simulator, by adding a DimSimConnection adapter, a DimSimProcess launcher (which auto-installs Deno and clones an external repo), a 900-line SceneClient WebSocket SDK for scene manipulation, and a suite of e2e tests. The --simulation CLI flag is changed from a boolean to a string (mujoco or dimsim), which is a breaking change for env-var users.

• New DimSimConnection: Robot connection adapter wiring DimSim to the existing Go2ConnectionProtocol; currently several core streams (odom_stream, lidar_stream, video_stream) are unimplemented stubs, and move() never sends a cmd_vel command to the simulator.
• New DimSimProcess / scene_client.py: Manages the DimSim subprocess and exposes a Python SDK for remote Three.js scene manipulation over WebSocket; thread-safety and lifecycle issues exist in both components.
• Breaking simulation type change: GlobalConfig.simulation was changed from bool to str, silently breaking existing SIMULATION=true environment variable usage.

Confidence Score: 2/5

Not safe to merge: the DimSim backend is non-functional in several core areas that the e2e tests depend on.

The DimSimConnection adapter ships with move() returning True without publishing any cmd_vel command, and all three data streams (odom_stream, lidar_stream, video_stream) are silent Subjects that never receive data. The e2e walk-forward test will always time out because wait_until_odom_position listens to /odom LCM messages that _handle_odom never forwards to the Subject. The SceneClient recv loop can crash permanently on a late exec result after a timeout. Together these issues mean the primary tested feature cannot work end-to-end as written.

dimos/robot/unitree/dimsim_connection.py (move() stub, silent streams), dimos/simulation/dimsim/scene_client.py (_recv_loop crash, WS send race), dimos/simulation/dimsim/dimsim_process.py (personal fork URL, partial clone recovery, stop/log-reader race)

Important Files Changed

Filename	Overview
dimos/robot/unitree/dimsim_connection.py	New DimSim connection adapter: core streams (odom, lidar, video) are silent stubs, move() never sends cmd_vel, and functools.cache on instance methods causes memory leaks and incorrect cache_clear() scope.
dimos/simulation/dimsim/dimsim_process.py	DimSim subprocess launcher: repo URL points to a personal fork, stop() closes stderr while log-reader thread iterates it, partial clone leaves repo in a broken state, ensure_playwright_chromium runs unconditionally on every start().
dimos/simulation/dimsim/scene_client.py	SceneClient WebSocket SDK: _recv_loop crashes permanently on KeyError after exec() timeout, self._ws.send() races with stop(), {name} interpolated directly into JS error strings allowing injection, set_embodiment/set_agent_position lack null-check on self._ws.
dimos/simulation/dimsim/deno_utils.py	Deno auto-installer: handles platform detection and safe atomic write; ensure_playwright_chromium runs unconditionally with no timeout.
dimos/e2e_tests/dim_sim_client.py	Test helper: stop() unconditionally invokes the lazy self.client property which creates and connects a new SceneClient when _client is None, hanging teardown if DimSim isn't running.
dimos/core/global_config.py	simulation field changed from bool to str; silently breaks SIMULATION=true/false env var users who will now get connection_type="true" and hit an assertion failure.
dimos/e2e_tests/test_dimsim_walk_forward.py	E2e test that relies on odom_stream() (currently a silent stub) and move() (currently a no-op); the odom position assertion will never be satisfied.
dimos/msgs/sensor_msgs/CameraInfo.py	New from_fov() and from_intrinsics() factory methods are clean and correct; simplifies camera info construction across all simulators.
dimos/robot/unitree/go2/connection.py	Adds dimsim branch to make_connection() factory and refactors camera info construction to use new from_intrinsics(); straightforward change.

_{Reviews (19): Last reviewed commit: "remove 3.15" | Re-trigger Greptile}

[codecov]

Codecov Report

❌ Patch coverage is 25.83979% with 287 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
dimos/simulation/dimsim/scene_client.py	15.57%	168 Missing ⚠️
dimos/e2e_tests/conftest.py	14.54%	47 Missing ⚠️
dimos/e2e_tests/test_dimsim_path_replaning.py	16.66%	15 Missing ⚠️
dimos/e2e_tests/dim_sim_client.py	52.00%	12 Missing ⚠️
dimos/e2e_tests/test_dimsim_walk_forward.py	30.00%	7 Missing ⚠️
dimos/e2e_tests/test_dimsim_spatial_memory.py	33.33%	6 Missing ⚠️
dimos/agents/skills/person_follow.py	0.00%	5 Missing ⚠️
dimos/conftest.py	44.44%	4 Missing and 1 partial ⚠️
dimos/e2e_tests/lcm_spy.py	33.33%	4 Missing ⚠️
...imos/experimental/security_demo/security_module.py	20.00%	4 Missing ⚠️
... and 8 more

📢 Thoughts on this report? Let us know!

[leshy]

I have no notes on this apart from LCM, can fix in the followup, amazing!