# K1646–K1650 bounded same-namespace rename

Rename validates both names and parents, locates the source entry, rejects an
existing destination, and checks directory ancestry before publication. Moving
a directory beneath itself or any descendant returns `Cycle` without changing
the source, destination, parent graph or inode allocation bitmap. An unchanged
source/destination pair succeeds as a no-op. Replacement rename is not supported.

One serialized in-memory assignment publishes the new parent and name while
retaining inode identity, child-parent references and every allocation bit.
Rename therefore also succeeds when the creation quota is exhausted. Afterward
the old name is absent and the new name resolves to the original inode.

Two host tests and an omitted-ancestry-guard mutant exercise this model, followed
by AArch64 compilation and six development guest profiles. No persistent disk,
journal, VFS syscall, cross-mount, concurrent-reader or power-loss guarantee is
claimed. Canonical product release acceptance remains open.