Summary

When /compact runs or auto-compaction triggers, a TypeError: Cannot read properties of undefined (reading 'length') occurs.

Stack Trace

The error occurs in limitHistoryTurns (history.js) when messages is undefined:

if (!limit || limit <= 0 || messages.length === 0) return messages;

Root Cause

In compact.js, session.messages can be undefined in edge cases (e.g., corrupted session file, SDK edge case). This undefined value flows through sanitizeSessionHistory to limitHistoryTurns, which doesn't guard against it.

Suggested Fix

Add a guard in limitHistoryTurns:

export function limitHistoryTurns(messages, limit) {
    if (!messages || !limit || limit <= 0 || messages.length === 0) return messages ?? [];
    // ...
}

Or guard upstream in compact.js:

const prior = await sanitizeSessionHistory({ messages: session.messages ?? [], ... });

Environment

• Clawdbot version: 2026.1.24-3
• OS: macOS (arm64)
• Node: v22.11.0