CDS Hooks

Use this when working in helios-cds-hooks. It provides Rust types and an async service trait for building CDS Hooks services conforming to HL7 CDS Hooks v3.0.0-ballot. It is a standalone protocol library — currently not wired into the hfs server — and is framework-agnostic (Axum, Actix, etc.).

What's in it

• Complete protocol types — request, response, discovery, Card, Suggestion, Action, Link, Feedback, with full serde support (models.rs).
• Strongly-typed hook contexts (compile-time validated) for the standard hooks (hooks.rs): patient-view, order-select, order-sign, encounter-start, encounter-discharge, appointment-book, order-dispatch, allergyintolerance-create, medication-refill, problem-list-item-create.
• Service trait + builders — CdsHooksService async trait and card/response builder helpers (service.rs, lib.rs).

Implementing a service

use async_trait::async_trait;
use helios_cds_hooks::{
    CdsHooksService, CdsService, CdsHooksError,
    hooks::{HookContext, PatientViewContext},
};

struct PatientGreeter;

#[async_trait]
impl CdsHooksService for PatientGreeter {
    type Context = PatientViewContext;

    fn definition(&self) -> CdsService { /* hook, id, title, description */ }
    // request handler returning cards — see crates/cds-hooks/src/service.rs
    // for the exact trait methods and signatures.
}

See the full quick-start in crates/cds-hooks/src/lib.rs. CdsHooksError::status_code() maps errors to HTTP status codes.

Code map

lib.rs (overview, re-exports, builders), models.rs (protocol types), hooks.rs (hook context structs + HOOK_NAME constants), service.rs (CdsHooksService trait, CdsHooksError). Tests are inline in src/; integration tests under crates/cds-hooks/tests/ where present.

Wiring it in

There is no CDS Hooks HTTP endpoint in hfs yet. To expose services, mount CdsHooksService implementations in a router (e.g. GET /cds-services discovery + POST /cds-services/{id} per service).