Struct ZPrepareArgs 

pub struct ZPrepareArgs<'a> {

    pub model: &'a Arc<CmfModel>,
    pub geom: ZGeom,
    pub key: u64,
    pub n_img: usize,
    pub n_img_p: usize,
    pub n_cap_p: usize,
    pub grid: (usize, usize),
    pub cap: &'a [f32],
    pub rope_img: (&'a [f32], &'a [f32]),
    pub rope_joint: (&'a [f32], &'a [f32]),
    pub x_emb_w: &'a [f32],
    pub x_emb_b: &'a [f32],
    pub x_pad: &'a [f32],
    pub final_w: &'a [f32],
    pub final_b: &'a [f32],
    pub noise_refiner: &'a [ZBlockRef<'a>],
    pub layers: &'a [ZBlockRef<'a>],
    pub mods_all: Option<&'a [f32]>,
    pub final_scale_all: Option<&'a [f32]>,
    pub neg: Option<ZNegArgs<'a>>,
}

Once per (prompt, resolution). The backend uploads/caches what it needs keyed by key; weight planes are keyed by the MODEL (not by key) and survive across prompts until zimage_release.

Fields

model: &'a Arc<CmfModel>

geom: ZGeom

key: u64

Caller-chosen identity of this (prompt, resolution) state; every ZStepArgs of the same image carries the same key.

n_img: usize

Image tokens (H/16 · W/16), padded count ceil32(n_img), caption padded count ceil32(L). S = n_img_p + n_cap_p.

n_img_p: usize

n_cap_p: usize

grid: (usize, usize)

The patch grid (H/16, W/16); n_img = grid.0 · grid.1. Row-major token order hp·grid.1 + wp.

cap: &'a [f32]

[n_cap_p, hidden], ALREADY context-refined (host or device).

rope_img: (&'a [f32], &'a [f32])

Noise-refiner RoPE: [n_img_p · hd/2] cos, sin (complex-interleaved pairs, hd/2 angles per token).

rope_joint: (&'a [f32], &'a [f32])

Main-layer RoPE: [(n_img_p + n_cap_p) · hd/2], rows ordered [img, cap].

x_emb_w: &'a [f32]

all_x_embedder.2-1.weight [hidden, 64], .bias [hidden], x_pad_token [hidden] (replaces rows ≥ n_img after the embed).

x_emb_b: &'a [f32]

x_pad: &'a [f32]

final_w: &'a [f32]

all_final_layer.2-1.linear.weight [64, hidden], .bias [64].

final_b: &'a [f32]

noise_refiner: &'a [ZBlockRef<'a>]

2 noise-refiner blocks (image rows only) and 30 main layers.

layers: &'a [ZBlockRef<'a>]

mods_all: Option<&'a [f32]>

OPTIONAL (backends may ignore): the modulation of EVERY step of this image, [steps][(2+30)·4·hidden] in the ZStepArgs::mods layout, and [steps][hidden] final scales, so a backend can upload them once per image and index them by ZStepArgs::step. ZStepArgs::mods is still always supplied and is authoritative.

final_scale_all: Option<&'a [f32]>

neg: Option<ZNegArgs<'a>>

OPTIONAL (B2): the CFG negative item. When Some, the backend prepares ONE batch-2 program under key — item 0 is this prompt, item 1 the negative — and every ZStepArgs of that key must carry out_neg. A backend without batch 2 returns false (the caller then prepares the two items separately or runs the CPU path).