[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 11,
    "timestamp_ns": 14720017920384,
    "event_type": "GoUnblock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14720017920448,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14720017923136,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14720017927104,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 15,
    "timestamp_ns": 14720017927744,
    "event_type": "GoStart",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 16,
    "timestamp_ns": 14720017927936,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 17,
    "timestamp_ns": 14720017944704,
    "event_type": "GoBlock",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 18,
    "timestamp_ns": 14720019040512,
    "event_type": "GoUnblock",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 19,
    "timestamp_ns": 14720019042688,
    "event_type": "GoStart",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 20,
    "timestamp_ns": 14720019063232,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      },
      "35": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "36": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "37": {
        "status": "blocked",
        "blocked_on": "system goroutine wait",
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
      },
      "38": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 20,
  "timestamp_ns": 14720019063232,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "running",
      "blocked_on": "syscall",
      "locals_hint": "syscall.syscall"
    },
    "35": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "36": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "37": {
      "status": "blocked",
      "blocked_on": "system goroutine wait",
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
    },
    "38": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoUnblock", "goroutine_id": 1}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 11,
    "timestamp_ns": 14720017920384,
    "event_type": "GoUnblock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14720017920448,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14720017923136,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14720017927104,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 15,
    "timestamp_ns": 14720017927744,
    "event_type": "GoStart",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 16,
    "timestamp_ns": 14720017927936,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 17,
    "timestamp_ns": 14720017944704,
    "event_type": "GoBlock",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 18,
    "timestamp_ns": 14720019040512,
    "event_type": "GoUnblock",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 19,
    "timestamp_ns": 14720019042688,
    "event_type": "GoStart",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 20,
    "timestamp_ns": 14720019063232,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      },
      "35": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "36": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "37": {
        "status": "blocked",
        "blocked_on": "system goroutine wait",
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
      },
      "38": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 20,
  "timestamp_ns": 14720019063232,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "running",
      "blocked_on": "syscall",
      "locals_hint": "syscall.syscall"
    },
    "35": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "36": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "37": {
      "status": "blocked",
      "blocked_on": "system goroutine wait",
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
    },
    "38": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 1}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 11,
    "timestamp_ns": 14720017920384,
    "event_type": "GoUnblock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14720017920448,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14720017923136,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14720017927104,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 15,
    "timestamp_ns": 14720017927744,
    "event_type": "GoStart",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 16,
    "timestamp_ns": 14720017927936,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 17,
    "timestamp_ns": 14720017944704,
    "event_type": "GoBlock",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 18,
    "timestamp_ns": 14720019040512,
    "event_type": "GoUnblock",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 19,
    "timestamp_ns": 14720019042688,
    "event_type": "GoStart",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 20,
    "timestamp_ns": 14720019063232,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      },
      "35": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "36": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "37": {
        "status": "blocked",
        "blocked_on": "system goroutine wait",
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
      },
      "38": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 20,
  "timestamp_ns": 14720019063232,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "running",
      "blocked_on": "syscall",
      "locals_hint": "syscall.syscall"
    },
    "35": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "36": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "37": {
      "status": "blocked",
      "blocked_on": "system goroutine wait",
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
    },
    "38": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoBlock", "goroutine_id": 1}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 11,
    "timestamp_ns": 14720017920384,
    "event_type": "GoUnblock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14720017920448,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14720017923136,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14720017927104,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 15,
    "timestamp_ns": 14720017927744,
    "event_type": "GoStart",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 16,
    "timestamp_ns": 14720017927936,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 17,
    "timestamp_ns": 14720017944704,
    "event_type": "GoBlock",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 18,
    "timestamp_ns": 14720019040512,
    "event_type": "GoUnblock",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 19,
