Cross-conversation references — ability to peek into another chat session

Problem

Conversations accumulate valuable context (lessons learned, architectural decisions, debugging insights) that's often relevant to other active sessions. Today there's no way to reference one conversation from another without a manual workaround: exit the chat, copy the conversation ID from the terminal output, then ask the other session to read the raw JSONL file from ~/.claude/projects/.../<id>.jsonl.

Use case

I had two concurrent sessions — one where I discovered an interesting technical insight, and another focused on broader architectural planning. I wanted the planning session to incorporate the insight from the other session. I had to:

1. Exit the first chat to get its ID from the claude -c <id> output
2. Paste the ID into the second chat
3. Ask Claude to manually read and parse the raw JSONL file

It worked, but it's fragile and unintuitive.

Proposed solution

A built-in command like /peek <conversation-id> that:

1. Reads and parses the target conversation's JSONL properly
2. Presents a summary of the conversation
3. Lets the current session selectively reference relevant parts

Nice-to-haves

• List recent conversations to pick from (instead of needing the UUID): /peek --list or /conversations
• Named/tagged conversations for easier discovery
• A summarized import rather than raw JSONL ingestion

Why this matters

Claude Code's auto-memory and CLAUDE.md solve the problem for durable, long-term knowledge. But there's a middle ground: ephemeral insights from one session that are relevant to another session right now but don't warrant permanent storage. Cross-conversation references would fill that gap.