Crate caputchin_replay_rs 

Rust authoring crate for Caputchin server-validated game replay.

Caputchin hosts a deterministic-replay captcha: a game records a trace, and the server re-runs the same sim over that trace and trusts only the replayed verdict. A conforming replay artifact is a freestanding WASM module exporting a tiny C-ABI the host marshals into. This crate writes that C-ABI for you.

Author a deterministic run (no clock, no RNG beyond the seed, no host calls), then invoke caputchin_replay! once at your crate root:

use caputchin_replay_rs::{caputchin_replay, Verdict};

fn run(seed: [u32; 4], config: &[i32], trace: &[u8]) -> Verdict {
    // decode config + trace, step the deterministic sim, return the result.
    Verdict { passed: true, score: 0, duration_ms: 0 }
}

caputchin_replay!(run);

The generated cap_alloc / cap_run exports, compiled to wasm32-unknown-unknown with crate-type = ["cdylib"], are a complete headless replay artifact: no wasm-bindgen, no imports.

config and trace are opaque to this crate. The host writes whatever bytes (trace) and i32 array (config) your game encoded; your run decodes them. The JS host glue lives in @caputchin/replay-wasm; the shapes are owned by @caputchin/replay-contract.

Macros

caputchin_live

Emit the Caputchin live-stepping C-ABI (live_new, live_step, live_state, live_trace, live_free) for a type implementing LiveGame. Pairs with caputchin_replay!: both compile from the SAME sim into ONE wasm, so the browser steps the identical module the server replays, and floats agree by construction. The JS host glue lives in @caputchin/replay-wasm.

caputchin_replay

Emit the Caputchin replay C-ABI (cap_alloc, cap_run) from a run function with signature fn([u32; 4], &[i32], &[u8]) -> Verdict.

Structs

Verdict

The result of a replay run. Matches the Verdict shape in @caputchin/replay-contract: a pass/fail flag, an integer score, and a duration in milliseconds. Serialized across the C-ABI as three little-endian i32s [passed, score, duration_ms].

Traits

LiveGame

A live-steppable game: the SAME deterministic sim the replay run drives, exposed for frame-by-frame stepping by a browser renderer (the Lane 2 pattern). The caputchin_live! macro emits the browser C-ABI over a type implementing this, so the renderer drives the identical wasm the server replays. Inputs, the render state, and the trace are opaque to this crate.