The decision point
If the error occurs at the bifurcation, the correction must occur there.
Every protected action already reaches a binary decision before execution: continue or stop.
The inherited decision
Earlier authority continues to answer a later question.
The system may know that identity was accepted, permission was granted, and the session remains open. It still has to decide whether the next protected action should proceed.
Without current presence, that decision relies on evidence inherited from an earlier moment.
The missing branch condition
Presence makes the other decision available.
Why timing matters
Detection cannot prevent an action that has already occurred.
Detection, investigation, recovery, insurance, and mitigation remain important. They address a different point in time.
Existence does not attempt to repair the decision afterward. It supplies the missing fact before the protected consequence crosses the boundary.
The application boundary
The intervention can be small.
verify_existence(...)The application asks one current question immediately before the selected function executes. A failed result halts that action. The application does not become the existence system; it honors the answer.