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use super::{
AppState, MAX_BODY_BYTES, MessageCall, ProviderError, RequestContext, StreamingDeploymentLease,
native_usage, settle, valid_message_envelope,
};
use crate::core::providers::base::sse::{AnthropicTransformer, SSETransformer};
use crate::server::guardrails::{GuardrailDecisionSink, messages_projection};
use crate::server::routes::ai::stream_output_guardrail::StreamOutputGuardrail;
use actix_web::HttpResponse;
use bytes::Bytes;
use futures::StreamExt;
use serde_json::{Value, json};
use tokio::sync::mpsc;
use tokio_stream::wrappers::ReceiverStream;
pub(super) fn response(
state: AppState,
context: RequestContext,
call: MessageCall,
lease: StreamingDeploymentLease,
) -> HttpResponse {
let (tx, rx) = mpsc::channel::<Bytes>(8);
let facts = crate::core::request_ledger::current_facts();
tokio::spawn(async move {
let MessageCall {
mut response,
callback,
provider,
model,
deployment,
pricing,
reservation,
key_reservation,
require_inference_geo,
} = call;
let sink = GuardrailDecisionSink::from_state(
&state,
Some(&model),
Some(&provider),
Some(&deployment),
);
let mut guard = StreamOutputGuardrail::new(state.guardrails()).with_decision_sink(sink);
let validator = AnthropicTransformer::new(&model);
let mut pending = Vec::new();
let mut usage = json!({});
let mut started = false;
let mut terminal = false;
let mut upstream_failed = false;
let mut final_usage = false;
let mut terminal_reason = false;
let mut failure = None;
let idle = state.config().gateway.server.stream_idle_timeout;
'upstream: loop {
let chunk = tokio::select! {
biased;
_ = tx.closed() => break,
chunk = async {
if idle == 0 { Ok(response.chunk().await) } else {
tokio::time::timeout(std::time::Duration::from_secs(idle), response.chunk()).await
}
} => match chunk {
Ok(chunk) => chunk,
Err(_) => { failure = Some(ProviderError::timeout("anthropic", "Messages stream idle timeout")); break; }
}
};
match chunk {
Ok(Some(chunk)) => {
if pending.len().saturating_add(chunk.len()) > MAX_BODY_BYTES {
failure = Some(invalid("Messages SSE buffer exceeds size limit"));
break;
}
pending.extend_from_slice(&chunk);
while let Some(frame) = next_frame(&mut pending) {
let value = match event(&frame) {
Ok(Some(value)) => value,
Ok(None) => {
if tx.send(frame).await.is_err() {
break 'upstream;
}
continue;
}
Err(error) => {
failure = Some(error);
break 'upstream;
}
};
let kind = value
.get("type")
.and_then(Value::as_str)
.unwrap_or_default();
if kind != "error" {
// Reuse the provider's tested lifecycle validation; emit the
// original frame, never the transformer's Chat chunk.
if let Err(error) = validator.transform_stream_chunk(&value.to_string())
{
failure = Some(error);
break 'upstream;
}
}
match kind {
"message_start" => {
if started {
failure = Some(invalid("Duplicate message_start"));
break 'upstream;
}
if !value.get("message").is_some_and(valid_message_envelope) {
failure = Some(invalid("Invalid message_start envelope"));
break 'upstream;
}
started = true;
usage = value
.pointer("/message/usage")
.cloned()
.unwrap_or(Value::Null);
}
"message_delta" => {
if !started {
failure = Some(invalid("message_delta before message_start"));
break 'upstream;
}
let ends_message = value
.pointer("/delta/stop_reason")
.and_then(Value::as_str)
.is_some_and(|reason| !reason.is_empty());
if let Some(delta) = value.get("usage") {
if delta.is_object() {
merge_usage(&mut usage, delta);
} else {
usage = Value::Null;
}
}
if ends_message {
terminal_reason = true;
final_usage = value
.pointer("/usage/output_tokens")
.and_then(Value::as_u64)
.is_some()
&& native_usage(&usage, require_inference_geo).is_some();
}
}
"message_stop" => {
if !started {
failure = Some(invalid("message_stop before message_start"));
break 'upstream;
}
if !terminal_reason {
failure = Some(invalid(
"Messages stream has no terminal stop reason",
));
break 'upstream;
}
if !final_usage
|| native_usage(&usage, require_inference_geo).is_none()
{
failure =
Some(invalid("Messages stream has no valid final usage"));
break 'upstream;
}
terminal = true;
}
"error" => {
terminal = true;
upstream_failed = true;
}
_ => {}
