🤖 fix: add context wrapper to post-compaction follow-up message #1688
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After compaction completes, the queued follow-up message was sent as raw
text without any context. This made it unclear to the model that this
message triggered compaction and that relevant context is in the summary.
The fix wraps non-default follow-up messages with a context note:
"(This was the message that triggered compaction - context is in the
summary above)"
The default resume sentinel ("Continue") is excluded since it's just a
signal to continue, not meaningful user content.
This is NOT a regression - the original implementation (dacc278, Nov 2025)
always sent follow-ups as raw text. This change improves upon that design.
When compaction fails (e.g., Gemini 'completing' without producing a valid summary), the queued follow-up message was still being sent. This caused the follow-up to go into the non-compacted chat, potentially hitting context limits again. The fix introduces a CompactionResult discriminated union: - 'not-compaction': Normal stream end, not a compaction request - 'success': Compaction completed successfully - 'failed': Compaction was attempted but failed Queued messages are now only sent when result is not 'failed', preventing the follow-up from being injected into a non-compacted chat.
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Summary
Fixes bug where queued follow-up messages were sent after compaction failed.
Problem:
When compaction fails (e.g., Gemini "completing" without producing a valid summary), the queued follow-up message was still being sent. This caused the follow-up to go into the non-compacted chat, potentially hitting context limits again.
Root cause:
handleCompletion()returnedbooleanwherefalsemeant both "not a compaction stream" (normal) AND "compaction failed" (bad). ThesendQueuedMessages()was called unconditionally on stream-end.Solution:
Introduce
CompactionResultdiscriminated union:"not-compaction": Normal stream end, proceed with queued messages"success": Compaction succeeded, proceed with queued messages"failed": Compaction was attempted but failed - do NOT send queued messagesThis prevents the follow-up from being injected into a non-compacted chat when the model fails to produce a valid summary.
Test Plan
compactionHandler.test.tsassertions to use newCompactionResulttypemake static-checkpassesGenerated with
mux• Model:anthropic:claude-opus-4-5• Thinking:high• Cost:$12.22