use serde_json::{json, Value};
use std::sync::atomic::Ordering;
use std::sync::{Arc, RwLock};
use std::time::Duration;
use tokio::sync::{mpsc, oneshot};
use super::super::{Tool, ToolContext, NEXT_SUBAGENT_ID};
use crate::runtime::subagent::{SubagentHandle, SubagentResult, SubagentState, SubagentStatus};
use crate::{AgentEvent, LlmEvent, Result, RuntimeError, SessionEvent};
pub struct SubagentResumeTool;
fn expired_context_error(handle_id: &str) -> RuntimeError {
RuntimeError::Tool(format!(
"Subagent '{}' has expired resumable context; call subagent_collect with reconciled=true to reconcile its retained tombstone.",
handle_id
))
}
#[async_trait::async_trait]
impl Tool for SubagentResumeTool {
fn origin(&self) -> crate::tools::ToolOrigin {
crate::tools::ToolOrigin::Builtin
}
fn name(&self) -> &str {
"subagent_resume"
}
fn description(&self) -> &str {
"Resume a finished or timed-out reactive subagent with new instructions. \
The previous subagent's conversation state is prepended as context so the \
new run has full history. Returns a new handle_id — the original handle \
remains readable for comparison. Only works on subagents in \
finished/timed_out/failed state."
}
fn parameters(&self) -> Value {
json!({
"type": "object",
"properties": {
"handle_id": {
"type": "string",
"description": "Handle ID of the completed subagent to resume (e.g. \"sa_3\")."
},
"instructions": {
"type": "string",
"description": "New task or context to prepend to the resumed subagent. \
Injected before the prior conversation history."
}
},
"required": ["handle_id", "instructions"]
})
}
async fn execute(&self, params: Value, ctx: ToolContext) -> Result<String> {
let prior_handle_id = params["handle_id"]
.as_str()
.ok_or_else(|| RuntimeError::Tool("Missing 'handle_id' parameter".to_string()))?
.to_string();
let instructions = params["instructions"]
.as_str()
.ok_or_else(|| RuntimeError::Tool("Missing 'instructions' parameter".to_string()))?
.to_string();
let registry = ctx.capabilities.subagent_registry.as_ref().ok_or_else(|| {
RuntimeError::Tool("SubagentRegistry not available on this ToolContext".to_string())
})?;
let (agent_name, model, prior_context, prior_system_prompt, prior_timeout) = {
let reg = registry.lock().unwrap();
let handle = reg.get(&prior_handle_id).ok_or_else(|| {
RuntimeError::Tool(format!(
"No subagent found with handle_id '{}'",
prior_handle_id
))
})?;
if handle.status() == SubagentStatus::Running {
return Err(RuntimeError::Tool(format!(
"Subagent '{}' is still running. Call subagent_collect first, \
or wait until it finishes.",
prior_handle_id
)));
}
if handle.is_tombstone() {
return Err(expired_context_error(&prior_handle_id));
}
let prior = {
let state = handle.conversation_state();
if state.is_empty() {
handle.partial_output()
} else {
serde_json::to_string(&state).unwrap_or_else(|_| handle.partial_output())
}
};
(
handle.agent_name.clone(),
handle.model.clone(),
prior,
handle.system_prompt.clone(),
handle.timeout_secs,
)
};
let resumed_task = format!(
"{instructions}\n\n\
---\n\
[Prior conversation context from handle {prior_handle_id}]\n\
{prior_context}"
);
let system_prompt = prior_system_prompt;
let timeout_secs = prior_timeout;
let label = agent_name.clone();
let task_preview: String = resumed_task.chars().take(80).collect();
let task_full = resumed_task.clone();
let subagent_id = NEXT_SUBAGENT_ID.fetch_add(1, Ordering::Relaxed);
let handle_id = format!("sa_{}", subagent_id);
let decision = ctx
.capabilities
.orchestration
.as_ref()
.ok_or_else(|| RuntimeError::Tool("delegation policy unavailable".into()))?
