assistant: Add Mistral support (#24879)

Closes #12519.

Release Notes:

- Added support for Mistral to the Assistant.

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/mistral/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "mistral"
+version = "0.1.0"
+edition.workspace = true
+publish.workspace = true
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/mistral.rs"
+
+[features]
+default = []
+schemars = ["dep:schemars"]
+
+[dependencies]
+anyhow.workspace = true
+futures.workspace = true
+http_client.workspace = true
+schemars = { workspace = true, optional = true }
+serde.workspace = true
+serde_json.workspace = true
+strum.workspace = true

crates/mistral/LICENSE-GPL

@@ -0,0 +1 @@
+../../LICENSE-GPL

crates/mistral/src/mistral.rs

@@ -0,0 +1,344 @@
+use anyhow::{anyhow, Result};
+use futures::{io::BufReader, stream::BoxStream, AsyncBufReadExt, AsyncReadExt, StreamExt};
+use http_client::{AsyncBody, HttpClient, Method, Request as HttpRequest};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::convert::TryFrom;
+use strum::EnumIter;
+
+pub const MISTRAL_API_URL: &str = "https://api.mistral.ai/v1";
+
+#[derive(Clone, Copy, Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum Role {
+    User,
+    Assistant,
+    System,
+    Tool,
+}
+
+impl TryFrom<String> for Role {
+    type Error = anyhow::Error;
+
+    fn try_from(value: String) -> Result<Self> {
+        match value.as_str() {
+            "user" => Ok(Self::User),
+            "assistant" => Ok(Self::Assistant),
+            "system" => Ok(Self::System),
+            "tool" => Ok(Self::Tool),
+            _ => Err(anyhow!("invalid role '{value}'")),
+        }
+    }
+}
+
+impl From<Role> for String {
+    fn from(val: Role) -> Self {
+        match val {
+            Role::User => "user".to_owned(),
+            Role::Assistant => "assistant".to_owned(),
+            Role::System => "system".to_owned(),
+            Role::Tool => "tool".to_owned(),
+        }
+    }
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, EnumIter)]
+pub enum Model {
+    #[serde(rename = "codestral-latest", alias = "codestral-latest")]
+    CodestralLatest,
+    #[serde(rename = "mistral-large-latest", alias = "mistral-large-latest")]
+    MistralLargeLatest,
+    #[serde(rename = "mistral-small-latest", alias = "mistral-small-latest")]
+    MistralSmallLatest,
+    #[serde(rename = "open-mistral-nemo", alias = "open-mistral-nemo")]
+    OpenMistralNemo,
+    #[serde(rename = "open-codestral-mamba", alias = "open-codestral-mamba")]
+    #[default]
+    OpenCodestralMamba,
+
+    #[serde(rename = "custom")]
+    Custom {
+        name: String,
+        /// The name displayed in the UI, such as in the assistant panel model dropdown menu.
+        display_name: Option<String>,
+        max_tokens: usize,
+        max_output_tokens: Option<u32>,
+        max_completion_tokens: Option<u32>,
+    },
+}
+
+impl Model {
+    pub fn from_id(id: &str) -> Result<Self> {
+        match id {
+            "codestral-latest" => Ok(Self::CodestralLatest),
+            "mistral-large-latest" => Ok(Self::MistralLargeLatest),
+            "mistral-small-latest" => Ok(Self::MistralSmallLatest),
+            "open-mistral-nemo" => Ok(Self::OpenMistralNemo),
+            "open-codestral-mamba" => Ok(Self::OpenCodestralMamba),
+            _ => Err(anyhow!("invalid model id")),
+        }
+    }
+
+    pub fn id(&self) -> &str {
+        match self {
+            Self::CodestralLatest => "codestral-latest",
+            Self::MistralLargeLatest => "mistral-large-latest",
+            Self::MistralSmallLatest => "mistral-small-latest",
+            Self::OpenMistralNemo => "open-mistral-nemo",
+            Self::OpenCodestralMamba => "open-codestral-mamba",
+            Self::Custom { name, .. } => name,
+        }
+    }
+
+    pub fn display_name(&self) -> &str {
+        match self {
+            Self::CodestralLatest => "codestral-latest",
+            Self::MistralLargeLatest => "mistral-large-latest",
+            Self::MistralSmallLatest => "mistral-small-latest",
+            Self::OpenMistralNemo => "open-mistral-nemo",
+            Self::OpenCodestralMamba => "open-codestral-mamba",
+            Self::Custom {
+                name, display_name, ..
+            } => display_name.as_ref().unwrap_or(name),
+        }
+    }
+
+    pub fn max_token_count(&self) -> usize {
+        match self {
+            Self::CodestralLatest => 256000,
+            Self::MistralLargeLatest => 131000,
+            Self::MistralSmallLatest => 32000,
+            Self::OpenMistralNemo => 131000,
+            Self::OpenCodestralMamba => 256000,
+            Self::Custom { max_tokens, .. } => *max_tokens,
+        }
+    }
+
+    pub fn max_output_tokens(&self) -> Option<u32> {
+        match self {
+            Self::Custom {
+                max_output_tokens, ..
+            } => *max_output_tokens,
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Request {
+    pub model: String,
+    pub messages: Vec<RequestMessage>,
+    pub stream: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub max_tokens: Option<u32>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub temperature: Option<f32>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub response_format: Option<ResponseFormat>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub tools: Vec<ToolDefinition>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ResponseFormat {
