Tria left home.
He did not vanish from the world. The boy received care, was diagnosed with schizophrenia, found treatment that helped, and grew older. He learned that hearing or seeing something was not the same as having proof of it.
That distinction is why he kept returning to the evidence: the cashier's reaction, the server timestamps, the future-dated drawing, the email and the old hard drive. Some of his experiences were symptoms. Some records existed outside his experience. The site kept both and did not label the difference.
In the scan of My Home's Window, the bars still divide the sky. Between their pencil shadows is one sentence:
Your shoelace is untied.
Tria was wearing slippers.