loopd: scheduler yields to a held subagent

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/loopd/src/channel.rs

@@ -59,6 +59,12 @@ impl Context {
         drop(busy);
         Ok(Held { ctx: self, id })
     }
+
+    /// True when any held session id starts with `prefix` (`sub-` for a live child).
+    pub fn holds_prefix(&self, prefix: &str) -> bool {
+        let busy = self.busy.lock().unwrap_or_else(|p| p.into_inner());
+        busy.iter().any(|id| id.as_str().starts_with(prefix))
+    }
 }
 
 /// While a turn runs, the session is in the busy set. The guard holds only an immutable borrow of

crates/loopd/src/scheduler.rs

@@ -43,6 +43,9 @@ impl Scheduler {
             self.leftovers_closed = true;
         }
         self.heartbeat(ctx, now, &mut work);
+        if ctx.holds_prefix("sub-") {
+            return work;
+        }
 
         let jobs_dir = ctx.cfg.paths.home.join("jobs");
         let runs_path = jobs_dir.join("runs.jsonl");
@@ -184,6 +187,9 @@ impl Scheduler {
         if !due {
             return;
         }
+        if ctx.holds_prefix("sub-") {
+            return;
+        }
 
         let id = match SessionId::new("heartbeat") {
             Ok(id) => id,

crates/loopd/tests/scheduler_subagent.rs

@@ -0,0 +1,89 @@
+//! Heartbeat and cron yield to a held subagent. Do not edit.
+
+mod support;
+
+use bxcore::{SessionId, Timestamp};
+use loopd::channel::Context;
+use loopd::llama::Client;
+use loopd::memory::NoMemory;
+use loopd::scheduler::{Scheduler, TickWork};
+use loopd::tools::Registry;
+use std::sync::Arc;
+use support::{FakeServer, Home, Reply, ScriptedPort};
+
+const CHAT: &str = "/v1/chat/completions";
+
+fn sse() -> Reply {
+    let data1 = r#"data: {"choices":[{"finish_reason":null,"index":0,"delta":{"content":"noted"}}],"id":"h","timings":{"cache_n":0,"prompt_n":10,"predicted_n":1}}"#;
+    let data2 = r#"data: {"choices":[{"finish_reason":"stop","index":0,"delta":{}}],"id":"h","timings":{"cache_n":0,"prompt_n":10,"predicted_n":1}}"#;
+    let body = format!("{data1}\n\n{data2}\n\ndata: [DONE]\n\n");
+    Reply::raw(format!(
+        "HTTP/1.1 200 OK\r\nContent-Type: text/event-stream\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{body}",
+        body.len()
+    ))
+}
+
+fn ts(s: &str) -> Timestamp {
+    Timestamp::parse(s).unwrap()
+}
+
+#[test]
+fn a_held_subagent_skips_a_due_heartbeat() {
+    let home = Home::new();
+    home.write("heartbeat.md", "Look around.\n");
+    home.write("compact.md", "Summarise.\n");
+    let server = FakeServer::start();
+    let mut cfg = home.config(&server.socket);
+    cfg.heartbeat.every_s = 60;
+    cfg.heartbeat.prompt = home.dir.join("heartbeat.md");
+    server.route(CHAT, vec![sse()]);
+    let ctx = Arc::new(Context::new(
+        cfg.clone(),
+        Client::new(cfg),
+        Box::new(ScriptedPort::new(vec![])),
+        Registry::m2b(),
+        Box::new(NoMemory),
+    ));
+    let held = ctx
+        .hold(SessionId::new("sub-mm-thread-1").unwrap())
+        .expect("hold");
+    let mut sched = Scheduler::new(ts("2026-10-03T07:00:00.000Z"));
+    let work = sched.tick(&ctx, ts("2026-10-03T07:01:00.000Z"));
+    assert!(work.is_empty(), "{work:?}");
+    assert!(server.requests_to(CHAT).is_empty());
+    drop(held);
+    let work = sched.tick(&ctx, ts("2026-10-03T07:02:00.000Z"));
+    assert_eq!(work, vec![TickWork::Heartbeat]);
+    assert_eq!(server.requests_to(CHAT).len(), 1);
+}
+
+#[test]
+fn a_held_subagent_skips_a_due_cron_job() {
+    let home = Home::new();
+    home.write("compact.md", "Summarise.\n");
+    home.write(
+        "jobs/mail.toml",
+        "schedule = \"0 7 * * *\"\nprompt = \"Check mail.\"\n",
+    );
+    let server = FakeServer::start();
+    let cfg = home.config(&server.socket);
+    server.route(CHAT, vec![sse()]);
+    let ctx = Arc::new(Context::new(
+        cfg.clone(),
+        Client::new(cfg),
+        Box::new(ScriptedPort::new(vec![])),
+        Registry::m2b(),
+        Box::new(NoMemory),
+    ));
+    let held = ctx
+        .hold(SessionId::new("sub-mm-thread-1").unwrap())
+        .expect("hold");
+    let mut sched = Scheduler::new(ts("2026-10-03T06:00:00.000Z"));
+    let work = sched.tick(&ctx, ts("2026-10-03T07:00:00.000Z"));
+    assert!(work.is_empty(), "{work:?}");
+    assert!(server.requests_to(CHAT).is_empty());
+    drop(held);
+    let work = sched.tick(&ctx, ts("2026-10-03T07:00:00.000Z"));
+    assert_eq!(work.len(), 1);
+    assert!(matches!(work[0], TickWork::Job { .. }), "{work:?}");
+}