# Read-only partition block view (K1531–K1535)

A view is created only from a validated partition interval and the measured
physical disk capacity. The interval is half-open: `start_lba` is included,
`end_lba = start_lba + sectors` is excluded. Creation rejects zero length,
integer overflow, or an interval beyond the device. The view borrows the
underlying block device; it never owns or releases its DMA frames.

`translate(logical_lba, sector_count)` checks a nonzero sector count and
requires the entire logical interval to fit inside the partition before it
adds the partition start. On success it returns the physical LBA and count.
The final logical sector maps to `end_lba - 1`. A request beginning at the
partition length, or crossing that length, returns `OutsidePartition` before
any physical I/O is submitted. Overflow returns an explicit error. The view
contains no write method; callers use the existing read-only block path.

The caller may publish a view after construction, then pass only translated
requests to the device. A refused request leaves view state, queue owners,
DMA buffers, the neighbouring disk sector, and any mounted service unchanged.
Local tests verify the first and final sectors, crossing ranges, zero length,
overflow, and that rejected translations never call a fake device. K1535
must read the final sector through a real Virtio disk and show a neighbouring
physical sector unchanged after an out-of-partition request is refused in all
direct and UEFI memory profiles.