j_agent/llm/
client.rs

1use super::error::LlmError;
2use super::stream::SseStream;
3use super::types::{ChatRequest, ChatResponse};
4
5/// OpenAI-compatible Chat Completions client backed by reqwest.
6#[derive(Debug)]
7pub struct LlmClient {
8    http_client: reqwest::Client,
9    base_url: String,
10    api_key: String,
11}
12
13impl LlmClient {
14    /// Create a new LLM client with the given API base URL and API key.
15    pub fn new(api_base: &str, api_key: &str) -> Self {
16        Self {
17            http_client: reqwest::Client::new(),
18            base_url: api_base.trim_end_matches('/').to_string(),
19            api_key: api_key.to_string(),
20        }
21    }
22
23    const CHAT_COMPLETIONS_PATH: &'static str = "/chat/completions";
24
25    fn endpoint(&self) -> String {
26        format!("{}{}", self.base_url, Self::CHAT_COMPLETIONS_PATH)
27    }
28
29    /// Non-streaming chat completion.
30    pub async fn chat_completion(&self, request: &ChatRequest) -> Result<ChatResponse, LlmError> {
31        let resp = self
32            .http_client
33            .post(self.endpoint())
34            .bearer_auth(&self.api_key)
35            .json(request)
36            .send()
37            .await?;
38
39        let status = resp.status();
40        if !status.is_success() {
41            let body = resp.text().await.unwrap_or_default();
42            return Err(LlmError::Api {
43                status: status.as_u16(),
44                body,
45            });
46        }
47
48        let body = resp.text().await?;
49        serde_json::from_str::<ChatResponse>(&body).map_err(|e| {
50            LlmError::Deserialize(format!("Failed to parse response: {} | body: {}", e, body))
51        })
52    }
53
54    /// Streaming chat completion — returns SSE stream.
55    pub async fn chat_completion_stream(
56        &self,
57        request: &ChatRequest,
58    ) -> Result<SseStream, LlmError> {
59        // Ensure stream is set to true in the serialized body
60        let mut body = serde_json::to_value(request)
61            .map_err(|e| LlmError::RequestBuild(format!("Failed to serialize request: {}", e)))?;
62        // SAFETY: `ChatRequest` always serializes as a JSON object (struct with named
63        // fields), so `serde_json::to_value(request)` is guaranteed to produce a Value::Object.
64        body.as_object_mut()
65            .expect("ChatRequest must serialize to a JSON object")
66            .insert("stream".to_string(), serde_json::Value::Bool(true));
67
68        let resp = self
69            .http_client
70            .post(self.endpoint())
71            .bearer_auth(&self.api_key)
72            .header("Content-Type", "application/json")
73            .body(body.to_string())
74            .send()
75            .await?;
76
77        let status = resp.status();
78        if !status.is_success() {
79            let resp_body = resp.text().await.unwrap_or_default();
80            return Err(LlmError::Api {
81                status: status.as_u16(),
82                body: resp_body,
83            });
84        }
85
86        Ok(SseStream::new(resp))
87    }
88}
j_agent/llm/client.rs

j_agent/llm/
client.rs
