litellm/litellm-rust/AGENTS.md

AGENTS.md

litellm-rust has exactly THREE crates. A crate is a LAYER, not a route. Routes (ocr, realtime, chat) and providers (mistral, openai) are MODULES inside the layers.

Crates

Crate	Role	Pure / I/O
litellm-core	Translation layer — types, route contracts (traits), provider transforms (modules under providers/), and the router. Builds requests/responses; no network.	Pure
litellm-ai-gateway	Routes + host — the only crate that touches the network. HTTP/WebSocket I/O (modules under io/) plus the axum server binary (behind the server feature).	I/O
litellm-python-bridge	PyO3 cdylib exposing Rust to the litellm Python SDK — a thin adapter over litellm-ai-gateway's I/O.	Binding

Dependency direction (acyclic): litellm-core ← litellm-ai-gateway ← litellm-python-bridge.

Adding a crate: default to a MODULE. New crate ONLY on a real trigger — separate artifact (binary/cdylib), proc-macro, shared foundation, or publishable standalone. A new provider or route is none of these.

Adding a crate fails crates/core/tests/workspace_crate_allowlist.rs until you update its allowlist and this file — intentional.

Style

All Rust in litellm-rust/ follows the official Rust Style Guide: https://doc.rust-lang.org/style-guide/

rustfmt implements its formatting by default, so run cargo fmt before committing; CI gates every PR on cargo fmt --check. Do not hand-format against rustfmt or add a rustfmt.toml that diverges from the default style.

Beyond formatting, follow the guide's naming and idiom conventions rustfmt cannot auto-apply: snake_case items/functions/modules, UpperCamelCase types/traits/variants, SCREAMING_SNAKE_CASE constants/statics (acronyms as one word, e.g. HttpClient), and the import grouping and item ordering it prescribes. See CLAUDE.md for the detailed version.