    "timestamp_ns": 14720019042688,
    "event_type": "GoStart",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 20,
    "timestamp_ns": 14720019063232,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      },
      "35": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "36": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "37": {
        "status": "blocked",
        "blocked_on": "system goroutine wait",
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
      },
      "38": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 20,
  "timestamp_ns": 14720019063232,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "running",
      "blocked_on": "syscall",
      "locals_hint": "syscall.syscall"
    },
    "35": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "36": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "37": {
      "status": "blocked",
      "blocked_on": "system goroutine wait",
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
    },
    "38": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 1}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 11,
    "timestamp_ns": 14720017920384,
    "event_type": "GoUnblock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14720017920448,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14720017923136,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14720017927104,
    "event_type": "GoStart",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 15,
    "timestamp_ns": 14720017927744,
    "event_type": "GoStart",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 16,
    "timestamp_ns": 14720017927936,
    "event_type": "GoBlock",
    "goroutine_id": 37,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 17,
    "timestamp_ns": 14720017944704,
    "event_type": "GoBlock",
    "goroutine_id": 36,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 18,
    "timestamp_ns": 14720019040512,
    "event_type": "GoUnblock",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 19,
    "timestamp_ns": 14720019042688,
    "event_type": "GoStart",
    "goroutine_id": 1,
    "goroutines": "... [TRUNCATED FOR LENGTH] ...",
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 20,
    "timestamp_ns": 14720019063232,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      },
      "35": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "36": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "37": {
        "status": "blocked",
        "blocked_on": "system goroutine wait",
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
      },
      "38": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 20,
  "timestamp_ns": 14720019063232,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "running",
      "blocked_on": "syscall",
      "locals_hint": "syscall.syscall"
    },
    "35": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "36": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "37": {
      "status": "blocked",
      "blocked_on": "system goroutine wait",
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked.func1"
    },
    "38": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 1}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14727426188608,
    "event_type": "GoCreate",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14727426197568,
    "event_type": "GoCreate",
    "goroutine_id": 22,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14727426207424,
    "event_type": "GoStart",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14727426213760,
    "event_type": "GoCreate",
    "goroutine_id": 23,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14727426217856,
    "event_type": "GoCreate",
    "goroutine_id": 24,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14727426235456,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 5,
  "timestamp_ns": 14727426235456,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "21": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    },
    "22": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime.(*traceAdvancerState).start"
    },
    "23": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
    },
    "24": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "main.main"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 23}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14727426188608,
    "event_type": "GoCreate",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14727426197568,
    "event_type": "GoCreate",
    "goroutine_id": 22,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14727426207424,
    "event_type": "GoStart",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14727426213760,
    "event_type": "GoCreate",
    "goroutine_id": 23,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14727426217856,
    "event_type": "GoCreate",
    "goroutine_id": 24,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14727426235456,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 5,
  "timestamp_ns": 14727426235456,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "21": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    },
    "22": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime.(*traceAdvancerState).start"
    },
    "23": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
    },
    "24": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "main.main"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 10}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14727426188608,
    "event_type": "GoCreate",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14727426197568,
    "event_type": "GoCreate",
    "goroutine_id": 22,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14727426207424,
    "event_type": "GoStart",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14727426213760,
    "event_type": "GoCreate",
    "goroutine_id": 23,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14727426217856,
    "event_type": "GoCreate",
    "goroutine_id": 24,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14727426235456,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 5,
  "timestamp_ns": 14727426235456,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "21": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    },
    "22": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime.(*traceAdvancerState).start"
    },
    "23": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
    },
    "24": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "main.main"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 21}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14727426188608,
