Bug Description

Session compaction enters a failure loop that causes severe responsiveness issues and eventually renders the session unusable.

Symptoms

1. Compaction repeatedly fails with: Full summarization failed, trying partial: Summarization failed: fetch failed
2. Logs show this error repeating in a loop (10+ times per minute)
3. Session becomes unresponsive or extremely slow
4. Only remedy is /clear to break the loop

Environment

• OpenClaw: 2026.4.2 (d74a122) ← upgraded from 2026.3.28 prior to bug appearing
• macOS: 26.4 (arm64)
• Node: v22.22.1
• Runtime: agent=main (tUI/main session)

Relevant Log Entries

{"subsystem":"compaction"} Full summarization failed, trying partial: Summarization failed: fetch failed
{"subsystem":"compaction"} Partial summarization also failed: Summarization failed: fetch failed
{"subsystem":"agent/embedded"} [timeout-compaction] LLM timed out with high prompt token usage (126%); attempting compaction before retry (attempt 1/2)

Additional Context

• Issue first appeared after upgrading from 2026.3.28 to 2026.4.2
• May be related to 2026.4.x changes; please confirm if compaction/summarization logic changed in 2026.4.1 or 2026.4.2
• A /clear command successfully broke the loop
• Compaction thresholds were adjusted as a workaround

Tags

bug, compaction, regression