D679 - No on-disk fallback for the archive index

Status: decided Date: 2026-09-26

The archive path-resolve call resolves only the paths the title's own index names; every other path gets the unresolved answer measured on the hardware, written at each slot's full width. orbistoun synthesises no id and no size from files on disk.

Why: an id for a path outside the index is a guessed output that no implemented read path consumes, and a size beside it asserts a resolve the hardware does not perform. The measured answer is exact: id 0xffffffff, size 0, status 0, return -1. A size slot is eight bytes, and a title reads an unwritten upper half as a real length.

Rejected:

• An on-disk fallback answering the real file size and a synthesised stable id: a guess that moves no title.
• Four-byte writes into each slot: they leave the upper half of a 64-bit size slot as the caller's stack held it.