Files
CC-Switch/src-tauri/src/proxy/providers/streaming.rs
T
Cod1ng dc4524e960 fix: handle UTF-8 multi-byte characters split across stream chunk boundaries (#1923)
* fix: handle UTF-8 multi-byte characters split across stream chunk boundaries

Replace String::from_utf8_lossy with append_utf8_safe in all four SSE
streaming paths. When a multi-byte UTF-8 character (e.g. Chinese, emoji)
is split across TCP chunk boundaries, from_utf8_lossy silently replaces
the incomplete halves with U+FFFD (�). This caused intermittent garbled
output in Claude Code when using the Copilot reverse proxy, because the
format conversion streams reconstruct SSE events from the corrupted buffer.

The new append_utf8_safe function preserves incomplete trailing bytes in
a remainder buffer and merges them with the next chunk before decoding,
ensuring characters are never split during UTF-8 conversion.

Fixes: intermittent U+FFFD replacement characters in Claude Code output
via Copilot proxy (not reproducible with direct Copilot connections like
opencode because they pass through raw bytes without format conversion).

* style: fix cargo fmt formatting in UTF-8 boundary tests

---------

Co-authored-by: Cod1ng <codingts@gmail.com>
Co-authored-by: encodets <encodets@gmail.com>
2026-04-08 10:02:35 +08:00

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//! 流式响应转换模块
//!
//! 实现 OpenAI SSE → Anthropic SSE 格式转换
use crate::proxy::sse::strip_sse_field;
use bytes::Bytes;
use futures::stream::{Stream, StreamExt};
use serde::{Deserialize, Serialize};
use serde_json::json;
use std::collections::{HashMap, HashSet};
/// OpenAI 流式响应数据结构
#[derive(Debug, Deserialize)]
struct OpenAIStreamChunk {
id: String,
model: String,
choices: Vec<StreamChoice>,
#[serde(default)]
usage: Option<Usage>,
}
#[derive(Debug, Deserialize)]
struct StreamChoice {
delta: Delta,
#[serde(default)]
finish_reason: Option<String>,
}
#[derive(Debug, Deserialize)]
struct Delta {
#[serde(default)]
content: Option<String>,
#[serde(default)]
reasoning: Option<String>, // OpenRouter 的推理内容
#[serde(default)]
tool_calls: Option<Vec<DeltaToolCall>>,
}
#[derive(Debug, Deserialize, Serialize)]
struct DeltaToolCall {
index: usize,
#[serde(default)]
id: Option<String>,
#[serde(rename = "type", default)]
call_type: Option<String>,
#[serde(default)]
function: Option<DeltaFunction>,
}
#[derive(Debug, Deserialize, Serialize)]
struct DeltaFunction {
#[serde(default)]
name: Option<String>,
#[serde(default)]
arguments: Option<String>,
}
/// OpenAI 流式响应的 usage 信息(完整版)
#[derive(Debug, Deserialize)]
struct Usage {
#[serde(default)]
prompt_tokens: u32,
#[serde(default)]
completion_tokens: u32,
#[serde(default)]
prompt_tokens_details: Option<PromptTokensDetails>,
/// Some compatible servers return Anthropic-style cache fields directly
#[serde(default)]
cache_read_input_tokens: Option<u32>,
#[serde(default)]
cache_creation_input_tokens: Option<u32>,
}
/// Nested token details from OpenAI format
#[derive(Debug, Deserialize)]
struct PromptTokensDetails {
#[serde(default)]
cached_tokens: u32,
}
#[derive(Debug, Clone)]
struct ToolBlockState {
anthropic_index: u32,
id: String,
name: String,
started: bool,
pending_args: String,
}
/// 创建 Anthropic SSE 流
pub fn create_anthropic_sse_stream<E: std::error::Error + Send + 'static>(
stream: impl Stream<Item = Result<Bytes, E>> + Send + 'static,
) -> impl Stream<Item = Result<Bytes, std::io::Error>> + Send {
async_stream::stream! {
let mut buffer = String::new();
let mut utf8_remainder: Vec<u8> = Vec::new();
let mut message_id = None;
let mut current_model = None;
let mut next_content_index: u32 = 0;
let mut has_sent_message_start = false;
let mut current_non_tool_block_type: Option<&'static str> = None;
let mut current_non_tool_block_index: Option<u32> = None;
let mut tool_blocks_by_index: HashMap<usize, ToolBlockState> = HashMap::new();
let mut open_tool_block_indices: HashSet<u32> = HashSet::new();
tokio::pin!(stream);
while let Some(chunk) = stream.next().await {
match chunk {
Ok(bytes) => {
crate::proxy::sse::append_utf8_safe(&mut buffer, &mut utf8_remainder, &bytes);
while let Some(pos) = buffer.find("\n\n") {
let line = buffer[..pos].to_string();
buffer = buffer[pos + 2..].to_string();
if line.trim().is_empty() {
continue;
}
for l in line.lines() {
