Return client requesting time, no agreement in place?

I have a client (growth company, about 80 employees and 12 years old) that I had worked with on a 7-month ongoing contract. They ended mine (+several other consultants' contracts) 8 weeks ago. They were then 20 days late on one of the final 2 payments. So, while concerned, I did end up receiving and also the final payment. All fine and left on good terms, they gave a full month's notice and no issues other than the late payment for one of the invoices.

They've now reached out to me as they're looking for additional help with their marketing content again. While they didn't show interest in continuing with a similar contract (2 days/16 hours per week) and rate, I just had a 30-minute call with them last week where they went into some of their copy needs and asked if I could have another discussion in more detail with their founders 3 weeks from now... Fine for me, no problem I say.

I followed up an hour later with some different price options (halving previous contract to 1 day/8 hours per week OR buying up to 20 or 30-hours/month at a set hourly rate OR a set project by project fee option OR a retainer where $1000/month gets this, $2000/month gets this, and so on).

No response to the fee options, but now they sent the meeting invite an hour later, and the invite is mentioning that we'll discuss their content needs AND that I'll be interviewing the two founders where the topics and discussion points can be used for content that I would help produce.

No problem for me to have another call to discuss their needs, but I'm definitely hesitant to do an interview for the intention of content with no agreement in place.

I'm asking for advice here on the best way to move forward. I've yet to accept the meeting invite and debating how to reply first. We have no agreement and no contract in place, and I don't like the idea of going through with interviewing their founders, then chance it that marketing will turn around after and say, "Yeah, we don't have budget or we changed our minds, so we're going to pass, but thanks anyway for the time..."

I'd appreciate any advice or how others would handle this, considering my history there. Do I just tell them flat out, we need to have an agreement in place before any interview takes place and be very firm about it?

Thanks for any and all advice!