An API returns a slice of names, but the backing allocation may be released or replaced before the caller finishes reading. The slice still carries an address and length. Those fields do not keep that allocation alive.
Within the specified Zig 0.15.2 reference, pointer validity and lifetime remain the programmer's responsibility. A slice references other memory. Function documentation therefore needs to identify ownership and the events that invalidate the returned access. Returning a slice does not extend the backing storage's lifetime.
Consider a hypothetical catalog whose names operation lends a view into an internal allocation. The catalog owns that allocation. The caller must not free the view. Destruction invalidates it, and a successful reload that replaces the allocation invalidates every earlier view. If adding a name can grow and relocate storage, that operation needs an invalidation rule too. Copying the slice descriptor does not copy the names or remove those dependencies.
Failure needs its own wording. A reload could build replacement storage separately and install it only after success. Under that proposed contract, failed preparation leaves the old allocation and its views valid. An implementation that clears old storage first would need a different promise.
Another API could return an allocated copy of the name data and transfer responsibility for freeing it with a documented allocator. That buys an independent lifetime by adding ownership work. I would choose between the two after tracing the caller's actual reads, reloads and cleanup boundary.