if let Some(data) = strip_sse_field(l, "data") {
if data.trim() == "[DONE]" {
log::debug!("[Claude/OpenRouter] <<< OpenAI SSE: [DONE]");
let event = json!({"type": "message_stop"});
let sse_data = format!("event: message_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
log::debug!("[Claude/OpenRouter] >>> Anthropic SSE: message_stop");
yield Ok(Bytes::from(sse_data));
continue;
}
if let Ok(chunk) = serde_json::from_str::<OpenAIStreamChunk>(data) {
log::debug!("[Claude/OpenRouter] <<< SSE chunk received");
if message_id.is_none() {
message_id = Some(chunk.id.clone());
}
if current_model.is_none() {
current_model = Some(chunk.model.clone());
}
if let Some(choice) = chunk.choices.first() {
if !has_sent_message_start {
// Build usage with cache tokens if available from first chunk
let mut start_usage = json!({
"input_tokens": 0,
"output_tokens": 0
});
if let Some(u) = &chunk.usage {
start_usage["input_tokens"] = json!(u.prompt_tokens);
if let Some(cached) = extract_cache_read_tokens(u) {
start_usage["cache_read_input_tokens"] = json!(cached);
}
if let Some(created) = u.cache_creation_input_tokens {
start_usage["cache_creation_input_tokens"] = json!(created);
}
}
let event = json!({
"type": "message_start",
"message": {
"id": message_id.clone().unwrap_or_default(),
"type": "message",
"role": "assistant",
"model": current_model.clone().unwrap_or_default(),
"usage": start_usage
}
});
let sse_data = format!("event: message_start\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
has_sent_message_start = true;
}
// 处理 reasoningthinking
if let Some(reasoning) = &choice.delta.reasoning {
if current_non_tool_block_type != Some("thinking") {
if let Some(index) = current_non_tool_block_index.take() {
let event = json!({
"type": "content_block_stop",
"index": index
});
let sse_data = format!("event: content_block_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
let index = next_content_index;
next_content_index += 1;
let event = json!({
"type": "content_block_start",
"index": index,
"content_block": {
"type": "thinking",
"thinking": ""
}
});
let sse_data = format!("event: content_block_start\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
current_non_tool_block_type = Some("thinking");
current_non_tool_block_index = Some(index);
}
if let Some(index) = current_non_tool_block_index {
let event = json!({
"type": "content_block_delta",
"index": index,
"delta": {
"type": "thinking_delta",
"thinking": reasoning
}
});
let sse_data = format!("event: content_block_delta\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
}
// 处理文本内容
if let Some(content) = &choice.delta.content {
if !content.is_empty() {
if current_non_tool_block_type != Some("text") {
if let Some(index) = current_non_tool_block_index.take() {
let event = json!({
"type": "content_block_stop",
"index": index
});
let sse_data = format!("event: content_block_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
let index = next_content_index;
next_content_index += 1;
let event = json!({
"type": "content_block_start",
"index": index,
"content_block": {
"type": "text",
"text": ""
}
});
let sse_data = format!("event: content_block_start\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
current_non_tool_block_type = Some("text");
current_non_tool_block_index = Some(index);
}
if let Some(index) = current_non_tool_block_index {
let event = json!({
"type": "content_block_delta",
"index": index,
"delta": {
"type": "text_delta",
"text": content
}
});
let sse_data = format!("event: content_block_delta\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
}
}
// 处理工具调用
if let Some(tool_calls) = &choice.delta.tool_calls {
if let Some(index) = current_non_tool_block_index.take() {
let event = json!({
"type": "content_block_stop",
"index": index
});
let sse_data = format!("event: content_block_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
current_non_tool_block_type = None;
for tool_call in tool_calls {
let (
anthropic_index,
id,
name,
should_start,
pending_after_start,
immediate_delta,
) = {
let state = tool_blocks_by_index
.entry(tool_call.index)
.or_insert_with(|| {
let index = next_content_index;
next_content_index += 1;
ToolBlockState {
anthropic_index: index,
id: String::new(),
name: String::new(),
started: false,
pending_args: String::new(),
}
});
