fix(control): never render compaction fold summaries as user bubbles#3932
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Compaction stores its summary as a user-role message so the model treats it as context, but IsSyntheticUserMessage did not recognize the three fold prefixes. A history reload that races a compaction pass (switch tabs mid-/compact, switch back -> missedTurnDone reload) then rendered the entire fold - tool calls, commands, console digests - as a giant user bubble. Closes #3653
This was referenced Jun 11, 2026
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Root cause
Compaction folds store their summary as a user-role message (so the model treats it as plain context):
Compact→<compaction-summary>…(internal/agent/compact.go)SummarizeFrom→Summary of the later conversation (compacted from here on):…SummarizeUpTo→Summary of earlier conversation (compacted up to here):…The chat surfaces filter injected user-role messages through
IsSyntheticUserMessage, but none of the three fold prefixes were registered. In the normal live flow you never notice — the transcript shows the compaction card built from events. The leak needs a history reload that races a compaction pass, which is exactly the repro @cinos-1 nailed down: tab A mid-/compact→ switch to tab B → switch back to A. The return trip seeslocal.running && !backend.running(missedTurnDone), resets the transcript, and re-renders fromHistoryForTab— which faithfully served the raw fold as a giant user bubble full of tool calls, commands, and console digests.Fix
Register the three fold prefixes in
syntheticPrefixes(with the sync note extended tocompact.go), so every history-replay surface — desktop reload, session resume, serve — drops them, matching what the live transcript shows. Table tests cover all three folds plus a guard that an ordinary user message starting with "Summary of…" is not swallowed.Closes #3653