Lead loses teammate results when a turn ends without a tool call (#291)

After the Lead spawns teammate agents, if the current round terminates with
plain text (stop_reason != tool_use), agent_loop returns and the REPL falls
back to a blocking input(). Teammates run as daemon threads and finish later,
so the results they send to the Lead's inbox stay unconsumed until the user
submits their next input.

The cause is that result delivery is bound to the turn loop, whose lifetime
ends when the model stops calling tools, while a teammate completes on its own
clock. Blocking a teammate is harmless because it runs as a background thread;
the problem is specific to the Lead, which owns the user prompt.

The fix follows real Claude Code (useInboxPoller, described in the appendix):
decouple input() from turn execution. MessageBus.peek(agent) reports whether
the inbox has unread messages without consuming them. In __main__, input()
moves to a dedicated daemon thread and an inbox poller thread peeks the Lead's
inbox every second; both push to one shared event queue. The main thread runs
one turn per event, woken by either user input or an incoming teammate message,
so teammate results become new turns without waiting for the user. Repeated
inbox wakeups are idempotent: an empty read is skipped when a prior read_inbox
already drained the messages. Only the Lead's main loop changes; the teammates'
idle loops are untouched.

s15_agent_teams/code.py

@@ -20,7 +20,7 @@ ASCII flow:
   Teammate: inbox → LLM → bash/read/write/send → loop (max 10 turns)
 """
 
-import os, subprocess, json, time, random, threading
+import os, subprocess, json, time, random, threading, queue
 from pathlib import Path
 from datetime import datetime
 from dataclasses import dataclass, asdict
@@ -617,6 +617,13 @@ class MessageBus:
         inbox.unlink()  # consume: read + delete
         return msgs
 
+    def peek(self, agent: str) -> bool:
+        """Non-destructive: True if the agent has unread inbox messages.
+        The Lead's inbox poller uses this to decide whether to wake a turn
+        without consuming the mailbox."""
+        inbox = MAILBOX_DIR / f"{agent}.jsonl"
+        return inbox.exists() and inbox.stat().st_size > 0
+
 
 BUS = MessageBus()
 
@@ -903,26 +910,53 @@ if __name__ == "__main__":
     print("Enter a question, press Enter to send. Type q to quit.\n")
     history = []
     context = update_context({}, [])
+
+    # input() and a 1s inbox poller feed one event queue (issue #291).
+    events = queue.Queue()
+
+    def input_reader():
+        while True:
+            try:
+                line = input("\033[36ms15 >> \033[0m")
+            except (EOFError, KeyboardInterrupt):
+                events.put(("quit", None))
+                return
+            events.put(("user", line))
+
+    def inbox_poller():
+        # Poll ~1s and submit the Lead's inbox as a new turn. Don't gate on
+        # active_teammates: a teammate sends its result and then removes itself,
+        # so the final message can outlive its registry entry.
+        while True:
+            time.sleep(1)
+            if BUS.peek("lead"):
+                events.put(("inbox", None))
+
+    threading.Thread(target=input_reader, daemon=True).start()
+    threading.Thread(target=inbox_poller, daemon=True).start()
+
     while True:
-        try:
-            query = input("\033[36ms15 >> \033[0m")
-        except (EOFError, KeyboardInterrupt):
+        kind, payload = events.get()
+        if kind == "quit":
             break
-        if query.strip().lower() in ("q", "exit", ""):
-            break
-        history.append({"role": "user", "content": query})
+        if kind == "user":
+            if payload.strip().lower() in ("q", "exit", ""):
+                break
+            history.append({"role": "user", "content": payload})
+        else:  # "inbox": a teammate message woke the Lead
+            inbox = BUS.read_inbox("lead")
+            if not inbox:
+                continue  # already drained by an earlier wake (idempotent)
+            inbox_text = "\n".join(
+                f"From {m['from']}: {m['content'][:200]}" for m in inbox)
+            history.append({"role": "user",
+                            "content": f"[Inbox]\n{inbox_text}"})
+            print(f"\n\033[33m[Inbox: {len(inbox)} messages → new turn]\033[0m")
+
+        # One turn for whichever source woke us.
         agent_loop(history, context)
         context = update_context(context, history)
         for block in history[-1]["content"]:
             if getattr(block, "type", None) == "text":
                 print(block.text)
-
-        # Check inbox for teammate results → inject into history
-        inbox = BUS.read_inbox("lead")
-        if inbox:
-            inbox_text = "\n".join(
-                f"From {m['from']}: {m['content'][:200]}" for m in inbox)
-            history.append({"role": "user",
-                            "content": f"[Inbox]\n{inbox_text}"})
-            print(f"\n\033[33m[Inbox: {len(inbox)} messages injected]\033[0m")
         print()