if let Some(id) = &tool_call.id {
state.id = id.clone();
}
if let Some(function) = &tool_call.function {
if let Some(name) = &function.name {
state.name = name.clone();
}
}
let should_start =
!state.started
&& !state.id.is_empty()
&& !state.name.is_empty();
if should_start {
state.started = true;
}
let pending_after_start = if should_start
&& !state.pending_args.is_empty()
{
Some(std::mem::take(&mut state.pending_args))
} else {
None
};
let args_delta = tool_call
.function
.as_ref()
.and_then(|f| f.arguments.clone());
let immediate_delta = if let Some(args) = args_delta {
if state.started {
Some(args)
} else {
state.pending_args.push_str(&args);
None
}
} else {
None
};
(
state.anthropic_index,
state.id.clone(),
state.name.clone(),
should_start,
pending_after_start,
immediate_delta,
)
};
if should_start {
let event = json!({
"type": "content_block_start",
"index": anthropic_index,
"content_block": {
"type": "tool_use",
"id": id,
"name": name
}
});
let sse_data = format!("event: content_block_start\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
open_tool_block_indices.insert(anthropic_index);
}
if let Some(args) = pending_after_start {
let event = json!({
"type": "content_block_delta",
"index": anthropic_index,
"delta": {
"type": "input_json_delta",
"partial_json": args
}
});
let sse_data = format!("event: content_block_delta\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
if let Some(args) = immediate_delta {
let event = json!({
"type": "content_block_delta",
"index": anthropic_index,
"delta": {
"type": "input_json_delta",
"partial_json": args
}
});
let sse_data = format!("event: content_block_delta\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
}
}
// 处理 finish_reason
if let Some(finish_reason) = &choice.finish_reason {
if let Some(index) = current_non_tool_block_index.take() {
let event = json!({
"type": "content_block_stop",
"index": index
});
let sse_data = format!("event: content_block_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
current_non_tool_block_type = None;
// Late start for blocks that accumulated args before id/name arrived.
let mut late_tool_starts: Vec<(u32, String, String, String)> =
Vec::new();
for (tool_idx, state) in tool_blocks_by_index.iter_mut() {
if state.started {
continue;
}
let has_payload = !state.pending_args.is_empty()
|| !state.id.is_empty()
|| !state.name.is_empty();
if !has_payload {
continue;
}
let fallback_id = if state.id.is_empty() {
format!("tool_call_{tool_idx}")
} else {
state.id.clone()
};
let fallback_name = if state.name.is_empty() {
"unknown_tool".to_string()
} else {
state.name.clone()
};
state.started = true;
let pending = std::mem::take(&mut state.pending_args);
late_tool_starts.push((
state.anthropic_index,
fallback_id,
fallback_name,
pending,
));
}
late_tool_starts.sort_unstable_by_key(|(index, _, _, _)| *index);
for (index, id, name, pending) in late_tool_starts {
let event = json!({
"type": "content_block_start",
"index": index,
"content_block": {
"type": "tool_use",
"id": id,
"name": name
}
});
let sse_data = format!("event: content_block_start\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
open_tool_block_indices.insert(index);
if !pending.is_empty() {
let delta_event = json!({
"type": "content_block_delta",
"index": index,
"delta": {
"type": "input_json_delta",
"partial_json": pending
}
});
let delta_sse = format!("event: content_block_delta\ndata: {}\n\n",
serde_json::to_string(&delta_event).unwrap_or_default());
yield Ok(Bytes::from(delta_sse));
}
}
if !open_tool_block_indices.is_empty() {
let mut tool_indices: Vec<u32> =
open_tool_block_indices.iter().copied().collect();
tool_indices.sort_unstable();
for index in tool_indices {
let event = json!({
"type": "content_block_stop",
"index": index
});
let sse_data = format!("event: content_block_stop\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
open_tool_block_indices.clear();
}
let stop_reason = map_stop_reason(Some(finish_reason));
// Build usage with cache token fields
let usage_json = chunk.usage.as_ref().map(|u| {
let mut uj = json!({
"input_tokens": u.prompt_tokens,
"output_tokens": u.completion_tokens
});
if let Some(cached) = extract_cache_read_tokens(u) {
uj["cache_read_input_tokens"] = json!(cached);
}
if let Some(created) = u.cache_creation_input_tokens {
