John Owen, in The Nature and Power of Indwelling Sin, dealt with those times when someone has decided to commit a sin but are physically hindered from doing so. "Ofttimes, when a cloud is full of rain and ready to fall, a wind comes and drives it away; and when the will is ready to bring forth its sin, God diverts it by one wind or other: but yet the cloud was as full of rain as if it had fallen, and the soul is as full of sin as if it had been committed." Perhaps this is the distinction between the thought and the intent in Hebrews 4:12For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.
See All.... God's word can discern when the thought becomes an intent. When that line is crossed, sin has been committed.