.resolve_and_authorize(&handle_id, Some(&model))
.map_err(|error| RuntimeError::Tool(error.to_string()))?;
let model = decision.model.as_str().to_owned();
tracing::info!(
"subagent_resume: dispatching '{}' (id={}, resumed_from={}) model={}",
label,
handle_id,
prior_handle_id,
model
);
let state = Arc::new(RwLock::new(SubagentState::new()));
let (steer_tx, steer_rx) = mpsc::unbounded_channel::<String>();
let (shutdown_tx, shutdown_rx) = oneshot::channel::<()>();
let (result_tx, result_rx) = oneshot::channel::<SubagentResult>();
if let Some(ref tx) = ctx.channels.tx_events {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentStart {
subagent_id,
agent_name: label.clone(),
task_preview: task_preview.clone(),
}));
}
let state_t = Arc::clone(&state);
let task_full_a = task_full.clone();
let label_inner = label.clone();
let model_inner = model.clone();
let tx_events_inner = ctx.channels.tx_events.clone();
let start_time = std::time::Instant::now();
let parent_queue = ctx.capabilities.event_queue.clone();
let handle_id_inner = handle_id.clone();
let prior_handle_for_finalizer = prior_handle_id.clone();
let system_prompt_for_handle = system_prompt.clone();
let handle = SubagentHandle::new(
handle_id.clone(),
subagent_id,
label.clone(),
task_preview,
model.clone(),
system_prompt_for_handle,
timeout_secs,
Arc::clone(&state),
Some(steer_tx),
Some(shutdown_tx),
Some(result_rx),
)
.with_authorization(&decision);
{
let mut reg = registry.lock().unwrap();
reg.register(handle);
}
let orchestration = ctx.capabilities.orchestration.as_ref().unwrap();
if let Err(error) = orchestration.mark_starting(&handle_id) {
orchestration.rollback(&handle_id);
return Err(RuntimeError::Tool(error));
}
let thread_handle = std::thread::spawn(move || {
let state_for_finalizer = Arc::clone(&state_t);
let label_for_finalizer = label_inner.clone();
let panic_result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
let rt = match tokio::runtime::Builder::new_current_thread()
.enable_all()
.build()
{
Ok(rt) => rt,
Err(_) => {
state_t.write().unwrap().status =
SubagentStatus::Failed("runtime initialization failed".into());
return;
}
};
let state_a = Arc::clone(&state_t);
let label_a = label_inner.clone();
let model_a = model_inner.clone();
let tx_events_a = tx_events_inner.clone();
let task_for_timeout = task_full_a.clone();
let task_for_complete = task_full_a.clone();
let task_for_stream = task_full_a;
let outcome: std::result::Result<SubagentResult, String> = rt.block_on(async move {
use futures::StreamExt;
let mut runtime = match crate::Runtime::new().await {
Ok(r) => r,
Err(_) => return Err("subagent runtime initialization failed".into()),
};
super::apply_subagent_runtime_policy(&mut runtime, &crate::config::load_config());
runtime.set_system_prompt(system_prompt);
runtime.set_model(model_a.clone());
runtime.set_tools(super::subagent_tools().await);
let cancel = crate::CancellationToken::new();
let cancel_inner = cancel.clone();
tokio::spawn(async move {
let _ = shutdown_rx.await;
cancel_inner.cancel();
});
let mut stream = runtime.run_stream_with_messages(
vec![std::sync::Arc::new(serde_json::json!({"role": "user", "content": task_for_stream}))],
cancel,
Some(steer_rx),
None,
false,
).await;
let mut tool_count = 0u32;
let mut total_input_tokens = 0u64;
let mut total_output_tokens = 0u64;
let mut total_cache_read = 0u64;
let mut total_cache_creation = 0u64;
let mut total_cache_5m: Option<u64> = None;
let mut total_cache_1h: Option<u64> = None;
let timeout_fut = tokio::time::sleep(Duration::from_secs(timeout_secs));
tokio::pin!(timeout_fut);
loop {
tokio::select! {
event = stream.next() => {
let Some(event) = event else { break };
match event {
crate::StreamEvent::Llm(LlmEvent::Thinking(_)) => {
if let Some(ref tx) = tx_events_a {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentUpdate {
subagent_id,
agent_name: label_a.clone(),
status: "💭 thinking...".to_string(),
}));
}
}
crate::StreamEvent::Llm(LlmEvent::Text(text)) => {
state_a.write().unwrap().partial_text.push_str(&text);
}
crate::StreamEvent::Llm(LlmEvent::ToolUseStart { tool_name: name, .. }) => {
tool_count += 1;