uj["cache_creation_input_tokens"] = json!(created);
}
uj
});
let event = json!({
"type": "message_delta",
"delta": {
"stop_reason": stop_reason,
"stop_sequence": null
},
"usage": usage_json
});
let sse_data = format!("event: message_delta\ndata: {}\n\n",
serde_json::to_string(&event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
}
}
}
}
}
}
}
Err(e) => {
log::error!("Stream error: {e}");
let error_event = json!({
"type": "error",
"error": {
"type": "stream_error",
"message": format!("Stream error: {e}")
}
});
let sse_data = format!("event: error\ndata: {}\n\n",
serde_json::to_string(&error_event).unwrap_or_default());
yield Ok(Bytes::from(sse_data));
break;
}
}
}
}
}
/// Extract cache_read tokens from Usage, checking both direct field and nested details
fn extract_cache_read_tokens(usage: &Usage) -> Option<u32> {
// Direct field takes priority (compatible servers)
if let Some(v) = usage.cache_read_input_tokens {
return Some(v);
}
// OpenAI standard: prompt_tokens_details.cached_tokens
usage
.prompt_tokens_details
.as_ref()
.map(|d| d.cached_tokens)
.filter(|&v| v > 0)
}
/// 映射停止原因
fn map_stop_reason(finish_reason: Option<&str>) -> Option<String> {
finish_reason.map(|r| {
match r {
"tool_calls" | "function_call" => "tool_use",
"stop" => "end_turn",
"length" => "max_tokens",
"content_filter" => "end_turn",
other => {
log::warn!("[Claude/OpenRouter] Unknown finish_reason in streaming: {other}");
"end_turn"
}
}
.to_string()
})
}
#[cfg(test)]
mod tests {
use super::*;
use futures::stream;
use futures::StreamExt;
use serde_json::Value;
use std::collections::HashMap;
#[test]
fn test_map_stop_reason_legacy_and_filtered_values() {
assert_eq!(
map_stop_reason(Some("function_call")),
Some("tool_use".to_string())
);
assert_eq!(
map_stop_reason(Some("content_filter")),
Some("end_turn".to_string())
);
}
#[tokio::test]
async fn test_streaming_tool_calls_routed_by_index() {
let input = concat!(
"data: {\"id\":\"chatcmpl_1\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"call_0\",\"type\":\"function\",\"function\":{\"name\":\"first_tool\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_1\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":1,\"id\":\"call_1\",\"type\":\"function\",\"function\":{\"name\":\"second_tool\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_1\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":1,\"function\":{\"arguments\":\"{\\\"b\\\":2}\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_1\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"{\\\"a\\\":1}\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_1\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{},\"finish_reason\":\"tool_calls\"}],\"usage\":{\"prompt_tokens\":8,\"completion_tokens\":4}}\n\n",
"data: [DONE]\n\n"
);
let upstream = stream::iter(vec![Ok::<_, std::io::Error>(Bytes::from(
input.as_bytes().to_vec(),
))]);
let converted = create_anthropic_sse_stream(upstream);
let chunks: Vec<_> = converted.collect().await;
let merged = chunks
.into_iter()
.map(|chunk| String::from_utf8_lossy(chunk.unwrap().as_ref()).to_string())
.collect::<String>();
let events: Vec<Value> = merged
.split("\n\n")
.filter_map(|block| {
let data = block
.lines()
.find_map(|line| strip_sse_field(line, "data"))?;
serde_json::from_str::<Value>(data).ok()
})
.collect();
let mut tool_index_by_call: HashMap<String, u64> = HashMap::new();
for event in &events {
if event.get("type").and_then(|v| v.as_str()) == Some("content_block_start")
&& event
.pointer("/content_block/type")
.and_then(|v| v.as_str())
== Some("tool_use")
{
if let (Some(call_id), Some(index)) = (
event.pointer("/content_block/id").and_then(|v| v.as_str()),
event.get("index").and_then(|v| v.as_u64()),
) {
tool_index_by_call.insert(call_id.to_string(), index);
}
}
}
assert_eq!(tool_index_by_call.len(), 2);
assert_ne!(
tool_index_by_call.get("call_0"),
tool_index_by_call.get("call_1")
);
let deltas: Vec<(u64, String)> = events
.iter()
.filter(|event| {
event.get("type").and_then(|v| v.as_str()) == Some("content_block_delta")
&& event.pointer("/delta/type").and_then(|v| v.as_str())
== Some("input_json_delta")
})
.filter_map(|event| {
let index = event.get("index").and_then(|v| v.as_u64())?;
let partial_json = event
.pointer("/delta/partial_json")
.and_then(|v| v.as_str())?
