[BUG] Go binaries hang 30-60 seconds in Bash tool on macOS (stdin issue)

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/8049
2. https://github.com/anthropics/claude-code/issues/12650
3. https://github.com/anthropics/claude-code/issues/12507

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🤖 Generated with Claude Code

This is similar to 12507, but for MacOS. Downgrading to 2.0.25 like that issue did not work for me on MacOS. The spawn() suggestion from that issue seems sane.

I tried three different languages to reproduce stdin behaviors with the claude Bash tool. node and go both fail. python succeeds. They do eventually succeed when the pipe finally produces EOF.

node

const fs = require('fs');

console.log("Checking stdin...");
const stats = fs.fstatSync(process.stdin.fd);
console.log(`Is CharDevice: ${stats.isCharacterDevice()}`);
console.log(`Is FIFO: ${stats.isFIFO()}`);
console.log(`Is Socket: ${stats.isSocket()}`);

console.log("Testing if stdin blocks...");
const start = Date.now();

// Set timeout for stdin read
const timeout = setTimeout(() => {
    console.log(`Stdin blocked for ${Date.now() - start}ms`);
    process.exit(0);
}, 2000);

// Try to read from stdin
process.stdin.once('readable', () => {
    clearTimeout(timeout);
    console.log("Stdin had data available");
    process.exit(0);
});

go

package main
import (
    "fmt"
    "os"
    "time"
)
func main() {
    fmt.Println("Checking stdin...")
    stat, _ := os.Stdin.Stat()
    fmt.Printf("Mode: %v\n", stat.Mode())
    fmt.Printf("Is CharDevice: %v\n", (stat.Mode() & os.ModeCharDevice) != 0)
    
    // Test if select would block
    fmt.Println("Testing if stdin would block...")
    done := make(chan bool, 1)
    go func() {
        var buf [1]byte
        os.Stdin.Read(buf[:])
        done <- true
    }()
    
    select {
    case <-done:
        fmt.Println("Stdin had data or EOF")
    case <-time.After(2 * time.Second):
        fmt.Println("Stdin blocked for 2+ seconds")
    }
}

python

import sys
import select
import os
import stat

print("Checking stdin...")
st = os.fstat(sys.stdin.fileno())
print(f"Mode: {stat.filemode(st.st_mode)}")
print(f"Is CharDevice: {stat.S_ISCHR(st.st_mode)}")
print(f"Is FIFO/Pipe: {stat.S_ISFIFO(st.st_mode)}")
print(f"Is Socket: {stat.S_ISSOCK(st.st_mode)}")

# Test if stdin would block
print("Testing if stdin blocks...")
ready, _, _ = select.select([sys.stdin], [], [], 2.0)
if ready:
    print("Stdin had data available")
else:
    print("Stdin blocked for 2+ seconds")

Sampled a hanging Node.js process using macOS sample tool and confirmed it's blocked in the kevent syscall:

2248 uv__io_poll  (in libuv.1.dylib) + 764
: 2248 kevent  (in libsystem_kernel.dylib) + 8

Out of 2265 samples over ~7 seconds, 2248 (99.25%) were blocked in kevent waiting for stdin I/O that never completes.

Call stack shows:

• node::SpinEventLoopInternal - Node.js event loop
• uv_run → uv__io_poll - libuv I/O polling
• kevent - waiting for stdin file descriptor to become readable

This indicates the stdin socket never closes and never provides data, causing the event loop to block indefinitely on macOS.

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go version is working quickly on claude code 2.0.76.

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.