if let Some(ref tx) = tx_events_a {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentUpdate {
subagent_id,
agent_name: label_a.clone(),
status: format!("⚙ {} (tool #{})", name, tool_count),
}));
}
}
crate::StreamEvent::Llm(LlmEvent::ToolUse { tool_name, input, .. }) => {
let input_str = input.to_string();
let input_preview: String = input_str.chars().take(200).collect();
state_a.write().unwrap().tool_log
.push(format!("[tool_use]: {} — {}", tool_name, input_preview));
let detail = match tool_name.as_str() {
"bash" => {
let cmd = input["command"].as_str().unwrap_or("");
let preview: String = cmd.chars().take(60).collect();
format!("$ {}", preview)
}
"read" => format!("reading {}", input["path"].as_str().unwrap_or("?").rsplit('/').next().unwrap_or("?")),
"write" => format!("writing {}", input["path"].as_str().unwrap_or("?").rsplit('/').next().unwrap_or("?")),
"edit" => format!("editing {}", input["path"].as_str().unwrap_or("?").rsplit('/').next().unwrap_or("?")),
"grep" => format!("grep /{}/", input["pattern"].as_str().unwrap_or("?").chars().take(30).collect::<String>()),
"find" => format!("find {}", input["pattern"].as_str().unwrap_or("?")),
"ls" => format!("ls {}", input["path"].as_str().unwrap_or(".").rsplit('/').next().unwrap_or(".")),
other => {
if other.starts_with("ext__") {
other.splitn(3, "__").last().unwrap_or(other).to_string()
} else {
other.to_string()
}
}
};
if let Some(ref tx) = tx_events_a {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentUpdate {
subagent_id,
agent_name: label_a.clone(),
status: detail,
}));
}
}
crate::StreamEvent::Llm(LlmEvent::ToolResult { result, .. }) => {
let preview: String = result.chars().take(300).collect();
state_a.write().unwrap().tool_log
.push(format!("[tool_result]: {}", preview));
}
crate::StreamEvent::Session(SessionEvent::Usage {
input_tokens, output_tokens,
cache_read_input_tokens, cache_creation_input_tokens,
cache_creation_5m, cache_creation_1h,
model: _,
}) => {
total_input_tokens += input_tokens;
total_output_tokens += output_tokens;
total_cache_read += cache_read_input_tokens;
total_cache_creation += cache_creation_input_tokens;
crate::core::rpc_dispatch::merge_split(&mut total_cache_5m, cache_creation_5m);
crate::core::rpc_dispatch::merge_split(&mut total_cache_1h, cache_creation_1h);
}
crate::StreamEvent::Session(SessionEvent::Error(e)) => return Err(format!("provider request failed [{}]", e.category_label())),
crate::StreamEvent::Session(SessionEvent::Done) => break,
_ => {}
}
}
_ = &mut timeout_fut => {
let (partial, log) = {
let mut s = state_a.write().unwrap();
s.status = SubagentStatus::TimedOut;
s.conversation_state = vec![
serde_json::json!({"role": "user", "content": task_for_timeout.clone()}),
serde_json::json!({"role": "assistant", "content": &s.partial_text}),
];
(s.partial_text.clone(), s.tool_log.clone())
};
let mut text = format!("[TIMED OUT after {}s — partial results below]\n\n", timeout_secs);
if !log.is_empty() {
text.push_str(&log.join("\n"));
text.push('\n');
}
if !partial.is_empty() {
text.push_str("\n[partial response]:\n");
text.push_str(&partial);
}
state_a.write().unwrap_or_else(|p| p.into_inner()).partial_text = text.clone();
return Ok(SubagentResult {
text,
model: model_a.clone(),
input_tokens: total_input_tokens,
output_tokens: total_output_tokens,
cache_read: total_cache_read,
cache_creation: total_cache_creation,
cache_creation_5m: total_cache_5m,
cache_creation_1h: total_cache_1h,
tool_count,
timed_out: true,
});
}
}
}
Ok(SubagentResult {
text: state_a.write().unwrap().partial_text.clone(),
model: model_a.clone(),
input_tokens: total_input_tokens,
output_tokens: total_output_tokens,
cache_read: total_cache_read,
cache_creation: total_cache_creation,
cache_creation_5m: total_cache_5m,
cache_creation_1h: total_cache_1h,
tool_count,
timed_out: false,
})
});
match outcome {
Ok(sa_result) => {
{
let mut s = state_t.write().unwrap();
if matches!(s.status, SubagentStatus::Running) && !s.cancel_requested {
s.status = SubagentStatus::Completed;
s.conversation_state = vec![
serde_json::json!({"role": "user", "content": task_for_complete.clone()}),
