smos_application/types/
chat_request.rs

1//! OpenAI-compatible chat-completion request envelope.
2//!
3//! The shape preserves *all* upstream fields (extra): the proxy must forward
4//! unknown fields verbatim so future OpenAI parameters (e.g. `reasoning_effort`,
5//! `response_format`) pass through without a release of this crate. `model`
6//! and `messages` are typed for the use cases that need to read or modify
7//! them; everything else falls through `extra`.
8
9use serde::{Deserialize, Serialize};
10use serde_json::{Map, Value};
11
12/// Wire-shape chat-completion request.
13#[derive(Debug, Clone, Serialize, Deserialize)]
14pub struct ChatRequest {
15    pub model: String,
16
17    /// Raw message bodies — kept as `serde_json::Value` so multipart content
18    /// (image_url, audio, tool calls with arbitrary payloads) round-trips
19    /// without bespoke enums.
20    pub messages: Vec<Value>,
21
22    /// Catch-all for every other OpenAI parameter (`temperature`, `stream`,
23    /// `tools`, …). `#[serde(flatten)]` makes them inline peers of `model`
24    /// and `messages` on the wire.
25    #[serde(flatten)]
26    pub extra: Map<String, Value>,
27}
28
29impl ChatRequest {
30    /// Build a request with `model`, `messages`, and no extras.
31    pub fn new(model: impl Into<String>, messages: Vec<Value>) -> Self {
32        Self {
33            model: model.into(),
34            messages,
35            extra: Map::new(),
36        }
37    }
38
39    /// Insert (or replace) one extra parameter. Builder-style.
40    pub fn with_extra(mut self, key: impl Into<String>, value: Value) -> Self {
41        self.extra.insert(key.into(), value);
42        self
43    }
44
45    /// Read one extra parameter by key.
46    pub fn extra(&self, key: &str) -> Option<&Value> {
47        self.extra.get(key)
48    }
49
50    /// `true` iff the request asks for streaming (`stream: true` in extras).
51    pub fn is_streaming(&self) -> bool {
52        self.extra
53            .get("stream")
54            .and_then(Value::as_bool)
55            .unwrap_or(false)
56    }
57}
58
59#[cfg(test)]
60mod tests {
61    use super::*;
62    use serde_json::json;
63
64    #[test]
65    fn serialises_known_fields_at_top_level() {
66        let req = ChatRequest::new("gpt-4o", vec![json!({"role": "user", "content": "hi"})]);
67        let v: Value = serde_json::to_value(&req).unwrap();
68        assert_eq!(v["model"], "gpt-4o");
69        assert_eq!(v["messages"][0]["role"], "user");
70    }
71
72    #[test]
73    fn extra_fields_flatten_alongside_known_fields() {
74        let req = ChatRequest::new("m", vec![]).with_extra("temperature", json!(0.7));
75        let v: Value = serde_json::to_value(&req).unwrap();
76        assert_eq!(v["temperature"], 0.7);
77        assert!(v.get("extra").is_none());
78    }
79
80    #[test]
81    fn deserialises_unknown_fields_into_extra() {
82        let raw = serde_json::json!({
83            "model": "m",
84            "messages": [],
85            "temperature": 0.3,
86            "tools": [{"type": "function"}],
87        });
88        let req: ChatRequest = serde_json::from_value(raw).unwrap();
89        assert_eq!(req.model, "m");
90        assert_eq!(req.extra("temperature"), Some(&json!(0.3)));
91        assert!(req.extra("tools").is_some());
92    }
93
94    #[test]
95    fn roundtrip_preserves_all_fields() {
96        let req = ChatRequest::new("m", vec![json!({"role": "system"})])
97            .with_extra("stream", json!(true))
98            .with_extra("max_tokens", json!(128));
99        let json = serde_json::to_string(&req).unwrap();
100        let back: ChatRequest = serde_json::from_str(&json).unwrap();
101        assert_eq!(back.model, "m");
102        assert_eq!(back.extra("stream"), Some(&json!(true)));
103        assert_eq!(back.extra("max_tokens"), Some(&json!(128)));
104    }
105
106    #[test]
107    fn is_streaming_reads_extra_bool() {
108        let streaming = ChatRequest::new("m", vec![]).with_extra("stream", json!(true));
109        let non_streaming = ChatRequest::new("m", vec![]).with_extra("stream", json!(false));
110        let unset = ChatRequest::new("m", vec![]);
111        assert!(streaming.is_streaming());
112        assert!(!non_streaming.is_streaming());
113        assert!(!unset.is_streaming());
114    }
115}
smos_application/types/chat_request.rs

smos_application/types/
chat_request.rs
