Lighthouse Router

Off-chain DEX route discovery for Solana. Built so that I'd stop hand-rolling the same constant-product math in every script I write.

Why?

When you want to quote a swap across Solana DEXs without delegating it to a third-party router, you end up reimplementing pool math, account decoding, and shortest-path search. This crate is the small set of primitives I use for that, kept honest by tests.

It is not a Jupiter replacement. It is small, dependency-light, and predictable. If you need cross-program invocation, MEV bundle building, or slippage protection in production: keep using something else.

What's in here

• Pool decoders for Raydium AMM v4, Orca Whirlpool, and Phoenix order books (the last is a typed model — feed it from phoenix-sdk).
• Constant-product and concentrated-liquidity quote math, with tests.
• A token graph and a depth-limited router for multi-hop quotes.
• Bellman-Ford negative-cycle detection for marginal-price arbitrage scans.
• A lighthouse CLI that wires it all up against an RPC endpoint.

Architecture

┌────────────────┐     ┌──────────────────┐     ┌──────────────┐
│  Solana RPC    │ ──► │  client::fetch_  │ ──► │  decoders    │
│  (mainnet/RPC) │     │  many (parallel) │     │  raydium /   │
└────────────────┘     └──────────────────┘     │  orca /      │
                                                │  phoenix     │
                                                └──────┬───────┘
                                                       │ AnyPool
                                                       ▼
                              ┌────────────┐   ┌───────────────┐
                              │  cache     │ ◄─┤  pool::Quoter │
                              │  (TTL)     │   └──────┬────────┘
                              └────────────┘          │
                                                      ▼
                                              ┌───────────────┐
                                              │  graph::Graph │
                                              └──┬──────────┬─┘
                                                 │          │
                                       router::best_route   │
                                                            ▼
                                                arbitrage::find_negative_cycle

The Quoter trait is the seam between pool decoding and routing — every DEX integration needs to provide mints(), quote(), and is_active(). AnyPool is the runtime sum type the graph stores, so the router doesn't need to be generic over each concrete venue.

Install & Run

cargo add lighthouse-router      # as a library
# or, for the CLI:
cargo install --path .

Quote a route:

lighthouse quote \
  --from EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v \
  --to   So11111111111111111111111111111111111111112  \
  --amount 1_000_000_000 \
  --max-hops 3

Library usage

use lighthouse_router::{best_route, AnyPool, Graph, Pool};

let pools: Vec<AnyPool> = load_pools_from_somewhere();
let graph = Graph::build(pools);

let route = best_route(&graph, usdc_mint, sol_mint, 1_000_000, 3)?;
println!("out = {}", route.amount_out);
for step in &route.steps {
    println!("  {} via {}", step.pool_idx, step.venue);
}

See examples/quote.rs and examples/find_arb.rs for runnable end-to-end examples that don't need an RPC connection.

Configuration

Flag	Default	Notes
--rpc	https://api.mainnet-beta.solana.com	Read from SOLANA_RPC_URL if unset.
--max-hops	3	Routing depth ceiling.
--probe (arb)	1_000_000	Probe size for marginal-price weights.

Status

Early but useful. The bits I rely on day-to-day (CP math, the graph builder, and the CLI quote command) are stable. The Whirlpool quoter is honest about its single-tick-range limitation: it refuses to quote rather than lie when a swap would cross a tick. Phoenix is a typed model — you wire it up.

License

Apache-2.0. See LICENSE.