serde_json::json!({"role": "assistant", "content": sa_result.text.clone()}),
];
}
}
let elapsed = start_time.elapsed().as_secs_f64();
let preview: String = sa_result.text.chars().take(120).collect();
if let Some(ref tx) = tx_events_inner {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentDone {
subagent_id,
agent_name: label_inner.clone(),
result_preview: preview,
duration_secs: elapsed,
}));
}
let _ = result_tx.send(sa_result);
}
Err(e) => {
state_t.write().unwrap().status = SubagentStatus::Failed(e.clone());
let elapsed = start_time.elapsed().as_secs_f64();
if let Some(ref tx) = tx_events_inner {
let _ = tx.send(crate::StreamEvent::Agent(AgentEvent::SubagentDone {
subagent_id,
agent_name: label_inner.clone(),
result_preview: format!("ERROR: {}", e),
duration_secs: elapsed,
}));
}
}
}
}));
if let Err(panic_info) = panic_result {
let msg = if let Some(s) = panic_info.downcast_ref::<&str>() {
s.to_string()
} else if let Some(s) = panic_info.downcast_ref::<String>() {
s.clone()
} else {
"unknown panic".to_string()
};
tracing::error!("Resumed subagent thread panicked: {}", msg);
state_t.write().unwrap_or_else(|p| p.into_inner()).status =
SubagentStatus::Failed(format!("panic: {}", msg));
}
super::finalize::finalize_subagent(
&state_for_finalizer,
parent_queue.as_ref(),
&handle_id_inner,
subagent_id,
&label_for_finalizer,
start_time,
Some(&prior_handle_for_finalizer),
);
});
{
let mut reg = registry.lock().unwrap();
if let Some(h) = reg.get_mut(&handle_id) {
h.set_thread_handle(thread_handle);
}
}
if let Err(error) = orchestration.mark_running(&handle_id) {
let mut handle = registry.lock().unwrap().remove(&handle_id);
if let Some(handle) = handle.as_mut() {
handle.cancel();
}
if let Some(handle) = handle {
let _ = handle.collect().await;
}
orchestration.rollback(&handle_id);
return Err(RuntimeError::Tool(error));
}
Ok(json!({
"handle_id": handle_id,
"resumed_from": prior_handle_id,
"agent_name": label,
"status": "running"
})
.to_string())
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::runtime::subagent::{reap_finished_with_ttl, SubagentRegistry};
use crate::tools::test_helpers::create_tool_context;
use std::sync::Mutex;
#[tokio::test]
async fn tombstone_resume_reports_expired_context_without_side_effects() {
let state = Arc::new(RwLock::new(SubagentState::new()));
{
let mut state = state.write().unwrap();
state.status = SubagentStatus::Completed;
state.partial_text = "terminal output".into();
state.conversation_state = vec![json!({"role": "assistant", "content": "context"})];
state.finished_at = Some(std::time::Instant::now());
}
let (steer_tx, _steer_rx) = mpsc::unbounded_channel();
let (shutdown_tx, _shutdown_rx) = oneshot::channel();
let (_result_tx, result_rx) = oneshot::channel();
let registry = Arc::new(Mutex::new(SubagentRegistry::new()));
registry.lock().unwrap().register(SubagentHandle::new(
"sa_expired".into(),
1,
"test".into(),
"task".into(),
"anthropic/claude-sonnet-4-6".into(),
"system".into(),
30,
state,
Some(steer_tx),
Some(shutdown_tx),
Some(result_rx),
));
let foreground =
agent_core::prompt::QualifiedModelId::parse("anthropic/claude-sonnet-4-6").unwrap();
let orchestration = Arc::new(
crate::orchestration::OrchestrationRuntime::baseline(foreground, 8, 64).unwrap(),
);
orchestration
.authorize("sa_expired", "anthropic/claude-sonnet-4-6")
.unwrap();
let gate_before = orchestration.completion_gate();
reap_finished_with_ttl(®istry, Some(orchestration.as_ref()), Duration::ZERO);
assert!(registry
.lock()
.unwrap()
.get("sa_expired")
.unwrap()
.is_tombstone());
let count_before = registry.lock().unwrap().list_active().len();
let mut ctx = create_tool_context();
ctx.capabilities.subagent_registry = Some(registry.clone());
ctx.capabilities.orchestration = Some(orchestration.clone());
let error = SubagentResumeTool
.execute(
json!({"handle_id": "sa_expired", "instructions": "continue"}),
ctx,
)
.await
.unwrap_err()
.to_string();
assert!(error.contains("expired resumable context"));
assert!(!error.contains("No subagent found"));
assert_eq!(registry.lock().unwrap().list_active().len(), count_before);
assert_eq!(orchestration.completion_gate(), gate_before);
}
}