Arenas

Callers lend memory, never a way to allocate it, and every byte has one owner that picks where it lives once:

• Weights and their packed copies belong to the model, placed by its load’s residency.
• Weights, gradients and optimizer moments under training belong to the trainer, on its executor’s devices.
• Activations, scratch and staging belong to the executor, grown to a high-water mark.

Every output whose length scales with the call lands in an arena, while fixed-size reports such as stats and descriptions stay caller fields. uform_arena_init places an arena where its executor computes, host pages or the memory of its GPU, and allocates nothing until a call writes into it. A call rewinds the arena it is given, invalidating the previous call’s outputs, and grows it only when the new outputs outsize everything it held, so a steady loop allocates once.

• A NULL arena, or inputs inside the arena the call rewinds, report uform_status_invalid_argument_k.
• An arena serves one call at a time, and a second call naming it finishes uform_status_contended_k.
• A call on another residency or device than the arena’s reports uform_status_device_k.
• A GPU arena grows on the first stream of the executor that made it, so it serves only that executor and is freed before it.

uform_arena_t arena = NULL;
uform_arena_init(&(uform_arena_init_t){.arena = &arena, .executor = executor, .outcome = &outcome});
for (size_t batch = 0; batch != batches_count; ++batch) {
    encode.texts = texts[batch], encode.arena = arena, encode.embeddings = &embeddings;
    uform_text_encode(&encode);
    if (encode.outcome->status != uform_status_success_k) break;
    consume(embeddings, encode.count); // valid until the next call given `arena`
}
uform_arena_free(arena);

§ Rows and Tapes

A verb’s count is its batch axis and nothing else. Outputs are views the call writes packed into its arena, so none carries a capacity for the caller to pick. uform_rows_view_t holds one row per item as data, stride, columns and scalar, field for field USearch’s rows, so pooled embeddings feed an index as they are. Ragged inputs are uform_tape_view_t tapes laid out as Apache Arrow lays them: elements end to end in data, and count + 1 offsets in host memory around them. Ragged outputs, such as per-token states, are uform_rows_tape_view_t: packed rows and one more offset than items. On a VRAM executor every output is device memory, which the caller copies out itself or hands to a USearch VRAM index as it is.