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/// Streaming implementation for agent loop.
///
/// pi-mono pattern: the provider accumulates content into a single `output`
/// message. Each event carries a snapshot (`partial`) of this message.
/// Done carries the complete accumulated message.
///
/// This module simply forwards events to the agent loop emit function.
use anyhow::{Error, Result};
use futures::StreamExt;
use oxi_ai::{
ContentBlock, Context, Message, ProviderEvent, StopReason, StreamOptions, Tool as OxTool,
};
use std::collections::HashSet;
pub(crate) async fn stream_assistant_response(
loop_ref: &super::AgentLoop,
messages: &mut Vec<Message>,
emit: &super::EmitFn,
) -> Result<oxi_ai::AssistantMessage> {
let model = loop_ref.resolve_model()?;
let mut context = Context::new();
if let Some(ref system_prompt) = loop_ref.config.system_prompt {
context.set_system_prompt(system_prompt.clone());
}
for msg in messages.iter() {
context.add_message(msg.clone());
}
// Cache tool definitions serialization once to avoid repeated serde work.
let tool_defs = loop_ref.tools.definitions();
if !tool_defs.is_empty() {
let mut oxi_tools = Vec::with_capacity(tool_defs.len());
for def in &tool_defs {
let schema = serde_json::to_value(&def.input_schema)
.unwrap_or_else(|_| serde_json::json!({"type": "object", "properties": {}}));
oxi_tools.push(OxTool::new(&def.name, &def.description, schema));
}
context.set_tools(oxi_tools);
}
let stream_options = StreamOptions {
temperature: Some(loop_ref.config.temperature as f64),
max_tokens: Some(loop_ref.config.max_tokens as usize),
api_key: loop_ref.config.api_key.clone(),
..Default::default()
};
let stream =
super::retry::stream_with_retry(loop_ref, &model, &context, Some(stream_options), emit)
.await?;
// pi-mono pattern: track whether we've emitted MessageStart.
// Start event initializes the stream. Subsequent deltas carry
// accumulated partial messages (content grows in-place at the provider).
let mut added_partial = false;
let mut event_count = 0u32;
let mut rx = stream;
while let Some(event) = rx.next().await {
event_count += 1;
match event {
ProviderEvent::Start { partial } => {
tracing::info!("Stream event #{}: Start", event_count);
messages.push(Message::Assistant(partial));
added_partial = true;
emit(super::AgentEvent::MessageStart {
message: messages.last().expect("non-empty after push").clone(),
});
}
ProviderEvent::TextDelta { delta, partial, .. } => {
// Replace the last assistant message with the provider's
// accumulated snapshot (pi-mono: content grows in partial).
if added_partial {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = partial;
}
}
let last_msg = messages.last().expect("non-empty").clone();
emit(super::AgentEvent::MessageUpdate {
message: last_msg,
delta: Some(delta),
});
}
ProviderEvent::ThinkingStart { partial, .. }
// ThinkingStart arrives before ThinkingDelta.
// Update the snapshot.
if added_partial => {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = partial;
}
}
ProviderEvent::ThinkingDelta { delta, partial, .. } => {
if added_partial {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = partial;
}
}
let last_msg = messages.last().expect("non-empty").clone();
emit(super::AgentEvent::MessageUpdate {
message: last_msg,
delta: Some(delta),
});
}
ProviderEvent::ToolCallStart { partial, .. }
if added_partial => {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = partial;
}
}
ProviderEvent::ToolCallDelta { partial, .. }
if added_partial => {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = partial;
}
}
ProviderEvent::ToolCallEnd { tool_call, .. }
// Add the tool call directly to our tracked message.
if added_partial => {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
m.content.push(ContentBlock::ToolCall(tool_call));
}
// CRITICAL: emit MessageUpdate so the TUI sees the ToolCall block.
// Without this, tool calls are never rendered (matching pi's behavior
// where toolcall_end emits message_update).
let last_msg = messages.last().expect("non-empty").clone();
emit(super::AgentEvent::MessageUpdate {
message: last_msg,
delta: None,
});
}
ProviderEvent::Done { message, .. } => {
// Record success in circuit breaker — the provider returned a
// complete response without errors.
loop_ref.circuit_breaker.record_success();
tracing::info!(
"Stream event #{}: Done (stop_reason={:?})",
event_count,
message.stop_reason
);
if added_partial {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
// Preserve tool calls we may have injected via ToolCallEnd.
// Some providers also include ToolCall blocks in the final Done message,
// so dedupe by tool_call_id to avoid executing the same tool twice.
let mut preserved_tool_calls: Vec<ContentBlock> = m
.content
.drain(..)
.filter(|b| matches!(b, ContentBlock::ToolCall(_)))
.collect();
let mut seen: HashSet<String> = message
.content
.iter()
.filter_map(|b| match b {
ContentBlock::ToolCall(tc) => Some(tc.id.clone()),
_ => None,
})
.collect();
preserved_tool_calls.retain(|b| match b {
ContentBlock::ToolCall(tc) => seen.insert(tc.id.clone()),
_ => true,
});
tracing::info!(
"Done: preserving {} tool_calls (deduped), Done message has {} content blocks",
preserved_tool_calls.len(),
message.content.len()
);
*m = message.clone();
m.content.extend(preserved_tool_calls);
tracing::info!(
"Done: final message has {} content blocks, stop_reason={:?}",
m.content.len(),
m.stop_reason
);
}
} else {
messages.push(Message::Assistant(message.clone()));
}
let last_msg = messages.last().expect("non-empty").clone();
emit(super::AgentEvent::MessageEnd {
message: last_msg.clone(),
});
// Return the message we actually stored (with tool calls preserved)
if let Message::Assistant(m) = &last_msg {
return Ok(m.clone());
} else {
return Ok(message);
}
}
ProviderEvent::Error { mut error, .. } => {
// Record failure in circuit breaker — the provider stream
// produced an error event after the connection was established.
// (connection-level failures are recorded in stream_with_retry)
loop_ref.circuit_breaker.record_failure();
tracing::info!("Stream event #{}: Error", event_count);
let raw_msg = error.text_content();
let friendly = if raw_msg.is_empty() {
"Unknown provider error".to_string()
} else {
raw_msg
};
tracing::error!(session_id = ?loop_ref.session_id, "Provider stream error: {}", friendly);
error.stop_reason = StopReason::Error;
if added_partial {
let last_idx = messages.len() - 1;
if let Message::Assistant(ref mut m) = messages[last_idx] {
*m = error.clone();
}
} else {
messages.push(Message::Assistant(error.clone()));
}
emit(super::AgentEvent::MessageEnd {
message: Message::Assistant(error.clone()),
});
emit(super::AgentEvent::Error {
message: format!("⚠ {}", friendly),
session_id: loop_ref.session_id.clone(),
});
return Ok(error);
}
_ => {}
}
}
tracing::info!("Stream ended after {} events", event_count);
let final_message = messages
.last()
.and_then(|m| match m {
Message::Assistant(a) => Some(a.clone()),
_ => None,
})
.ok_or_else(|| Error::msg("No assistant message in context"))?;
emit(super::AgentEvent::MessageEnd {
message: Message::Assistant(final_message.clone()),
});
Ok(final_message)
}