Meeting prep brief from Mem notes in Slack

Build me an agent workflow that prepares me for every meeting using my Mem knowledge base as a personal memory store.

Trigger: poll Google Calendar for new_event so the workflow fires whenever a new meeting lands on my calendar. Only run for events more than 30 minutes in the future (so the brief is actually useful at meeting time), and skip personal holds that have no external attendees beyond me.

When the trigger fires, the agent should:

1. Use Get Event (google-calendar) to load the full event: title, description, start time, attendees, and any conference link. Extract the external attendees, their email domains, and the likely company (from the dominant non-personal email domain or the event title).

2. Use Search Notes (mem) to find past notes that mention each external attendee by name or email, and a second search for the company. For the top one or two hits, optionally call Find Related Notes (mem) to widen the context with anything semantically related (other deals, shared projects, intros).

3. Synthesize a short prep brief in markdown. It should cover: who is on the call and their role if known, the company in one line, our relationship history (when and how we last interacted), open threads or unresolved questions, any commitments I made previously, and 2 or 3 suggested talking points or questions to ask. Keep it scannable: bullets, not paragraphs. If there is no prior context in Mem, say so honestly rather than inventing one.

4. Use Create Note (mem) to save the brief as a new note, linking it to a collection titled "Meeting Briefs" (create the collection if it does not exist, or use Add Note to Collection if the collection already exists). The first line of the note should be the meeting title and date so it is easy to find later.

5. Use Open a Conversation (slack) to open a DM channel with me, then Send a Message (slack) to that DM. The message should include the meeting time in my local timezone, the brief itself formatted with Slack mrkdwn (single asterisks for bold), and a link to the new Mem note so I can open the full version with one tap.

Guardrails: never fabricate a relationship history that is not supported by a note. If the Mem search returns nothing relevant, the Slack DM should still go out, but it should plainly say there is no prior context. Do not run for cancelled events. Do not re-run if the same event id has already produced a brief.