Personalized HeyGen welcome video for every Calendly booking

Build me an agent workflow that emails every newly booked Calendly invitee a short, personalized AI welcome video so they walk into the meeting already feeling like they know the rep.

Trigger: a Calendly webhook on the invitee.created event. The workflow should run the moment a booking lands.

When the webhook fires, call the Calendly Get Event Invitee operation to fetch the invitee's name, email address, the event's scheduled start time, the invitee's timezone, and every question and answer pair from the booking form (the questions_and_answers field).

Then check how far away the meeting is. If the scheduled start time is more than two hours from now, take the personalized path. If it is less than two hours away, take the fast fallback path described below.

Personalized path: draft a 20 to 30 second spoken script that (1) greets the invitee by their first name, (2) references the meeting time formatted in the invitee's local timezone in a natural way (e.g. 'Tuesday at 2pm your time'), and (3) acknowledges at least one specific answer from the booking-form questions, such as the goal they typed in or the company they listed. Keep the tone warm, conversational, and brief. End with one short sentence about what to expect on the call.

Call HeyGen's Generate Avatar Video operation with the script, the configured avatar_id, and voice_id. Then poll HeyGen's Retrieve Video Status operation every 8 to 10 seconds until status is 'completed' or 'failed'. Cap the wait at 5 minutes. Once completed, call HeyGen's Retrieve Shareable Video URL operation to get a public share link.

Fast fallback path (meeting is less than two hours away, or the personalized render failed or timed out): call HeyGen's Generate Video from Template operation using a pre-configured fallback template_id with the invitee's first name filled in as a template variable. Poll Retrieve Video Status the same way and then fetch the Retrieve Shareable Video URL.

Finally, send the email via Gmail's Send a Message operation to the invitee. The subject should reference the upcoming meeting (e.g. 'A quick hello before our chat'). The HTML body should include a one-line warm intro, the share link rendered as a clickable thumbnail or button labeled 'Watch your welcome video', and a sign-off from the rep. Send from the configured Gmail account.

Configuration the workflow should expose: the HeyGen avatar_id, the HeyGen voice_id, the HeyGen fallback template_id, the fallback cutoff in hours (default 2), the polling timeout in seconds (default 300), the sender name, and the email subject template.

Error handling: if the Calendly event has been canceled or rescheduled between the webhook firing and the invitee lookup, skip silently. If HeyGen returns a 403 (plan limit) or a failed render, fall back to the template path. If Gmail send fails, log the error with the invitee email and video link so the rep can resend manually.