Helius-stream: a small Rust crate I extracted from a mainnet MEV experiment, sharing for feedback

RFP
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Hi all, :face_with_monocle:

Sharing a Rust crate I extracted from a recent Solana MEV experiment, in case anyone here is building Rust-based bots, indexers, or monitoring tools and wants something lighter than pulling the full solana-client SDK for account subscriptions.

Context

I built a small cross-DEX arbitrage engine targeting SOL/USDC on Solana mainnet, running on a €4.50/month VPS for 15 hours straight. The engine captured zero profitable opportunities — the market was efficient to within ~29 bps on that route, which matches what I’d expect for a hobbyist setup without colocation or a private RPC tier.

What the experiment did produce was a resilient WebSocket layer that ran continuously for 15h without crashing. I extracted it and published it as helius-stream.

What it is

A focused Rust client for one specific use case: subscribing to Solana account updates over Helius WebSocket, with gap detection, reconnect, and a stream health state machine. 408 SLoC, 8 direct deps (vs ~200 transitive for the full solana-client SDK).

What it does today (v0.1)

  • accountSubscribe over Helius WebSocket
  • Gap detection (slot delta tracking, you know when you missed slots)
  • Exponential backoff reconnect (100ms → 10s, configurable)
  • Stream health state machine: Connected / Degraded / Stale / Failed
  • Zero panics in normal paths

What it doesn’t do yet

  • Async — v0.1 is sync, tokio coming in v0.2 behind a feature flag
  • programSubscribe, logsSubscribe, signatureSubscribe — only accountSubscribe for now (there’s an open good first issue for programSubscribe if anyone wants to contribute)
  • It’s not a Solana SDK; it’s an RPC client for one specific subscription type

Why I’m posting here

Two reasons:

  1. Feedback before committing to v0.2 design. Especially interested in opinions from people who’ve built bots or indexers and have war stories about WebSocket flakiness or stale-data incidents.

  2. Visibility — if your project pulls solana-client purely for account subs and you’d benefit from something smaller, this might save you time.

Happy to discuss the MEV side of the experiment too. The short version: small-VPS SOL/USDC arb is dead unless you have colocation or your own validator, but the journey of finding that out empirically was worth the €4.50.

Critiques welcome.