Stoic assent is the critical control point because people usually do not fail merely by having impressions; they fail by agreeing too quickly with what the impression seems to mean.
Stoic philosophy does not claim control over what first appears. It locates responsibility at the point of assent.
An impression arrives. The question is whether the mind grants it agreement. This is where judgment becomes moral and cognitive work rather than passive reception.
This maps directly to interpretation inside the discernment model. The act is no longer simply what is present, but what the mind says the presence means. Assent is where appearances become judgments.
That is why so many errors occur here. People do not only see. They agree. They do not only feel. They conclude. They do not only notice. They ratify.
The Stoic discipline is not emotional deadness. It is refusal to let the first reading harden into truth without examination.