Rust warn on dropped LCM packets

[jeff-hykin]

Backpressure from heavy faster-than-real-time lidar benchmarks is kind of evitable. Right now its a silent failure.

This includes a warning message, and some higher default rust buffer sizes to handle more throughput to match.

Tests added to make sure rust native modules aren't bottlenecking LCM.

Run the tests:

cd native/rust/dimos-module
cargo test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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[greptile-apps]

Greptile Summary

This PR adds a rate-limited drop warning to TypedRoute::try_dispatch so that silent LCM packet loss under backpressure is now surfaced on stderr, and bumps both mpsc channel capacities from 16/64 to 1024 to reduce the frequency of drops during faster-than-real-time lidar benchmarks. New concurrency tests and a drop-logging unit test are included.

• Drop warning: when try_send returns Full, the per-route drop_count (AtomicU64) is incremented and a rate-limited (≤1/sec) eprintln! is emitted with the topic name and queue capacity. The Closed variant continues to be silently ignored.
• Capacity increase: INPUT_CHANNEL_CAPACITY 16 → 1024 and PUBLISH_CHANNEL_CAPACITY 64 → 1024; the larger buffers give downstream consumers more headroom before drops occur.

Confidence Score: 4/5

Safe to merge; the logic change is isolated to warning output and does not affect message delivery or control flow.

The functional change — emitting a warning on dropped messages — is correct and well-tested for the happy path. The two findings are about warning message clarity and test coverage for rate limiting; neither affects message delivery or system behaviour. The larger channel capacities are a straightforward tuning change with no downstream breakage risk.

native/rust/dimos-module/src/module.rs — the drop warning message and its test are the only areas worth a second look.

Important Files Changed

Filename	Overview
native/rust/dimos-module/src/module.rs	Adds per-route drop counting + rate-limited eprintln warning when mpsc channel is full; bumps both channel capacities to 1024; adds TypedRoute unit test. Minor issue: n in the warning is an all-time cumulative total, not a per-interval delta, which can be misleading after recovery periods.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Transport recv loop] -->|channel, data| B{Route lookup}
    B -->|No route| C[Ignore]
    B -->|Route found| D[TypedRoute::try_dispatch]
    D --> E{decode bytes}
    E -->|Err| F[eprintln decode error]
    E -->|Ok msg| G{sender.try_send}
    G -->|Ok| H[Message delivered to Input]
    G -->|Closed| I[Silently ignore]
    G -->|Full - backpressure| J[drop_count.fetch_add]
    J --> K{rate-limit check\nlast_log within 1s?}
    K -->|Yes, suppress| L[Silent drop]
    K -->|No, emit| M[eprintln warning\ndrop_count + topic + cap]
    M --> N[Update last_log]

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