What causes "read stdout: %w" in chenhg5/cc-connect?

Check whether the agy process crashed (dmesg / OOM killer logs) and fix the underlying crash

read stdout: %w

Error message

read stdout: %w

What it means

The goroutine reading the agy process's stdout hit a read error other than EOF or the benign 'file already closed' (which happens on normal cancellation). The raw OS read error is wrapped as 'read stdout: %w' and delivered as a core.EventError. It indicates the stdout pipe broke unexpectedly rather than the process finishing.

Source

Thrown at agent/antigravity/session.go:303

	reader := bufio.NewReader(stdout)
	buf := make([]byte, 1024)

	for {
		n, err := reader.Read(buf)
		if n > 0 {
			text := string(buf[:n])
			select {
			case as.events <- core.Event{Type: core.EventText, Content: text}:
			case <-as.ctx.Done():
				return
			}
		}
		if err != nil {
			if err != io.EOF && !strings.Contains(err.Error(), "file already closed") {
				slog.Error("antigravitySession: read error", "error", err)
				select {
				case as.events <- core.Event{Type: core.EventError, Error: fmt.Errorf("read stdout: %w", err)}:
				case <-as.ctx.Done():
				}
			}
			return
		}
	}
}

func (as *antigravitySession) detectNewSessionID(preEntries map[string]bool, sendStartedAt time.Time) string {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	slug := antigravityProjectSlug(as.workDir)
	chatsDir := filepath.Join(homeDir, ".gemini", "tmp", slug, "chats")

	entries, err := os.ReadDir(chatsDir)
	if err != nil {

View on GitHub (pinned to 4000b2338a)

Solutions

Check whether the agy process crashed (dmesg / OOM killer logs) and fix the underlying crash
Verify ulimit -n and system resources are not exhausted
Retry the turn; transient pipe errors usually disappear on rerun
If you cancel sessions, confirm cancellation goes through ctx (which closes stdout gracefully and is filtered) rather than killing the process directly

Defensive patterns

Strategy: retry

Validate before calling

// pre-flight: ensure resources OK
if n := len(processList("agy")); n > 0 { /* prior agy still running? kill stale ones */ }

Try / catch

if evt.Type == core.EventError && strings.HasPrefix(evt.Error.Error(), "read stdout:") {
    slog.Warn("transient stdout read failure; retrying turn", "err", evt.Error)
    // re-dispatch the turn
}

Prevention

Avoid SIGKILLing agy; cancel via session Stop/ctx so stdout close is filtered
Raise fd limits on hosts running many sessions
Monitor for OOM kills of the agy process

When it happens

Trigger: reader.Read on the agy stdout pipe returns a non-EOF error, e.g. the pipe descriptor is invalid, the process was killed with SIGKILL leaving a broken pipe, or an fd was closed concurrently outside the normal ctx cancellation path.

Common situations: agy process crashed hard or was OOM-killed; system resource exhaustion (fd limits); external kill of the child process; rare kernel-level pipe errors.

Related errors

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/0afacd4aa74b1165. Report an issue: GitHub.