el-core — shared domain vocabulary

The foundational crate of the Edge Intelligence SDK: the ubiquitous language of the project turned into Rust types. Every other crate speaks in terms of the ids, value objects, errors, events, and the provider trait defined here.

el-core has zero external dependencies — pure std, so it compiles offline on any target including wasm32 (ADR-008). It contains no I/O, no network, and no unsafe (#![forbid(unsafe_code)]).

What it provides

Module	Key types	Purpose
`ids`	`SessionId`, `ModelId`, `ModelVersion`	Identifier value objects
`value_objects`	`Token`, `ModelFormat`, `RuntimeKind`, `DeviceTarget`, `Phase`, `SafetyMode`, `SpeculationMode`, `StopReason`	Core enums and the `Token = u32` alias
`config`	`SessionConfig`	Immutable per-session configuration
`error`	`EdgeError`, `Result<T>`	The SDK-wide error type
`events`	`DomainEvent`, `EventEnvelope`, `DegradeReason`	Content-free domain events
`provider`	`LlmProvider`, `ChatRequest`, `ChatResponse`, `ChatMessage`, `ChatRole`, `ChatToken`, `CredentialRef`	The unified backend abstraction

All names are re-exported at the crate root, e.g. use el_core::{LlmProvider, ChatRequest};.

Cross-cutting invariants encoded here

These are enforced by the type system, not by convention:

Content-free events (ADR-007). DomainEvent and EventEnvelope derive Copy. A String/Vec/heap field is not Copy, so adding one fails to compile — "no prompt or response content on an event" is a compile-time guarantee. Ratios and scores are carried as fixed-point integers (*_milli).
Air-gap by default (ADR-004). SessionConfig::default().hybrid_mode is false. The only network seam is an explicit opt-in.
Unified provider (ADR-010). LlmProvider covers both the local Candle engine and cloud frontier backends behind one trait, so host apps can swap local ↔ frontier without touching their UI.
Redacted credentials. CredentialRef's Debug output is CredentialRef([REDACTED]), so bearer keys cannot leak into logs or panic messages.

Usage

This is the crate-local part of a real local SDK call. In an app, the request can be served by el_engine_candle::QwenChatProvider::from_paths(...) with models/qwen2.5-0.5b-instruct-q4_k_m.gguf and models/qwen2.5-0.5b-instruct.tokenizer.json; el-core only defines the backend-agnostic contract.

use el_core::{ChatMessage, ChatRequest, LlmProvider, SessionConfig};

// Configuration is air-gapped by default (ADR-004).
let cfg = SessionConfig::default();
assert!(!cfg.hybrid_mode);

// A backend-agnostic request. `model` is a routing hint:
//   "local"/"" → local engine, "openai/…", "anthropic/…", "ollama/…", "gemini/…"
let req = ChatRequest::new(
    "local/qwen2.5-0.5b-instruct-q4_k_m",
    vec![ChatMessage::user("Summarize edge inference in one sentence.")],
)
    .with_max_tokens(256)
    .with_temperature(700); // 700 = 0.7 (milli to keep the type Eq-able)

// Any backend is reached through the same trait.
fn run(provider: &dyn LlmProvider, req: &ChatRequest) -> el_core::Result<String> {
    Ok(provider.chat(req)?.content)
}

Place in the workspace

el-core is the root of the dependency graph: el-memory, el-telemetry, el-provenance, el-safety, el-runtime, and every adapter depend on it, and it depends on nothing. Keep it dependency-free — that property is what lets the local core cross-compile to WASM and mobile targets.

Status

Implemented and tested.