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Merged
Ken Jiang (knjiang) merged 2 commits into from
Jul 13, 2026
+37 −20
Merged

add lingua_passthrough to router metadata #352

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2157b99
add lingua_passthrough to router metadata
knjiang Jul 13, 2026
6120782
fixxxx
knjiang Jul 13, 2026
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49 changes: 33 additions & 16 deletions crates/braintrust-llm-router/src/router.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,9 @@ pub struct RouterMetadata {
/// that was detected.
pub detected_input_format: ProviderFormat,

/// Whether Lingua forwarded the request body without transforming it.
pub lingua_passthrough: bool,

/// The alias of the provider that was used to execute the request.
pub provider_alias: String,

Expand Down Expand Up @@ -228,22 +231,28 @@ async fn prepare_provider_request(
format: ProviderFormat,
stream: bool,
options: RequestPreparationOptions,
) -> Result<(Bytes, Option<ProviderFormat>, ProviderFormat)> {
) -> Result<(Bytes, Option<ProviderFormat>, ProviderFormat, bool)> {
Comment thread
knjiang marked this conversation as resolved.
if requires_bedrock_request_preparation(format) {
let bytes = prepare_bedrock_request(body, spec, format).await?;
return Ok((bytes, Some(format), format));
return Ok((bytes, Some(format), format, false));
Comment thread
knjiang marked this conversation as resolved.
}

let model_override = options.rewrite_body_model.then_some(spec.model.as_str());
let (transformed, detected_format, actual_format, maybe_rewrite_model) =
let (transformed, detected_format, actual_format, maybe_rewrite_model, lingua_passthrough) =
match lingua::transform_request(body.clone(), format, model_override) {
Ok(TransformResult::PassThrough(bytes)) => (bytes, None, format, true),
Ok(TransformResult::PassThrough(bytes)) => (bytes, None, format, true, true),
Ok(TransformResult::Transformed {
bytes,
source_format,
actual_target_format,
}) => (bytes, Some(source_format), actual_target_format, false),
Err(TransformError::UnsupportedTargetFormat(_)) => (body, None, format, true),
}) => (
bytes,
Some(source_format),
actual_target_format,
false,
false,
),
Err(TransformError::UnsupportedTargetFormat(_)) => (body, None, format, true, true),
Err(err) => return Err(err.into()),
};

Expand All @@ -260,9 +269,15 @@ async fn prepare_provider_request(
enable_streaming_payload(transformed, actual_format),
detected_format,
actual_format,
lingua_passthrough,
))
} else {
Ok((transformed, detected_format, actual_format))
Ok((
transformed,
detected_format,
actual_format,
lingua_passthrough,
))
}
}

Expand Down Expand Up @@ -293,7 +308,7 @@ impl Router {
stream: bool,
options: RequestPreparationOptions,
) -> Result<(PreparedRequestInner, RouterMetadata)> {
let (payload, detected_format, actual_format) =
let (payload, detected_format, actual_format, lingua_passthrough) =
prepare_provider_request(body, route.spec.as_ref(), route.format, stream, options)
.await?;
Ok((
Expand All @@ -308,6 +323,7 @@ impl Router {
},
RouterMetadata {
detected_input_format: detected_format.unwrap_or(route.format),
lingua_passthrough,
provider_alias: route.provider_alias.clone(),
provider_format: actual_format,
},
Expand Down Expand Up @@ -1514,7 +1530,7 @@ mod tests {
);
let spec = openai_spec("gpt-5-mini", ModelFlavor::Chat);

let (payload, _, _) = prepare_provider_request(
let (payload, _, _, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand All @@ -1537,7 +1553,7 @@ mod tests {
);
let spec = openai_spec("gpt-5-mini", ModelFlavor::Chat);

let (payload, _, _) = prepare_provider_request(
let (payload, _, _, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand Down Expand Up @@ -1575,7 +1591,7 @@ mod tests {
available_providers: vec!["vertex".to_string()],
};

let (payload, _, actual_format) = prepare_provider_request(
let (payload, _, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::VertexAnthropic,
Expand Down Expand Up @@ -1615,7 +1631,7 @@ mod tests {
available_providers: vec!["google".to_string()],
};

let (payload, _, actual_format) = prepare_provider_request(
let (payload, _, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::Google,
Expand All @@ -1642,7 +1658,7 @@ mod tests {
);
let spec = openai_spec("gpt-4o", ModelFlavor::Chat);

let (payload, _, actual_format) = prepare_provider_request(
let (payload, _, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand All @@ -1668,7 +1684,7 @@ mod tests {
);
let spec = openai_spec("gpt-4o", ModelFlavor::Chat);

let (payload, _, actual_format) = prepare_provider_request(
let (payload, _, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand Down Expand Up @@ -1696,7 +1712,7 @@ mod tests {
);
let spec = openai_spec("gpt-4o", ModelFlavor::Chat);

let (payload, detected_format, actual_format) = prepare_provider_request(
let (payload, detected_format, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand Down Expand Up @@ -1744,7 +1760,7 @@ mod tests {
);
let spec = openai_spec("gpt-5.4-mini", ModelFlavor::Chat);

let (_, _, actual_format) = prepare_provider_request(
let (_, _, actual_format, _) = prepare_provider_request(
body,
&spec,
ProviderFormat::ChatCompletions,
Expand Down Expand Up @@ -1948,6 +1964,7 @@ mod tests {
metadata.detected_input_format,
ProviderFormat::ChatCompletions
);
assert!(!metadata.lingua_passthrough);
assert_eq!(metadata.provider_format, ProviderFormat::Google);
assert_eq!(request.inner.format, ProviderFormat::Google);
assert_ne!(request.inner.payload, body);
Expand Down
8 changes: 4 additions & 4 deletions crates/braintrust-llm-router/tests/router.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -152,10 +152,10 @@ async fn router_routes_to_stub_provider() {
]
}));

let (request, _metadata) =
create_request(&router, body, model, ProviderFormat::ChatCompletions)
.await
.expect("create request");
let (request, metadata) = create_request(&router, body, model, ProviderFormat::ChatCompletions)
.await
.expect("create request");
assert!(metadata.lingua_passthrough);
let bytes: Bytes = router
.complete(request, &ClientHeaders::default())
.await
Expand Down
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