refactor(rust): extract shared auth foundation from core

litellm-rust/Cargo.lock

@@ -1420,6 +1420,13 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "litellm-auth"
+version = "0.1.0"
+dependencies = [
+ "tokio",
+]
+
 [[package]]
 name = "litellm-auth-aws"
 version = "0.1.0"

litellm-rust/Cargo.toml

@@ -1,6 +1,7 @@
 [workspace]
 members = [
     "crates/core",
+    "crates/auth",
     "crates/config",
     "crates/ai-gateway",
     "crates/python-interop",

litellm-rust/crates/auth/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "litellm-auth"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["macros", "rt"] }

litellm-rust/crates/core/AGENTS.md

@@ -101,14 +101,21 @@ errors are language-neutral.
 
 ```
 core must not depend on PyO3, Axum or gateway integration types
+litellm-auth owns shared credential values, capability contracts and future static helpers
 cloud-auth crates own reusable native credential and signing mechanisms
 core owns provider precedence, header policy and authorization timing
 Tower/Axum types stop at the gateway adapter boundary
-provider transformation, auth and I/O remain in core
+provider transformation, auth policy and I/O remain in core
 request-scoped host state belongs to a call session
 service construction dependencies do not leak into service interfaces
 ```
 
+`litellm-auth` has only standard-library production dependencies and does not
+depend on core or cloud crates. Add it as a dependency only where consumed.
+Cloud crates retain their own credential types and errors. `AuthorizationFuture`
+lives in `core::providers` because its result uses the core error type. The former
+`core::auth` module is removed without compatibility re-exports
+
 ## Not the target
 
 Do not introduce a dynamic `TypeId` service map, a shared gateway callback

litellm-rust/crates/core/src/lib.rs

@@ -1,5 +1,4 @@
 pub mod audio_transcription;
-pub mod auth;
 pub mod chat_completions;
 pub mod constants;
 pub mod error;

litellm-rust/crates/core/src/providers/mod.rs

@@ -1,3 +1,6 @@
+use std::future::Future;
+use std::pin::Pin;
+
 pub mod anthropic;
 pub mod azure_ai;
 #[cfg(feature = "bedrock-auth")]
@@ -6,3 +9,6 @@ pub mod mistral;
 pub mod openai;
 pub mod reducto;
 pub mod vertex_ai;
+
+pub type AuthorizationFuture<'a> =
+    Pin<Box<dyn Future<Output = Result<Vec<(String, String)>, crate::Error>> + Send + 'a>>;