Avoid duplicate entries in router builder

Currently the router builder silently drops duplicate entries, solve this by
returning an error if the builder sees that. Also explicitly set default format
-> provider mappings, and also error if there are duplicate entries in the
builder there.

Also clean up some override client stuff.

Author: aswink

crates/braintrust-llm-router/README.md

@@ -123,9 +123,11 @@ let stream = router.complete_stream(body, "gpt-4", ProviderFormat::ChatCompletio
 ### Authentication
 
 ```rust
-use braintrust_llm_router::AuthConfig;
+use braintrust_llm_router::{api_key_auth, AuthConfig};
 
 // OpenAI-style (Authorization: Bearer <key>)
+api_key_auth("sk-...")
+// Or equivalently:
 AuthConfig::ApiKey {
     key: "sk-...".into(),
     header: Some("authorization".into()),

crates/braintrust-llm-router/examples/custom_auth.rs

@@ -15,8 +15,8 @@
 
 use anyhow::Result;
 use braintrust_llm_router::{
-    serde_json::json, AuthConfig, ClientHeaders, OpenAIConfig, OpenAIProvider, ProviderFormat,
-    Router,
+    api_key_auth, serde_json::json, AuthConfig, ClientHeaders, OpenAIConfig, OpenAIProvider,
+    ProviderFormat, Router,
 };
 use bytes::Bytes;
 use serde_json::Value;
@@ -119,8 +119,12 @@ async fn main() -> Result<()> {
 
     let router = Router::builder()
         .with_catalog(catalog)
-        .add_provider("openai", openai_provider)
-        .add_api_key("openai", api_key) // Convenience method
+        .add_provider(
+            "openai",
+            openai_provider,
+            api_key_auth(&api_key),
+            vec![ProviderFormat::ChatCompletions],
+        )
         .build()?;
 
     let model = "gpt-4";
@@ -132,7 +136,7 @@ async fn main() -> Result<()> {
 
     println!("   Sending authenticated request to GPT-4...");
     let body = Bytes::from(serde_json::to_vec(&payload)?);
-    let bytes = router
+    let bytes: Bytes = router
         .complete(
             body,
             model,

crates/braintrust-llm-router/examples/multi_provider.rs

@@ -10,8 +10,8 @@
 
 use anyhow::Result;
 use braintrust_llm_router::{
-    serde_json::json, AnthropicConfig, AnthropicProvider, AuthConfig, ClientHeaders, ModelCatalog,
-    OpenAIConfig, OpenAIProvider, ProviderFormat, Router,
+    api_key_auth, serde_json::json, AnthropicConfig, AnthropicProvider, AuthConfig, ClientHeaders,
+    ModelCatalog, OpenAIConfig, OpenAIProvider, ProviderFormat, Router,
 };
 use bytes::Bytes;
 use serde_json::Value;
@@ -40,25 +40,28 @@ async fn main() -> Result<()> {
     // Add OpenAI provider if key is available
     if let Some(key) = &openai_key {
         let openai_provider = OpenAIProvider::new(OpenAIConfig::default())?;
-        builder = builder
-            .add_provider("openai", openai_provider)
-            .add_api_key("openai", key.clone());
+        builder = builder.add_provider(
+            "openai",
+            openai_provider,
+            api_key_auth(key),
+            vec![ProviderFormat::ChatCompletions],
+        );
         println!("✅ OpenAI provider configured");
     }
 
     // Add Anthropic provider if key is available
     if let Some(key) = &anthropic_key {
         let anthropic_provider = AnthropicProvider::new(AnthropicConfig::default())?;
-        builder = builder
-            .add_provider("anthropic", anthropic_provider)
-            .add_auth(
-                "anthropic",
-                AuthConfig::ApiKey {
-                    key: key.clone(),
-                    header: Some("x-api-key".into()),
-                    prefix: None,
-                },
-            );
+        builder = builder.add_provider(
+            "anthropic",
+            anthropic_provider,
+            AuthConfig::ApiKey {
+                key: key.clone(),
+                header: Some("x-api-key".into()),
+                prefix: None,
+            },
+            vec![ProviderFormat::ChatCompletions],
+        );
         println!("✅ Anthropic provider configured");
     }
 

crates/braintrust-llm-router/examples/simple.rs

@@ -7,8 +7,8 @@
 
 use anyhow::Result;
 use braintrust_llm_router::{
-    serde_json::json, ClientHeaders, ModelCatalog, OpenAIConfig, OpenAIProvider, ProviderFormat,
-    Router,
+    api_key_auth, serde_json::json, ClientHeaders, ModelCatalog, OpenAIConfig, OpenAIProvider,
+    ProviderFormat, Router,
 };
 use bytes::Bytes;
 use serde_json::Value;
@@ -37,8 +37,12 @@ async fn main() -> Result<()> {
 
     let router = Router::builder()
         .with_catalog(catalog)
-        .add_provider("openai", openai_provider)
-        .add_api_key("openai", api_key)
+        .add_provider(
+            "openai",
+            openai_provider,
+            api_key_auth(&api_key),
+            vec![ProviderFormat::ChatCompletions],
+        )
         .build()?;
 
     // Simple chat completion
@@ -57,7 +61,7 @@ async fn main() -> Result<()> {
 
     // Convert payload to bytes and send request
