Summary

When OpenClaw enters context overflow recovery (for example, logs like [context-overflow-recovery] Attempting tool result truncation), the agent session JSONL can end up with duplicated role=user entries (same content hash and length), even when tool-result bloat is not present in the session file. This amplifies transcript growth and can cascade into additional overflows.

Evidence (one capture)

• sessionKey: agent:main:main:heartbeat
• session JSONL contained 3 copies of the same user message (1 unique message):
  • sha256(content) prefix: b266b2bfea51
  • len: 442
  • occurrences: 3
  • createdAt timestamps:
    • 2026-04-14T08:36:16.018Z
    • 2026-04-14T08:40:28.997Z
    • 2026-04-14T08:46:41.910Z
  • content preview: Read HEARTBEAT.md if it exists (workspace context)...

Gateway log correlation (same machine):

• 2026-04-14T01:40:25.557-07:00 [context-overflow-diag] ... diagId=ovf-mnydfsgk-5y5CJA
• 2026-04-14T01:40:25.559-07:00 [context-overflow-recovery] Attempting tool result truncation ...
• 2026-04-14T01:45:06.714-07:00 [context-overflow-diag] ... diagId=ovf-mnydltei-OtPZfw compactionAttempts=1

Expected

Overflow recovery should not duplicate existing user messages in the persisted session store.

Observed

After recovery, the persisted session contains duplicate copies of a prior user message (byte-identical).

Possible repro (hypothesis)

1. Start a session with a single short user prompt.
2. Force a context overflow (large tool result or repeated messages) until overflow recovery triggers.
3. Let recovery complete (tool result truncation / compaction).
4. Inspect the session JSONL for duplicated role=user entries (dedupe by content hash and len, or by message id if present).

Why it matters

This creates artificial transcript growth that can worsen or re-trigger overflows, especially in long-running sessions.

Suspected root area

Overflow recovery / truncation code path may be re-appending the last user message (or replaying a block) without idempotency or deduping in the session writer.

Ask

• Confirm and patch overflow recovery/session persistence so prior user messages are not duplicated.
• Add guardrails (for example, dedupe by stable message id, or a last-N hash window) when writing recovered transcripts.