One client, forty hours a week, their standups and their laptop - am I a contractor in name only?

I was in almost exactly this and untangled it over about two months without losing the account. What changed on paper: a written statement of work per project with deliverables and dates instead of an open-ended engagement, my own machine, no attendance at their internal ceremonies unless they were relevant to a deliverable, and a line saying I could use substitutes. What changed in practice was less than you would think, because the client mainly wanted the work done. Worth saying clearly: the tests for employment status are different in every country and an accountant or employment solicitor will answer this in one paid hour, which is money well spent when the exposure is this size.

Three years of this with one client, treated as staff in every way except the ones that cost them money, and then a budget freeze arrived and I was gone in a week with no notice period and no redundancy. Nothing improper happened - I just had none of the protections and had stopped noticing. The lesson was not about paperwork, it was that I had let my pipeline die.

Price it properly and a lot of the discomfort resolves itself. My rule for a full-time-shaped engagement is that the day rate has to cover the holiday I am not paid for, the sick days, the pension nobody is contributing to, the accountant, insurance and roughly six to eight weeks a year of no work between contracts. When I actually did that arithmetic, the rate I needed was well above what a salary for the same role would look like, and that gap is the whole reason to be a contractor. If your rate does not reflect it, you have taken an employment risk profile at a freelance price.

Ask for a statement of work, use your own machine, keep one small second client alive even at a discount. That is most of the distance, and the second client is the part that changes how the conversation feels.

Mild pushback on the panic in this thread. In several jurisdictions the misclassification risk sits mostly with the client, and they usually have advisers watching it more closely than you are. The thing that should actually worry you is concentration: one client, eight months, their equipment and their calendar. Fix that first and the paperwork tends to follow.