     let body = Bytes::from(serde_json::to_vec(&payload)?);
-    let bytes = router
+    let bytes: Bytes = router
         .complete(
             body,
             model,
@@ -91,7 +95,7 @@ async fn main() -> Result<()> {
     // Print model information
     println!("\n🔍 Model Information:");
     if let Some(spec) = router.catalog().get("gpt-4") {
-        let spec = spec.as_ref();
+        let spec: &braintrust_llm_router::ModelSpec = spec.as_ref();
         println!(
             "  Display Name: {}",
             spec.display_name.as_deref().unwrap_or("GPT-4")

crates/braintrust-llm-router/examples/streaming.rs

@@ -30,14 +30,15 @@ async fn main() -> Result<()> {
 
     let router = Router::builder()
         .with_catalog(catalog)
-        .add_provider("anthropic", anthropic_provider)
-        .add_auth(
+        .add_provider(
             "anthropic",
+            anthropic_provider,
             AuthConfig::ApiKey {
                 key: anthropic_api_key,
                 header: Some("x-api-key".into()),
                 prefix: None,
             },
+            vec![ProviderFormat::ChatCompletions],
         )
         .build()?;
 
@@ -59,7 +60,7 @@ async fn main() -> Result<()> {
     });
 
     let body = Bytes::from(serde_json::to_vec(&payload)?);
-    let mut stream = router
+    let mut stream: ResponseStream = router
         .complete_stream(
             body,
             model,

crates/braintrust-llm-router/src/auth/mod.rs

@@ -50,6 +50,15 @@ pub enum AuthConfig {
     },
 }
 
+/// Convenience function to create an API key authentication configuration.
+pub fn api_key_auth(api_key: &str) -> AuthConfig {
+    AuthConfig::ApiKey {
+        key: api_key.to_string(),
+        header: Some("authorization".into()),
+        prefix: Some("Bearer".into()),
+    }
+}
+
 impl AuthConfig {
     pub fn auth_type(&self) -> AuthType {
         match self {

crates/braintrust-llm-router/src/client.rs

@@ -40,22 +40,16 @@ pub fn build_client(settings: &ClientSettings) -> Result<Client> {
 }
 
 pub fn build_middleware_client(settings: &ClientSettings) -> Result<ClientWithMiddleware> {
+    if let Some(existing) = OVERRIDE_CLIENT.read().clone() {
+        return Ok(existing);
+    }
     let client = build_client(settings)?;
     Ok(reqwest_middleware::ClientBuilder::new(client).build())
 }
 
 static OVERRIDE_CLIENT: Lazy<RwLock<Option<ClientWithMiddleware>>> =
     Lazy::new(|| RwLock::new(None));
 
-pub fn override_client() -> Result<ClientWithMiddleware> {
-    if let Some(existing) = OVERRIDE_CLIENT.read().clone() {
-        return Ok(existing);
-    }
-    let client = build_middleware_client(&ClientSettings::default())?;
-    *OVERRIDE_CLIENT.write() = Some(client.clone());
-    Ok(client)
-}
-
 pub fn set_override_client(client: ClientWithMiddleware) {
     *OVERRIDE_CLIENT.write() = Some(client);
 }

crates/braintrust-llm-router/src/lib.rs

@@ -14,6 +14,7 @@ mod streaming;
 pub use lingua::serde_json;
 
 pub use auth::{
+    api_key_auth,
     azure::{AzureEntraCredentials, AzureEntraTokenManager},
     databricks::{DatabricksCredentials, DatabricksTokenManager},
     google::{GoogleServiceAccountConfig, GoogleTokenManager, ServiceAccountKey},

crates/braintrust-llm-router/src/providers/anthropic.rs

@@ -8,7 +8,7 @@ use reqwest_middleware::ClientWithMiddleware;
 
 use crate::auth::AuthConfig;
 use crate::catalog::ModelSpec;
-use crate::client::{build_middleware_client, override_client, ClientSettings};
+use crate::client::{build_middleware_client, ClientSettings};
 use crate::error::{Error, Result, UpstreamHttpError};
 use crate::providers::ClientHeaders;
 use crate::streaming::{single_bytes_stream, sse_stream, RawResponseStream};
@@ -48,7 +48,7 @@ impl AnthropicProvider {
         if let Some(timeout) = config.timeout {
             settings.request_timeout = timeout;
         }
-        let client = override_client().or_else(|_| build_middleware_client(&settings))?;
+        let client = build_middleware_client(&settings)?;
         Ok(Self { client, config })
     }
 

crates/braintrust-llm-router/src/providers/azure.rs

@@ -9,7 +9,7 @@ use reqwest_middleware::ClientWithMiddleware;
 
 use crate::auth::AuthConfig;
 use crate::catalog::ModelSpec;
-use crate::client::{build_middleware_client, override_client, ClientSettings};
+use crate::client::{build_middleware_client, ClientSettings};
 use crate::error::{Error, Result, UpstreamHttpError};
 use crate::providers::ClientHeaders;
 use crate::streaming::{single_bytes_stream, sse_stream, RawResponseStream};
@@ -49,7 +49,7 @@ impl AzureProvider {
         if let Some(timeout) = config.timeout {
             settings.request_timeout = timeout;
         }
-        let client = override_client().or_else(|_| build_middleware_client(&settings))?;
+        let client = build_middleware_client(&settings)?;
         Ok(Self { client, config })
     }