    "event_type": "GoCreate",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14727426197568,
    "event_type": "GoCreate",
    "goroutine_id": 22,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14727426207424,
    "event_type": "GoStart",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14727426213760,
    "event_type": "GoCreate",
    "goroutine_id": 23,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14727426217856,
    "event_type": "GoCreate",
    "goroutine_id": 24,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14727426235456,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 5,
  "timestamp_ns": 14727426235456,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "21": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    },
    "22": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime.(*traceAdvancerState).start"
    },
    "23": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
    },
    "24": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "main.main"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 10}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14727426188608,
    "event_type": "GoCreate",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14727426197568,
    "event_type": "GoCreate",
    "goroutine_id": 22,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14727426207424,
    "event_type": "GoStart",
    "goroutine_id": 21,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14727426213760,
    "event_type": "GoCreate",
    "goroutine_id": 23,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14727426217856,
    "event_type": "GoCreate",
    "goroutine_id": 24,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14727426235456,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "21": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "22": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      },
      "23": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      },
      "24": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 5,
  "timestamp_ns": 14727426235456,
  "event_type": "GoBlock",
  "goroutine_id": 1,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "21": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    },
    "22": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime.(*traceAdvancerState).start"
    },
    "23": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
    },
    "24": {
      "status": "runnable",
      "blocked_on": null,
      "locals_hint": "main.main"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 6}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14726385218816,
    "event_type": "GoCreate",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14726385223616,
    "event_type": "GoCreate",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14726385224448,
    "event_type": "GoStart",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14726385235136,
    "event_type": "GoStart",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14726385235648,
    "event_type": "GoCreate",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14726385241280,
    "event_type": "GoCreate",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 6,
    "timestamp_ns": 14726385258624,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 7,
    "timestamp_ns": 14726385259008,
    "event_type": "GoStart",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 8,
    "timestamp_ns": 14726385260608,
    "event_type": "GoBlock",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 9,
    "timestamp_ns": 14726385260992,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 10,
    "timestamp_ns": 14726385261376,
    "event_type": "GoBlock",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 11,
    "timestamp_ns": 14726385266048,
    "event_type": "GoBlock",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14726385290368,
    "event_type": "GoBlock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14726385332672,
    "event_type": "GoUnblock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14726385332736,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 14,
  "timestamp_ns": 14726385332736,
  "event_type": "GoStart",
  "goroutine_id": 9,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "10": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    },
    "7": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "8": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "9": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoSched", "goroutine_id": 9}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14726385218816,
    "event_type": "GoCreate",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14726385223616,
    "event_type": "GoCreate",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14726385224448,
    "event_type": "GoStart",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14726385235136,
    "event_type": "GoStart",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14726385235648,
    "event_type": "GoCreate",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14726385241280,
    "event_type": "GoCreate",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 6,
    "timestamp_ns": 14726385258624,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 7,
    "timestamp_ns": 14726385259008,
    "event_type": "GoStart",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 8,
    "timestamp_ns": 14726385260608,
    "event_type": "GoBlock",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 9,
    "timestamp_ns": 14726385260992,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 10,
    "timestamp_ns": 14726385261376,
    "event_type": "GoBlock",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 11,
    "timestamp_ns": 14726385266048,
    "event_type": "GoBlock",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14726385290368,
    "event_type": "GoBlock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14726385332672,
    "event_type": "GoUnblock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14726385332736,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 14,
  "timestamp_ns": 14726385332736,
  "event_type": "GoStart",
  "goroutine_id": 9,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "10": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    },
    "7": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "8": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "9": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 6}


