feat(config): add remote config layer fetched from S3

.claude/CODEBASE.md

@@ -103,6 +103,7 @@ See `docs/ARCHITECTURE.md` for the full architecture diagram and detailed compon
 | `HTTP_HOST` | HTTP bind address (default: `0.0.0.0`) |
 | `HTTP_PORT` | API port (default: `3000`) |
 | `CONFIG_FILE` | Solver config file (default: `fynd.toml` if present) |
+| `REMOTE_CONFIG_URL` | Remote config URL (default: chain-specific PropellerHeads S3 URL; `--no-remote-config` disables) |
 | `WORKER_POOLS_CONFIG` | Deprecated legacy pools-only config file; its pools override the config file's |
 | `BLOCKLIST_CONFIG` | Blocklist config file |
 | `RUST_LOG` | Tracing filter (e.g. `info,fynd=debug`) |
@@ -120,7 +121,7 @@ See `docs/ARCHITECTURE.md` for the full architecture diagram and detailed compon
 
 | File | Purpose |
 |---|---|
-| `fynd.toml` | Full solver config: any subset of tuning fields + `[pools]`. Resolved field-by-field: CLI > file > embedded default (`fynd-core/src/config/default_config.toml`) |
+| `fynd.toml` | Full solver config: any subset of tuning fields + `[pools]`. Resolved field-by-field: CLI > file > remote config (S3, per chain) > embedded default (`fynd-core/src/config/default_config.toml`) |
 | `worker_pools.toml` | Deprecated legacy pools-only file, still honored (its pools override the config file's) |
 | `blocklist.toml` | Component IDs to exclude from the Tycho stream. Optional — falls back to tycho-simulation defaults if not found |
 

docs/guides/server-configuration.md

@@ -87,6 +87,8 @@ Run `fynd serve --help` for the full list.
 | `--worker-router-timeout-ms`       | —                     | `100`                      | Default solve timeout (ms)                                                                                                                                                                                     |
 | `--worker-router-min-responses`    | —                     | `0`                        | Early return threshold (0 = wait for all pools)                                                                                                                                                                |
 | `--config-file`                    | `CONFIG_FILE`         | `fynd.toml` (if present)   | TOML config file overriding the embedded defaults (see [Config file](#config-file-fyndtoml)).                                                                                                                  |
+| `--remote-config-url`              | `REMOTE_CONFIG_URL`   | _(chain-specific S3 URL)_  | Remote config with the latest tuned values, pulled at startup. Fetch failures never block startup.                                                                                                             |
+| `--no-remote-config`               | —                     | `false`                    | Disable the remote config fetch.                                                                                                                                                                               |
 | `-w, --worker-pools-config`        | `WORKER_POOLS_CONFIG` | `worker_pools.toml` (if present) | **Deprecated** — legacy pools-only config file; move the `[pools]` section into `fynd.toml`. Still honored: its pools override the config file's.                                                        |
 | `--blocklist-config`               | `BLOCKLIST_CONFIG`    | [tycho-simulation default](https://github.com/propeller-heads/tycho-simulation/blob/main/blocklist.toml)                          | Path to blocklist TOML config file. Components listed here are excluded from the Tycho stream.                                                                                                                                                                                     |
 | `--disable-tls`                    | —                     | `false`                    | Disable TLS for Tycho connection                                                                                                                                                                               |
@@ -104,8 +106,8 @@ Run `fynd serve --help` for the full list.
 
 ## Config file (`fynd.toml`)
 
-Every solver-tuning flag above resolves field-by-field through three layers, highest priority
-first: **CLI flags > config file > embedded defaults**. The config file may set any subset of
+Every solver-tuning flag above resolves field-by-field through four layers, highest priority
+first: **CLI flags > config file > remote config (S3) > embedded defaults**. The config file may set any subset of
 the fields (same names as the flags) plus the worker pools; `./fynd.toml` is picked up
 automatically, or pass `--config-file`.
 