.to_string();
Some((index, partial_json))
})
.collect();
assert_eq!(deltas.len(), 2);
let second_idx = deltas
.iter()
.find_map(|(index, payload)| (payload == "{\"b\":2}").then_some(*index))
.unwrap();
let first_idx = deltas
.iter()
.find_map(|(index, payload)| (payload == "{\"a\":1}").then_some(*index))
.unwrap();
assert_eq!(second_idx, *tool_index_by_call.get("call_1").unwrap());
assert_eq!(first_idx, *tool_index_by_call.get("call_0").unwrap());
assert!(events.iter().any(|event| {
event.get("type").and_then(|v| v.as_str()) == Some("message_delta")
&& event.pointer("/delta/stop_reason").and_then(|v| v.as_str()) == Some("tool_use")
}));
}
#[tokio::test]
async fn test_streaming_delays_tool_start_until_id_and_name_ready() {
let input = concat!(
"data: {\"id\":\"chatcmpl_2\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"{\\\"a\\\":\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_2\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"call_0\",\"type\":\"function\",\"function\":{\"name\":\"first_tool\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_2\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"1}\"}}]}}]}\n\n",
"data: {\"id\":\"chatcmpl_2\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{},\"finish_reason\":\"tool_calls\"}],\"usage\":{\"prompt_tokens\":6,\"completion_tokens\":2}}\n\n",
"data: [DONE]\n\n"
);
let upstream = stream::iter(vec![Ok::<_, std::io::Error>(Bytes::from(
input.as_bytes().to_vec(),
))]);
let converted = create_anthropic_sse_stream(upstream);
let chunks: Vec<_> = converted.collect().await;
let merged = chunks
.into_iter()
.map(|chunk| String::from_utf8_lossy(chunk.unwrap().as_ref()).to_string())
.collect::<String>();
let events: Vec<Value> = merged
.split("\n\n")
.filter_map(|block| {
let data = block
.lines()
.find_map(|line| strip_sse_field(line, "data"))?;
serde_json::from_str::<Value>(data).ok()
})
.collect();
let starts: Vec<&Value> = events
.iter()
.filter(|event| {
event.get("type").and_then(|v| v.as_str()) == Some("content_block_start")
&& event
.pointer("/content_block/type")
.and_then(|v| v.as_str())
== Some("tool_use")
})
.collect();
assert_eq!(starts.len(), 1);
assert_eq!(
starts[0]
.pointer("/content_block/id")
.and_then(|v| v.as_str())
.unwrap_or(""),
"call_0"
);
assert_eq!(
starts[0]
.pointer("/content_block/name")
.and_then(|v| v.as_str())
.unwrap_or(""),
"first_tool"
);
let deltas: Vec<&str> = events
.iter()
.filter(|event| {
event.get("type").and_then(|v| v.as_str()) == Some("content_block_delta")
&& event.pointer("/delta/type").and_then(|v| v.as_str())
== Some("input_json_delta")
})
.filter_map(|event| {
event
.pointer("/delta/partial_json")
.and_then(|v| v.as_str())
})
.collect();
assert!(deltas.contains(&"{\"a\":"));
assert!(deltas.contains(&"1}"));
}
#[tokio::test]
async fn test_streaming_chinese_split_across_chunks_no_replacement_chars() {
// "你好" split across two TCP chunks inside a streaming text delta.
// Before the fix, from_utf8_lossy would produce U+FFFD for each half.
let full = concat!(
"data: {\"id\":\"chatcmpl_3\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"content\":\"你好\"}}]}\n\n",
"data: {\"id\":\"chatcmpl_3\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{},\"finish_reason\":\"stop\"}],\"usage\":{\"prompt_tokens\":5,\"completion_tokens\":2}}\n\n",
"data: [DONE]\n\n"
);
let bytes = full.as_bytes();
// Find "你" in the byte stream and split inside it
let ni_start = bytes.windows(3).position(|w| w == "".as_bytes()).unwrap();
let split_point = ni_start + 1; // split after first byte of "你"
let chunk1 = Bytes::from(bytes[..split_point].to_vec());
let chunk2 = Bytes::from(bytes[split_point..].to_vec());
let upstream = stream::iter(vec![
Ok::<_, std::io::Error>(chunk1),
Ok::<_, std::io::Error>(chunk2),
]);
let converted = create_anthropic_sse_stream(upstream);
let chunks: Vec<_> = converted.collect().await;
let merged = chunks
.into_iter()
.map(|chunk| String::from_utf8_lossy(chunk.unwrap().as_ref()).to_string())
.collect::<String>();
// Must contain the original Chinese characters, not replacement chars
assert!(
merged.contains("你好"),
"expected '你好' in output, got replacement chars (U+FFFD)"
);
assert!(
!merged.contains('\u{FFFD}'),
"output must not contain U+FFFD replacement characters"
);
}
}