[System] You are a code execution simulator.

[User]
You are reasoning about concurrent Go program execution.

Here is a Go program:
<program>
// WEAVE_META
// outcome: leak
// concurrency_pattern: select
// goroutine_count: 2
// expected_nondeterminism: low
// description: Select statement on unbuffered channel, leak_bug=True

package main

import (
	"fmt"
	"os"
	"runtime/trace"
	"time"
)

func main() {
	if tf := os.Getenv("WEAVE_TRACE_FILE"); tf != "" {
		f, err := os.Create(tf)
		if err == nil {
			if err := trace.Start(f); err == nil {
				defer func() { trace.Stop(); f.Close() }()
			}
		}
	}

	ch := make(chan int)

	go func() {
		// Simulate processing delay
		time.Sleep(time.Millisecond * 10)
		ch <- 42
	}()

	select {
	case val := <-ch:
		fmt.Println("received:", val)
	case <-time.After(1 * time.Millisecond):
		fmt.Println("timeout occurred")
	}

	// Small delay to allow the leaked goroutine to lock into GoWaiting block
	time.Sleep(time.Millisecond * 20)
}

</program>

Here is a partial execution trace showing goroutine scheduler events so far:
<trace>
[
  {
    "event_id": 0,
    "timestamp_ns": 14726385218816,
    "event_type": "GoCreate",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 1,
    "timestamp_ns": 14726385223616,
    "event_type": "GoCreate",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.traceStartReadCPU"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 2,
    "timestamp_ns": 14726385224448,
    "event_type": "GoStart",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime.(*traceAdvancerState).start"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 3,
    "timestamp_ns": 14726385235136,
    "event_type": "GoStart",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 4,
    "timestamp_ns": 14726385235648,
    "event_type": "GoCreate",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 5,
    "timestamp_ns": 14726385241280,
    "event_type": "GoCreate",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 6,
    "timestamp_ns": 14726385258624,
    "event_type": "GoBlock",
    "goroutine_id": 1,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "main.main"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 7,
    "timestamp_ns": 14726385259008,
    "event_type": "GoStart",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 8,
    "timestamp_ns": 14726385260608,
    "event_type": "GoBlock",
    "goroutine_id": 8,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "runtime/trace.(*traceMultiplexer).startLocked"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 9,
    "timestamp_ns": 14726385260992,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 10,
    "timestamp_ns": 14726385261376,
    "event_type": "GoBlock",
    "goroutine_id": 7,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 11,
    "timestamp_ns": 14726385266048,
    "event_type": "GoBlock",
    "goroutine_id": 10,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 12,
    "timestamp_ns": 14726385290368,
    "event_type": "GoBlock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": "syscall",
        "locals_hint": "syscall.syscall"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 13,
    "timestamp_ns": 14726385332672,
    "event_type": "GoUnblock",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "runnable",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  },
  {
    "event_id": 14,
    "timestamp_ns": 14726385332736,
    "event_type": "GoStart",
    "goroutine_id": 9,
    "goroutines": {
      "1": {
        "status": "blocked",
        "blocked_on": "select",
        "locals_hint": "runtime.selectgo"
      },
      "10": {
        "status": "blocked",
        "blocked_on": "sleep",
        "locals_hint": "time.Sleep"
      },
      "7": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "8": {
        "status": "blocked",
        "blocked_on": "chan receive",
        "locals_hint": "runtime.chanrecv1"
      },
      "9": {
        "status": "running",
        "blocked_on": null,
        "locals_hint": "unknown"
      }
    },
    "channels": {},
    "mutexes": {}
  }
]
</trace>

The current goroutine states are:
<current_state>
{
  "event_id": 14,
  "timestamp_ns": 14726385332736,
  "event_type": "GoStart",
  "goroutine_id": 9,
  "goroutines": {
    "1": {
      "status": "blocked",
      "blocked_on": "select",
      "locals_hint": "runtime.selectgo"
    },
    "10": {
      "status": "blocked",
      "blocked_on": "sleep",
      "locals_hint": "time.Sleep"
    },
    "7": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "8": {
      "status": "blocked",
      "blocked_on": "chan receive",
      "locals_hint": "runtime.chanrecv1"
    },
    "9": {
      "status": "running",
      "blocked_on": null,
      "locals_hint": "unknown"
    }
  },
  "channels": {},
  "mutexes": {}
}
</current_state>

Predict the next scheduler event. What happens next?
Respond in JSON only — no markdown fences, no text outside the JSON object:
{"event_type":"GoStart|GoBlock|GoUnblock|GoCreate|GoEnd|GoSched","goroutine_id":<integer>,"reasoning":"<brief explanation>","confidence":"high|medium|low"}

[Assistant] {"event_type": "GoStart", "goroutine_id": 23}