elicit_server

Compositions that no single crate can hold

The elicitation library teaches agents to think in types — constructing valid domain values through typed, contract-carrying operations rather than filling in JSON forms. Each shadow crate (elicit_reqwest, elicit_url, elicit_serde_json, …) exposes one slice of that language.

elicit_server is where those slices compose into something greater.

What makes cross-crate composition special

Individual crates prove local invariants. Composition proves end-to-end contracts that span multiple domains. The typestate proof chains here are not validation — they are compiler-enforced proofs that an agent cannot skip a step:

SecureFetchPlugin (elicit_url + elicit_reqwest)

UnvalidatedUrl → UrlParsed → HttpsRequired → RequestCompleted ∧ StatusSuccess

An agent cannot reach RequestCompleted without first passing through HttpsRequired. The HTTPS contract is not a runtime check — it is structurally unreachable to bypass.

FetchAndParsePlugin (elicit_reqwest + elicit_serde_json)

RequestCompleted → JsonParsed → PointerResolved

The JSON pointer is only resolvable against a value that was provably fetched and parsed. The agent builds the proof chain step by step.

Code recovery (emit feature)

When an agent has assembled a verified workflow interactively, it can ask EmitBinaryPlugin to recover that session as a standalone, compilable Rust binary — with all typestate ceremony, proof tokens, and contract types intact.

Agent builds workflow → calls emit_binary → gets a main.rs → cargo build → ships it

The output is not a script. It is idiomatic Rust that compiles and runs without the MCP server. The agent's exploration becomes production code.

Plugins

Usage

use elicitation::PluginRegistry;
use elicit_server::{SecureFetchPlugin, FetchAndParsePlugin};

#[tokio::main]
async fn main() {
    let registry = PluginRegistry::new()
        .register("secure_fetch", SecureFetchPlugin)
        .register("fetch_and_parse", FetchAndParsePlugin);
    // registry.serve(rmcp::transport::stdio()).await.unwrap();
}