fynd-core/CLAUDE.md

@@ -9,7 +9,7 @@ applications.
 |-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `algorithm/`          | `Algorithm` trait + built-in `MostLiquidAlgorithm`, `BellmanFordAlgorithm`, `PathFrankWolfeAlgorithm`. Pluggable via associated graph types. `AlgorithmConfig` shared by all         |
 | `solver.rs`           | `FyndBuilder` assembles the full pipeline (feed + gas + computations + pools + encoder + router). `Solver` runs it                                                                 |
-| `config/`             | Layered solver config: `embedded_default()` parses `default_config.toml` (single source of truth for all tuning defaults) into a complete `Config`; `PartialConfig` layers overlay via `Config::apply` (CLI/file > embedded); `Config::validate` range-checks the result |
+| `config/`             | Layered solver config: `embedded_default()` parses `default_config.toml` (single source of truth for all tuning defaults) into a complete `Config`; `PartialConfig` layers overlay via `Config::apply` (CLI > file > remote > embedded); `config::remote` fetches per-chain tuned values from S3 (fail-safe: retries, size cap, warn-and-fallback, never panics), `get_default(chain)` = embedded + remote in one call; `Config::validate` range-checks the result |
 | `worker_pool/`        | `WorkerPool` manages dedicated OS threads. `SolverWorker` runs a prioritized select loop (shutdown > market events > derived events > tasks). `TaskQueue` is `async_channel`-based |
 | `worker_pool_router/` | `WorkerPoolRouter` fans out orders to all pools, ranks candidates by `amount_out_net_gas` descending; price guard (if enabled) validates in rank order; optionally encodes          |
 | `feed/`               | `TychoFeed` (WebSocket → MarketState), `GasPriceFetcher`, `MarketEvent` broadcasting, `ProtocolRegistry`                                                                           |

fynd-core/src/config/mod.rs

@@ -5,7 +5,8 @@
 //!
 //! 1. **Explicit overrides** — lib builder setters or CLI flags
 //! 2. **Local config file** — any subset of the fields, same schema as the embedded default
-//! 3. **Embedded default** — `default_config.toml`, compiled into the binary
+//! 3. **Remote config** — tuned values pulled from S3 per chain (see [`remote`])
+//! 4. **Embedded default** — `default_config.toml`, compiled into the binary
 //!
 //! The embedded default deserializes directly into a complete [`Config`] — every field
 //! (except the chain-specific `min_tvl`) is required, so a gap between the struct and
@@ -26,6 +27,8 @@
 //! let overrides = PartialConfig { worker_router_timeout_ms: Some(50), ..Default::default() };
 //! let config = embedded_default()
 //!     .clone()
+//!     .apply_remote(&remote::default_remote_config_url(chain), timeout)
+//!     .await
 //!     .apply(&PartialConfig::from_file("fynd.toml")?)
 //!     .apply(&overrides);
 //! let builder = FyndBuilder::new(chain, tycho_url, rpc_url, config.protocols.clone(), min_tvl)
@@ -39,6 +42,8 @@ use tycho_simulation::tycho_common::models::{Chain, TvlThresholdTier};
 
 use crate::solver::PoolConfig;
 
+pub mod remote;
+
 /// The embedded default configuration, compiled into the binary.
 const EMBEDDED_DEFAULT_TOML: &str = include_str!("default_config.toml");
 
@@ -151,6 +156,25 @@ pub fn embedded_default() -> &'static Config {
     &EMBEDDED_DEFAULT
 }
 
+/// Overall time budget (including retries) for the fetch inside [`get_default`].
+/// Callers wanting a different budget use [`Config::apply_remote`] directly.
+const GET_DEFAULT_FETCH_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(2);
+
+/// Returns the embedded default configuration with the latest remotely tuned values for
+/// `chain` applied on top, fetched from the default S3 URL (see
+/// [`remote::default_remote_config_url`]).
+///
+/// The simple one-call form of `embedded_default().clone().apply_remote(...)`, with a
+/// built-in 2 s fetch budget. Never fails or panics: on any fetch problem the embedded
+/// defaults are returned unchanged (a warning is logged). Layer local overrides on top
+/// with [`Config::apply`]; for a custom URL or timeout use [`Config::apply_remote`].
+pub async fn get_default(chain: Chain) -> Config {
+    embedded_default()
+        .clone()
+        .apply_remote(&remote::default_remote_config_url(chain), GET_DEFAULT_FETCH_TIMEOUT)
+        .await
+}
+
 impl Config {
     /// Returns `min_tvl`, falling back to `chain`'s default TVL threshold when unset.
     pub fn min_tvl_or_chain_default(&self, chain: Chain) -> f64 {