CedarCopilot/cedar-mail

Branch: staging

fix(slack): cancel an in-flight run when the user sends another message

merged#2931CedarCopilot

CedarCopilot wants to merge 2 commits into staging from fix/slack-supersede-inflight-turn

A teammate's Slack message remains outside the current user's request
Libra ran this behavior against the change and confirmed the check detects when it breaks.
Technical evidence
- a teammate's trailing Slack message is labeled separately instead of being presented as the current user's request
Changed code: slack-bot-chat.ts.
Out-of-order Slack events preserve both author requests
Libra ran this behavior against the change and confirmed the check detects when it breaks.
Technical evidence
- the resulting Slack history retains both same-author messages in Slack send-time order when events are processed out of order
Changed code: slack-bot-chat.ts.