}
let mut surfaces = vec![(u32::MAX, messages_projection(&value))];
if kind == "content_block_delta" {
let Some(index) = value
.get("index")
.and_then(Value::as_u64)
.and_then(|v| u32::try_from(v).ok())
.filter(|v| *v != u32::MAX)
else {
failure = Some(invalid("Invalid content block index"));
break 'upstream;
};
for field in ["text", "thinking", "partial_json"] {
if let Some(text) = value
.get("delta")
.and_then(|v| v.get(field))
.and_then(Value::as_str)
{
surfaces.push((index, text.to_string()));
}
}
}
match guard.push_many_until_closed(&tx, surfaces, frame).await {
Ok(Some(events)) => {
for event in events {
if tx.send(event).await.is_err() {
break 'upstream;
}
}
}
Ok(None) => break 'upstream,
Err(error) => {
failure = Some(ProviderError::api_error(
"guardrail",
403,
error.message(),
));
break 'upstream;
}
}
if matches!(kind, "ping" | "message_start") {
match guard.flush_to_until_closed(&tx).await {
Ok(Some(_)) => {}
Ok(None) => break 'upstream,
Err(error) => {
failure = Some(ProviderError::api_error(
"guardrail",
403,
error.message(),
));
break 'upstream;
}
}
}
if terminal {
break 'upstream;
}
}
}
Ok(None) => {
if !terminal {
failure = Some(invalid("Messages stream ended before message_stop"));
}
break;
}
Err(_) => {
failure = Some(ProviderError::network(
"anthropic",
"Messages stream interrupted",
));
break;
}
}
}
if terminal
&& failure.is_none()
&& let Err(error) = guard.flush_to_until_closed(&tx).await
{
failure = Some(ProviderError::api_error("guardrail", 403, error.message()));
}
let usage = (terminal && final_usage && !upstream_failed)
.then(|| native_usage(&usage, require_inference_geo))
.flatten();
settle(
&state,
&context,
&provider,
&model,
pricing,
usage.as_ref(),
reservation,
key_reservation,
facts,
)
.await;
if let Some(error) = failure {
callback.fail(error.to_string(), "stream_error");
let blocked = matches!(
error,
ProviderError::ApiError {
provider: "guardrail",
..
}
);
if blocked {
drop(lease);
} else {
lease.finish_failure(&error);
}
let kind = if blocked {
"permission_error"
} else {
"api_error"
};
let event = json!({"type":"error", "error":{"type":kind,"message":error.redacted().to_string()}});
let _ = tx
.send(Bytes::from(format!("event: error\ndata: {event}\n\n")))
.await;
} else if upstream_failed {
callback.fail("Upstream Messages stream failed", "provider_error");
lease.finish_failure(&ProviderError::api_error(
"anthropic",
502,
"Upstream Messages stream failed",
));
} else if terminal {
callback.complete_pricing_usage(
usage.as_ref().map(|u| &u.normalized),
usage.as_ref().map(|u| &u.pricing),
"success",
);
lease.finish_success(
usage
.as_ref()
.map_or(0, |u| u64::from(u.normalized.total_tokens)),
);
} else {
callback.fail("Client disconnected", "client_disconnect");
}
});
HttpResponse::Ok()
.insert_header(("content-type", "text/event-stream"))
.insert_header(("cache-control", "no-cache"))
.streaming(ReceiverStream::new(rx).map(Ok::<_, actix_web::Error>))
}
fn invalid(message: &str) -> ProviderError {
ProviderError::response_parsing("anthropic", message)
}
fn next_frame(pending: &mut Vec<u8>) -> Option<Bytes> {
let lf = pending.windows(2).position(|w| w == b"\n\n").map(|p| p + 2);
let crlf = pending
.windows(4)
.position(|w| w == b"\r\n\r\n")
.map(|p| p + 4);
let end = lf.into_iter().chain(crlf).min()?;
Some(Bytes::from(pending.drain(..end).collect::<Vec<_>>()))
}
fn event(frame: &[u8]) -> Result<Option<Value>, ProviderError> {
let text = std::str::from_utf8(frame).map_err(|_| invalid("Invalid Messages SSE UTF-8"))?;
let data = text
.lines()
.filter_map(|line| {
line.strip_prefix("data:")
.map(|v| v.strip_prefix(' ').unwrap_or(v))
})
.collect::<Vec<_>>()
.join("\n");
if data.is_empty() {
return Ok(None);
}
serde_json::from_str(&data)
.map(Some)
.map_err(|_| invalid("Invalid Messages SSE JSON"))
}
fn merge_usage(target: &mut Value, delta: &Value) {
if let (Some(target), Some(delta)) = (target.as_object_mut(), delta.as_object()) {
for (key, value) in delta {
if value.is_object() && target.get(key).is_some_and(Value::is_object) {
merge_usage(&mut target[key], value);
} else {
target.insert(key.clone(), value.clone());
}
}
}
}