Skip to content

add lingua_passthrough to router metadata #353

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Ken Jiang (knjiang) merged 7 commits into from
Jul 13, 2026
Merged

add lingua_passthrough to router metadata #353

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
ed5d722
bump
ankrgyl Jul 12, 2026
ad614a3
Merge branch 'main' into remove-forced-translation
ankrgyl Jul 12, 2026
ae9e9e7
Merge branch 'main' into remove-forced-translation
knjiang Jul 13, 2026
be73aab
we should always upgrade to responses
knjiang Jul 13, 2026
2157b99
add lingua_passthrough to router metadata
knjiang Jul 13, 2026
6120782
fixxxx
knjiang Jul 13, 2026
a635219
Merge branch 'main' into ken/lingua-passthrough
knjiang Jul 13, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
49 changes: 33 additions & 16 deletions crates/braintrust-llm-router/src/router.rs
View file
Open in desktop
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)> {
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));
}

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),

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 13, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

P2 Badge Distinguish unsupported targets from Lingua pass-through

When the target has no Lingua adapter (for example, ProviderFormat::Mistral is not registered in the adapter registry), transform_request returns UnsupportedTargetFormat after detection, not TransformResult::PassThrough. Marking this as lingua_passthrough = true makes observability report a validated Lingua pass-through even when the router is merely falling back to forwarding the original body unchanged, so unsupported-target fallbacks cannot be separated from real same-format pass-throughs.

Useful? React with 👍 / 👎.

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
Loading