Summary

compaction.mode: "safeguard" fails to produce a summary when session hits ~186k tokens, resulting in:

"Summary unavailable due to context limits. Older messages were truncated."

Expected Behavior

Safeguard mode should chunk the large history and produce a summarized compaction, preserving conversation context.

Actual Behavior

Compaction entry shows:

{
  "type": "compaction",
  "summary": "Summary unavailable due to context limits. Older messages were truncated.",
  "tokensBefore": 186094,
  "fromHook": true
}

Environment

• Session ran for ~12.5 hours before hitting the limit
• Config: agents.defaults.compaction.mode: "safeguard"
• Model: anthropic/claude-opus-4-5
• Memory flush did fire (~38s before compaction)
• Two compactions fired in quick succession (186k tokens, then 19 tokens)

Notes

• Memory flush safeguard worked correctly (fired at soft threshold)
• Bug appears to be in chunked summarization logic — it should have broken 186k tokens into pieces but bailed out instead
• Gemini embeddings showed quota exhaustion (429 RESOURCE_EXHAUSTED) ~40s before compaction, but that is for memory search, not summarization