Feature: Link subagent sessions to main session view

[Koomook]

Problem

When a subagent (Task tool) runs in Claude Code, its output is recorded as a type: "user" message in the main session's JSONL file. This makes it appear as if a human typed the message, when it was actually produced by a subagent.

Example

In session ccb768a6-b559-478c-a66b-114fa4c95239:

• A subagent was invoked to summarize text
• The subagent's response ("요약할 텍스트: 확인 결과:...") was recorded with "type": "user"
• This displays as "Human" in the cops dashboard, which is misleading

Proposed Solution

1. Identify subagent messages: Detect messages that originate from subagents (they may have metadata like sourceToolAssistantUuid or similar markers)

2. Visual differentiation: Display subagent-originated messages differently from regular human input (e.g., different icon, label like "Subagent Result" instead of "Human")

3. Link to subagent session: If Claude Code creates separate session files for subagents (e.g., agent-*.jsonl), provide a way to:

   • Show a link/button to view the full subagent session
   • Inline expand the subagent's conversation within the main session view

Questions to Investigate

• Does Claude Code record subagent sessions in separate JSONL files?
• Is there metadata in the JSONL that identifies a message as coming from a subagent vs direct human input?
• How are subagent sessions linked to parent sessions?

Related Files

• web/src/feature/session/util/parse-content.ts - Message parsing logic
• web/src/feature/session/component/message-bubble.tsx - Message display component
• shared/domain/transcript_user.go - User transcript domain model (has SourceToolAssistantUUID field)