[vibed experiment] Add Rust language interop example

[leshy]

Summary

• Adds a Rust example to examples/language-interop/rust/ matching the existing C++, Lua, and TypeScript examples
• Implements a minimal pure-Rust LCM UDP multicast transport (~100 lines, no system LCM library needed)
• Subscribes to /odom (PoseStamped) and publishes /cmd_vel (Twist) at 10 Hz
• Uses generated Rust message types from dimos-lcm#20 (rust-codegen branch)

Dependencies

• lcm-msgs git dependency from dimos-lcm rust-codegen branch — once that PR merges, update to main
• byteorder and socket2 from crates.io (no system deps)

Test plan

• cargo check passes
• cargo build --release passes
• cargo clippy passes with no warnings
• End-to-end test with simplerobot (requires running robot instance)

🤖 Generated with Claude Code

[leshy]

Non-interactive Rust LCM interop test results

Added automated tests to the rust-codegen branch of dimos-lcm (commit d188578):

7 roundtrip/binary tests (generated/rust_lcm_msgs/tests/roundtrip.rs):

• Vector3, Twist, PoseStamped encode/decode roundtrips
• Fingerprint consistency (same struct → same first 8 bytes)
• Corruption detection (flipped fingerprint byte → Err)
• Exact binary layout verification (known byte values for Vector3{1.5, 2.5, 3.5} and Twist fingerprint)

4 UDP multicast pubsub tests (tools/rust/lcm/tests/loopback.rs):

• try_recv returns None on empty channel
• Typed publish+receive for Vector3 and Twist (bounded retries, no manual steps)
• Raw byte round-trip

All 11 tests pass. No external services, no interactive steps.

A few non-blocking observations for the PR author:

1. transport.rs: stack-allocates 64 KB per try_recv call — could pre-allocate as a struct field
2. transport.rs: publish heap-allocates a Vec per message — same fix applies
3. encode_one/decode_one: consider pub(crate) visibility to prevent fingerprint bypass
4. encode_one currently panics on I/O error — returning io::Result<()> would be more idiomatic
5. encoded_size() excludes the 8-byte fingerprint header — worth a doc comment to clarify

None of these block the PR.

[leshy]

Non-interactive language interop tests added

Following the request to add non-interactive tests for Rust and other languages, the following test files were added to examples/language-interop/tests/:

Wire compatibility tests (test_wire_compat.py) — pure Python, no build tools needed:

• 6 tests verifying LCM message byte layout matches known values for Vector3, Twist, PoseStamped
• Cross-language compat: Python-encoded bytes checked against Rust-expected values

Subprocess integration tests (skip gracefully if toolchain absent):

• test_rust_interop.py — runs cargo build + Rust binary, checks pose subscription and twist publication
• test_ts_interop.py — runs Deno TypeScript example
• test_cpp_interop.py — runs cmake build + C++ example
• test_lua_interop.py — runs Lua example

All integration tests use @pytest.mark.interop, skip if toolchain not found, and respect CI_NO_MULTICAST=1 env var.

Run wire-only tests with no dependencies: pytest examples/language-interop/tests/test_wire_compat.py --import-mode=importlib

[paul-nechifor]

Should be marked with slow

[paul-nechifor]

Should be marked with slow.

[paul-nechifor]

Two of the tests fail for me:

_________________________________________________________________________________________ test_cpp_receives_pose_and_publishes_twist __________________________________________________________________________________________

simplerobot = <Popen: returncode: None args: ['/home/p/pro/dimensional/dimos/.venv/bin/pyt...>, cpp_binary = PosixPath('/home/p/pro/dimensional/dimos/examples/language-interop/cpp/build/robot_control')

    def test_cpp_receives_pose_and_publishes_twist(
        simplerobot: subprocess.Popen[str],
        cpp_binary: Path,
    ) -> None:
        """Run the C++ binary for a few seconds and verify message exchange."""
        try:
            result = subprocess.run(
                [str(cpp_binary)],
                capture_output=True,
                text=True,
                timeout=5,
            )
        except subprocess.TimeoutExpired as e:
            stdout = e.stdout or ""
            stderr = e.stderr or ""
        else:
            stdout = result.stdout
            stderr = result.stderr
    
>       assert "[pose]" in stdout, (
            f"C++ binary never received a PoseStamped.\nstdout: {stdout!r}\nstderr: {stderr!r}"
        )
E       TypeError: a bytes-like object is required, not 'str'

examples/language-interop/tests/test_cpp_interop.py:46: TypeError
__________________________________________________________________________________________ test_ts_receives_pose_and_publishes_twist __________________________________________________________________________________________

simplerobot = <Popen: returncode: None args: ['/home/p/pro/dimensional/dimos/.venv/bin/pyt...>, deno_available = None

    def test_ts_receives_pose_and_publishes_twist(
        simplerobot: subprocess.Popen[str],
        deno_available: None,
    ) -> None:
        """Run the Deno TS script for a few seconds and verify message exchange."""
        try:
            result = subprocess.run(
                ["deno", "run", "--allow-net", "--unstable-net", str(TS_DIR / "main.ts")],
                capture_output=True,
                text=True,
                timeout=5,
                cwd=str(TS_DIR),
            )
        except subprocess.TimeoutExpired as e:
            stdout = e.stdout or ""
            stderr = e.stderr or ""
        else:
            stdout = result.stdout
            stderr = result.stderr
    
>       assert "[pose]" in stdout, (
            f"TS script never received a PoseStamped.\nstdout: {stdout!r}\nstderr: {stderr!r}"
        )
E       TypeError: a bytes-like object is required, not 'str'

examples/language-interop/tests/test_ts_interop.py:55: TypeError
=================================================================================================== short test summary info ===================================================================================================
SKIPPED [1] examples/language-interop/tests/test_lua_interop.py:35: lua not found on PATH
FAILED examples/language-interop/tests/test_cpp_interop.py::test_cpp_receives_pose_and_publishes_twist - TypeError: a bytes-like object is required, not 'str'
FAILED examples/language-interop/tests/test_ts_interop.py::test_ts_receives_pose_and_publishes_twist - TypeError: a bytes-like object is required, not 'str'

[paul-nechifor]

What is the use for this interop mark?

[paul-nechifor]

Please delete.

[paul-nechifor]

@leshy These commits have Claude as a co-author... not sure if we care about that anymore.

Also, I assume Claude doesn't run pre-commit run --all-files before committing because I see CI commit fixes in there.

[paul-nechifor]

Some of the scripts and docs use pytest dimos. That means these tests will not be executed. Can you please move them or change all those places to remove dimos.

Actually, the tests don't get executed at all even in CI because we have testpaths = ["dimos"] in pyproject.toml

[leshy]

yeah sorry, I should have tagged the PR (talked on discord on this also) was experimenting with fully autonomous PRs last night