# K1611–K1615: bounded three-extent file reader

The read-only file descriptor contains exactly three nonempty extents. Their
block intervals are ascending, disjoint, nonzero, and within the device.
The logical file size is positive and no larger than the total extent capacity.
Validation completes before the descriptor can be used to read.

The reader copies exactly the logical file bytes into caller-owned output.
An undersized output is rejected before device I/O. If a device read fails,
the copied prefix is cleared and the error is returned. The read never writes
past the logical file length. Host tests cover three separated blocks, overlap,
reversed order, disk bounds, capacity, short output, and a failed second read.

These tests use a synthetic block reader. Real device sectors, an independent
file hash oracle, and six guest profiles require separate K1615 evidence.