Resonate Basic Debugging — Rust

SDK note. This SDK is in active development (v0.6.0, published on crates.io), and documented behaviors may shift between releases. Failure modes listed here are what the documented surface produces; new ones will appear as the SDK grows.

Overview

Rust's failure modes differ from TS's and Python's. Compile-time type errors catch many bugs the other SDKs only discover at runtime; the remaining runtime failures are usually serde, tokio, or registration-name related. This skill covers the shapes you'll actually see.

For the language-agnostic replay + recovery mental model, read durable-execution first.

Triage flow

1. Does it compile? If cargo build fails, you're in type-error territory (likely: missing Result<T> return, wrong first-parameter type, forgotten & on Context/Info, missing ? on an await)
2. Does it register? resonate.register(fn) returns a Result; unwrap it and look at the error (duplicate name, bad signature)
3. Does the function kind match expectations? The SDK infers kind from the first parameter — &Context vs &Info vs a value type
4. Is serde happy? Input/output types need Serialize + Deserialize derives; stack traces mentioning serde_json::Error mean a type doesn't derive correctly
5. Is the tokio runtime correct? #[tokio::main] or #[tokio::test(flavor = "multi_thread")] needed; single-threaded runtime can deadlock on SDK internals
6. Check server + SDK compatibility. The SDK version in Cargo.toml must align with the server version you're testing against; check the SDK CHANGELOG for compatibility notes