Opus 4.6 Extended thinking:
```
Finding the Inner Diameter The coaster sits beneath the glass on the table, meaning the glass rests on top of it. Assuming the coaster matches the outer diameter of the glass base:
Outer diameter of glass = diameter of coaster = 9 Wall thickness = 1 (on each side, so subtract twice)
dinner=9−2(1)=7d_{\text{inner}} = 9 - 2(1) = 7dinner =9−2(1)=7 The inner diameter of the glass is 7.
```
Makes its assumption clear, seems reasonable?
Assumptions need to be stated or you're solving only a discreet part of the problem! Try this, see if you get another deadpan assumption.
I mean, the model is intended to help the user, not fight against the user trying to break it. IMO, it is reasonable for such model to default on making assumptions and going forward as long as the assumptions are clearly stated.