A sub-agent's sidechain run used to spill loose into the main chain,
indistinguishable from main-thread items. Now:
- _sidechainFold routes every sidechain item to its owning Agent/Task
tool-use by walking the parentUuid chain up to the Agent message it
branches off (nearest-preceding Agent as fallback) — correct even for
parallel agents.
- The run (prose / thinking / tool cards) nests in an "agent run"
ClideHolderCard UNDER the Agent card, suppressed from the top level. The
prompt still folds into the call (T-263); a successful sidechain tool
result folds into its own tool card inside the run, so it isn't a
separate step.
- When a run is shown, the Agent card's returned-result segment is dropped
(it duplicates the run's final output, note E) — but kept when no run
was captured, so output is never lost.
Tests: run nesting, returned-result dedup, parallel-run attachment (would
fail under nearest-preceding), and folded-result-not-double-counted.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.8
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