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use std::pin::Pin;
use std::time::Duration;
use async_trait::async_trait;
use futures::Stream;
use futures::StreamExt;
use thiserror::Error;
use crate::ids::AgentId;
use crate::message::{AgentContent, AgentMessage, Role, RunStatus};
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct AgentSpec {
pub agent_id: AgentId,
pub agent_name: String,
pub instructions: String,
}
#[derive(Clone, Debug)]
pub struct RunRequest {
pub agent: AgentSpec,
/// Conversation thread; stateful tools (code mode REPL) scope by it.
/// Runs on one thread never overlap (the runtime queues them).
pub thread_id: Option<String>,
pub messages: Vec<AgentMessage>,
}
#[derive(Clone, Debug)]
pub struct RunOutcome {
pub status: RunStatus,
pub messages: Vec<AgentMessage>,
pub final_output: Option<AgentContent>,
pub last_error: Option<String>,
}
#[derive(Clone, Debug)]
pub enum BackendEvent {
Message(AgentMessage),
Completed(RunOutcome),
}
#[derive(Clone, Debug, PartialEq, Eq, Error)]
#[error("{0}")]
pub struct BackendError(pub String);
impl BackendError {
pub fn new(message: impl Into<String>) -> Self {
Self(message.into())
}
}
pub type BackendStream = Pin<Box<dyn Stream<Item = Result<BackendEvent, BackendError>> + Send>>;
#[async_trait]
pub trait AgentBackend: Send + Sync {
async fn start_run(&self, request: RunRequest) -> Result<BackendStream, BackendError>;
}
#[derive(Clone, Debug)]
enum MockReply {
Fixed(String),
Echo,
}
/// Deterministic in-process backend used by the CLI and tests.
#[derive(Clone, Debug)]
pub struct MockBackend {
reply: MockReply,
failure: Option<String>,
delay: Option<Duration>,
}
impl MockBackend {
pub fn fixed(reply: impl Into<String>) -> Self {
Self {
reply: MockReply::Fixed(reply.into()),
failure: None,
delay: None,
}
}
pub fn echo() -> Self {
Self {
reply: MockReply::Echo,
failure: None,
delay: None,
}
}
pub fn with_failure(mut self, message: impl Into<String>) -> Self {
self.failure = Some(message.into());
self
}
pub fn with_delay(mut self, delay: Duration) -> Self {
self.delay = Some(delay);
self
}
}
#[async_trait]
impl AgentBackend for MockBackend {
async fn start_run(&self, request: RunRequest) -> Result<BackendStream, BackendError> {
if let Some(failure) = &self.failure {
return Err(BackendError::new(failure.clone()));
}
let reply = match &self.reply {
MockReply::Fixed(reply) => reply.clone(),
MockReply::Echo => request
.messages
.iter()
.rev()
.find_map(|message| message.content.as_text().map(str::to_owned))
.unwrap_or_else(|| "hello from asyncai".to_string()),
};
let assistant = AgentMessage {
role: Role::Assistant,
content: AgentContent::Text(reply.clone()),
};
let mut messages = request.messages;
messages.push(assistant.clone());
let events: Vec<Result<BackendEvent, BackendError>> = vec![
Ok(BackendEvent::Message(assistant)),
Ok(BackendEvent::Completed(RunOutcome {
status: RunStatus::Completed,
messages,
final_output: Some(AgentContent::Text(reply)),
last_error: None,
})),
];
let stream = futures::stream::iter(events);
match self.delay {
Some(delay) => Ok(Box::pin(stream.then(move |event| async move {
tokio::time::sleep(delay).await;
event
}))),
None => Ok(Box::pin(stream)),
}
}
}
