Enum Backend 

pub enum Backend {
    OpenAiChat(HttpBackendConfig),
    OpenAiResponses(HttpBackendConfig),
    Anthropic(HttpBackendConfig),
}

A configured upstream backend, one variant per built-in wire format.

The variant fixes the wire format, URL path, and auth scheme together so no invalid combination can be constructed.

Variants

OpenAiChat(HttpBackendConfig)

OpenAI-compatible Chat Completions API.

OpenAiResponses(HttpBackendConfig)

OpenAI Responses API.

Anthropic(HttpBackendConfig)

Anthropic Messages API.

Implementations

impl Backend

pub fn wire_format(&self) -> WireFormat

The wire format the request IR is encoded to for this backend.

pub fn url(&self) -> String

The fully resolved upstream URL for this backend’s endpoint.

Tolerates base URLs that already include the provider path (or a bare /v1), matching the join rules of the existing native backends.

pub fn apply_auth(&self, builder: RequestBuilder) -> RequestBuilder

Applies this backend’s configured auth and version headers to a request builder.

OpenAI variants use Authorization: Bearer <key>; Anthropic uses x-api-key: <key> plus the required anthropic-version header. A backend with forward_auth uses the caller’s provider credential instead.

pub fn extra_headers(&self) -> &BTreeMap<String, String>

Custom per-backend headers to forward on every call.

pub fn extra_body(&self) -> &BTreeMap<String, Value>

Default top-level fields to merge into outbound request bodies.

pub fn omit_body_fields(&self) -> &BTreeSet<String>

Top-level fields dropped from outbound request bodies before extra_body is merged.

pub fn reasoning_effort(&self) -> Option<&str>

Reasoning effort forced on outbound requests, if the target configures one.

pub fn max_retries(&self) -> u32

Additional attempts allowed after the initial request.

pub fn failure_cooldown(&self) -> Duration

Cooldown after an exhausted transient completion failure.

pub fn timeout(&self) -> Option<Duration>

Deadline for all attempts and the complete response; None leaves the wait unbounded.

pub fn is_anthropic(&self) -> bool

Whether this backend speaks the Anthropic Messages wire format — the only one with a count_tokens endpoint.

pub fn count_tokens_url(&self) -> String

The upstream /v1/messages/count_tokens URL, derived from the same base URL join as url.

Trait Implementations

impl Clone for Backend

fn clone(&self) -> Backend

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Backend

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.