conversationKey derived the group session key from chat_id alone, so in
Feishu topic groups every topic shared one Harness session: context,
/new, pending approvals, and batch-input state all leaked across topics.
Append the event's thread_id to the session key when present. Topic
groups stamp every message with a thread_id, so each topic now maps to
its own group:<chat_id>🧵<thread_id> session. Regular group chats
carry no thread_id and keep the single shared group:<chat_id> key; p2p
keys are untouched.
- message-utils.mjs: thread-aware conversationKey
- message-utils.test.mjs: topic isolation + regular-group fallback cases
- lib/index.js: regenerated host bundle
