chenhg5/cc-connect · error

pi: read history: %w

Error message

pi: read history: %w

What it means

readPiHistory streams a pi session JSONL file with a bufio.Scanner and appends HistoryEntry items; if scanner.Err() reports an I/O failure mid-read (not EOF), it wraps the error as 'pi: read history'. Called by GetSessionHistory when fetching past conversation turns.

Source

Thrown at agent/pi/pi.go:673

		var text string
		content, _ := msg["content"].([]any)
		for _, c := range content {
			item, _ := c.(map[string]any)
			if item != nil {
				if t, ok := item["text"].(string); ok && t != "" {
					text = t
					break
				}
			}
		}
		if text == "" {
			continue
		}
		all = append(all, core.HistoryEntry{Role: role, Content: text})
	}
	if err := scanner.Err(); err != nil {
		return nil, fmt.Errorf("pi: read history: %w", err)
	}

	if limit > 0 && len(all) > limit {
		all = all[len(all)-limit:]
	}
	return all, nil
}

View on GitHub (pinned to 4000b2338a)

Solutions

1. If the cause is bufio.ErrTooLong (very large single line), the scanner buffer must be enlarged in the adapter (scanner.Buffer with a larger max) — report/patch, since callers cannot fix it externally.
2. Re-run GetSessionHistory; transient I/O errors on network filesystems often resolve on retry.
3. Verify the session file still exists and is readable at the path findSessionFile resolved.
4. Check disk/FS health if errors persist (dmesg, mount status).

Example fix

// caller-side retry before
entries, err := agent.GetSessionHistory(ctx, sessionID, 50)
if err != nil {
    return err
}
// after
entries, err := agent.GetSessionHistory(ctx, sessionID, 50)
if err != nil {
    time.Sleep(500 * time.Millisecond)
    entries, err = agent.GetSessionHistory(ctx, sessionID, 50)
    if err != nil {
        return fmt.Errorf("get history: %w", err)
    }
}

sessFile := findSessionFile(sessDir, sessionID)
f, err := os.Open(sessFile)
if err != nil {
    return fmt.Errorf("history file unreadable: %w", err)
}
f.Close()

entries, err := agent.GetSessionHistory(ctx, sessionID, limit)
if err != nil {
    select {
    case <-time.After(500 * time.Millisecond):
        entries, err = agent.GetSessionHistory(ctx, sessionID, limit)
    case <-ctx.Done():
        return ctx.Err()
    }
}

When it happens

Trigger: Calling GetSessionHistory for a session whose JSONL file exists but becomes unreadable during scanning: I/O errors, file deleted/truncated mid-read, or device errors. Note: an overly long JSONL line exceeding bufio.Scanner's default 64KB token limit also surfaces as a scanner error here.

Common situations: Very long agent messages/tool outputs producing single JSONL lines >64KB (bufio.ErrTooLong); network-mounted home directories dropping connections mid-read; files rotated by cleanup jobs while history is being fetched.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• pi: read settings: %w
• read stdout: %w
• save config: %w
• listen for Agy permission hooks: %w
• generate permission bridge token: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/e6a46500ca1d230f. Report an issue: GitHub.