+    Text,
+    #[serde(rename = "json_object")]
+    JsonObject,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum ToolDefinition {
+    Function { function: FunctionDefinition },
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct FunctionDefinition {
+    pub name: String,
+    pub description: Option<String>,
+    pub parameters: Option<Value>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct CompletionRequest {
+    pub model: String,
+    pub prompt: String,
+    pub max_tokens: u32,
+    pub temperature: f32,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub prediction: Option<Prediction>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub rewrite_speculation: Option<bool>,
+}
+
+#[derive(Clone, Deserialize, Serialize, Debug)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum Prediction {
+    Content { content: String },
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum ToolChoice {
+    Auto,
+    Required,
+    None,
+    Other(ToolDefinition),
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(tag = "role", rename_all = "lowercase")]
+pub enum RequestMessage {
+    Assistant {
+        content: Option<String>,
+        #[serde(default, skip_serializing_if = "Vec::is_empty")]
+        tool_calls: Vec<ToolCall>,
+    },
+    User {
+        content: String,
+    },
+    System {
+        content: String,
+    },
+    Tool {
+        content: String,
+        tool_call_id: String,
+    },
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ToolCall {
+    pub id: String,
+    #[serde(flatten)]
+    pub content: ToolCallContent,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(tag = "type", rename_all = "lowercase")]
+pub enum ToolCallContent {
+    Function { function: FunctionContent },
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct FunctionContent {
+    pub name: String,
+    pub arguments: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct CompletionChoice {
+    pub text: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Response {
+    pub id: String,
+    pub object: String,
+    pub created: u64,
+    pub model: String,
+    pub choices: Vec<Choice>,
+    pub usage: Usage,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Usage {
+    pub prompt_tokens: u32,
+    pub completion_tokens: u32,
+    pub total_tokens: u32,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Choice {
+    pub index: u32,
+    pub message: RequestMessage,
+    pub finish_reason: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct StreamResponse {
+    pub id: String,
+    pub object: String,
+    pub created: u64,
+    pub model: String,
+    pub choices: Vec<StreamChoice>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct StreamChoice {
+    pub index: u32,
+    pub delta: StreamDelta,
+    pub finish_reason: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct StreamDelta {
+    pub role: Option<Role>,
+    pub content: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub tool_calls: Option<Vec<ToolCallChunk>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reasoning_content: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ToolCallChunk {
+    pub index: usize,
+    pub id: Option<String>,
+    pub function: Option<FunctionChunk>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct FunctionChunk {
+    pub name: Option<String>,
+    pub arguments: Option<String>,
+}
+
+pub async fn stream_completion(
+    client: &dyn HttpClient,
+    api_url: &str,
+    api_key: &str,
+    request: Request,
+) -> Result<BoxStream<'static, Result<StreamResponse>>> {
+    let uri = format!("{api_url}/chat/completions");
+    let request_builder = HttpRequest::builder()
+        .method(Method::POST)
+        .uri(uri)
+        .header("Content-Type", "application/json")
+        .header("Authorization", format!("Bearer {}", api_key));
+
+    let request = request_builder.body(AsyncBody::from(serde_json::to_string(&request)?))?;
+    let mut response = client.send(request).await?;
+
+    if response.status().is_success() {
+        let reader = BufReader::new(response.into_body());
+        Ok(reader
+            .lines()
+            .filter_map(|line| async move {
+                match line {
+                    Ok(line) => {
+                        let line = line.strip_prefix("data: ")?;
+                        if line == "[DONE]" {
+                            None
+                        } else {
+                            match serde_json::from_str(line) {
+                                Ok(response) => Some(Ok(response)),
+                                Err(error) => Some(Err(anyhow!(error))),
+                            }
+                        }
+                    }
+                    Err(error) => Some(Err(anyhow!(error))),
+                }
+            })
+            .boxed())
+    } else {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+        Err(anyhow!(
+            "Failed to connect to Mistral API: {} {}",
+            response.status(),
+            body,
+        ))
+    }
+}