A fan-out of N agents (Task/Agent) merged into one shared "Activity / N
steps" cluster — groupConversation folded an Agent spawn like any Bash/
Read call. Now an Agent spawn is a cluster boundary, rendering as its own
first-class collapsing card (reusing the existing sticky-agent path: folded
prompt T-263 + nested run T-264), while adjacent non-agent foldables keep
clustering into the normal Activity card.
Two changes:
- activity_cluster: a shared isAgentTool() predicate; _isFoldable returns
false for agent spawns at every level (incl. L3), so parallel agents
never merge. Only the grouping boundary changes; fold mechanics are
unchanged.
- conversation_view: harden resolveOwner. Its nearest-preceding-agent
fallback is safe with one agent but mis-routes under a parallel fan-out
(an unattributable item lands in whichever agent was emitted last —
a sibling's card). With >1 agent, drop the fallback so the item orphans
(rendered inline) instead of cross-attributed. The T-338 direct route
(parent_tool_use_id) still attributes interleaved items correctly.
Tests: two consecutive agents → two cards (not one cluster); agent breaks
a sibling cluster; agents first-class at L3; regression — consecutive
Bash still one cluster; interleaved parallel-agent runs route to their own
card; an unattributable item orphans instead of being swept into the last
agent.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.8
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