/btw conversations not persisted to disk in 2.1.104

Description

/btw (aside) conversations are no longer persisted to disk as of Claude Code 2.1.104. The UI works — you can open a /btw side conversation, type messages, and get responses — but when the conversation closes, nothing is written to disk.

Expected behavior

In 2.1.97 and earlier, /btw created agent-aside_question-*.jsonl files in the session's subagents/ directory. These files contained the full conversation and could be referenced later.

Actual behavior

In 2.1.104, no aside_question files are created. The main session JSONL has isSidechain: false on every message. The /btw conversation simply vanishes when closed.

Steps to reproduce

1. Start a Claude Code session (2.1.104)
2. Open a /btw conversation and have a multi-message exchange
3. Close the /btw conversation
4. Check ~/.claude/projects/<project>/<session-id>/subagents/ — no aside_question files exist
5. Check the main session JSONL — no isSidechain: true messages

Impact

Users who rely on /btw for capturing ideas mid-session lose all that content. This is especially impactful for users who have built tooling to mine /btw conversations (e.g., extracting ideas and feedback into external memory systems).

Environment

• Claude Code 2.1.104
• macOS Darwin 25.4.0
• Last working version: 2.1.97